Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1053~01
The present invention is directed to a muffler for an
explosive powder driven stud setting device in which a driving
piston is axially displaceable between a firing position and
a driven position with an opening from the space through which
the piston is displaced to a multi-chambered muffler.
Known stud setting devices of the kind mentioned above
include muffler chambers which provide a throttle effect on
the ouflowing explosive powder gases so that, on the one hand,
only a slight muffling effect is achieved and, on the other
hand, the muffler members are exposed to intensive heating
which considerably impairs the handling of the setting device.
Experience has shown that in known muffler chambers there
occurs a whirling of the flowing gases. Accordingly, for this
type of flow a tubular shaped muffler chamber is used with the
axial direction of the chamber being the same as the flow
direction of the propellent gases with the gases entering
through outflow apertures. Within the tubular shaped muffler
chamber is a second muffler chamber formed by a perforated
sleeve. As a result, the explosive powder gàses sweep through
the holes in the sleeve as they enter the second chamber and
then pass through a bore of relatively small cross-section
into the atmosphere. By repeated deflection of the propellent
gases, a whirling action is obtained, however, such whirling
does not afford a sufficient muffling effect. Another feature
of known muffler chambers is that they are relatively small
in comparison to the quantity of outflowing gases with the
result that the naturally very small bores traversed by the
gases may become blocked by the solid residues in the gases.
Therefore, in accordance with the present invention, an
effective muffler system is provided which counteracts the
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disadvantages experienced in the past.
In accordance with the present invention, at least two
muffler chambers are serially interconnected by openings
extending through partitions with the volume of the first
chamber, that is the chamber into which the explosive powder
gases flow from the bore of the setting device, representing
three to ten times the volume within the bore between the
position of the trailing end of the piston in the firing posi- i
tion and the position at which it commences its movement past
the aperture or opening from the bore into the first muffler
chamber. Further, the last chamber in the direction of flow
of the explosive powder gases through the muffler includes an
outlet for the gases to the atmosphere. The first chamber of
the muffler which is large in relation to the quantity of gases
flowing out of the bore, preferably it represents seven times
the operating space, ensures expansion of the gases entering
under high pressure, that is, it affords the reduction of the
pressure o;E ~he gases. The gases expanded to a considerable
degree in the first chamber possess only a fraction of the
pressure oE the gases entering that chamber from the bore of
the setting device. This characteristic effectively counter-
acts the development of sound, which is primarily dependent
on the gas pressure. Further, the pressure reduction also
results in only a slight heating effect on the muffler.
In the next or second chamber in the direction of f;ow,
or in additional chambers whose volume may be much smaller than
that of the first chamber, no appreciable additional reduction
in the pressure of the gases occurs. Primarily, these further
chambers e~fect a breaking of the sound waves by avoiding
direct flow of the gases from the first chamber into the
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atmosphere. In the last chamber form which the gases flow to
the atmosphere, the outlet for the gases should have as
large a cross-section as possible for avoiding any throttling
effect whereby the pressure of the gases in that chamber
corresponds approximately at atmospheric pressure. In view
of the criteria, on the one hand, of a good muffling effect
and, on the other, of providing the smallest possible construc-
tion of the muffler parts, it has proven best to provide three
muffler chambers in series.
To make sure that in the chambers following the first
chamber a dynamic gas pressure does not occur, the cross-
section of the passage openings in the partition at the exit
from the first chamber are advantageously equal to or smaller
than the total cross-sectional area of the passage openings
in the partitions at the exits from the otller chambers. The
passage openings may have any desired configura-tion since it
is not important whether the partition or partitions have one
or more exit openings.
To avoid throttling of the gases issuing in the outlet
direction of flow from the last chamber into the atmosphere,
the cross-sectional area of the outlet from the last chamber
corresponds preferably to two to ten times the cross-sectional
area of the openings in the partition at the outlet from the
first chamber.
To ensure that the gases do not flow from the first chamber
along a rectilinear line of flow into the atmosphere, the out-
let openings from adjacent chambers are offset one to another
with respect to the direction of flow. As a result, the path
of flow of the gases is deflected several times from chamber
to chamber and this appreciably improves the muffling effect
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in the range of the outlet.
Tne various features of novelty which characterize the
invention are pointed out with particularity in the claims
annexed to and forming a part of this disclosure. For a
better understanding of the invention, its operating advantages
and specific objects attained by its use, reference should be
had to the accompanying drawing and descriptive matter in
which there are illustrated and described preferred embodiments
of the invention.
IN rr~l~ DRAWINÇS.
The drawing is a side view, mostly in section, of an
explosive powder charge driven stud setting device embodying
the present invention and shown inserting a stud into a re-
ceiving material.
In the drawing the setting device is shown driving a
stud 9 into a receiving material 4. The device includes a
housing 1 having an axially elongated space containing an
axially displaceable piston guide 2. For purpose of des-
cription the end of the setting device and the corresponding
end of its various parts facing toward the receiving material
are called the front end while the opposite end of the various
parts is called the rear end.
