Improvements in Automatic Weighing Apparatus.
Year: 1896

page_text: Date of Application, 14th Dec., 1896-Accepted, 30th Oct., 1897
COMPLETE SPECIFICATION.
Improvements in Automatic Weighing Apparatus.
I, EDWARD G. THOMAS, of Waltham, County of Middlesex, State of Massa-
chusetts, United States of America, and of 383 Federal Street, in the City of
Boston, State of Massachusetts, United States of America, Mechanical Engineer,
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and pascertained in and by the
following statement:-
The invention relates to automatic weighing devices, in which the material to
be weighed is fed through a valve or other feeding device, and in which the feed-
ing is automatically controlled by the opening or closing of an electric circuit by
the movement of the scale. The invention is equally applicable to spring balances
and to beam balances, the control being caused in either case by the descent of
the material when a sufficient amount has been received upon the scales.
I will describe the invention in connection with certain preferred embodiments
of it, which I have shown in the drawings, though it will be seen that the precise
details there shown are not necessary to the accomplishment of the functions.
Fig. 1 is the side elevation of the scale, parts being in section.
Fig. 2 is a section on the plane 2-2 of Fig. 1.
Fig. 3 shows another position of Fig. 1.
Fig. 4 shows a modification and
Figure 5 shows the application to a spring balance.
At BI show the scale beam, which is only intended as a conventional representa-
tion, and not, therefore, intended to show details of construction. B' is a receptacle,
which receives the material to be weighed. I have selected, for my main illus-
tration, a simple balance scale, the weighing being done with the weights C;
as I believe this form of scale shows my automatic apparatus more simply than
a spring balance or a more complicated sliding-weight scale-beam. The material
to be weighed is fed through any suitable feeding device, as at D. This feeding
device is opened, closed, and controlled, by the connection F and the lever or
arm G. The spring H tends to close the valve, or other feeding device, D. An
electric circuit J, which includes a magnet K and a source of electric current L,
is opened and closed, directly or indirectly, by the movement of the scale. In
Fig. 1 I have shown at M a fixed contact against which the scale beam rests
when less than the desired weight of material is in the receptacle B¹. The
movable contact M¹ moves with the scale, so as to make and break contact with M
when the scale is tipped one way or the other. In Fig. 1 this connection is
through the metal of the beam itself. When the contacts M and M' touch, the
circuit through the electro-magnet or solenoid, is completed. The magnet K acts
upon the armature K' and holds the lever arm 0 against the arm G, when the
parts are in the position shown in Fig. 1; the valve or feeding device D being
slightly open. This is the position of the parts during the last moments of the
feeding; and as soon as the weight of the material in the receptacle B₁ tips
the scale and breaks the circuit at M M, the magnet K is disenergized. This
allows the spring H to draw the arm G to the right, closing the feeding device D.

page_text: At P is shown a cam, which turns upon the shaft P. This shaft P1 is driven
by the belt P. The arm or stop Q turns with the cam P, and during the last
few moments of the filling action the arm Q comes in contact with the stop Q
upon the armi G, and prevents the rotation of the cam P. The form of the
stops QQ will be clear from Figures 1 and 2. When the arm O is released,
the arm is drawn to the right to close the valve D, and the stop Qmoves
clear of the stop Q, allowing the cam P to rotate. The shape of the cam is such
that after it has rotated a certain distance it bears against the arm. G, as clearly
shown in Fig. 3, thereby opening the valve or feeding device D to its full extent.
The cam is so proportioned, and its revolution so timed, that the valve D will
remain wide open until the receptacle 13 is nearly filled to the required extent.
The arm O meanwhile is held in the position shown in Fig. 3, by the attraction
of the magnet K, and also by the spring 01. As soon as the rotation of the
cam P allows the arm G to move to the right, the arm G comes into contact with
and is stopped by the arm O, as in Fig. 1, very nearly but not quite closing
the valve D; so that the final feeding may be slow and an accurate measure be
obtained. The rotation of the cam is stopped by the stops Q Q. As soon as the
full measure is obtained, the receptacle B descends, breaking the circuit J, as
already described, and permitting the closing of the valve and the re-starting
of the cam. It will be seen that so long as the material is being fed slowly
through the feeding device D, the stop Q interferes with the rotation of the
cam. As soon as the feeding is stopped, the receptacle B is quickly emptied,
or is removed and replaced by another empty receptacle, before the rotation of
the cam P again opens the feeding device D. In this manner an intermittent and
accurate delivery and weighing of material is accomplished.
The regulation of the position of the valve for the final feeding of the material
is obtained in a delicate manner by means of the screw O". The duration of
time which the valve or feeding device D remains wide open is determined by
the speed of rotation of the cam P. When the rotation is checked by the stop Q
the driving connection for the cam P may continue to rotate, a slip being allowed
at some point in the connection. If the parts are operated by clock work, or
by a weight, no such connection is necessary.
By the two levers G and O, or other equivalent, I obtain the first quick feeding
of the material and the subsequent slower feeding. By forming the two arms
as one, the successive adjustments may be dispensed with and the magnet K may
merely hold the feeding device open until the scale tips. The arm O may be
present in a widely different form, as, for instance, in Fig. 4, in which it is a
mere pawl, which checks the movement of the arm G, and which is raised to
release the arm G when the receptacle B¹ tips the beam.
In Fig. 4 I have also shown the magnet K arranged to raise the arm (), and
release the arm G when its circuit J' is closed. This is the reverse of Fig. 1, and
is in some respects preferable, as the circuit will then remain open during the
filling action and be closed only when the receptacle B is filled and descends.
One advantage of this arrangement is that any jarring of the scale during the
filling action cannot affect the apparatus, whereas a jarring of the apparatus as
arranged in Fig. 1 might open the electric circuit at the contact M M. At D
I show a hand-controlled valve or gate, which must be opened to start the apparatus.
But this device D', like the device 1), is merely intended to represent any form
of device for controlling and regulating the feeding of the material to be weighed.
By the omission of the cam P, the apparatus may be operated by hand in the
following manner: The empty receptacle is put in position, as shown in the
drawings, and the arm G, which may he in one part with the arm 0, is drawn
to the left to open the valve or feeding device 1). The magnet K holds it in
position until the receptacle B is filled. As soon as the requisite amount of
inaterial has been fed into the receptacle B, the circuit is broken, the armature K¹
ereby released from the magnet, and the arm G drawn to the right by the
spring H, closing the feeding device D.

