Flow meter and method of calibrating same

By a load detector, a magnitude of a dynamic load, depending on a downward-flow impact of a particulate material flowing through a flow passage, is measured, and also a magnitude of a static load, corresponding to a total amount of the particulate material flown through a predetermined position for a predetermined time period, is measured. A value of a dynamic load-type flow rate of the particulate material, corresponding to a measured value of the dynamic load, is calculated from the measured value of the dynamic load by a first calculation formula, and also a value of an actual flow rate of the particulate material is calculated from a measured value of the static load during the predetermined time period by a second calculation formula. A correction factor for bringing the dynamic load-type flow rate value, depending on the difference of the particulate materials, into agreement with the actual flow rate value is found. The first calculation formula is corrected by the correction factor, and a corrected dynamic load-type flow rate value is calculated from the measured dynamic load value by the use of the corrected first calculation formula. With this construction, there can be obtained a flow meter in which the correction of the flow rate of the flow meter or calibration of the flow meter can be effected easily.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a flow meter for measuring the flow rate of a 
particulate material flowing continuously through a flow passage, and also 
relates to a method of calibrating the flow meter. 
The term "particulate material" means herein grains or particles which can 
flow substantially continuously, and examples thereof include not only 
grains of wheat and rice and grain powder such as wheat powder or flour, 
but also particles which vary in characteristics (such as a specific 
gravity), depending on external conditions such as an environmental 
condition and a production condition, and particles different in average 
size of the particles, and the size of the particles or grains is not 
limited. 
2.Description of the Related Art 
In a plant for processing cereal such as rice and wheat, the amount of 
processing of the grains is measured in terms of a flow rate. Herein, "the 
flow rate of the particulate material" means the weight of the particulate 
material flowing per unit period of time. In order to continuously measure 
the flow rate of a continuously-flowing particulate material, there is 
used an impact load detection-type or impact-type flow meter in which the 
particulate material is received by an impact-receiving detection plate 
(impact-receiving plate-like member), and its impact load on the plate is 
measured, and this impact load is converted into the flow rate. 
In this impact flow meter, however, a downward-flow impact, applied by the 
particulate material to the impact-receiving detection plate, varies 
depending on the nature or characteristics of the particulate material, 
such as its bulk specific gravity, water content and temperature. When the 
flow rate is measured only for the raw grains of the same kind in the same 
condition, this variation does not cause substantial problem. Actually, 
however, it is seldom that the environment for raw materials is in good 
order, and in most cases the flow rate of various kinds of grains must be 
measured. And besides, even grains of the same kind often varies in water 
content, depending on various conditions the grains have been subjected 
to. Therefore, in a processing plant or facility where various kinds of 
grains were processed, much time was required for calibrating the flow 
meter or correcting the indication of the flow rate in the flow meter. The 
term "correcting the flow rate" and "correction of flow rate" in or of the 
flow meter mean herein "correcting the indication of the flow rate" and 
"correction of the indication of the flow rate" in or of the flow meter, 
i.e. "calibrating the flow meter" or "calibration of the flow meter". 
In the correction (of the indication) of the flow rate in the impact flow 
meter, usually, a certain amount of grains are extracted or sampled from a 
flow of the grains (to be measured) for a predetermined period of time, 
and an actual flow rate is calculated from the weight of the grains thus 
extracted for the predetermined time period, and the correction of the 
flow rate or calibration is effected according to this actual flow rate 
value. Most of these correction or calibration operations are carried out 
manually. If trying to accurately effect the correction of the flow rate 
or calibration for each of many flow meters installed in one processing 
facility, much time (for example, one to two days) is often required for 
this correction or calibration operation. If trying to keep the labor, 
required for the correction or calibration operation, to a minimum, the 
correction of the flow rate or the calibration is omitted when the raw 
grains are similar to the grains of the preceding lot, and as a result the 
accuracy of the value of the flow rate measured by the flow meter is 
lowered. 
