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Патент USA US2128742

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2,128,742
Patented Aug. 30, 1938
UNITED STATES PATENT OFFMIE
2,128,742
MUFFLING DEVICE
George H. Fuehrer, Phillipsburg, N. J., assigncr
to Ingersoll-Rand Company, Jersey City, N. J.,
a corporation of New Jersey
Application April 9, 1937, Serial No. 135,831
4 Claims. (Cl. 121-1)
This invention relates to muf?ing devices, and
3i and that portion of the cylinder
de?ning
more particularly to a mu?iing device adapted
the piston chamber 25. The rearriost end 33
to receive the exhaust fluid from a. pneumatic
of the sleeve 32 seats against a shoulder at of
tool of the percussive type.
the back head it and is centralized with respect
One object of the invention is to suppress the to the back head by a projection
of the back 5
noise induced by the exhaust ?uid issuing from head extending into the sleeve. Thefront end
the pneumatic tool.
36 of the sleeve encircles the boss 31 on the
Another object is to effectively shield the pneu
front head and abuts a shoulder s52, also on the
matic tool against the chilling effects of the front head.
expanded fluid flowing through the muiiiing de
The sleeve
is of larger diameter than the 10
vice, and still another object is to equip the cylinder
and cooperates therewith to de?ne
pneumatic tool with a simpli?ed and e?ective
mmiling device of light weight and which may
be readily and cheaply replaced.
Other objects will be in part obvious and in
part pointed out hereinafter.
In the drawing accompanying this speci?ca
tion and in which similar reference numerals
refer to similar parts,
20
Figure 1 is an elevation, in section, of a mu?iing
device constructed in accordance with the prac
tice of the invention and showing it applied to
a pneumatic tool of the percussive type, the tool
being partly broken away, and
Figures 2 and 3 are transverse views taken
through Figure 1 on the lines 2-2 and 3-3,
respectively.
Referring more particularly to the drawing,
the mufl‘ling device, designated in general by 2D,
30 is shown applied to a ?uid actuated percussive
tool it comprising a cylinder 22 and front and
back heads 23 and 24, respectively.
The interior of the cylinder constitutes a pis
ton chamber 25 containing a hammer piston 26
35 which actuates a working implement 21 extend
ing into the front head and controls the free
exhaust port 23 for the piston chamber 25. The
piston is of the differential type and has a stem
29 which extends slidably through a bushing 30
40 in the front end of the piston chamber to strike
against the working implement 21.
The pressure fluid employed for actuating the
piston 26 may be distributed to the ends of the
piston chamber 25 by suitable valve mechanism
45 of which only the outer casing part 3| is shown.
The valve mechanism may, as illustrated, be
arranged between the piston chamber and the
back head 24 and be in communication with
the ends of the piston chamber through the
usual ports and passages (not shown).
The muf?er
constructed in accordance with
an expansion space or chamber is to receive
the exhaust fluid issuing from the port 263.
At
the ends of the expansion chamber
are trans‘
verse ring plates M5 and [it which may be suit
ably secured to the inner surface of the sleeve
32. The plate Ml, which forms the upper bound
ing surface of the chamber
is disposed inter
mediate the exhaust port 23 and the valve mecha_
nism 32 to protect the valve mechanism against 20
exposure to the expanded ?uid flowing through
the chamber
The plate 40 serves a similar
function with respect to the parts lying imme
diately forwardly of the front end of the piston
chamber 25.
25
In order that maximum suppression of the
sound waves
be obtained in the expansion
chamber 3b a. series of baflles 552, Q3,
and d5
are arranged therein in staggered relationship
with respect to each other and to extend longi 30
tudinally of the chamber 3?}. The
may
be said to be arranged in groups on opposite
sides of the exhaust port
Those designated
42 and "133 constitute one group of which the
baf?e t2 extends from the uppermost portion of
the chamber St to a point near the partition M,
thus leaving a space [it between the baffle and
the partition through which ?uid may flow into
the space between the battles 42 and 43. The
ba?‘le 43, on the other hand, abuts the partition
4| and terminates a su?icient distance below
the partition 43 to provide a space M between
the ba?le A13 and the partition 41!} for the free
passage of ?uid into the portion of the chamber
39 wherein ?nal expansion of the exhaust ?uid
takes place before it passes to the atmosphere
through outlet openings its in the sleeve
and
preferably located adjacent the partition M.
The other group of battles, consisting of those
designated 413 and t5, are arranged in substan—
tially the same manner as the baffles 42 and 43,
35
40
45
50
the practice of the invention, is in the form
respectively. More speci?cally, the arrangement
of a tubular member or sleeve 32 which sur
of the ba?ie 44 corresponds with that of the
baffle Q2 and the baf?e ‘2-5 is arranged in the
manner of the ba?le Q3. Thus, as will be readily 55
rounds the intermediate portion of the pneumatic
tool or, more particularly the valve mechanism
2
2,128,742
understood, two tortuous paths are provided for
the passage oi the exhaust ?uid from the ex~
haust port 28 to the outlet openings G8. The
fluid is thereby required to travel along extended
paths and a maximum damping effect is, there
fore, obtained.
