U.S. patent application number 13/130218 was filed with the patent office on 2011-10-06 for vaporisation system.
Invention is credited to Hamish William Hamilton.
Application Number | 20110239854 13/130218 |
Document ID | / |
Family ID | 42339974 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110239854 |
Kind Code |
A1 |
Hamilton; Hamish William |
October 6, 2011 |
VAPORISATION SYSTEM
Abstract
A gas powered device includes a vaporisation system. The
vaporisation system includes a conduit connected at one end, or
configured to connect at one end, to a regulator for a high
pressure fluid source. The other end of the conduit supplies an
operating mechanism of the device The path of the conduit is such
that a substantial length of the conduit is adjacent the operating
mechanism.
Inventors: |
Hamilton; Hamish William;
(Oxford, NZ) |
Family ID: |
42339974 |
Appl. No.: |
13/130218 |
Filed: |
December 24, 2009 |
PCT Filed: |
December 24, 2009 |
PCT NO: |
PCT/NZ2009/000307 |
371 Date: |
May 19, 2011 |
Current U.S.
Class: |
91/232 |
Current CPC
Class: |
B25D 9/20 20130101; B25F
5/008 20130101; B25C 1/042 20130101; F15B 15/02 20130101; F15B
15/20 20130101 |
Class at
Publication: |
91/232 |
International
Class: |
F01L 21/02 20060101
F01L021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2008 |
NZ |
573990 |
Dec 24, 2008 |
NZ |
573991 |
Dec 24, 2008 |
NZ |
573992 |
Claims
1. A gas powered device including a vaporisation system comprising:
a conduit connected at one end, or configured to connect at one
end, to a regulator for a high pressure fluid source, and wherein
the other end of the conduit supplies an operating mechanism of the
device, the operating mechanism comprising a piston slidable in a
piston chamber; wherein the path of the conduit is such that a
substantial length of the conduit is adjacent the operating
mechanism and the portion of the conduit adjacent the operating
mechanism is longer than the operating mechanism.
2. The device as claimed in claim 1 wherein gas supplied through
the conduit drives motion of the piston in the piston chamber.
3. The device as claimed in claim 1 wherein the high pressure
source comprises a portable container in which pressurised fluid is
stored.
4. The device as claimed in claim 3 wherein the high pressure
source is a canister configured to store the pressurised fluid
above 600 PSI.
5. The device as claimed in claim 1 wherein the regulator produces
a differential pressure between the high pressure source and the
conduit, and the regulator controls the pressure on the conduit
side to be below 600 PSI.
6. (canceled)
7. The device as claimed in claim 1 wherein the conduit is
fabricated from thermally conductive material.
8. The device as claimed in claim 1 wherein the conduit is in
intimate heat transfer relationship with the operating mechanism
and surrounding environment.
9. The device as claimed claim 1 wherein the conduit is contained
within a body of the transfer device and the body is formed of a
thermally conductive material.
10. The device as claimed in claim 9 wherein the body of the device
is thickest surrounding the operating mechanism.
11. The device as claimed in claim 1 wherein the conduit is
substantially encased by or integrated into a body of, or both, the
motion transfer device adjacent to the operating mechanism.
12. The device as claimed in claim 1 wherein the portion of the
conduit adjacent the operating mechanism loops back along the
operating mechanism.
13. The device as claimed in claim 1 wherein the length of conduit
adjacent the operating mechanism is at least twice the length of
the piston chamber.
14. The device as claimed in claim 1 wherein the operating
mechanism is contained within a barrel.
15. The device as claimed in claim 14 wherein the barrel includes
an extrusion of heat conductive material, and the conduit includes
at least a first and second conduit portion, each extending the
length of the extrusion.
16. The device as claimed in claim 15 including an end cap for the
barrel with a channel in the end cap joining the first conduit
portion and the second conduit portion.
17. The device as claimed in claim 16 wherein at least one of the
conduit portions has an internal cross section where the ratio of
the square of the perimeter to the area is greater than 16.
18. The device as claimed in claim 1 wherein for at least part of
the length of the conduit adjacent the mechanism, the conduit has
an internal cross section where the ratio of the square of the
perimeter to the area is greater than 16.
19. The device as claimed in claim 18 wherein the ratio of the
square of the perimeter is greater than 18.
20. The device as claimed in claim 1 wherein the high pressure gas
source is near one end of the operating mechanism, and the conduit
passes along the operating mechanism to the other end and back.
