Note: Descriptions are shown in the official language in which they were submitted.
~07434~;
WEIGIIT ME,~SURING APl~l~RATUS
This invention relates to measuring technoloc3y and, in
particular, to a weight measuring apparatus which is basically
employed in processes of automatic dosage measurements and weigh-
ing in various bxanches of industry.
In modern practice development of automatic weighers
is directed towards improvement of their design and proccssing
technology, increasing their sensitivity and accuracy of measure-
ments, as well as standardization and normalization of their
types and parameters. In this case one of the basic tasks is to
provide weight measuring devices featuring a system of remote
transmission of data. The main element of such a system is a
transducer converting displacements of a weight sensitive element
into electrical signals. This system is mounted on some moving
part of the weighing scales, e.g. on a beam. It is advisable
that these transducers could be installed not only in new weigh-
ing equipment but in second hand weighing scales without altera-
tions in their design and unnecessary waste of money.
The main difficulty involved here is the selection of
the type of a transducer and Matching the working range of ~he
weight scales beam travel and the working range of the moving
member of the transducer. This usually requires an intermediate
kinematic link and increased accuracy of adjustment, because even
insignificant transverse and longitudinal displacements inherent
in beam weighing systems result in sharp increase of errors and
even jamming.
.' ~
10743~
There are known weighing scales with quadrant or spring
balancing. When such weighing scales are used for automa~ic con-
trol they are cguipped with potentiometers provided with movable
contacts, that is a contact system. Deficiencies of a contact
system are co~monly known. One of them is insufficient relia-
bility due to existing contact junc~ions, possible sealing of
contacts and their low sensitivity.
There are also known weight measuring apparatuses,
wherein the transducer is installed on a metering and balancing
mechanism and made as a magslip connected to the axis of the
pointer of the metering device which moves with respect to the
dial face.
Such type of conversion of the pointer angular motion
into an electrical signal requires introduction of a receiving
selsyn which is to be identical to the transmitting selsyn and
that in general complicates the system of transmission of weigh-
ing scales readings.
These weight measuring apparatuses are also deficient
in that thelr resolution is rather low and, conse~uently, the
area of application is limited.
The forementioned weight measuring apparatuses with
selsyn remote transmission of readings to obtain a signal to
start and stop dosing are provided with contactless discrete
pickups interacting with the pointer. For this purpose the
pickups are installed on the dial face and the pointer carries
a plate
~743~
moving within the pickup response area.
Such positioning of pickups and associated plates
results in considerable additional inertial and frictional load
on the pointer axis. There appear slowly damping oscillations
of considerable amplitude, which reduce the speed of action of
the weight measuring device and distort its readings.
There is also known a weight measuring apparatus com-
prising an encased weight sensitive elemcnt connected to a met-
allic moving member of a weight sensitive element displacement-
to-electric signal transducer, which moves in relation to induc-
tance coils of this transducer secured rigidly on the casing.
The winding of the coils is electrically connected to a metering
circuit, whercas the winding of the other coil is joined to the
power source.
The forementioned apparatus is intended for batch
weighing and comprises a weight pan mounted on a leverage system
which is the weight sensitive elcment, a metering and balancing
device and a weight sensitive element displacement-to-electrical
signal inductive transducer.
The forementioned inductive transducer is a differ-
ential transformer and the voltage difference in its secondary
windings depends on the position of the moving element, that is
the position of the armature in relation to the windings, the
armature being connected directly to the weight sensitive
element.
The drawback of this weight measuring apparatus consists
~)7~3~
in its insufficient sellsitivity and accuracy, which is condi-
tioned by the rcadings being dcpendent on uncontrollable mutual
motions of the windings of the inductance coils and the armature
and caused by the necessity of making the design more complicated
and employment of guides.
Besides, in such an apparatus a reverse phenomenon
takes place, which consists in the fact that, when the armature
moves in the magnetic field of the inductance coils, the result-
ing electrical interaction brings about a mechanical motive
force applied to the armature in the direction opposite to its
movement and resisting this movement. Said force is proportional
to the current intensity, voltage and distance. That is why its
influence has to be reduced at the expense of reducing the out-
put signal, which requires its amplification and employment of
complicated secondary equipment, limits the distance between the
transducer and the amplifier of the electrical metering circuit
and makes the field of application of such weight measuring
apparatuses much narrower.
