U.S. patent application number 09/946056 was filed with the patent office on 2002-06-20 for multi-stage weight scale.
Invention is credited to Al-Modiny, Khalid F..
Application Number | 20020074169 09/946056 |
Document ID | / |
Family ID | 23394720 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020074169 |
Kind Code |
A1 |
Al-Modiny, Khalid F. |
June 20, 2002 |
Multi-stage weight scale
Abstract
A weight scale having an operational weighing range, comprising
an overall response characteristic having at least first, second
and third discrete stages over the operational weighing range. The
first, second and third stages are defined by first, second and
third predetermined response characteristics, respectively. The
weight scale further comprises first, second and third scale
arrangements or mechanisms which establish the first, second and
third response characteristics, respectively, of the three
stages.
Inventors: |
Al-Modiny, Khalid F.;
(Riyadh, SA) |
Correspondence
Address: |
LAWRENCE P. TRAPANI, ATTORNEY AT LAW
333 EAST ONONDAGA STREET
2ND FLOOR, MONROE BUILDING
SYRACUSE
NY
13202
US
|
Family ID: |
23394720 |
Appl. No.: |
09/946056 |
Filed: |
September 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09946056 |
Sep 4, 2001 |
|
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09354740 |
Jul 29, 1999 |
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Current U.S.
Class: |
177/1 |
Current CPC
Class: |
F17C 2201/0109 20130101;
F17C 2223/0153 20130101; F17C 2250/036 20130101; F17C 2223/033
20130101; F17C 2250/0421 20130101; F17C 2250/077 20130101; F17C
2201/0119 20130101; F17C 2221/033 20130101; F17C 2223/0161
20130101; F17C 2201/058 20130101; F17C 2221/035 20130101; G01G
17/04 20130101; F17C 2201/032 20130101; F17C 13/023 20130101; G01G
1/08 20130101 |
Class at
Publication: |
177/1 |
International
Class: |
G01G 009/00 |
Claims
What I claim is:
1. A weight scale including: an operational weighing range; and an
overall response characteristic having a plurality of discrete
stages over the operational weighing range, each stage being
defined by a predetermined response characteristic.
2. A weight scale having an operational weighing range, comprising:
an overall response characteristic having at least first and second
discrete stages over the operational weighing range, the first
stage being defined by a first predetermined response
characteristic and the second stage being defined by a second
predetermined response characteristic; first scale means for
establishing the first response characteristic of the first stage;
and second scale means for establishing the second response
characteristic of the second stage.
3. The weight scale of claim 2, wherein said overall response
characteristic further includes a third discrete stage within its
operational weighing range, the third stage being defined by a
third predetermined response characteristic; and wherein said
weight scale further comprises third scale means for establishing
the third response characteristic of the third stage.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of Application Ser. No.
09/354,740, filed Jul. 29, 1999.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to weighing scales, and is
more particularly directed to a device for detecting and indicating
changes in a small weight that is embedded within a much larger,
i.e., heavier, residual weight.
[0003] It is difficult for the consumer to measure a small variable
weight that is contained within a much larger weight, most of which
is a relatively constant residual weight. It is also difficult to
monitor and obtain an advance warning of the impending exhaustion
of a given variable weight, which can be considered a critical
weight.
[0004] A weight load can be considered to consist of two or more
components, that is, an initial part, a critical part, and an end
part. The critical part is typically significantly smaller than
either of the other two components, but this is typically the
component whose weight is of the most interest. Consequently, any
weighing device that detects variations, i.e., gradual depletion,
of the critical component should have a more sensitive scale for
the critical part than for the other two parts. In many cases, the
consumer needs to monitor only the critical part, and the weighing
device or scale only needs to read and monitor the critical
component, and not the initial or end parts.
[0005] A particular example of this is a cylinder of a consumable
gas, such as propane or natural gas. The cylinder has an empty or
residual weight which does not vary for that cylinder. Also, when
completely filled with propane or natural gas, the cylinder has a
full or initial weight, which also is a fixed value for that
cylinder. The customer is interested in monitoring the weight of
the cylinder so that he or she will be aware when the contents have
been nearly consumed, and the cylinder is approaching an empty
condition. Where the cylinder contains, for example, ten kilograms
of propane, the consumer needs to know when it has emptied down to
about the final one or two kilograms, which constitute the
"critical weight." Consequently, the weighing scale needs to
monitor only for that range of zero to two kilograms, which lies
somewhere between the cylinder's residual weight and the cylinder's
full or initial weight. Thus, there is a need for a weighing device
that monitors the critical part of the load.