21. The device as claimed in claim 12, wherein the looped path of
the conduit does not cross back through an area of the operating
mechanism more than once.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a vaporisation system. The
invention has particular application to a motion transfer device
such as a high pressure impact device.
[0003] 2. Description of the Prior Art
[0004] Pneumatic drive systems are used in a variety of
applications, particularly with regard to tools. Traditionally,
pneumatic tools have been designed to be connected to a source of
compressed air, such as a stationary air compressor.
[0005] While air compressors provide an effectively unlimited
supply of compressed air, they do have several disadvantages. In
particular, the need to connect a tool to the air compressor via a
hose limits the portability of the tool and also the positions into
which the tool can be manoeuvred. Additionally, air compressors are
generally expensive and outside the financial means of some
users.
[0006] Further, safety issues arise from having the hoses lying
around the work place which may become caught on various objects or
trip up persons within the space.
[0007] In an attempt to address these problems, several different
systems have been developed. One such system utilises a combustible
gas, such as butane, to provide an explosion that drives the tool's
operation. Such combustion systems have safety issues of their own
given that the tool usually includes a storage device for
combustible gas and a combustion source close to each other. The
gas and gas cartridges tend to be expensive and only available from
select suppliers. Further, the heat and impact of the combustion
tends to be hard wearing on the tools causing them to require
frequent maintenance. The electrical components are very
susceptible to failure if the tool is exposed to moisture such as
rain. all of these factors add additional costs and an element of
inconvenience to the user.
[0008] More recently, portable pressure sources have been developed
by which a vessel containing a pressurised fluid such as carbon
dioxide is used as a power source. These systems allow pneumatic
tools to be used in a more portable fashion without continual
connection to an air compressor.
[0009] The mass of fluid stored in the vessel in order to power the
tool must be sufficient for a practical number of repetitions. In
the case where carbon dioxide is used, this means that at ambient
temperature the vessel will contain both liquid and gaseous carbon
dioxide at a pressure of approximately 750 psi.
[0010] However, the tools operated from these portable pressure
sources are designed for a pneumatic setup where the fluid supplied
to the operating mechanism of the tool is essentially guaranteed to
be gaseous.
[0011] As a result, the quantity, of liquid passing from the
pressure source to the tool should be minimised. Further, any
liquid entering the tool should be vaporised, and maintained in
that gaseous state in order to ensure that the fluid does not
return to the liquid state.
[0012] Previous systems have looked to meet this requirement by
maintaining the vertical orientation of the pressure vessel so that
liquid carbon dioxide is kept remote from the outlet valve of the
vessel. However, if the vessel is rigidly connected to the tool,
this restricts the range of orientation of the tool itself. This
limits the usefulness of the tool, which may be required to be
orientated in a variety of ways in order to be used safely and
correctly in the available space. Alternatively, the pressure
source may be connected to the tool by way of a flexible hose.
However, this inhibits full movement of the tool and presents an
additional hazard as it may easily catch on objects.
[0013] In either case, it is highly probable that at least some
liquid carbon dioxide will pass out of the pressure vessel into the
tool.
[0014] Previous devices have attempted to account for this by
including heat sources using fuel such as butane to heat and
vaporise the fluid as it is transferred to the operating mechanism.
However, this includes numerous disadvantages by adding to the
weight of the gun and increasing costs associated with the heating
devices.
[0015] In order to prevent reversion of the gaseous fluid to a
liquid phase typically requires that the operating pressure in the
tool is significantly below that in the portable pressure source.
This is intended to aid and maintain the carbon dioxide in the
gaseous state over a wide range of ambient operating temperatures.
This necessitates some form of pressure regulator between the
pressure source and the tool.
[0016] One technique used in the prior art is to have the regulator
remote from the tool--either at the outlet of the pressure source,
or in the flexible line connecting the pressure source to the tool.
This retains all of the disadvantages associated with having a
remote pressure source. Further, the regulator is often adjustable,
which increases the risk of the pressure of fluid supplied to the
tool not being matched to the optimal operating pressure of the
tool.
[0017] An alternative is to have the regulator and pressure source
rigidly attached to the tool, which accentuates issues associated
with the carry over of liquid carbon dioxide, as previously
discussed. It is an object of the present invention to address the
foregoing problems or at least to provide the public with a useful
choice.
[0018] All references, including any patents or patent applications
cited in this specification are hereby incorporated by reference.
