Im- PROVEMENTS IN BLOWERS OR APPARATUS FOR COMPRESSING OR FORCING FLUIDS
Year: 1875

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "Im-
PROVEMENTS IN BLOWERS OR APPARATUS FOR COMPRESSING OR FORCING
FLUIDS "A communication from abroad by Thomas Spencer
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 21st July 1875.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN BLOWERS OR APPARATUS FOR COMPRESSING OR
FORCING FLUIDS," a communication to me from abroad by Thomas
Spencer Disston, of Philadelphia, Pennsylvania, United States of
America, to be as follows.-

page_text: combination of two or more revolving vanes having curved sides, two or
more revolving segments with intervening concave recesses adapted to
the said vanes, a chest or casing adapted to the vanes and segments, and
a valve or valves operating in unison with the vanes, segments, and
recesses for controlling the outlet of the blast.
According to one mode of carrying out this Invention the chest of
the blower consists of two side plates and an intermediate casing, the
latter being of such a shape as to form with the side plates a large
chamber and a smaller chamber, the two being arranged one below the
other and so as to communicate with cach other. The portion of the
casing which incloses the larger chamber is cylindrical and is true
internally, the only interruption of the continuity beng at the opening
between the two chambers. The portion of the casing which pailly
incloses the latter chamber is also cylindrical, but is made of smaller
diameter at one portion of its circumference than at the other, so that at
one portion there may be à chanuel for the purpose hercin-after
explained.
Through the centre of the upper or larger chamber passes a shaft, and
through the centre of the lower or smaller chamber passes another shaft,
both shafts having bearings in the two opposite side plates, and being
geared together by wheels so as to revolve at the same speed. The
upper shaft carries a hollow cylinder which has two chambers herein-
after more fully referred to, the cylinder being open at the opposite ends,
which however are very close to the side plates of the chest, without
being in absolute contact therewith. From opposite sides of tho
cylinder project two hollow vanes, each vane being closed at its opposite
ends, but having an opening through which and through an opening in
the cylinder air may pass under the circumstances and for a purpose
herein-after described.
The opposite sides of each hollow vane are made on a curve and
converge to a comparatively sharp edge, which is as close to tho
cylindrical casing of the chamber as possible without being in absolute
contact therewith, the ends of the vancs being also very near the two
opposite side plates.
The lower shaft carries a cylinder, the continuity of which is
interrupted by two opposite concave recesses, which in fact convert the
cylinder into two opposite segments of a cylindor, the segments being

page_text: precisely ankе and projectng from opposite sides of the shaft. The
periphery of each segment revolves in close proximity to the upper
cylinder and to one portion of the casing, but so far from the other
portion of the casing that there shall always be a channel as before-
mentioned between the segment and casing. The segments at one end
revolve in proximity to the interior of the corresponding side plate, and
the opposite ends of both segments are closed by a disc which revolves
with the shaft in a recess formed in the inside of the other side plate.
This plate which has two openings or ports performs the function of a
valve, as will be hercin-after explained.
The valve face against which the disc or valve revolves has a port
through which, and through an outlet pipe opposite thereto, the com-
pressed air is discharged from the blower.
The disc valve may be cast on and form a part of the segments of the
lower cylinder and the two shafts may be dispensed with by casting
journals on the upper cylinder and the hub of the segments.
In operating with this apparatus the air admitted through an inlet
opening into the upper chamber is acted upon by the vanes and caused
to pass first into the recesses between the segments of the lower cylinder,
thence through the ports in the disc valve and through the port in the
valve scat into the outlet through which the air under pressure is
forced.
When one of the vanes has reached such a position that it is in
contact with the edge of one of the recesses between the segments the
port in the disc valve belonging to the other recess has commenced to
open and the aur between the two vanes in the upper chamber will be
forced through the channel before-mentioned into the other recess
between the segments, thence through the corresponding port of the
disc valve, and through the port of the valve seat into the outlet. No
communication can take place between the two compartments into
which the upper chamber is separated by the cylinder and its vanes
when the latter are passing through the recesses. A body of air is thus
entrapped by each vane as it enters one of the recesses between the
segments, and this air is compressed as the rocess is contracted by tho
vanc, and the compressed air forced through the outlet. After the
space in a recess has been contracted and the air disposed of, the space
.