[0006] There are many other applications as well, where the
critical part of the load is embedded within the overall weight of
the load, between the residual weight and the initial weight.
[0007] There may also be a need to monitor the fill, rather than
the depletion of a container's contents, in which case the critical
weight would be increasing instead of decreasing. The critical
weight range can be close to the initial weight instead of close to
the residual weight.
OBJECTS AND SUMMARY OF THE INVENTION
[0008] Accordingly, it is an object of this invention to provide a
weighing and monitoring technique that avoid the drawbacks of the
prior art.
[0009] It is another object to provide a weighing scale of simple
design which accurately monitors the critical part of the weight
load.
[0010] It is yet another object to provide a weighing scale that
can be adjusted for its range and sensitivity in measuring changes
within the critical weight range.
[0011] It is a further object to provide a weighing scale of rugged
design and which can provide an audible and/or visible alarm.
[0012] In accordance with an aspect of the present invention, an
embedded weight scale indicates variations in weight of an article
wherein the variable weight is embedded within a heavier weight,
and where the article has a base residual weight and a variable
embedded weight. The scale has a base with first and second
upstanding walls and a top pan adapted for supporting the article
whose weight is to be monitored. There is a linkage, in this case
formed of a pair of long levers and a pair of short levers. The
long levers each have a first end pivotally supported on the first
wall of the base and a second end, the second ends being joined
together by a pivot pin or the like. The short levers each have a
first end pivotally supported on the second wall of the base, and
each has a second end that is pivotally joined to a midpoint of a
respective one of the long levers. The top pan is supported at four
points, i.e., at a respective position on each of the long levers
and the short levers. There is a counterbalance pivot on said base,
and this is preferably customer adjustable, i.e., by turning a
wheel or screw. A counterbalance weight lever is joined at its
first end to the second ends of said long levers, and this lever
extends across the base, over the counterbalance pivot, to a second
end. A counterbalance weight is supported on the second end of this
counterbalance weight lever. The counterbalance weight lever has a
range of movement that corresponds to the range of weight that
includes the embedded weight, i.e., the critical weight, of the
article.
[0013] An adjustable tensioning spring means permits the consumer
to adjust the tension between the base and the long levers. Weight
indicating means are also provided, including a sensor for sensing
variation in the position of the counterbalance weight lever as it
moves within its range, i.e., within the critical weight range of
the embedded weight.
[0014] The weight indicating means may take the form of a
potentiometer having a rotary slider, and a lever connecting the
slider with the counterbalance weight lever. A gear multiplier or
other means can be employed to increase the sensitivity range of
the potentiometer.
[0015] The adjustable tensioning spring means can employ a spring
holder plate affixed to said base, a spring tension adjusting screw
on the spring holder plate, and a tensioning spring positioned
between the spring holder plate and the second ends of the long
levers.
[0016] The counterbalance weight may be selectively adjustable in
its position on the counterbalance weight lever, so as to adjust
the critical weight range. Also, there are stops provided to limit
the movement of the counterweight lever, with the positions of the
stops being selected to affect the selection of the critical weight
range.
[0017] As can be understood, the range of counterbalance movement
is governed by the height of the unit, and the positions of the
stops, whereas the range of the critical weight is governed by the
settings of the counterbalance weight, the counterbalance pivot,
and the spring.
[0018] The above and many other objects, features, and advantages
of this invention will become apparent to persons skilled in the
art from the ensuing description of a preferred embodiment, which
is to be read in conjunction with the accompanying Drawing.
BRIEF DESCRIPTION OF THE DRAWING
[0019] FIG. 1A is perspective view of an embedded weight scale
monitoring unit and load, in the form of a cylinder of propane or
liquefied natural gas, according to an embodiment of this
invention.
[0020] FIG. 1B shows the warning unit of this embodiment.