No admission is made that any reference constitutes prior art. The
discussion of the references states what their authors assert, and
the applicants reserve, the right to challenge the accuracy and
pertinency of the cited documents. It will be clearly understood
that, although a number of prior art publications are referred to
herein, this reference does not constitute an admission that any of
these documents form part of the common general knowledge in the
art, in New Zealand or in any other country.
[0019] Throughout this specification, the word "comprise", or
variations thereof such as "comprises" or "comprising", will be
understood to imply the inclusion of a stated element, integer or
step, or group of elements integers or steps, but not the exclusion
of any other element, integer or step, or group of elements,
integers or steps.
[0020] Further aspects and advantages of the present invention will
become apparent from the ensuing description which is given by way
of example only.
[0021] In this specification where reference has been made to
patent specifications, other external documents, or other sources
of information, this is generally for the purpose of providing a
context for discussing the features of the invention. Unless
specifically stated otherwise, reference to such external documents
is not to be construed as an admission that such documents, or such
sources of information, in any jurisdiction, are prior art, or form
part of the common general knowledge in the art.
DISCLOSURE OF THE INVENTION
[0022] According to a first aspect, the invention consists in a gas
powered device including a vaporisation system comprising: [0023] a
conduit connected at one end, or configured to connect at one end,
to a regulator for a high pressure fluid source, [0024] wherein the
other end of the conduit supplies an operating mechanism of the
device, [0025] characterised in that [0026] the path of the conduit
is such that a substantial length of the conduit is adjacent the
operating mechanism.
[0027] According to a further aspect, the operating mechanism
includes a piston slidable in a piston chamber, and gas supplied
through the conduit drives motion of the piston in the piston
chamber.
[0028] According to a further aspect, the high pressure source
comprises a portable container in which pressurised fluid is
stored.
[0029] According to a further aspect, the high pressure source is a
canister configured to store the pressurised fluid above 600
PSI.
[0030] According to a further aspect, the regulator produces a
differential pressure between the high pressure source and the
conduit.
[0031] According to a further aspect, the regulator controls the
pressure on the conduit side to be below 600 PSI.
[0032] According to a further aspect, the conduit is fabricated
from thermally conductive material.
[0033] According to a further aspect, the conduit is in intimate
heat transfer relationship with the operating mechanism and
surrounding environment.
[0034] According to a further aspect, the conduit is contained
within a body of the transfer device and the body is formed of a
thermally conductive material.
[0035] According to a further aspect, the body of the device is
thickest surrounding the operating mechanism.
[0036] According to a further aspect, the conduit is substantially
encased by or integrated into a body of the motion transfer device
adjacent to the operating mechanism.
[0037] According to a further aspect, the portion of the conduit
adjacent the operating mechanism is longer than the operating
mechanism.
[0038] According to a further aspect, the length of conduit
adjacent the operating mechanism is at least twice the length of
the piston chamber.
[0039] According to a further aspect, the operating mechanism is
contained within a barrel.
[0040] According to a further aspect, the barrel includes an
extrusion of heat conductive material, and the conduit includes at
least a first and second conduit portion, each extending the length
of the extrusion.
[0041] According to a further aspect, the device includes an end
cap for the barrel with a channel in the end cap joining the first
conduit portion and the second conduit portion.
[0042] According to a further aspect, at least one of the conduit
portions has an internal cross section where the ratio of the
square of the perimeter to the area is greater than 16.
[0043] According to a further aspect, for at least part of the
length of the conduit adjacent the mechanism, the conduit has an
internal cross section where the ratio of the square of the
perimeter to the area is greater than 16.
[0044] According to a further aspect, the ratio of the square of
the perimeter is greater than 18.
[0045] According to a further aspect, the high pressure gas source
is near one end of the operating mechanism, and the conduit passes
along the operating mechanism to the other end and back.
[0046] TO those skilled in the art to which the invention relates,
many changes in construction and widely differing embodiments and
applications of the invention will suggest themselves without
departing from the scope of the invention as defined the appended
claims. The disclosures and the descriptions herein are purely
illustrative and are not intended to be in any sense limiting.
[0047] The term "comprising" is used in the specification and
claims, means "consisting at least in part of". When interpreting a
statement in this specification and claims that includes
"comprising", features other than that or those prefaced by the
term may also be present. Related terms such as "comprise" and
"comprises" are to be interpreted in the same manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] Further aspects of the present invention will become
apparent from the following description which is given by way of
example only and with reference to the accompanying drawings in
which:
[0049] FIG. 1 illustrates the vaporisation system of the present
invention according to a preferred embodiment;
[0050] FIG. 2 illustrates the conduit of the vaporisation system of
the present invention according to a preferred embodiment.