There are known the type of flow meters which comprise a load-receiving 
plate-like member provided in an inclined manner in a flow passage of a 
particulate material--the term "particulate material", here in the 
Description of the Related Art, is not limited to the material with 
properties or nature easily changed or varied in specific gravity etc. 
depending on environmental conditions, but means broadly any particulate 
materials of a medium or a small particle size, and powders--for receiving 
a dynamic load corresponding to the flow rate of the particulate material 
flowing through the flow passage, a load detector for detecting a 
magnitude of the load received by the load-receiving plate-like member, 
and an arithmetic and control unit having a dynamic load-type flow rate 
calculation means for calculating a "dynamic load-type flow rate" (defined 
later in this specification) from a measured value of the load detector 
obtained during a period when the particulate material is flowing through 
the flow passage. Such flow meters are disclosed, for example, in Japanese 
Patent Unexamined Publication No. 1-105120 (A) (convention priority of U. 
S. patent application Ser. No. 07/049,666 filed May 13, 1987 being 
claimed), Japanese Patent Unexamined Publication No. 63-195524 (A), U.S. 
Pat. No. 5,065,632, Japanese Patent Unexamined Publication Nos. 8-14962 
(A) and 57-189013 (A), and WO-A-93-22,633. 
Among the above prior art references, Japanese Patent Unexamined 
Publication No. 1-105120 (A), U.S. Pat. No. 5,065,632 and Japanese Patent 
Unexamined Publication No. 8-14962 (A) disclose a typical impact 
detection-type flow meter in which the load-receiving plate-like member 
receives a downward-flow impact of the particulate material falling a 
substantial distance. 
On the other hand, among the above prior art references, Japanese Patent 
Unexamined Publication No. 63-195524 (A) and Japanese Patent Laid-Open 
Specification No. 6-511558 (A) corresponding to WO-A-93-22,633 disclose a 
structure in which the load-receiving plate-like member receives a 
relatively small downward-flow impact of the particulate material falling 
a relatively small distance from an upstream-side slanting surface, and 
also the load-receiving plate-like member supports the particulate 
material so that the particulate material can flow down over an upper 
surface of this plate-like member, and the total load (hereinafter 
referred to as "dynamic load"), which the plate-like member receives, is 
the sum of the two (that is, the downward-flow impact and the load of the 
particulate material flowing down over the upper surface of the plate-like 
member). 
In this specification, the term "dynamic load" means the total load 
including a load applied by the flowing particulate material to the load 
detector, and it may include, as a part thereof, a static load due to the 
weight of particulate material being flown with proviso that the static 
load of the particulate material, deposited or accumulated in a 
non-flowing condition on the plate-like member, is not included in the 
dynamic load. 
Japanese Patent Unexamined Publication No. 1-105120, corresponding to U.S. 
patent application Ser. No. 07/049,666, discloses an impact flow meter in 
which a downward-flow impact is detected as the dynamic load, and its 
output span is adjusted or corrected. 
More specifically, Japanese Patent Unexamined Publication No. 1-105120 
discloses an impact flow meter 120 as shown in FIG. 15. The impact flow 
meter 120 comprises a cylindrical housing 123, having a downstream end 
opening 121 at its lower end and a side opening in which a particulate 
material inflow tube 122 is inserted, an impact-receiving plate 124 for 
receiving a downward-flow impact of a particulate material flowing through 
the inflow tube 122, and a strain gauge unit (serving as a load detector) 
125 which is suspendedly mounted at its upper end on an inner peripheral 
surface of the housing 123, and supports the impact-receiving plate 124 at 
its lower end in a suspended manner. The strain gauge unit 125 detects a 
horizontal component force of the downward-flow impact, received by the 
impact-receiving plate 124, as an impact load. The impact flow meter 120 
further comprises a calibration weight 127 which is connected to an outer 
surface of the impact-receiving plate 124 through a cable 126 if 
necessary. This calibration weight 127 is used for adjusting the span of 
an amplifier constituting the load detector. 
However, in this case, also, in order to determine whether or not the value 
of the actual flow rate, obtained by converting the detected load of the 
impact-receiving plate 124, is correct, it is necessary "to check the 
calibration by passing the flow material at a known flow rate through the 
flow meter". 
SUMMARY OF THE INVENTION 
With the above problems in view, it is an object of this invention to 
provide a flow meter in which a flow rate (indication) can be easily 
corrected or calibrated, and also to provide a method of or calibrating 
the flow meter or correcting (an indication of) the flow rate measured by 
the flow meter. 