The object of this invention is to provide a weight
measuring apparatus possessing high accuracy of measurements.
Another ob~ect of this invention is to increase the
reliability of the weight measuring apparatus.
Still another object of this invention is to widen the
area of application of the weight measuring apparatus.
-3~
iO74346
In particular, there should be a considerahle
operational clearance between the inductively connected coils
large enough for the uncontrollable (transverse) motions of the
transducer moving member not to cause any changes of the output
signal. The configuration of the field of the inductively
connected coils should be such as to ensure employment of plates
with working edges of any specified configuration.
Accordingly, the present invention provides a weight
measuring apparatus comprising: a casing; a weight sensitive
element positioned in said casing; an inductive transducer for
converting displacements of said weight sensitive element into
electrical signals; a movable metallic plate forming part of
said inductive transducer connected to said weight sensitive
element; two opposing inductance coils also forming part of said
inductive transducer and secured on said casing with a gap
therebetween, said metallic plate extending into said gap; said
inductance coils including windings arranged on cores, each core
having a front face with an annular recess formed therein to
define a central post, the associated winding of each core being
arranged in said recess around said control post such that it
does not project from said front face of the core; a high
fre~uency oscillator connected to one of said inductance coils;
and a metering circuit electrically connected to the other of
said inductance coils.
It is advisable that in a device comprising a mechanism
for weight balancing and metering which axis carries a pointer
capable to move with respect to a dial calibrated in weight
units and is kinematically connected to the weight sensitive
1074346
element, the plate of the inductive transducer should be rigidly
secured on the axis of the weight balancing and metering
mechanism and have a work edging made in a curve of a radius
g Rmin to RmaX within the angle ~ corresponding
to the maximum angle the pointer is able to turn in a specified
range.
A preferred embodiment comprise:s discrete pointer
angle pickups electrically connected by means of electric
signal counter to some inputs of the weight indicator, its other
inputs being electrically connected to the metering circuit.
The working edge of the plate of the inductive transducer is
provided with stepped portions, their number being equal to
the number of subranges and their length being determined by
f' the difference between RmaX and Rmin w
subrange, and two discrete pointer angle pickups are secured
on the casing in the same plane as said plate and spaced at
an angular distance larger than ~, interacting with the edge
of said plate and designed to define the sign of weight changes.
It is advantageous that in an apparatus comprising
discrete pointer angle pickups, equal in number to the number of
subranges, electrically connected to the inputs of the weight
indicator, its other inputs being electrically connected to
the metering circuit, the working edge of the plate of the
inductive transducer should be provided with
--6--
1~74346
stepped portions, equal in number to the number of subrange,
: their length being determined by the difference between RmaX and
Rmin when ~ = 0 for each band, and with an additional plate
secured on the axis of the mechanism and having a work edge
shap~d in a curve of a constant radius R, its arc extention
corresponding to the angle ~ to which the main plate is able
to turn within one subrange, whereas the discrete pointer angle
pickups should be secured in the casing in one plane with the
additional plate, being spaced at an angular distance from
one another and interacting with the.working edge of said addi-
tional plate.
; It is also expedient that an apparatus be provided with
an additional inductive transducer converting displacements of
the weight sensitive element into electrical signals and compris-
ing two inductance coils secured on the casing, their winding
being arranged on cores similar to those used in the first-
mentioned transducer, and a metallic plate secured on the weight
balancing and metering mechanism and positioned in the clearance
between the inductance coils of the additional transducer, one of
them being connected to the high frequency oscillator and the
other being connected to the metering circuit, said plate being
provided with a working edge made as a curve of a radius diminish-
ing from RmaX to Rmin within the angle a corresponding to the
maximum angle the pointer is able to turn in a specified measur-
ing band.
It is advantageous that an apparatus should comprise
an ad-
107434~;
ditional inductive transducer converting displacements of theweight sensitive element into eleetrical signals and having two
inductance coils secured on the casing, their windings being
, arranged on cores similar to those used in the first mentioned
transducer, and a metallic plate secured on the axis of the
weight balancing and metering mechanism and positioned in the
elearance between the induetance eoils of the additional trans-
ducer, one of these coils being connected to the high frequency
oscillator and the other to the metering circuit, the plate being
made as a ratchet wheel with a tooth for each band, the edge of
eaeh tooth having a portion made as a curve of a radius diminish-
ing from RmaX to Rmin and a portion which length is determined
by the difference between RmaX and Rmin when ~ = 0 for each band.