[0051] FIG. 3 illustrates a nail gun incorporating a vaporisation
system according to the present invention.
[0052] FIG. 4 is an exploded view of two components of a nail gun
illustrating a preferred implementation of the present invention
where the conduit is incorporated in the body of the device.
[0053] FIG. 5 illustrates a preferred cross section of the
conduit.
BEST MODES FOR CARRYING OUT THE INVENTION
[0054] FIG. 1 illustrates a vaporisation system (generally
indicated by arrow 1) for use in a nail, gun (not clearly shown) in
a preferred embodiment.
[0055] The vaporisation System (1) includes a high pressure source
(2). The high pressure source (2) contains liquid and gaseous
carbon dioxide at approximately 750 psi.
[0056] The vaporisation system (1) also includes a regulator (3).
The regulator (3) is configured to regulate the pressure of the
carbon dioxide flowing from the high pressure source (2) to 450
psi.
[0057] The transition in pressure partially vaporises the carbon
dioxide.
[0058] The vaporisation system (1) includes a conduit (4). The
conduit (4) is formed of highly heat conductive material, and is
configured to connect to the regulator (3) in order to convey the
flow of the carbon dioxide-away from the high pressure source
(2).
[0059] The nail gun includes an operating mechanism (5). The distal
end of die conduit (4) is configured to connect to the operating
mechanism (5) in order to supply the pressurised carbon dioxide
required to drive the operating mechanism (5).
[0060] The nail gun includes a main body (6), surrounding the
operating mechanism (5). The main body (6) is formed of material
having good heat conductive properties as well as having strength
and weight properties conducive to a hand held tool such as the
nail gun.
[0061] The conduit (4) is positioned such that the substantial
length of the conduit (4) is encased by or integrated into the main
body (6) adjacent the operating mechanism (5).
[0062] Heat absorbed by the main body (6) from the surrounding
environment and the operating mechanism (5) is transferred to the
conduit (4). The carbon dioxide within the conduit (4) is heated,
and complete vaporisation is achieved before supply to the
operating mechanism (5).
[0063] FIG. 2 illustrates positioning of the substantial length of
the conduit (4) in relation to the operating mechanism (5).
[0064] The conduit (4) runs alongside the operating mechanism (5),
encased by or integrated into the main body (not illustrated),
before looping back along the other side of the operating mechanism
(5). This means the conduit (4) is exposed to the greatest mass of
the main body containing heat. As partially vaporised carbon
dioxide flows through the conduit (4) from the high pressure source
(not illustrated) in the direction indicated by arrow (7), heat is
absorbed. Because the path of the conduit (4) does not cross back
through areas of the main body (6) from which heat has already been
transferred, efficient use of ambient heat in vaporising the carbon
dioxide is achieved.
[0065] On entry to the operating mechanism (5) the carbon dioxide
is completely vaporised, and of a temperature less likely to cause
the nail gun to malfunction or become damaged.
[0066] FIG. 3 is useful to illustrate how this vaporisation system
works with a preferred arrangement of the nail gun. However the
mechanism is applicable to other nail gun embodiments and to tools
generally that include a drive piston.
[0067] In the nail gun of FIG. 3 gas is supplied from a regulator
through CO2 inlet (22). The chamber (21) is maintained charged with
gas from the regulator between actuations. No additional valve is
required in the inlet path from the regulator to the chamber.
[0068] According to a preferred form the fluid path from the
regulator to the inlet (22) includes an extended conduit, with a
large part of the path of the conduit being adjacent the actuation
mechanism of the gun. In particular adjacent the barrel of the gun,
outside and around the piston chamber.
[0069] The dose chamber (21) is essentially annular around the body
of valve (23). Dose chamber (21) may include an annex (40)
providing, additional volume. The annex (40) may include an
adjustable divider (41) dividing the annex into a primary space
(42) and a secondary space (43). Movement of the divider (41)
increases the size of one of the spaces at the expense of the
other.
[0070] The gun includes a triggering and reset mechanism.
Triggering is driven by releasing a compressed spring to drive the
dose valve hammer onto the dose valve. Reset, including returning
the triggering spring to the compressed condition, is driven by the
last available expansion of the charge of gas.
[0071] The triggering and reset mechanism includes a reset piston
(50) sliding in a bore (51) adjacent the piston chamber bore (49).