page_text: as the vane leaves the recess must be expanded, and a partial vacuum
would be caused therein but for the following provisions :-
When each vane reaches such a position in its recess that the space
within the latter commences to expand, there is a communication
between the recess and the outside of the blower through the openmg 5
into the hollow vane, thence through the opening in the upper cylinder
Thus
and through an opening in one of the side plates in the chest
the creation of a partial vacuum in the recesses is obviated, and the
shocks which would result from such a vacuum prevented.
During every complete revolution of the upper cylinder two volumes 1
of compressed air are discharged by the vanes through the outlet, but
there are two additional volumes of air discharged from the outlet, that
is, the minor volumes caused by the vanes forcing the air from the
recesses, and these minor volumes tend to equalize the blast, for cach
minor volume is being forced through the outlet during the time when 1
one vane is concluding its duty and the other vane is commencing its
duty.
An air vessel may be provided at the top with a safety valve for
determining the pressure of the blast.
According to another modification two shafts are employed, each 2
carrying two vanes similar to those hercin-before described, but these
vanes in heu of being on a cylinder separate from the segments are
attached, two vanes directly to cach pair of segments, the vanes of onc
pair of segments being adapted to the recesses between the other pair of
segments and operating in conjunction with the said recess as herein-
before described Two valves and valve seats and two outlets are
provided, both of the outlets communicating with one discharge pipe.
•
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Scal Patent
Office on the 13th January 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middle-
sex, Gentleman, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of July, in the year of
our Lord One thousand eight hundred and seventy-five, in the 39th year
of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said John Henry Johnson, Her special license,
that I, the said John Henry Johnson, my executors, administrators, and
assigns, or such others as I, the said John Henry Johnson, my executors,
administrators, or assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
BLOWERS OR APPARATUS FOR COMPRESSING OR FORCING FLUIDS," a communi-
cation to me from abroad by Thomas Spencer Disston, of Philadelphia,
Pennsylvania, United States of America, upon the condition (amongst
others) that I, the said John Henry Johnson, my executors or admını-
strators, by an instrument in writing under my hand and seal, should
particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawings and to the letters and figures marked thereon, that is
to say.
The object of the said Invention is to obtain a continuous supply of
compressed air by the combination of two or more revolving vanes
having curved sides, two or more revolving segments with intervening
concave recesses adapted to the said vanes, a chest or casing adapted to
the vanes and segments, and a valve or valve's operating in unison with
the vanes, segments, and recesses, for controlling the outlet of the blast,
all substantially as shown in the accompanying Drawing, in which,
Figures 1, 2, and 3, are vertical sections of the improved rotary
blower, shewing the operating parts in different positions, Figure 4, a
transverse vertical section of the blower; Figure 5, a detail,
and

page_text: Figures 6, 7, 8, 9, and 10, viows illustrating modifications of the said
Invention.
The chest of the blower, as illustrated in Figures 1, 2, 3, and 4,
consists of the two side plates A and A' and the intermediate casing B,
the latter being of the shape shewn in the Drawing, so as to form with
the side plates the larger chamber D and the smaller chamber E, com-
municating with each other. The portion a of the casing B which
incloses the larger chamber is cylindrical and is true internally, the only
interruption of its continuity being at the opening between the two
chambers. The portion of the casing B which partly incloses the
latter chamber is also cylindrical, but is made of smaller diameter from
x to y than it is from y to m, so as to form between the latter points a
channel n for a purpose herein-after explained.
Through the centre of the upper chamber D passes a shaft F, and
through the centre of the lower chamber a shaft G, both shafts having
bearings in the opposite side plates A and A', and being geared together
by wheels C, C, so as to revolve at the same speed. The upper shaft
carries a hollow cylinder H, which has two chambers 1 and 2 (herein-
after more fully referred to), the cylinder being open at the opposite
ends, which however are very close to the side plates A and A¹ of the
chest without being in absolute contact therewith From opposite sides
of the cylinder II project two hollow vanes I and I', cach vane being
closed at its opposite ends but having an opening d, through which and
through an opening d¹ in the cylinder II air may pass under the
circumstances and for a purpose herein-after described.
The opposite sides of each hollow vane are made on a curve and con-
verge to a comparatively sharp edge, which is as close to the cylindrical
casing of the chamber as possible without being in absolute contact
therewith, the ends of the vanes being also very near to the opposite
side plates A and A'.
The form of the curve on which the sides of the vanes are made will
be determined by the requirements demanded in the operation of the
blower, as herein-after explained, and will be readily understood by
those familiar with machinery of this class.
The shaft G carries a cylinder, the continuity of which is interrupted
by two opposite concave recesses of and f¹, these recesses, in fact
convert the cylinder into two opposite segments e and e' of a cylinder,