The proposed weight measuring apparatus ensures local
elosing of the magnetic circuit of the coils opposing each other
producing a concentrated non-scattering magnetie flux, whieh
permits increase of the clearance therebetween (with the high
signal level aehieved by employment of the high freguency oscil-
ator) and reduction of the level and influence of uncontrollable
displacements of the plate in the clearanee attained by employ-
ment of eores of special configuration.
The proposed transducer used in weight measuring appara-
tuses permits five or tenfold increase of 'che output signal with
similar reduction in consumed energy as compared to known induc-
tive transducers.
~07~3~6
The proposed weight measuring apparatus offers a two or
threefold increase in accuracy of weight measuring as compared to
other types of weighing devices, whereas the time required for
ad]ustment in operational conditions is cut threefold.
This invention will now be described in greater detail
with reference to specific embodiments thereof, taken in conjunc-
tion with the accompanying drawings, wherein:
Fig. 1 shows a longitudinal section view of a weight
sensitive element displacement-to-electrical signal inductive
transducer of the proposed weight measuring apparatus, according
to the invention;
Fig. 2 shows a section view taken along line II-II of
Fig. 2, according to the invention;
Fig. 3 shows an embodiment of the proposed weight
measuring apparatus exemplified as a laboratory beam scales with
secondary inductance coils removed, according to the invention;
Fig. 4 shows a section view taken along line IV-IV of
Fig. 3 with the secon~ary inductance coil, according to the inven-
tion;
Fig. 5 shows an embodiment of the claimed weight measur-
ing apparatus exemplified by a beam balance, according to the
invention;
Fig. 6 shows an embodiment of the proposed weight
measuring apparatus provided with an inductive transducer posi-
tioned on the weight balancing and metering mechanism, according
to
1074346
the invention;
Fig. 7 shows an embodiment of the proposed weight
measuring apparatus provided with multirange inductive trans-
ducer and pickups, which determine the sign of weight change,
according to the invention;
Fig. ~ shows the embodiment of Fig. 7 featuring an
additional plate and pickups connected directly to corresponding
higher levels of the remote weight indicator, according to the
invention;
Fig. 9 shows a key diagram of a self-exciting oscilla-
tor and the metering circuit of the proposed weight measuring
apparatus, according to the invention.
A first embodiment of the proposed weight measuring
apparatus is described by way of example of a beam balance and
comprises a weight sensitive element made as a beam 1 (Fig. 1).
Alternating motion of the beam 1 is transformed by means of an
intermediate member 2, which is in this embodiment a toothed rack
3 engaged with a gear wheel 4, into the rotary motion of an axis
5. A metallic moving member of an inductive transducer 6 convert-
ing displacements of the weignt sensitive element into electrical
signals is secured at the end of the axis 5. Said moving member
is made as a plate 7 and moves in the clearance 8 formed by two
inductance coils of the transducer 6. The windings 9 and 10 of
the inductance coils are arranged on recessed cores 11 and 12
rigidly
-- 10 --
1074346
.
attached the casing 13. The cores 11 and 12 each have a front
face with an annular recess 9' and 10' formed therein to define
respective central posts 11' and 12' around which the windings
9 and 10 are arranged so as not to project from the front face
of the cores. The winding 9 is connected to a high frequency
oscillator, which is in this embodiment a self-exciting generator
14, and the winding 10 is connected to a metering circuit 15.
One more pair of inductance coils is provided in the
inductive transducer 6 to increase the sensitivity and accuracy
of measurements. Their windings 16 and17 are arranged on
recessed cores 18 and 19 (similar to cores 11 and 12) secured
on the casing 13.
The windings 9 and 16 are primary windings as to their
circuit and are connected in series and joined to the self-
exciting oscillator 14.
The windings 10 and 17 are secondary windings as to
their circuit position, and are connected in series and joined
to the metering circuit 15, which is in this embodiment a
differential phase-sensitive circuit.