The reset bore and the piston chamber bore are connected by fluid
ports at a first position adjacent the forward end and a second
position spaced from the forward end. The transfer ports (62) at
the second position are covered by a valve member so that gases can
only flow from the piston chamber to the bore (51). In the
preferred form the bore (51) is an annular chamber surrounding the
piston chamber. In this arrangement the reset piston (50) is an
annular ring, and the valve member for covering the second ports
may be an elastomeric o-ring (64).
[0072] A spring (52) is located between the reset piston and the
rear end wall (53) of the bore (51). A trigger arrangement includes
a tang (58) that extends into the bore (51) and engages the reset
piston (50) in a cocked position. In this position the spring (52)
is compressed between the reset piston (50) and the wall (53).
Depressing the trigger moves the tang to release the reset piston
(50). The spring (52) accelerates the piston (50) in a forward
direction down bore (51).
[0073] A connecting member (55), (which may be in the form of a
rod) extends rearward from the reset piston (50). The connecting
member extends through a port in the end wall (53) of the bore (51)
and connects to dose valve hammer (31).
[0074] When the reset piston (50) accelerates forward along the
bore (51) the connected dose valve hammer (31) accelerates toward
the impact point (33) of valve (23). The hammer (31) passes opening
(32) and impacts the valve (23). Upon impact, the momentum of the
hammer (31) depresses valve (23), releasing high pressure gas from
the dose chamber (21) into the piston chamber. This high pressure
gas drives the piston head forward along the piston chamber.
[0075] The valve spring (26) returns the valve to the closed
position, at the same time pushing back the dose valve hammer (31)
until it just protrudes through port (32). The opening time of the
dose valve depends on the stiffness of and compression or extension
of springs (26) and (52), the mass of the moving parts and the
exposed surfaces subjected to the gas pressures. Adjustment of
these factors can provide for adjustment of the amount of the time
the valve remains open.
[0076] Once the outer seal (60) of the piston head (28) passes
transfer ports (62) the transfer ports are exposed to the driving
gases at a reduced, but still elevated, pressure. The pressure of
these gases opens ring valve (64) and the gases flow into the bore
(51). These gases push against the reset piston (50), pushing it
rearward, compressing the spring (52). As the reset piston moves to
the rear the connected dose valve hammer moves in a rearward
direction to open an exhaust opening (68) from the piston chamber
through port (32) and exhaust passage (34) through port (32) and
exhaust passage (34).
[0077] Once the reset piston has returned sufficiently far to the
rear it is engaged by the tang (58) of the trigger.
[0078] Further expansion of the gases in the bore (51) forces gas
through a barrel vent (65) from the outer bore (51) to the piston
chamber in front of the piston (28). This gas pushes the piston
head to the rear of the piston chamber, expelling excess gases
behind the piston head through the exhaust opening (34).
[0079] FIG. 3 shows the reset piston and dose valve hammer in the
cocked position ready for firing. The released position of the
hammer and reset piston, where the hammer holds the dose valve
open, is shown in broken lines. The connecting member 55 is also
shown in broken lines as it is hidden from view. The dose valve is
shown in the open position, displaced away from seat (25). A
resilient seal and buffer (70) is provided at the forward end of
the gun. This buffer absorbs any impact of the piston into the end
of the piston chamber, and seals against the driver blade (29) so
that the residual gas pressure can push the piston back to the rear
end of the piston chamber before dissipating.
[0080] If the nail gun fails to reset properly, for example due to
inadequate gas pressure against the reset piston, the system can be
recocked by pulling back the dose valve hammer. This has the effect
of also pulling back the reset piston until it is locked by the
tang. Preferably a cocking lever is provided on the rear of the
housing. The cocking lever includes a pivot and a handle portion.
The dose valve hammer is engaged by the lever midway between the
pivot and the handle portion, providing the user additional
leverage in recocking.
[0081] FIG. 4 is an exploded view of two components of a tool
incorporating a preferred form of the present invention. The
particular tool illustrated is in relation to the nail gun but the
illustration is only to exemplify how the conduit can be
incorporated into the body of the tool.
[0082] In this tool, the operating mechanism is enclosed in a
barrel. An inner surface (84) of the barrel encloses the mechanism.
The barrel is formed from a first component (80) providing an axial
space and a second component (82) providing an end closure to the
axial space.