[0021] FIG. 2 is a schematic sectional elevation of the monitoring
unit of this embodiment.
[0022] FIG. 3 is a schematic top view of this embodiment.
[0023] FIGS. 4A and 4B are schematic top plan and side views for
explaining the operation of this embodiment of this invention.
[0024] FIGS. 5A and 5B are charts for explaining the dependency of
counterbalance weight.
[0025] FIGS. 6A and 6B are charts for explaining the dependency of
spring and stopper settings.
[0026] FIGS. 7A and 7B are charts for explaining sensitivity in the
critical weight range.
[0027] FIG. 8 is a graphical chart for explaining the general
principles of the counterbalance weight leverage system employed in
this embodiment.
[0028] FIG. 9 is a schematic side view of the counterbalance weight
lever for explaining this embodiment.
[0029] FIG. 10 is a top view of the counterbalance weight lever and
sensor element of this embodiment.
[0030] FIG. 11 is an overall response characteristic of a Type D
embodiment of the present invention, showing three discrete
stages.
[0031] FIG. 12A-12D are a series of overall response
characteristics for Types A, B, C and D embodiments, respectively,
of the present invention.
[0032] FIG. 13 is a simplified schematic diagram of a Type B
embodiment of the present invention.
[0033] FIG. 14 is a simplified schematic diagram of a Type C
embodiment of the present invention.
[0034] FIG. 15 is a simplified schematic diagram of a Type D
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0035] With reference to the Drawing, an embodiment of the embedded
weight measuring weighing scale of this invention is shown in FIGS.
1A and 1B. Here, a weighing scale device 10 has a rectangular or
square base 12, and a top or weighing pan 14 supported over the
base 12. A load 16 is shown here to take the form of a gas
cylinder, with a fill of a compressed consumable gas, such as
propane or liquid natural gas. This is only an example, of course,
and the load 16 can be any load that has a basic, residual weight,
and a larger total weight when filled. In this embodiment the tank
or cylinder 16 is shown with a partial remaining fill 18 (shown in
ghost lines), with the contents being depleted and approaching
exhaustion. In this example, the empty weight of the cylinder or
tank may be, for example ten KG, and the contents of the tank, when
filled may be a similar weight, that is, another ten KG. The
customer is interested in being alerted when the tank is nearing
exhaustion, that is, when there are about two KG of gas remaining
inside the cylinder 16. This last two KG of gas is considered the
critical weight in this example. That is, the cylinder has an
initial (filled) weight of twenty KG, a residual (empty) weight of
ten KG, and a critical weight range between ten and twelve KG. A
wire or cable 20 extends from the weighing or sensing unit 10 to an
alarm or customer interface unit 22, which is shown in FIG. 1B. The
unit 22 may have an audible alarm to alert the consumer when the
critical weight is detected, and may also have visible indicators,
here a green lamp 26A which lights to indicate that the weight is
above the critical weight range, a yellow lamp 26B to provide a
warning when the weight has dropped into the critical range, and a
red lamp 26C to provide a warning when the weight has dropped below
the critical range, i.e., the propane or natural gas is exhausted.
The unit 22 contains batteries and electronic circuitry, which are
not shown here.
[0036] The construction of the weighing scale device 10 is
illustrated in FIGS. 2 and 3. As shown, there is a linkage
mechanism between the base 12 and the top pan 14, in this case
formed of a pair of long levers 28 and a pair of short levers 30.
The long levers 28 have one end pivoted on a back wall 32 of the
base 12, and the short levers 30 have one end pivoted on a front
wall 34 of the base, with another end pressing down at the
midpoints of the long levers 28, respectively. The top or pan 14 is
shown to have four legs 36 that extend down and rest upon locations
along the long and short levers 28, 30, respectively. There is a
pivot pin 38 through the second or free ends of the two long levers
28.
[0037] A counterbalance weight lever 40 has one end attached to the
long levers at the pivot pin 38, and proceeds from there towards
the back wall 32 of the base 12. A movable pivot 42 is positioned
on the base 12 and the lever 40 rests upon the pivot 42. A pivot
adjusting screw 44, which is user actuable, permits the user to
adjust the position of the pivot relative to the lever 40. A
counterbalance weight 46 is positioned at the rear end of the
counterbalance weight lever 40, and may be adjustable in its
position along the lever. Shown near the front wall 34 of the base
12 is a stopper 48 (which may be either factory-set or
field-adjustable) that limits the downward motion of the second
ends of the long levers 28 and the front end of the counterbalance
weight lever 40.