page_text: the segments being precisely alike and projecting from opposite sides
of the shaft G. The periphery of each segment revolves in close
proximity to the cylinder II, and to that portion of the casing 6 which
extends from x to y, but so far from the portion of the casing which
extends from y to m that there shall always be a channel n before
alluded to between the segment and casing. The segments at one end
revolve in proximity to the interior of the side plate A, and the opposite
ends of the two segments are closed by a disc K, which revolves with
the shaft G in a recess formed in the inside of the side plate A'. This
disc performs the duty of a valve, as will be seen by the description
hercin-after given, and has two ports k and k³, as shewn clearly in
Figuro 1.
The valve face against which the disc or valve K revolves has a
port w (shown in Figures 4 and 5), through which and through the
outlet pipe M the compressed air is discharged from the blower. The
disc valve K may be cast on and form a part of the segments e and e¹,
and the shafts F and G may be dispensed with by casting journals on
the cylinder H and on the hub of the segments
In Figures 1, 2, and 3, the cylinder H with its vanes is assumed to
be revolving in the direction of the arrow 3, the segments e and e¹ with
the disc valve K consequently turning in the direction indicated by the
arrow 4. The vane I in the position shewn in Figure 1 has just passed
the inlet opening 2, and is pushing before it without yet subjecting it
to pressure a supply of air which had been admitted to the chamber D
through the said inlet. In the meantime the vane I' is pushing before
it another supply of air, which is unable to escape between the cylinder H
and the segment with which the cylinder is in contact, or very nearly so,
the only avenue for the escape of this supply of air in advance of the
vane I' boing first into the recess f¹ between the segments e and e¹,
thence through the port k in the disc valve K, and thence through the
port w in the valve seat, and thence into the outlet M, through which
the air under pressure is forced.
When the vanes have reached the position shown in Figure 2, a
portion of the air in advance of the vane I' has been entrapped by the
latter in the recess f¹ between the segments e and e', and as the space
within the recess necessarily becomes gradually contracted by the
continued movement of the said vane, the air under pressure due to

page_text: this contraction must be disposed of, hence the port k of the disc valve
remains open for the discharge of this entrapped air through the port w
in the valve seat t, Figure 5, and thence through the outlet until the
contraction of the space within the said recess f¹ by the vane ceases or
until shortly after it ceases. When the vane I¹ has reached the position
shown in Figure 2 the port k¹ in the disc valve K has commenced to
open, and the air in advance of the vane I in the chamber D will bo
forced through the channel n into the recess f between the segments e
and c¹, thence through the port k¹ of the disc valve, and through the
port w of the valve seat t into the outlet M.
It will be understood that as each vane passes into and from its recess
between the segments the extreme edge of the vane is in contact or
very nearly so with the concave edge of the recess, and that the
comparatively sharp ends of the segments are in contact or nearly so
with the curved sides of the vane, hence there can be no communication
between the two compartments into which the chamber D is separated
by the cylinder II and its vanes when the latter are passing through
the recesses. The several views morcover will show that under no
circumstances, and during no relative position of the operating parts, can
there be any such communication.
It is already been remarked that a body of air is entrapped by cach
vane as it enters one of the recesses between the segments (see Figure 2),
and that this air is compressed as the recess is contracted by the vane,
and that the compressed air is forced through the outlet after the space
in this recess has been contracted and the air disposed of; the space as
the vane leaves the recess is necessarily expanded and a partial vacuum
would be caused therein but for certain provisions which will be best
understood by reference to Figure 3.
.
d
When each vane reaches such a position in its recess that the space
within the latter commences to expand, a communication is formed
between the recess and the outside of the blower through the opening
into the hollow vane, thence through the opening d in the cylinder H,
and thence through an opening p in one of the side plates in the chest.
Thus the creation of a partial vacuum in the recesses f and f¹ is
obviated, and the shocks which would result from such a vacuum ;
prevented.

page_text: openings, one at each end of the casing, both openings communicating
with one exit pipe M.
It should be observed that both modifications have more blowing
capacity in proportion to their size than the apparatus shown in Figures
1, 2, 3, and 4.
As the mode of operation is the same in both modifications as in the
blower shown in Figures 1 to 4, further description of their construction
and operation will be unnecessary.
5
Having now described and particularly ascertained the nature of the
said Invention and the manner in which the same is or may be used or 1
carried into effect, I would observe in conclusion that what I consider
to be novel and original and therefore claim as the Invention secured
to mo by the berein-before in part recited Letters Patent 15,-
First. A rotary blower in which are combined the following elements,
namely, two or more revolving vanes having curved sides, revolving 1
segments with concave recesses adapted to the said vanes, a chest casing
adapted to the vanes and segments, and a valve or valves operating in
unison with both vanes and segments for controlling the outlet of the
blast, all substantially as heroin-before described.
Secondly. The combination with the vanes and with the recesses 2
between the segments of an opening or passage through cach vanc with
an opening pin the casing of the blower, substantially as and for the
purpose herein-before described.
•
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and scal, the Thirteenth day of 2
January, One thousand cight hundred and seventy-six.