[0083] In the preferred form the first component is formed as an
extrusion, for example of an aluminium based material. In the
preferred form, the second component is an end cap. The end cap
(82) includes a flange (86) for securing to the end of extrusion
(80). A collar (88) projects from the fate of the end cap (82) to
fit within the open end of the axial space of the extrusion
(80).
[0084] The flange (86) includes holes (90) for fasteners to
pass-through. Fasteners passing through the holes (90) can be
secured in the ends of fastener channels (92) formed in the
extrusion.
[0085] The extrusion (80) has heat dissipating fins (94)
distributed around its perimeter.
[0086] Fastener channels (92) may each be provided as a pair of
adjacent fins arranged with concave adjacent faces to provide a
substantially cylindrical space for receiving a fastener, for
example in the form of a screw.
[0087] The extrusion includes at least a pair of conduit portions
(96). The conduit portions (96) are the longitudinally extending
internal passages of hollow ribs (98) provided on the extrusion
(80).
[0088] The end cap (82) includes a channel for passing the fluid
from the forward end of one of the conduit portions (96) to the
forward end of the other conduit portion (96).
[0089] The end cap may be constructed as a casting and the channel
formed by subsequent machining steps. In the illustrated form, the
channel is enclosed within the flange of the end cap, but could
alternatively be formed on the face of the end cap and closed along
the length of the channel by an end surface of the end face of the
extrusion.
[0090] In the illustrated form, the channel includes channel
openings (104), one of which will act as the channel entrance and
the other as the channel exit. The channel openings (104) lead to a
cross hole (106) which spans between the channel entrances. This
may typically be formed as a hole through from the edge of the
flange and plugged at its open end or ends. In FIG. 4, the
reference (106) is applied to the plugged end of the cross
hole.
[0091] Each opening (104) is surrounded by a seat (102) for
receiving a seal, for example, in the form of O-ring (100). The
seat (102) is in the form of a recess. Alternative seats and seals
may be provided. For example, the seat may be a projecting lip for
locating the O-ring (100), or the recessed seat may be provided on
the end face of the extrusion (80) as well as or instead of on the
face of the end cap (82).
[0092] When assembled, the conduit extends through a first conduit
portion (96) through the channel of the end cap (82) and then back
through the other conduit portion (96). Thus the conduit runs twice
the length of the barrel and across the width of the end cap, all
in intimate heat transfer relationship with the operating mechanism
contained within the barrel.
[0093] FIG. 5 illustrates in greater detail a preferred feature of
the conduit portions (96). According to this detail, each of the
conduit portions (96) includes one or more projecting fins (114)
extending from the inward surface. These fins (114) enlarge the
contact area for the fluid passing through the conduit portion. For
example, in the illustrated embodiment, the surface area for
contact with the fluid passing through the conduit is substantially
increased compared to a path of similar diameter but circular cross
section and the cross sectional area (112) is Substantially reduced
compared to a path of similar diameter but circular cross section.
As an indication, the ratio of the square of the perimeter to the
area is in the order of 30. The similar ratio in relation to a
conduit of circular cross section is approximately 12.5, and of
square cross section is, approximately 16.
[0094] According to one aspect of the present invention there is
provided a vaporisation system for use in a motion transfer device,
the vaporisation system including:
a conduit configured to connect to a regulator for a high pressure
fluid source, wherein the distal end of the conduit connects to an
operating mechanism of the motion transfer device, characterised in
that the conduit is positioned such that a substantial length of
the conduit is encased by the motion transfer device approximate to
the operating mechanism.
[0095] Reference to a vaporisation system should be understood to
refer to any way by which fluid is converted from a liquid phase to
a gaseous phase.
[0096] Reference to a motion transfer device should be understood
to mean any device whereby the movement of at least part of the
device is transferred to another object in order to perform a
particular operation. It is envisaged that the motion transfer
device may be in the form of a pneumatic tool. In particular, the
motion transfer device may be a nail gun.
[0097] It should be understood that this is not intended to be
limiting, and that the present invention may be implemented in any
situation where it is desirable to convert a pressurised fluid from
a liquid phase to a gaseous phase. For example, the motion transfer
device may be a hammer drill, jackhammer, grinder, paintball gun or
any other device known to be driven pneumatically.
[0098] Reference to fluid throughout the specification should be
understood to mean any flowing substance which may be converted
from a liquid to a gas. Preferably the fluid is carbon dioxide,
which is inexpensive and non-flammable. Further, it may be stored
in the liquid phase at an attainable pressure--allowing for a
greater amount of mass to be stored within a limited space. It
should be appreciated that this is not intended to be limiting, and
the fluid could be any other fluid with properties suited to the
particular application.