In the described embodiment of the weight measuring
apparatus the plate 7 of the inductive transducer 6 has a work
edge 20 (Fig. 2) made as a curve of a radius increasing from
Rmin to RmaX in the angle ~ proportional to the maximum distance
the beam 1 is able to move (Fig. 1). Such shape of the plate
7 ensures production of an analog output signal of the transducer
6.
The proposed weight measuring apparatus may have
another
;
--11--
~074346
embodiment described by way of laboratory beam scales, wherein
the weight sensitive element is a beam 21 (Fig. 3) and the induc-
tive transducer 6 (Fig. 1) is made similarly to the first embodi-
ment.
T'ne only difference o~ the inductive transducer 6 is
that due to the design peculiarities of this type of scales the
moving member is made as two alike plates 22 (Fig. 3) and 23
rigidly secured at the opposite arms of the beam 21. Cores 11,
18 and 12 (Fig. 1), 19, which are not shown in Fig. 3, are
arranged conformably to the position of the plates 22 and 23.
Said recessed cores 11, 12, 18, 19 are attached to the casing
24 by means of brackets 25. The plates 22 and 23 move in the
clearance 8 (Fig. 4 between the respective pair of corès 11, 12
and 18 (Fig. 3), 19 (Fig. 1). Work edges 26 (Fig. 3) and 27 of
the plates 22 and 23 respectively are shaped so that the degree
of screening of the inductance coils and, consequently, the total
output signal of the transducer 6 (Fig. 1) are proportional to
the weight P being measured.
In the embodiment of the proposed weight measuring
apparatus described by way o~ the beam balance the ~oving member
of the inductive transducer 6 can be made as two plates 22 (Fig.
5) and 23 similar to the ones described above. The plates 22
and 23 are secured each side of a cantilever rod 29 suspended to
the weight sensitive element, in this case a beam 28.
Recessed cores 11, 18 and 12 (Fig. 1), 19, which are
not shown in Fig. 5, are attached by means of brackets 30 (Fig.
5) on a guide 31 to be moved for zero setting. The cores 11, 18,
12 (Fig. 1) and 19 are moved by an electric drive 32 (Fig. 5).
In this case it is not necessary to install the trans-
ducer directly on the weighing scales structural elements and theweight measuring apparatus is equipped with a device called
"weight balancing and metering mechanism", the ind~lctive trans-
~074346
ducer is preferably ~laced on the elements of this mechanism.As it will be shown lower, such arrangement offers additional
advantages by widening the area of application of the proposed
apparatus.
It is, therefore, proposed that the claimed weight
~easuring ap~aratus comprise a mechanism 33 ~Fig. 6) for weight
balancing and metering. Its cross-piece 34 is from one end
kinematically connected to the weight sensing element, that is
the beam 28, and from the other end is connected by means of
weight carrying strips 35 to large quadrants 36 which are posi-
tioned on one axis 37 with small quadrants 38 and joined to
counterweights, that is quadrants 39. The quadrants 39 are levers
of the first order on strip supports 40, where the arms of the
lever are the quadrants 36 and 38. The axes 37 are joined by a
bar 41 connected by means of an intermediate member 42 to a
toothed rack 43 engaged with a gear wheel 44 fixed on an axis 45
of the mechanism 33. The alternating motion of the beam 28 is
transformed into the rotary motion of the axis 42 and a pointer
46 secured on this axis 45. Thepointer 46 moves in the process of
0 measurement with respect to a dial face 47 calibrated in weight
units.
The described weight measuring apparatus can also use
a spring type weight balancing and metering mechanism.
Also secured on the axis 45 is a plate 7 of the induc-
tive transducer 6 made similarly to that of Fig. 2. The work
edge 20 of the plate 7 is positioned in the clearance 8 between
the recessed cores 11 and 12 of respective primary and secondary
inductance coils attached by means of a brac~et 48 on a casing
49 of the mechanism 33.
?O To increase the level of the output signal of the trans-
ducer and, consequently, the accuracy of weight measuring and
doing the proposed weight measuring apparatus is provided with an
107434~
additional plate 50 sccured on the axis 45. Said plate moves in
the clearance 8 of the other pair of inductance coi]s, which
recessed cores 18 and 19 with the windings 16 (Fig. 1) and 17
are placed similarly to the first pair of cores 11 and 12, form-
ing in combination witn the plate 50 (Fig. 6) an additional
weight sensitive element displacement-to-electrical signal induc-
tive transducer 51.
