IMPROVEMENTS IN FLUID METERS
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
" IMPROVEMENTS IN FLUID METERS," A communication from abroad by Joel
Herbert Shedd, of Providence, Rhode Island, United States of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 24th August 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN FLUID METERS." A com-
munication from abroad by Joel Herbert Shedd, of Providence, Rhode Island,
United States of America.
The Invention hereinafter described relates to rotary water or fluid meters of
that class in which revolving pistons are employed and comprises a novel con-
struction of the rotary pistons which enables them, in addition to performing their
proper functions as pistons or plungers to perform the further function of toothed
connections to alternately drive and be driven by each other at an alternately
varying speed, whereby I am able to dispense in this class of fluid-meters with a
gear-chamber and a measuring or piston chamber separate from each other, and
simplify the apparatus by employing a single chamber for both the pistons and the
driving gearing.
The said Invention further comprehends as a novel feature the peculiar con-
struction of the peripheries of the pistons or plungers, whereby the areas of surface
of the teeth in contact in the operation of revolving the pistons, and in excluding
the passago of the water under pressure from pressing between the pistons are made
very considerable, and a complete rolling movement instead of a partial sliding
movement of such surfaces upon each other is obtained.
The said Invention also comprises modifications hereinafter described.
In the accompanying Drawing,
A indicates the metallic case of the meter composed of two parts which are
flanged and bolted together so as to be water-tight at the joint, as shewn in
Figure 1, which is an elevation of the said meter. The portion a contains the
revolving plungers or pistons with suitable interior bearings for one end of their

page_text: shafts, and the portion b is the cover which is also furnished with similar bearings
for the other ends of the shafts and supports the clockwork train of registering
apparatus employed, with the usual stuffing box to pack the spindle which passes
through the cover to the outside and drives the clockwork train.
In
In all meters of this class heretofore made the interior of the case has been
divided longitudinally by a diaphragm, thus forming two separate chambers.
one of these chambers the revolving pistons are placed, and the other chamber is
occupied by the train of gearing attached to the shafts of the pistons, which enables
them to drive, and in turn be driven by each other.
Figure 2 is a sectional view; Figure 3, a perspective view, and Figure 4, & view
partly in section and partly in elevation illustrating my improvements.
B and C indicate respectively the induction and the eduction passages for the
water, which is supposed to be entering through the pipe B under pressure. The
water pistons or plungers are indicated by D and E. They are both elliptical, and
are identical in form and character, and are furnished with teeth c of peculiar
construction, as hereinafter explained. They thus form toothed gearing as well as
pistons and perform the double functions of gear-wheels and pistons. They are
mounted upon shafts d and c, which have their lower bearings in the dome-like
projections and g cast upon the case. The interior end surfaces of the portion a
of the case A. from a to x, and from y to y, are true semi-circles struck from the
axes of the revolving plungers respectively with a radius equal to one half the
major axis of the plunger. The ends of the teeth c on each side of the major axis
of the two plungers are nicely finished so as to make a practically water-tight
joint with the circular parts of the case, and all the teeth of each piston or plunger
are fitted so as to make practically water-tight joints with each other at all points
in their revolution. Consequently no water can pass from the induction to the
eduction orifice between the plungers, nor between either plunger and the case, and
as the top and bottom sides of the plungers are fitted to a joint with the interior
bottom surface of the case and the interior surface of the cover portion b, it follows
that no water can flow through the meter, but it is discharged only as the result
of being forced out by the revolving plungers.
The manner in which the revolving plungers, each alternately acting as a
diaphragm and a piston, perform their office of causing the water received into the
case of the apparatus through the induction passage to be discharged afterwards
through the eduction passage, as the result of the continuous revolution of the
plungers under the force of unbalanced pressure is well understood, and constitutes
no part of my Invention. By this Invention this well known class of water-meters
is improved by dispensing with a separate gear-chamber and a separate measuring
chamber, and the plungers have given to them a form and construction which
enables them to act both as plungers or pistons, and as gearing for driving and
being driven by each other, and this improvement involves a change in the form of
the plungers heretofore employed so as to adapt them to be furnished with teeth
upon their peripheries which will engage throughout the entire revolution of the
plungers with each other. The transverse section of the plungers is shown in
Figure 2. The configuration or Figure is not that of a true ollipse, although
resembling it. The minor axis is shorter than it would be if the Figure were an
ellipse causing the Figure of the section to be a bi-lobe or one bounded by four
intersecting curves. It is necessary to give this figure to the plungers to obtain
the most complete engagement between the teeth during all parts of their
revolution.
Another feature of my Invention is illustrated in Figure 5, which represents
upon an enlarged scale the peculiar formation of the teeth which surround the
edges or peripheries of the water-plungers and enable them to act as gear-wheels.
The object of the peculiar form given to the teeth is to obtain an easy rolling
motion and a continuous engagement of the teeth with each other, and also as
large an extent of surfaces in contact for the security of the joint between the
teeth against the passage of water as is possible.