[0099] Reference to a high pressure source should be understood to
mean any way in which pressurised fluid is stored. For example, it
is envisaged that the high pressure source is a canister configured
to store the pressurised fluid at a pressure in the order of 750
psi. It should be appreciated that this is not intended to be
limiting, and the pressure at which the fluid is stored may vary
according to the application or ambient temperature of the high
pressure source.
[0100] Reference to a regulator should be understood to mean any
device known to one skilled in the art for controllably altering
the flow of fluid through the device, particularly with regard to
the pressure created by the flow of fluid. In particular, the
regulator produces a differential pressure between the high
pressure source and the conduit. It is envisaged that the pressure
created on the conduit side of the regulator will be in the order
of substantially 450 psi.
[0101] At 450 psi, carbon dioxide vaporises at approximately
-5.degree. C., whereas at 600 psi it vaporises at 6.degree. C.
[0102] Table 1 illustrates the transition point at which carbon
dioxide vaporises in degrees Celsius for a range of operating
pressures.
TABLE-US-00001 TABLE 1 Transition points for carbon dioxide between
liquid and gaseous phases Pressure (psi) Temperature (.degree. C.)
305 -17 360 -12 421 -6 490 -1 567 4 653 10 748 15 853 21 986 26
1069 31
[0103] The selection of the operating pressure in the conduit
assists vaporisation of the fluid, even at lower operating
temperatures.
[0104] This change in pressure causes the fluid to at least
partially vaporise. However, at least a portion of the fluid will
either not have been vaporised or will condense back into the
liquid phase if no further action is taken.
[0105] The regulator sets conditions that are suitable for
vaporisation at the ambient temperature. But vaporisation requires
heat input equal to the latent heat of vaporisation. In the absence
of sufficient heat input to the fluid, the vaporising fluid draws
heat from the liquid. Accordingly the temperature of the liquid
drops as more fluid vaporises until the liquid temperature reaches
the transition temperature for the fluid at the lower pressure.
[0106] If the heating isn't sufficient to vaporise all of the
liquid at the mass flow rate at which the tool is operating, liquid
will remain at the transition temperature on the low pressure side
of the regulator and may reach the operating mechanism with the
tool inverted.
[0107] By locating the vaporisation system along the body of the
tool in close thermal communication with the working mechanism and
the ambient environment, and, providing sufficient length of
conduit, more heat is available to vaporise the liquid. The mass
flow rate is a result of the firing rate of the tool. The firing
rate of the tool directly influences the amount of heat generated
in the working mechanism. As the mass flow rate increases so does
the heat available to vaporise the fluid. The tool is therefore
improved for use at higher mass flow rates without requiring an
additional active heat source.
[0108] Reference to a conduit should be understood to mean any
passage by which fluid may be conveyed to the operating mechanism
of the motion transfer device.
[0109] In a preferred embodiment, the conduit is fabricated from
thermally conductive material. It is envisaged that the body or
casing of the motion transfer device will also be formed of a
similar material. This provides efficient transfer of heat from the
motion transfer device to the fluid in the conduit. The material
may be aluminium, which has good heat conductive, strength and
weight properties for application to the present invention. It
should be appreciated that this is not intended to be limiting, and
the conduit may be made of any material known to one skilled in the
art to be useful for the conduction of heat.
[0110] Effectively, the conduit containing the fluid acts as a heat
sink for the motion transfer device--transferring heat from the
surrounding environment and heat generated during operation of the
motion transfer to the fluid contained within the conduit.
[0111] This heating facilitates vaporisation of the fluid within
the conduit before being supplied to the operating mechanism of the
motion transfer device.
[0112] The casing of motion transfer devices such as nail guns,
drills or jackhammers are generally the thickest surrounding the
operating mechanism in order to provide strength, and dampen
vibration and noise.
[0113] For example, the operating mechanism of a nail gun includes
a piston head and driver blade which is driven at high speed by the
pressurised gas to impact a nail and drive it into an intended
target. By necessity, the operation has significant kinetic energy,
which is partially dissipated in the body of the nail gun in the
form of heat and vibration.
[0114] Positioning the conduit such that its length is
substantially encased by or integrated into the motion transfer
device adjacent to the operating mechanism exposes the conduit to
the largest natural heat sources of the motion transfer device.
[0115] Typically the operating mechanism is contained within a
barrel.