To the end that the portion of the cylinder ly
ing in the transverse plane of the expansion
chamber 39 may be amply protected against ex
10 posure to the low temperature resulting upon ex‘
pansion of the fluid issuing from the exhaust port
28, the cylinder is encased in a jacket 49 of in
sulating material, as for example ?bre. The
jacket 49 may ?t the cylinder 22 snugly. Its
15 upper and lower ends are preferably embedded
in the back head 24 and the partition 4 I, respec
tively. In the periphery of the jacket 49 are 1on~
gitudinally extending grooves 50 which inter
lockingly engage the inner edges of the bailles to
assure against relative rotation between the
sleeve 32 and the jacket 49 and also to maintain
ing the sound vibrations caused by the intermit
tent impulses of the exhaust ?uid ?owing from
the piston chamber. During its passage through
the sleeve the exhaust ?uid passes in opposite di
rections from the exhaust port 28, thence in zig
zag fashion along different paths to the atmos
phere. The exhaust impulses are thereby evened
out without causing an appreciable back pres
sure and the ?uid passes through the outlet open
ings 48 to the atmosphere as a substantially con 10
stant stream.
I claim:
1. In a mufliing device, the combination of a
pneumatic tool casing having a piston chamber
and an exhaust port for the piston chamber, a 15
sleeve to surround the casing and cooperating
therewith to define an expansion chamber for
exhaust ?uid, an outlet opening in the sleeve, and
means to prevent contact of the exhaust ?uid in
the expansion chamber with the casing.
the jacket seated against the cylinder.
pneumatic tool casing having a piston chamber
In order to prevent buckling or distortion of the
jacket 49 as a result of expansive and contractile
movements of the metal parts incident to their
and an exhaust port for the piston chamber, a
exposure to temperatures of widely spaced degree,
haust ?uid, an outlet opening in the sleeve, and
a rubber ring 5| is disposed in the partition M to
act as a seat for the adjacent end of the jacket.
The ring 5| may be of such thickness as to cause
30 partial displacement of the rubber when the cas~
ing parts of the rock drill and the muifiing device
are clamped together, in assembled relationship.
The jacket 49 will thereby, at all times, be held
against endwise vibratory movement and conse
‘ quent damage.
As is well known under certain climatic condi
tions the temperature resulting upon expansion
of the exhaust ?uid causes the moisture en-
trained by the fluid to congeal and seriously re
40 strict the areas of the passages through which the
?uid ?ows to the atmosphere. In order to pre
vent an occurrence of this nature in the immedi~
ate vicinity of the exhaust port 28 a flexible sheet
or ?ap 52 of rubber or fabric is arranged within
the sleeve to confront the exhaust port 28.
sleeve to surround the casing and cooperating
therewith to define an expansion chamber for ex
a jacket of insulating material encasing the eas
expansion chamber with the casing.
3. In a muii'ling device, the combination of a 30
penumatic tool casing having a piston chamber
and an exhaust port for the piston chamber, a
sleeve to surround the casing and cooperating
therewith to de?ne an expansion chamber for;
the exhaust ?uid issuing from the piston cham 35
ber, a jacket consisting of insulating material en
casing the casing to prevent contact of the ex
haust ?uid in the expansion chamber with the
surface of the casing, and bail‘les in the sleeve to
form a tortuous path for ?uid between the ex
haust port and the outlet opening and to support
the jacket.
40
4. In a mufiling device, the combination of a
pneumatic tool casing having a piston chamber
and an exhaust port for the piston chamber, a 45
sleeve to surround the casing and cooperating
tion of the sheet 52 may be effected said sheet
therewith to de?ne an expansion chamber for
is suspended from the partition 40 and spaced
with respect to the sleeve 32. Thus, when the ex
ill) haust impulses strike the sheet it will be ?exed
the exhaust ?uid issuing from the piston cham
ber, an outlet opening in the sleeve, a jacket of
material of low heat conductivity to insulate the
casing, and baffles in the sleeve arranged in stag
broken up and be carried to the atmosphere by
the stream of exhaust ?uid.
In practice, the present invention has been
gered relationship between the exhaust port and
the outlet opening and engaging the jacket to
hold said jacket against the casing.
1 found to be a highly e?icient device for suppress
25
ing to prevent contact of the exhaust ?uid in the
To the end that an undulatory or flapping mo
and any ice which may form on the sheet will be
20
2. In a mu?iing device, the combination of a
GEORGE H. FUEHRER.
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