page_text: The formula for laying out the teeth of a gear-wheel so that the centre of each
tooth as well as a point upon each side thereof, located in the pitch-line shall all be
intersected by radii drawn from the centre of revolution of the gear-wheel is as
follows, that is to say :-I divide the pitch-line into spaces by points which denote
in succession the front edge of a tooth, the centre of a tooth, the back edge of a
tooth, and the centre of a space. Through the points denoting the edges of teeth
I draw radial lines from the centre of the gear-wheel, and through the points
denoting centres of teeth and centres of spaces I draw circular arcs to intersect the
aforesaid radial lines. Two points of intersection are thus obtained upon each arc,
one of which lies within and the other lies without the pitch line of the gear-wheel.
The points lying within the pitch-line on the arcs drawn through the centres of
teeth are designated in the figure as a¹, a², a³, a. From these points as centres I
strike curves external to the pitch-line with a radius equal to the distance from the
point within the pitch-line to the point without the pitch-line. I divide equally
the distance between the points of intersection previously referred to as outside the
pitch-line and corresponding points in the pitch-line, and from such division points
as centres (marked b¹, b², b³, b, in Figure 5) I strike curves external to the pitch-
line with a radius equal to the distance from 61, 62, 63, 64, respectively to points in
the pitch-line indicating the opposite edges of the teeth. The intersection of these
curves with the curves previously struck from a³, a², a³, a, as centres will locate
the extreme points of the teeth. I continue the bounding line of each tooth within
the pitch-line by a curve struck from a point on the pitch-line denoting the near
edge of the next succeeding tooth. On the arcs passing through the centres of
spaces intersecting the radial lines before mentioned, the points of intersection
lying without the pitch-line are designated in the figure as c', c², c³. From each of
these points as centres I strike curves internal to the pitch-line with a radius in
each case equal to the distance from the point of intersection without to the point
of intersection within the pitch-line. The intersection of these curves will locate
the angular point of the spaces. The construction of the remaining side of each
tooth is completed by that portion of the line radial to the centre of the gear-wheel
which passes through the point denoting that side of the tooth on the pitch-line,
and which connects the arcs previously drawn through the centres of spaces internal
to the pitch-line with the arcs drawn through the centres of teeth external to the
pitch-line.
In Figures 1 to 4 the pistons or plungers D and E are shown as attached to their
respective shafts & and e, which must be provided with sufficient journal bearings
in the top and bottom of the case. When the plungers are made of metal it is
easy to mount them on shafts as shown, but for various reasons it is desirable to
make the plungers of hard india rubber, in which case it is not easy to attach
them to a metallic shaft, 1 therefore in such a case employ the method shown in
Figures 6 to 10 for combining a plunger, which revolves around a stationary shaft
with a train of gearing for driving a registering apparatus. This arrangement
possesses very considerable advantage even in case metallic plungers are employed,
for the reason that the apparatus is more economically constructed and is less bulky
and cumbrous in appearance than would otherwise be the case. This arrangement
is shown in perspective in Figure 6, in section in Figure 7, and plan in Figure 8.
A cylindrical hole is bored through the centre of revolution of the plungers, and
stationary shafts to fit such holes are properly combined with the top and bottom
of the case of the meter in the right relation to each other; F (Figure 8) is an
annular gear-wheel which surrounds the axial hole through the plunger selected to
drive the register, and is secured to the plunger by dowel-pins or by a sleeve
concentric with the hole, and having radial ribs thereon, or by any other con-
venient device that will cause the said gear-wheel to revolve with the plunger.
The stationary shaft around which the plunger revolves is shown at d' (Figure 6).
The annular gear-wheel F engages with the toothed wheel F¹ which is upon the
spindle shaft h, which passes through a stuffing box G, Figure 7, and the cover of
the meter, and carries the gear-wheel F2 which drives the train of gearing located

page_text: upon the cover.
It will be observed that the annular gear-wheel F and the
toothed wheel F¹ engaging therewith are located in recesses or chambers cut in the
underside of the cover, as shown at I, and although the cover is so chambered, no
water can pass from one side of the plunger to the other through the same, because
one side of such chamber is always covered by the plunger. It would be
practicable to form the recesses in the plunger itself, but in that case the recess
must be considerably smaller in diameter or width, otherwise it would extend into
the roots of the peripheral teeth upon the plunger and make a water-passage.
In Figure 10 a modified arrangement is shown which is the same as the one just
described, except that in place of the gear-wheel F and the toothed wheel F¹ a
"Geneva Stop" is substituted, and consequently the plunger D will revolve six
times to one revolution of the spindle shaft h.
I am aware that heretofore in pumps and motors pistons having a general
elliptical outline have been geared together within a case, but therein the gear
teeth all occupy a line concentric to the axis of the piston, and the sides of each
piston being deeply recessed to receive the ends of its fellow piston, said recesses
and ends merely operate as large gear-teeth, and so that both pistons are always
moved together, and at the same speed, and do not operate alternately as plunger
and diaphragm, and at variable speeds as when the teeth occupy an elliptical line,
as in a meter constructed according to this Invention. This alternate action by
the plungers as pistons and diaphragms enables all of the water-pressure to be
devoted to the driving movement of that piston, which for the time being is not
operating as a diaphragm; and the teeth of my pistous occupying as they do an
elliptical line are capable of being provided with a more extensive area of close
contact of tooth with tooth than is possible with teeth which occupy a concentric
line, as in the pumps or motors herein before referred to.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it under-
stood that I claim,-
First. The combination substantially as herein before set forth of a suitable
meter-case with revolving elliptical pistons or plungers in constant direct con-
nection by means of teeth formed on their peripheries, each of the said pistons or
plungers in turn acting as a plunger and as a diaphragm during one revolution, for
the purpose above set forth.
Second. The combination substantially as above set forth of a suitable meter
case with revolving elliptical pistons or plungers in constant direct connection, by
means of teeth radial to the axis of revolution of the plungers and formed on the
peripheries thereof, which teeth have the peculiar configuration shown in Figure 5,
for the purpose herein described.
Third. The combination of a suitable meter-case, revolving pistons or plungers
in direct connection by means of teeth formed on their peripheries, each of said
pistons or plungers in turn acting as a plunger and as a diaphragm during one
revolution, an annular gear-wheel or equivalent device located around the axis of
revolution of one of the plungers and contained in a chamber communicating with
the chamber in which the pistons revolve, and the train of a registering apparatus,
all substantially as above set forth for the purpose specified.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty fourth day of August, in the year of our Lord
One thousand eight hundred and eighty.