[0038] An adjustable spring 50 is positioned at the second ends of
the long levers 28, and its tension is user-adjustable by means of
a spring tension adjusting screw 52. A spring holder plate 54 holds
the spring in position at the front wall 34 of the base, so that
there is a spring tension accorded between the base 12 and the
counterbalance weight lever 40. Also shown is a sensor element 56,
e.g., a potentiometer, which serves as an active detector and is
sensitive to upwards or downwards motion of the counterbalance
weight lever 40.
[0039] As shown in FIGS. 4A and 4B, the weight of the load 16,
which is transmitted via the legs 36 to the long levers 28 and
short levers 30, creates an image load or virtual load weight
W.sub.L at the position of the pivot pin 38, i.e., at the end of
the counterbalance weight lever 40. At the other end of the lever
40, the counterbalance weight has a weight W.sub.C. The pivot 42 is
positioned to define a lever arm l between the pivot and the
virtual weight W.sub.L, and a counterbalance lever arm L between
the counterbalance weight 46 and the pivot 42. The virtual weight
W.sub.L depends on the actual weight of the load 16, and the
virtual weight W.sub.L is in balance with the counterbalance weight
W.sub.C when this relation is satisfied:
L.times.W.sub.C=l.times.W.sub.L. When the load 16 is above the
critical range, the lever 40 is deflected to a maximum point d
determined by the stopper 48. When the load weight drops into the
critical range, the virtual weight W.sub.L is balanced by the
counterbalance weight W.sub.C, and the lever 40 moves through a
deflection range D, i.e., until the counterbalance weight 46
bottoms out and rests on the base 12. In this range, the lever 40
is free to move up and down, and changes in the virtual weight
W.sub.L are balanced by increasing or decreasing the tension on the
spring 50 under deflection of the lever 40. The sensitivity in this
range depends on the spring setting, which the user can adjust by
means of the adjusting screw 52. The lengths of the lever arms L
and l can be adjusted by moving the pivot 42, and also by moving
the counterbalance weight 46. Also, the size of the counterbalance
weight 46 can be adjusted, i.e., by adding trim weights.
[0040] The initial weight value for the scale 10 can be set by
adjusting the counterbalance weight value, and its position on the
lever 40, i.e., from a relatively lower value x.sub.0 to a higher
value x.sub.0', as shown in FIGS. 5A and 5B. This does not affect
the width of the critical range. The other bound of the critical
range can be adjusted by adjusting the spring 50 and/or the stopper
48, i.e., from a relatively lower setting x.sub.1 (FIG. 6A) to a
relatively higher setting x.sub.1' (FIG. 6B). This can widen or
narrow the range of interest, i.e., the critical range. The
sensitivity to load weight variation within the critical range of
deflection can depend on the sensitivity of the potentiometer 56,
as well as various mechanical parameters, such as the spring
constant (stiffness) of the spring 50.
[0041] FIG. 8 is a chart for explaining the operation of the unit
10, i.e., calibrated to sense the critical weight range 18 of the
propane or natural gas cylinder 16 of FIG. 1. Here, the abscissa
shows values of load weight values, with X.sub.0 corresponding to
the residual weight, i.e., the empty weight of the tank or cylinder
16; X.sub.RCW corresponds to the critical weight range, i.e., the
final two KG 18 of propane or natural gas in the cylinder, with
X.sub.1 being the upper limit of the critical weight range
X.sub.RCW. Above this is the residual weight range X.sub.RES, which
is limited by the maximum rated weight X.sub.M for the scale. The
expected full weight of the cylinder 16 would be somewhat smaller
than this value X.sub.M. Deflection of the counterbalance weight
lever 40 is depicted on the ordinate. This also corresponds to the
scale sensitivity.