Near the front end of the piston guide 2 within the
housing 1, a compression spring 3 laterally encircles the
piston guide and is held between a pin la extending inwardly
from the housing and a shoulder formed on the rear end of a
sleeve 2a threaded on the front end of the piston guide. AS
shown in the drawing, the piston guide is displaced inwardly
into the housing since at its front end it is pressed against
the receiving material 4, however, when the device is lifted
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away from the receiving material, the piston guide is displaced
in the driving direction by spring 3 out of the space within
the housing. As the piston guide is displaced away from the
rear end of the housing, a cartridge 6 located in the cartridge
chamber 5 is displaced out of the effective range of firing
pin 7 mounted in the rear end of the housing. The additional
parts of the firing mechanism, such as a tension spring for
the firing pin 7 are known per se and, therefore, are not
shown for reasons of simplification and clarity.
In the upper portion of the housing 1 near its rear end,
is an injection or feed opening lb for loading cartridges 6
into the cart~idge chamber. Within the piston guide 2, a
piston 8 which drives the stud 9 into the receiving material 4,
is mounted in sealing relation with the bore within the guide
and i8 axially displaceable through the guide. In the drawing,
the piston 8 is shown moving through the bore in the piston
guide 2 and the rear end of the piston is just beginning to
clear an exhaust opening 2b from the bore in the guide. As can
be seen in the dra~ing, the opening 2b is located intermediate
the ends of the enlarged bore within the guide through which
the enlarged head of the piston moves. As the piston moves
forwardly toward the front end of the guide 2 the explosive
powder gases are compressed in the space 2c behind the en- ¦
larged head of the piston and they start to exit through the
opening 2b as the enlarged head crosses the opening 2b per-
mitting the gases to flow into a first muffler chamber lOa
of a substantially tubular-shaped muffler body 10. Within the
first muffler chamber lOa the compressed or pressurized gases
can expand.
In the embodiment of the setting device illustrated in t
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the drawing, the volume of the first muffler chamber is about
five ti]mes the volume of the space 2b located within the bore
in the piston guide 2 between the rear end of the bore and
the rear end of the enlarged head of the piston as it starts
to move over or the clear the opening 2b from the bore. The
differences in volume cause an expansion or pressure reduction
of the gases flowing into the first muffler chamber lOa and,
after passage through that chamber, the gases exit through a
centrally located opening lla in a partition 11 separating the
first chamber from a second chamber lOb. As the gases flow
in the axial direction of the tubular-shaped muffler 10
through the second chamber lOb, they strike against a second
partition 12 separating the second chamber lOb from a third
or last chamber lOc. The outlet openings 12a from the second
partition are offset from the axis of the opening lla. ~ecause
of this offset arrangement, the gases are deflected within
the second chamber and, as experience teaches, they develop
a whirling effect as they move toward the opening 12a into
the third muffler chamber lOc. ~gain, as can be seen in the
drawing, the third partition 13 separating the third chamber
lOc from the atmosphere, has an outlet opening 13a which is
also in staggered relation to the axes of the openings 12a
from the second chamber. Accordingly, the g'ases flowing
from the second to the third chamber are also deflected before
flowing through the outlet opening 13a into the atmosphere.
To avoid any throttling effect on the flow of exhaust gases
from the third muffler chamber lOc, the cross-sectional area
of the outlet opening 13a is considerably larger than the
opening lla in the partition 11 located between the first and
second chambers.
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As shown in the drawings, handle lc extends downwardly
from the body of the housing 1 transversely of the axial
direction of the piston guide 2 and piston 8. Advantageously,
the muffler 10 is positioned within the hollow handle lc and
is in threaded connection with the housing 1.
In principle, the muffler can be proVided with a different
form and associated with the device in the driving direction
without any impairment of the muffling effect.
Having described what is believed to be the best mode
by which the invention may be performed, it will be seen ~hat
the invention may be particularly defined as follows:
An explosive powder driven stud setting device in-
cluding a housing, said housing forming an axially extending
bore, an axially elongated stud driving piston located within
and axially displaceable through said bore and h~ving a
leading end and a trailing end with the trailLng end arranged
to receive the force of explosive powder gases and said leading
end arranged to drive a stud into a receiving material, said
trailing end of said piston being displaceable in the axial
direction thereof between a firing position with the piston
read~ to be displaced axially be explosive powder gases for
driving the stud from the housing into the receiving material
and a driven position with the piston displaced axially through
the bore by the explosive powder gases from the firing position
for driving the stud into the receiving material, said bore
having an opening therefrom intermediate the firi~g position
and the driven position of the trailing end of said piston
means forming a muffler chamber in communication with th~
opening from said bore intermediate the firing position and
the driven position for receiving explosive powder gases there-
. from after the trailing end of said piston moves past the
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~05340~
opening as it is displaced from the firing position toward the
driven position, wherein the improvement comprises that said
means forming a muffler chamber comprises at least a first
muffler chamber and a second muffler chamber with said first
muffler chamber arranged to receive the explosive gases from
the opening in said bore intermediate the firing position and
the driven position and said second muffler chamber arranged
to receive the explosive powder gases from said first muffler
chamber, and said first muffler chamber having a volume at least
I 10 three to ten times greater than the volume of that portion of
¦ said bore located between the location of the trailing end of
said piston in the firing position and the location of the
trailing end of said piston as it commences to move past the
opening in said bore located intermediate the firing position
¦ and the driven position.
While specific embodiments of the invention have been
shown and described in detail to illustrate the application of
the inventive principles, it will be understood that the invention
may be embodied otherwise without departing from such principles.
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