A work edge 52 of the plate 50 is made in a curve of
diminishing radius from RmaX to Rmin in the angle ~ also corres-
ponding to the maximum angle the pointer 46 can turn within the
specified subrange.
The inductance coils of the main and additional trans-
ducer 6 and 51 of the described embodiment are similar to that
of the first embodiment of the weight measuring apparatus of
Fig. 1.
When the plates 7 and 50 move with respect to any pOillt
of the dial face 47, the fixed point of the work edge 20 of the
plate 7 recedes from the axis 45 of the pointer 46, whereas the
respective fixed point of the work 52 of the other plate 50
approaches the axis 45 by the same distance. The degree of
screening of the inductance coils alters in this case so that a
double signal is produced at the output of the metering circuit
15.
-- There can be also another embodiment of the weight
measuring apparatus, wherein a multistage (multiband) remote
transmission of readings. This embodiment is characterized by
that the working edge 20 of the plate 7 is made in a curve of
a radius growing from Rmin to RmaX and is provided with tran-
sitional portions 53 (Fi~. 7) equal in number to the number of
30 ranges, thei.r length being determined by the difference between
and R . when ~ = 0 for each range, whereas the length of
max mln
the edge 20 between two stepped portions 53 corresponds to the
1~74346
.
measurement range.
Two discrete pickups 54 and 55 are installed in one
plane with the plate 7 on the casing 49 of the weight balancing
and metering mechanism 33 to determine the direction of rotation
of the axis 45 and the plate 7 and, consequently, the sign of
weight change. In this embodiment they are contactless generator-
type pickups which are in cyclic interaction with the working
edge 20 of said plate 7. The pickups 54 and 55 operate at the
moment of interaction with the stepped portions 53. In this case
0 to obtain two successive signals from these pickups 54 and 55,
their se~uence being an indication of the direction where the
pointer 46 moves, the pickups 54 and 55 are set up at an angular
distance somewhat greater than ~ within one subrange.
The pickups 54 and 55 are electrically connected by
means of the electrical signal counter to the inputs of the
weight indicator. In this embodiment a bidirectional electric
signal counter 56 and a remote weight indicator 57 are employed.
Higher orders of the remote weight indicator 57 are by means of
the bidirectional counter 56 electrically connected to the pick-
~0 ups 54 and 55, whereas its lower order is by means of the meter-
ing circuit 15 electrically connected to the secondary inductance
coils of the transducers 6 and 51. When one of the pickups 54
or 55 operates, the bidirectional counter 56 is switched over to
addition or subtraction.
The plate 50 of the additional inductive transducer
~1 is made in this embodiment being described as a ratchet wheel
provided with teeth 58 equal in number to the number of sub-
ranges. The working edge of each tooth within the limits of one
subrange has a portion 59 made in a curve of a radius diminishing
from RmaX to Rmin and a portion ~0 which length is determined by
the difference between RmaX and Rmin with ~ = 0.
In this way the shape of the plate 50 corresponds to
- 15 -
10743~6
the shape of the plate 7, the only ~ifference being that curve
ra~ii of their working edges change in opposite directions.
There can be one more embodiment of a weight measuring
apparatus similar to that of Fig. 7.
It is different in that there is provided an additional
plate 61 (Fig. 8) secured together with the plates 7 and 50 on
the axis 45 of the mechanism 33. A working edge 62 of the plate
61 is made in a curve of a constant radius R extending along the
arc in accordance with the angle ~ to which the plates 7 and 50
can turn within one subrange. Discrete pickups 63 indicating the
angle of the pointer 45 and e~ual in number to the number of sub-
ranges are positioned in one plane with the plate 61 by being
secured on the casing 49 of the mechanism 33 at an angular dis-
tance a with respect to one another.
Each of the pickups 63 is directly connected to a res-
pective digit of the high order of the remote indicator 57,
whereas the lower order of said indicator 57 is ~similarly to
the circuit of Fig. 7) electrically connected by means of the
metering circuit 15 to the windings 10 (Fig. 1) and 17 of the
secondary coils of the inductive transducers 6 and 51 (Fig. 8).