[0042] The stopper 48 blocks any deflection of the counterbalance
weight lever 40 for weights in the range X.sub.RES, and the
counterbalance weight 46 is bottomed out in its range for load
values at or below the residual value X.sub.0. For loads in the
critical range X.sub.RCW, the action of the spring 50 determines
the deflection of the lever 40.
[0043] As shown in FIG. 9, a virtual load bearing point 58 is shown
on the counterbalance weight lever 40 to the right of the pivot 42.
At the position shown, the scale is at or below the residual
weight, and the counterbalance weight 46 is fully descended. The
beginning of the critical weight range, i.e., the value X.sub.1, is
characterized by the right end of the lever 40 being descended into
contact with the stopper 48. The weight values where these occur
depends on the size of the weight 46 and its position along the
lever 40, and also on the position of the pivot 42. These depend to
some extent as well on the stiffness of the spring 50, and its
tension. Thus, the customer or user can field-adjust the scale 10
to adjust the weight values in which an alarm or warning is
received.
[0044] As shown in FIG. 10, the sensor element for this weighing
scale can be a potentiometer 56, here of the rotary type, with a
rotor stem 60 for moving the rotary wiper of the potentiometer. The
rotor stem 60 has attached to it a potentiometer lever arm 62,
whose distal end is coupled to a mover element 64 on the lever 40,
so that the potentiometer rotor stem 62 follows the up and down
motion of the counterbalance weight lever 40. This can be
mechanically arranged for optimal sensitivity. In one possible
arrangement, a planetary gear multiplier can be used to increase
the angular response of the potentiometer 56 to motion of the lever
40. Also, instead of a potentiometer, other devices may be used,
such as a magnetic sensor (i.e., Hall device), optical indexer, or
other known arrangement. Also, instead of the coil spring 50 shown
here, another spring arrangement, e.g., a leaf spring or a torsion
spring could be employed. In addition, the spring 50 could include
an air bladder or other resilient means within the ambit of the
present invention. The spring 50 may be positioned either above or
below the lever 40.
[0045] Also, the scale need not have the square or rectangular
shape as shown. Also, in some versions, rather than using the
stopper 48 to limit the motion of the lever 40, the lever 40 and
the counterbalance weight 46 can be limited in their upward
direction by the height of the unit.
[0046] Well known systems, such as levers, hydraulics, springs and
others, are used to reduce, proportionally, the actual weight of a
load into a fraction of that weight. Spring leverage systems and
adjustable counterbalance weight systems are the most commonly
used, in ordinary consumer scales. It is a common practice in the
art to use the leverage principles (or equivalent) in conjunction
with either spring or adjustable counterbalance weight principles
to obtain a scale weighing action (i.e., "single action").
[0047] In the preferred embodiment of the weighing scale of the
present invention, a leverage system principle in combination with
an adjustable counterbalance weight principle is used for one stage
of the scale's weighing operation (hereinafter "counterbalance
weight arrangement"); a leverage system principle in combination
with a tension spring is used for another stage of the scale's
weighing operation (hereinafter "leverage spring arrangement"); and
another counterbalance weight arrangement is used to provide a
third stage of the scale's weighing operation. In the preferred
embodiment of the present invention, the two arrangements are
incorporated to work together, independently, in three sequences,
i.e., in three discrete stages. Thus, the present invention can be
considered as three different scales, each one independent of the
other, but working in sequence.
[0048] With reference to FIG. 11, an embodiment of the weight scale
of the present invention will now be described. In the following
description, we start from zero load and end at full load. FIG. 11
shows a three-stage response over the operational range of the
scale. In a first stage, the scale will measure a constant or
variable weight (for example, an initial load) according to a
predetermined units-vs.-weight characteristic or proportionality
102. In a second stage, the scale will measure a constant or
variable weight (for example, critical load) according to another
predetermined units-vs.-weight characteristic or proportionality
104. In a third stage, the scale will measure a constant or
variable weight (for example, end load, maximum load, exhausted
load, etc.) according to yet another predetermined units-vs.-weight
characteristic or proportionality 106.
[0049] FIG. 11 shows characteristics 102, 104 and 106 as being
linear; however, they may be a single value (a point), a constant
(flat line), or a non-linear response. In the example shown in FIG.