[0116] The barrel may include an extrusion of heat conductive
material, and the conduit include at least a first and second
conduit portion, each extending the length of the extrusion.
[0117] An end cap of the barrel may have a channel joining the
first conduit, portion and the second conduit portion.
[0118] At least one of the conduit portions may have an internal
cross section where the ratio of the square of the perimeter to the
area is greater than 16.
[0119] For at least part of the length of the conduit adjacent the
mechanism, the conduit has an internal cross section where the
ratio of the square of the perimeter to the area is greater than
16. The ratio of the square of the perimeter may be greater than
18.
[0120] The high pressure gas source may be near one end of the
operating mechanism, and the conduit may pass along the operating
mechanism to the other end and back.
[0121] It is envisaged that the ratio of the length of the conduit
at this point in comparison with the remainder of the vaporisation
system will be in the order of 6:1.
[0122] Preferably the portion of the conduit adjacent the operating
mechanism is longer than the operating mechanism.
[0123] In general the length of conduit adjacent the operating
mechanism may be at least twice the length of the piston
chamber.
[0124] In doing so, the need for additional sources of heat for
supply to the fluid within the conduit is eliminated--greatly
reducing costs and increasing the safety factor of the device.
[0125] The conduit may be integrated into the body of the gun, as a
series of channels or passages in the body. Integrating the conduit
into the body of the gun may also reduce material and assembly
costs.
[0126] Further, positioning the substantial length of the conduit
in this locality negates discomfort to the user caused by cooling
the motion transfer device at gripping points. Previous systems
utilising additional heat sources have formed the conduit as a coil
within the handle of the device. This cools the handle to a point
of discomfort to the user. By locating the conduit away from these
points of connection to the user, user comfort is improved.
[0127] Heating the fluid within the conduit reduces the cooling
effect of the fluid as it enters the operating mechanism. Where the
cooling effect is high, the operating mechanism may freeze and
malfunction, or at least perform below an optimal level.
[0128] This effect becomes evident after a number of repetitions in
rapid succession, each repetition contributing to lowering the
temperature by an accumulated level. By heating and improving
vaporisation of the fluid a greater number of repetitions of the
operating cycle may be achieved before this cooling effect becomes
prominent.
[0129] The combination of an integrated regulator and vaporisation
within the conduit enables the motion transfer device to be used
without an external regulator. This reduces the overall size of the
motion transfer device, increasing it's usability over systems
implementing an external regulator.
[0130] Further, this serves to protect the regulator from impact
damage. An external or remote, regulator is more exposed and prone
to impact damage or catching on objects. This necessitates a more
robust design, which is expensive. The present invention alleviates
this cost.
[0131] Where external regulators are used, there is the possibility
of the pressure being increased or decreased away from the desired
level. By ensuring a consistent pressure is applied to the motion
transfer device, the system may be designed to operate optimally at
a set pressure without sacrificing performance to compensate for
large tolerances in pressure levels.
[0132] It also simplifies the exchange of high pressure fluid
sources. In known portable pressure sources, the inclusion of an
external regulator and hose for connection to a tool adds
additional steps to the replenishing of the source. The hose and
regulator must be disconnected from the tool as well as the storage
vessel--increasing the complexity of the process.
[0133] The present invention offers a number of advantages over the
prior art: [0134] Complete vaporisation of the fluid within the
conduit leads to an efficient transfer of energy from the fluid to
the operating system of the motion transfer device. This reduces
inefficiencies created when liquid is introduced to the operating
mechanism. This also allows the most efficient amount of fluid to
be used per operating cycle. [0135] Encasing the substantial length
of the conduit with the motion transfer device approximate to the
operating mechanism makes use of ambient heating, without requiring
external heat sources for vaporisation of the fluid. It also
reduces user discomfort due to cooling of the device at the
handle(s) of the device. [0136] Complete vaporisation of the fluid
in the conduit in most conditions of use means that the pressure
source may be rigidly attached to the motion transfer device while
still allowing the device to be used in any orientation, without
relying solely on the regulation of pressure to ensure vaporisation
of the fluid. This increases the usability of the motion transfer
device. [0137] More complete vaporisation of the fluid reduces the
freezing effect of these fluids on the operating mechanism of the
motion transfer device. This allows the device to achieve a greater
number of repetitions without negative impact on performance or
causing damage to the device. [0138] Aspects of the present
invention have been described by way of example only and it should
be appreciated that modifications and additions may be made thereto
without departing from the scope thereof.
* * * * *