page_text: My invention may also be used to measure liquids by volume. This may be
done without knowing the specific gravity of the liquid, by using two receptacles,
and filling one with the desired quantity of the liquid and using it instead of the
weight C. Of course a properly determined weight C may be used in the same
manner, for measuring oil, or other liquids.
From the foregoing it will be observed that the valve is actuated by cam P
and spring H. The weight of the material weighed is not relied upon to furnish
the power for opening and closing the valve; the power is derived entirely from
some other, mechanical, source. The magnet K, is controlled by the scale beam,
and in its turn, it controls the application of this mechanical power. The
mechanical power alternately opens and closes the valve. The magnet K checks
the closing of the valve and holds it, until the weighing is completed. It also
suspends the operation of the mechanical power. As soon as the magnet K
releases the valve, the valve closes under the action of the spring I, the operation
recommences, and, shortly after, the valve is again opened.
I believe these characteristics distinguish the invention from other weighing
apparatus.
Fig. 5 shows the invention as applied to a spring balance instead of a weight
balance. As all the parts may be identical in character to those already described,
with the exception of the scale arm and its mounting, I have lettered the drawing
in the same manner as Fig. 1, so that the description of Fig. 1 is perfectly appli-
cable so far as such parts are concerned. The scale beam of the spring balance,
however, may be advantageously fulcrumed at one end, as at b, and supported
by the balance spring C against the contact point M. The weighing plate or
platform may be advantageously placed between the spring C and the con-
tacts M M. The scale may be set for any determined weight by placing such
weight upon the platform and adjusting the tension of the spring C¹ by the
screw adjustment until the contacts just fail to touch each other. Of course,
however, though I illustrate but one form of spring balance construction, other
forms are equally adapted to the invention.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what J
claim is :-
1. The automatic weighing apparatus, provided with mechanical power, (not
actuated by the material to be weighed) operating to alternately open and close
the feeding device, electrically controlled stops or detents for interrupting the
said operation while the said feeding device is open, and a circuit controller, the
electric circuit being controlled by the movement of descent of the material which
is weighed, substantially as set forth.
2. The automatic weighing apparatus provided with mechanical power (not
actuated by the material to be weighed) for opening the valve or feeding device,
a spring for closing the valve, a stop motion, and an electric control for the said
stop motion, the electric control being actuated by the movement of the said
weighing apparatus under the weight of material to be weighed, substantially
as described.
3. The automatic weighing apparatus provided with mechanical power (not
actuated by the material to be weighed), for opening and closing the valve, an
electrically controlled detent or stop mechanism checking the motion of the valve
when partly closed, and the electric circuit therefor controlled by the weight of
the material which is weighed, substantially as set forth.
4. An automatic weighing apparatus provided with a spring, which tends to
close the feeding mechanism, a mechanical power (not actuated by the material
to be weighed) for opening the feeding mechanism, an electro-magnetic stop
mechanism which interferes with the closing of the feeding mechanism, and an
electric circuit therefor, which is controlled by the movement of the scale, sub-
stantially as set forth.

page_text: 5. The automatic weighing apparatus provided with means for automatically
opening and closing the valve, at fixed intervals, a detent for interrupting this
operation, and means for releasing the detent when the weight of material moves
the scale, substantially as set forth.
6. In an automatic weighing apparatus, the feeding device D operatively con-
nected with the lever arm G, a rotary cum mechanism alternately moving the
arm G to and fro to open and close the valve, detents for interrupting the motion
of the said cam and of the said arm G, an electro-magnet controlling the detents,
and an electrical circuit therefor, controlled by the movement of the scale or
balance; substantially as set forth.