11, the load is increasing in all three stages. Of course, the
scale function is the same in either direction, whether the load is
increasing or decreasing. It is apparent from the above description
and FIG. 11 that the scale's overall response is defined by three
discrete responses or stages.
[0050] The embedded weight scale of the present invention can be
configured in different types of embodiments. One embodiment, which
we refer to as "Type A," is suitable for a consumable gas cylinder
or tank scale, the application described above with reference to
FIGS. 1-10. Other types, which will be referred to as Types B, C
and D, will be described hereinbelow. The response characteristics
(weight units vs. load weight) of Types A, B, C and D scales are
shown in FIGS. 12A-12D, respectively. Again, the responses are from
zero to full load.
[0051] In a Type A embodiment, a counterbalance weight arrangement
and a leverage spring arrangement are utilized. An example of this
embodiment is shown in FIGS. 2 and 9. Lever 40 is initially biased
down by counterbalance weight 46 (unbalanced), and needs a force
W.sub.L at bearing point 58 large enough to induce upwards movement
of counter weight 46 (See FIG. 9). The magnitude of W.sub.L is
dependent on the weight of counterbalance weight 46, its distance
from pivot point 42, and the distance of point 58 from pivot 42.
These are the controlling factors in determining a first stage R1
of the Type A scale's response (FIG. 12A). As shown in FIG. 12A,
the response is zero units over first stage (or weight range) R1.
At this stage, spring 50 is still under its predetermined state of
tension, and it will remain so until forced to expand. Once lever
40 begins to move upwards (actuated by force W.sub.L at point 58),
spring 50 will begin to expand. This expansion marks the beginning
of a second stage R2 in the Type A embodiment (FIG. 12A). The
second stage continues until lever 40 hits stopper 48, at which
point a third stage R3 in the scale's response begins (FIG. 12A).
Third stage R3 has a flat constant unit response, which may have an
upper weight limit where the load at point 58 could damage or
destroy the scale (i.e., maximum mechanical limit).
[0052] With further reference to FIG. 12A, first stage R1 could be
made smaller or larger (i.e., varying W.sub.L), according to the
specific application, by altering one or more of the controlling
factors mentioned above. Second stage R2 can be altered by altering
the specifications of spring 50 and pre-tensioning spring 50 using
adjustment screw 52 (FIG. 2). Second stage R2 is limited by the
distance lever 40 can travel without exceeding the expansion
limitation of spring 50. Stopper 48 is used to limit the lever
travel distance in this embodiment. Thus, in the second stage of a
Type A scale, a critical weight (or embedded weight), defined for a
gas cylinder, can be measured at a higher sensitivity
(units-vs-weight proportionality) than the other variable weights
(weight ranges) associated with the gas cylinder. (In this example,
the scale has a nil response as to these other variable weights).
From this example, it is seen that three stages of weighing a load
is obtained and controlled independently.
[0053] In a Type B embodiment, an adjustable counterbalance weight
arrangement and a leverage spring arrangement are utilized. As
shown in FIG. 12B, the scale of this embodiment also has a
three-stage response--two linear responses (during a first and a
second stage R1 and R2) and one nil response (during a third stage
R3). A simplified schematic diagram of a Type B scale is shown in
FIG. 13. FIG. 13 represents a scale identical to that shown in FIG.
2, except that lever 40 and counterbalance weight 46 have been
replaced with a lever 140 and an adjustable counterbalance weight
146. Lever 140 is initially maintained in equilibrium over a pivot
142, and counter weight 146 is allowed to slide across lever 140
automatically (by means well known in the art) to maintain the
equilibrium (balance) of lever 140. This action defines the first
stage (R1) of this embodiment (FIG. 12B).
[0054] Referring again to FIG. 13, when a load or force W.sub.L is
applied at a virtual load bearing point 158, lever 140 is forced
off balance, causing the system to re-adjust (or balance itself).