The pickups63 operate when the working edge 62 of the additional
plate 61 passes in their operational zo~e.
The electric circuitry of the self-exciting oscillator
14 of the proposed weight ~easuring apparatus in all foremen-
tioned embodiments comprises a resistor 64 (Fig. 9) and a stabi-
litron 65 of the first stage of stabilization, a resistor 66 and
a stabilitron 67 of the second stage of stabilization, as well
as a capacitor 68 which is the filter ~or alternating voltage of
the self-exciting oscillator 14 (any known stabilization circuit
can be used to match the requirements of the transducer opera-
tional conditions). The self-exciting oscillator 14 uses a
tapped ca~acitor arrangement and is built around a transistor 69
1074346
and comprises resistors 70 and 71 as a bias circuit, a resistor
72 included into the circuit of the emitter of the transis~or 69
to stabilize current for the transistor 69, and a capacitor 73
shunting the resistor 72 with respect to the alternating current.
The windings 9 and 16 of the primary inductance-coils
of the transducer 6 are connected in series and included into the
eireuit of the collector of the transistor 69 (for the transducers
6 and 51 of the embodiments of Figs. 6, 7 and 8). The windings
9 and 16 in eombination with a eapaeitor 74 connected parallel -
to the resistor 71 and a eapaeitor 75 connected into the emitter-
eolleetor eixcuit of the transistor 69 ensure eonditions for self-
exeitation of the self-exeiting oseillator 14.
The metering eireuit 15 of all the above described
embodiments of the weight measuring apparatus is a phase-sensi-
tive deteetor linked with the windings 10 and 17 of the second-
ary inductanee eoils of the transducer 6, said windings being
in series and opposing eonneetion, (for the transducers 6 and
51 of the embodiments of Figs. 6, 7 and 8). The circuit 15
eomprises eapacitors 76 and 77 whieh, when eonnected to the
windings 10 and 17, form in eombination with these windings a
secondary circuit of the self-exeiting oseillator, whereas the
diodes 78 and 79 eonneeted thereto serve to reetify the alternat-
ing eurrent.
Rectification and filtration by capacitors 80 and gl
produces voltages in resistors 82 and 83 which are equal in
magnitude ~in zero position of the plate 7) and opposite in
sign. Thus the potential difference ~etween points 84 and 85
in this state of the transducer 6 (Fig. 1) is equal to zero.
The differential circuitry of the inductance coils
permits increase in accuracy of measurements, a twofold gain in
sensitivity and ensures zero voltage at the output (zero signal)
in the initial position of the inductive transducer 6.
1~74346
When an output signal of a certain (not zero) lcvel is
required owing to conditions of the measuring process involving
the inductive transducer 6, one pair of inductance coils featur-
ing windings 9 and 10 can be used as shown in Figs. 1-5.
All embodiments of the proposed weight measuring appar-
atus can be classified into two groups: in one group of devices
the inductive transducer is positioned directly on the structural
elements of a weighing apparatus, whereas in the other group the
inductive transducer is placed on the axis of the point~r of the
inductive device referred to as "weight balancing and metering
mechanism".
Due to forementioned peculiarities the principles of
operation of these mechanisms differ only in the method of trans-
- mitting the deflection of a weight sensitive element to the
moving member of the inductive transducer. In other respects
the operation of weight measuring apparatuses is similar for all
variations and embodiments.
When feed bars are energized by direct current ~oltage,
the circuit of the self-exciting oscillator 14 (Fig. 9) is ex-
cited producing the sine-wave voltage in the primary windings 9
and 16. This voitage produces in the secondary windings 10 and
17 voltages which amplitude depends on the controllable movement
of the plate 7 kinematically connected to a weight sensitive
element, t'hat is the beam 1 tFig. 1), and, consequently is the
function of weight P.
For weignt measuring apparatuses of Figs. l-S the
load acting on the beam 1 (Fig. 1) and 2~ (Fig. S) or the beam
21 (Fig. 3) of the weighing device moves the beam, its deflec-
tion being proportional to the load. Deflection of the beam 1
(Fig. 1) of the weight sensitive element causes respective dis-
placement of the moving member, that is the plate 7 of the induc-
tive transducer 6 connected tnereto. In this case the trans-
- 18 -
107~3~6
ducer is of a differential transformer type. The plate 7 acts
as a screen which changes as it moves the degree of the induc-
tive connection between the primary and secondary windings 9 and
10 of the transducer 6.
