Improvements in Silencing Boxes for Exhausts of Gas or Oil Engines.
Year: 1891

page_text: Date of Application, 13th June, 1891
Complete Specification Left, 14th Mar., 1892-Accepted, 16th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Silencing Boxes for Exhausts of Gas or Oil Engines.
JOHN BILBIE and WILFRED HOBSON both of 80 Queen Victoria Street in the
City of London Engineers do hereby declare the nature of this invention to be as
follows:
The usual method of silencing the exhaust of gas or oil engines is to place in
the ordinary exhaust outlet pipe one or more vessels of cylindrical or other suitable
shape and size to allow the gases which escape at a high pressure from engine to
expand and reduce the pressure before reaching the outer air. Another method
in common use is to make a pit in brickwork of considerable dimensions and filled
with loose stone or shingle. The exhaust passes into this pit and not having free
exit the pressure is reduced and the noise at outlet silenced. The first of the above
named methods will not totally silence the exhaust, and the second method entails
considerable expense and the stones & shingle become pulverised and have to be
frequently replaced.
Our improvement consists in producing an expansion chamber which will render
the exhaust absolutely noiseless and which can be produced at a much lower cost
and in a more efficient manner than has hitherto been obtained.
We make a chamber of cast iron or any other suitable material and of con-
venient shape and of dimensions suitable to the size of engine.
As a rule the exhaust expansion boxes ordinarily supplied with a gas engine could
be used. Instead of the exhaust gases entering direct into the interior of the box
and so escaping from the outlet at a still very considerable pressure we carry a pipe
a considerable distance into the interior of the box and plug the end. This
pipe or the part which is inside the box is perforated with a great number of
small holes.
The exhaust gases entering this pipe at a considerable pressure strike most
materially against this plugged end of the pipe and then rise getting away
gradually through the small holes into the main chamber. The main chamber may
or may not be filled or partially filled with loose stones or shingle offering further
resistance. The exit or outlet of this main chamber may be either as usual by a
pipe connection leading to a flue or outer air-or this main chamber may in turn
be drilled with small holes at any convenient points to get a still further reduction
of pressure and a greater time for expansion of the exhaust gases before the outer
air is reached. The position of this new kind of exhaust chamber as above
described in relation to engine may be fixed as is most convenient.
It may be placed at the extreme end of exhaust pipe or it may be placed close to
engine in the usual position allotted to these silencing chambers in the type
of engine referred to. Where it is placed in the middle of a room or in any position
where the exit of exhaust gases would be offensive or injurious to health the
silencing chamber when drilled on its outer periphery may be enveloped by any
suitable smoke box arrangement and carried thence by any suitable kind of piping
to a flue or to outer air.
JNO. BILBIE.
WILFRED HOBSON.

page_text: COMPLETE SPECIFICATION.
Improvements, in Silencing Boxes for Exhausts of Gas or Oil Engines.
We JOHN BILBIE and WILFRED HOBSON both of 80 Queen Victoria Street in
the City of London Engineers do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The usual method of silencing the exhaust of gas or oil engines is to place in
the ordinary exhaust outlet pipe one or more vessels of cylindrical or other
suitable shape and size to allow gases which escape at a high pressure from the
engine to reduce the pressure before reaching the outer air. Another method in
common use is to make a pit of brickwork of considerable dimensions and filled
with loose stones or shingles. The exhaust passes into this pit and not having free
exit the pressure is reduced and the noise at outlet silenced. The first of the
above named methods will not totally silence the exhaust and the second method
entails considerable expense and the stones and shingle become pulverised and have
to be frequently replaced.
Our improvements consist in producing an expansion chamber which will render
the exhaust absolutely noiseless and which can be produced at a much lower
cost and in a more efficient manner than has hitherto been obtained.
We make a chamber of cast iron or any other suitable material and of convenient
shape and of suitable dimensions and carry the exhaust pipe or branches from it a
considerable distance into the interior of the box and plug the end to form an
abutment to receive the rush of the incoming gases.
The pipe or pipes or the part or parts thereof inside the box are perforated at
the incoming end or ends with small holes of suitable numbers and sizes so that
their combined area shall be equal to the area of the exhaust or otherwise arranged
to suit conditions.
To more clearly illustrate the various forms of our invention reference is made to
the accompanying drawings in which,
Figure 1 shows a sectional elevation of one form of our improved silencing
chamber A being the exhaust pipe from engine connected with the silencing
chamber C C. The pipe B which is a prolongation of pipe A is closed or plugged
at its outermost extremity which nearly approaches the lower end of the silencing
chamber. The upper portion of the pipe B is perforated with small holes D in
sufficient numbers and of sufficient diameters to ineet the requirements of the case.
The joints between the pipes A and B and between B and the silencing chamber C C
may be made good to prevent escape of gas from them.
The final discharge of the exhaust gases from the silencing box is provided for
by the holes E E at its lower extremity; the number and diameters of which must
be suitable to the requirements of the casc. The interior of the box may be filled
with shingle or similar material as shown F on the right hand side of the section.
Figure 2 shows a sectional elevation of another form in which the exhaust gases
from the pipe A instead of being taken through one perforated pipe is led through
any suitable number of pipes, of which three B B B are shown in the section.
With this arrangement a suitable distributing chamber G is provided. As in
Figure 1, C C shows the silencing chamber and E E the holes for the final escape
of the gases and F, shingle which may be used if required.
In Figure 3 the plugged and perforated pipe B is surrounded within the silencing
chamber CC by another pipe H jointed to the under side of the upper end of
the silencing chamber.
The tube B being perforated at its upper and blocked at its lower end. The
tube H is perforated at the opposite or lower end where it is also plugged. In
this case the final escape holes E E of the exhausted gases are at the upper end
of the silencing box.

page_text: The course followed by the gases is through the exhaust pipe A, thence
cushioning against the closed end of the pipe B, escaping through the perforations D
into the space between the pipes B and H from whence they pass through the
openings d d at the lower end of the pipe H into the exhaust chamber C C
whence they escape through the holes E E at its upper end.
Similarly to the arrangements shown in the Figures 1 and 2, shingle may be
used if required.
Where it is desirable to carry away the exhaust gases from the silencing
chamber to a chimney or flue, instead of allowing them to escape freely into the
atmosphere, the holes E E in Figures 1 and 2 may be omitted and the pipe K
employed as shown in Fig. 4 to carry away the gases. Where the design shewn
in Fig. 3 is used a pipe in the position shewn by k in Fig. 4 is employed.
Another means for effecting the same purpose is shown in Fig. 5 where I I show
a casing surrounding the silencing chamber C and having a pipe k¹ to carry away
the exhaust gases emitted from the holes E.
When however the form of chamber in Figure 3 is used the exhaust holes being
at the top as at E¹ the flue pipe K' will be taken from the lower end of the casing
as shown.
In all the above cases we do not confine ourselves to the size or shape of the
pipe or pipes within the chamber which may be of different dimensions and forms
to the exhaust pipe nor the size or the position of the holes.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
The use of a plugged and perforated pipe or pipes enclosed in a chamber for the
purposes and in the manner herein before described.
Dated this 12th day of March 1892.
JOHN BILBIE.
WILFRED HOBSON.