Counterbalance weight 146 slides to a new position until balance is
re-established. The sliding action of weight 146 will continue as
load W.sub.L increases, but ultimately weight 146 will reach a
limit and stop, as shown in broken lines in FIG. 13. At this point,
the first stage (R1) of the scale's response ends and the second
stage (R2) begins (FIG. 12B). A spring 150, like spring 50, comes
into play during the second stage (R2). During stage R2, spring 150
expands until lever 140 hits a stopper 148. At the point when lever
140 hits stopper 148, the third stage (R3) begins. During stage R3,
load W.sub.L can increase up to an allowable maximum mechanical
limit for the scale. Stage R1 is altered by altering the distance
counter weight 146 is able to slide along lever 140 (d.sub.WC), by
changing the weight of counter weight 146, and by changing the
distance of bearing point 158 from pivot 142.
[0055] In a Type C embodiment, an adjustable counterbalance weight
arrangement replaces stopper 48 in the Type A embodiment, and the
remaining arrangements of the Type A embodiment are unchanged.
Thus, the Type C embodiment has a counterbalance weight
arrangement, a leverage spring arrangement, and an adjustable
counterbalance weight arrangement. The response for the Type C
embodiment is shown in FIG. 12C. It has three stages--a nil
response (during a first stage R1) and two linear responses (during
a second and a third stage R2 and R3). A simplified schematic
diagram of a Type C scale is shown in FIG. 14. FIG. 14 represents a
scale identical to that shown in FIG. 2, except that stopper 48 has
been replaced with an adjustable counterbalance weight arrangement
248. The Type C embodiment of FIG. 14 further includes a lever 240,
a pivot 242, a counterbalance weight 246, a spring 250, and a
virtual load bearing point 258.
[0056] In the Type C embodiment, the response of first stage R1 is
identical to the response of the first stage in the Type A
embodiment (compare FIGS. 12A and 12C). The response of the second
stage R2 is identical to the response of the second stage in the
Type A embodiment until lever 240 pushes down against adjustable
counterbalance weight arrangement 248. Adjustable counterbalance
weight arrangement 248 functions in the same manner as the
adjustable counterbalance weight arrangement described above with
respect to the Type B embodiment.
[0057] As shown in FIG. 14, arrangement 248 includes a lever 248a,
a load bearing point 248b, a counterweight 248c, and a pivot 248d.
The force of lever 240 against bearing point 248b causes an
imbalance in lever 248a. Counterbalance weight 248c slides toward
the left end (FIG. 14) of lever 248a to reestablish balance or
equilibrium of lever 248a. The displacement of counterbalance
weight 248c will eventually be limited by a stop at the end of
lever 248a or by the action of a stopper (like stopper 48) located
under the right side (FIG. 14) of lever 248a. Of course, the
responses of each of stages R1, R2 and R3 can be altered as
described above with respect to Type A and B embodiments.
[0058] A Type D embodiment was already introduced with reference to
FIG. 11. A Type D embodiment is the fullest version of the present
invention. It includes an adjustable counterbalance weight
arrangement, a leverage spring arrangement, and another adjustable
counterbalance weight arrangement. The response for the Type D
embodiment is shown in FIG. 12D. It has three stages R1, R2 and R3,
with linear responses in each stage. It functions like the Type B
embodiment for the first two stages and like the Type C embodiment
for the third stage (compare FIGS. 12B and 12C with 12D). A
simplified schematic diagram of the Type D scale is shown in FIG.
15. FIG. 15 represents a scale identical to that shown in FIG. 2,
except that lever 40 and counterbalance weight 46 has been replaced
with an adjustable counterbalance weight arrangement 340, 346, and
stopper 48 has been replaced with an adjustable counterbalance
weight arrangement 348. The operation of the Type D embodiment of
FIG. 15 is self-evident in view of the descriptions of the Type B
and C embodiments.
[0059] Each one of the stages in a Type A, B, C or D embodiment may
be equipped with its own controlling and sensing elements. These
elements can be of a conventional type, well known in the art, or
especially designed, depending on the particular weighing
application.
[0060] It should now be understood that an appropriate
proportionality (or sensitivity) and range can be predetermined for
each operational stage of the weight scale of the present
invention.
[0061] While the preferred embodiments of the invention have been
particularly described in the specification and illustrated in the
drawings, it should be understood that the invention is not so
limited. Many modifications, equivalents and adaptations of the
invention will become apparent to those skilled in the art without
departing from the spirit and scope of the invention, as defined in
the appended claims.
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