As the plate 7 moves with respect to rigidly attached
armour cores 11, 12, 18 and 19 and as the relation between
screen areas oftlle inductance coils changes, different voltages
are produced in the secondary windings 10 and 17 to be rectified
; in the metering circuit 15 by the diodes 78 (Fig. 9) and 79,
smoothed by the filter-capacitors 80 and 81 bringing about a
potential difference between the points 84 and 85 which is pro-
portional to ~he voltage difference in the windings 10 and 17.
In this way the signal produced at the output of the
metering circuit 15 as an alternating voltage is directly propor-
tional to the weight being measured.
For weight measuring apparatuses shown in Figs. 6-8
the load acting upon the beam 28 of the weighing device causes
its deflection which is transmitted through the use of a kinema-
tic ~ember to the device, that is the weight balancing and meter-
ing mechanism 33. Its cross-piece 34 with weight carrying strips
35 transforms this deflection into an angular turn of the quad-
rants 36 and 38 joined with balancing quadrants 39. When the
quadrants 36 and 38 turn, they impart through connecting elements,
such as the strip supports 40, the bar 41 and the intermediate
member 42 reciprocal motion to the toothed rack 43 engaging the
gear wheel 44 which is mounted together with the pointer 46 on
the axis 45 of the mechanism 33.
The motion of the toothed rack 43 is transformed into
a rotary motion of the gear wheel 44 which in turn turns the axis
45 with the pointer 46 to a respective angle.
~n ,he embodiments of the weight measuring apparatus of
Figs. 6-~ the moving member, the plate 7 of the inductive trans-
- 19 -
10743~6
ducer 6 is fixed on the axis 45 like the plate 50 of the addi-
tional transducer 51.
The working edges 20 and 52 of the plates 7 and 50 are
made in a curve of a variable radius: increasing in the first
instance and diminishing in the second one.
That is why, when the axis 45 turns to a certain angle
proportional to the load value, the plates 7 and 50 turn to the
same angle and, due to the opposite direction of changing of the
radii of the working edges 20 and 52, the degree of screening of
the inductance coils of the transducer 51 is decreased, which
results in upsetting the balance, and a double signal is produced
at the output of the metering circuit 15, its magnitude being
proportional to the weight being measured.
In case of a multirange remote transmission of readings
the process of measuring involves apart from the output analog
signal taken from the transducers 6 and 51 the signals from two
discrete pic~ups 54 (Fig. 7) and 55 interacting with the plate 7
at the boundaries of measurement subranges. In this case the
analog signal of the transducers 6 and 51 is displayed by lower
orders of the remote indicator 57, whereas the higher orders of
the indicator 57 receive signals via the bidirectional counter
56 switched over to either addition or subtraction from the dis-
crete pickups 54 and 55.
If the load is in excess of the first range, the read-
ings of lower orders of the remote indicator 57 are passed
through the analog trans~ucer 6 of the shortcut portion 53 of
the plate 7 and immediately returned to zero. At the same time
the plate 7 interacts with a discrete pickup, e.g. the pic~up
55, and the higher order of the indicator 57 displays "one".
3~ ~n the course of further rotation of the plate 7 the process of
its interaction with the analog transducer 6 and the discrete
pickups 54 is cyclically repeated, the number of ranges being
- 20 -
1074346
displayed in the higher order of the indicator 57 and the posi--
tion of the plate 7 within the limits of one range is displayed
in lower orders of this indicator 57.
In the embodiment of Fig. 8 each of the discrete pick-
ups 63 is connected to a respective digit of the higher order of
the remote indicator 57. The bidirectional counter 56 is not
required in this case as well as determination of the direction
of rotation of the plate 7, which simplifies the circuitry.
Employment of this invention in weighing dosing devices,
including dial scales, permits increase of accuracy and speed of
action, makes their design simpler, steps up resolution and sig-
nificantly widens their field of application.
This invention can provide conditions for integrated
automation, particularly of concrete producing plants employing
multibrand technology.