Another object of the invention is to provide a flow meter in which less 
time and labor are required for the correction thereof or for the 
correction (of the indication) of the flow rate thereby, and also to 
provide a method of or calibrating the flow meter or correcting (the 
indication of) the flow rate measured by the flow meter. 
A further object of the invention is to provide a flow meter capable of 
accurately measuring a flow rate in accordance with a change of raw 
particulate materials, and also to provide a method of calibrating the 
flow meter or correcting (the indication of) the flow rate measured by 
this flow meter. 
A still further object of the invention is to provide a flow meter in which 
each time before measurement of a flow rate of a particulate material of 
different nature or characteristics is started, calibration thereof or 
correction (of the indication) of the flow rate thereby is substantially 
or automatically carried out, and also to provide a method of correcting 
the flow meter or calibrating (the indication of) the flow rate measured 
by the flow meter. 
To achieve at least a part of the above objects, according to a first 
aspect of the invention, there is provided a flow meter comprising: 
a tubular member forming a flow passage for a particulate material; 
an opening-closing valve member connected to the tubular member so as to 
open and close a downstream end opening of the tubular member, the 
opening-closing valve member being adapted to receive a dynamic load 
corresponding to a flow rate of the particulate material, flowing through 
the flow passage, when the opening-closing valve member is in its open 
position to open the downstream end opening of the tubular member; and 
a load detector for detecting a load acting on the opening-closing valve 
member; wherein the flow meter further comprising: 
an arithmetic and control unit including: 
dynamic load-type flow rate calculation means for finding or calculating a 
dynamic load-type flow rate of the particulate material from a measured 
value of the load detector when the opening-closing valve member allows 
the flow of the particulate material, so that the particulate material is 
flowing through the flow passage; 
actual flow rate calculation means for finding or calculating an actual 
flow rate of the particulate material based on a measured value of the 
load detector, representing a static load of the particulate material 
deposited or accumulated within the tubular member for a predetermined 
time period after the flow of the particulate material is interrupted or 
blocked by the opening-closing valve member, and a value of the 
predetermined time period; and 
means for finding or obtaining or calculating a correction factor for 
correcting the dynamic loadtype flow rate value into the actual flow rate 
value. 
To achieve at least a part of the above objects, according to a second 
aspect of the invention, there is provided a flow meter comprising: 
a load-receiving plate-like member provided or disposed in an inclined or 
oblique manner in a flow passage for a particulate material, the 
load-receiving plate-like member being adapted to receive a dynamic load 
corresponding to a flow rate of the particulate material flowing through 
the flow passage; 
a load detector for detecting a magnitude of a load acting on the 
load-receiving plate-like member; and 
a weir or stop or block member movable between a block position where the 
weir member blocks the flow of the particulate material at a position 
downstream of the load-receiving plate-like member and an open position 
where the weir member allows the flow of the particulate material; wherein 
the flow meter further comprising: 
an arithmetic and control unit including: 
dynamic load-type flow rate calculation means for finding or calculating a 
dynamic load-type flow rate of the particulate material from a measured 
value of the load detector when the weir member allows the flow of the 
particulate material so that the particulate material is flowing through 
the flow passage; 
actual flow rate calculation means for finding or calculating an actual 
flow rate of the particulate material based on a measured value of the 
load detector, representing a static load of the particulate material 
deposited or accumulated on the load-receiving plate-like member for a 
predetermined time period after the weir member is set to the block 
position, and a value of the predetermined time period; and 
means for finding or calculating a correction factor for correcting the 
dynamic load-type flow rate to the actual flow rate. 
In either of the above two flow meters, preferably, the load detector has a 
range for detecting the dynamic load of the particulate material, and a 
range for detecting the static load or weight of the particulate material. 
In a flow meter system comprising a plurality of flow meters of either or 
both of the above two types, preferably, the arithmetic and control unit 
of each of the plurality of flow meters has a normal operating mode for 
finding or obtaining the dynamic load-type flow rate, and a correction or 
calibration mode for finding or obtaining the correction factor, and the 
arithmetic and control units are connected to a centralized control unit 
which controls the arithmetic and control units in a centralized manner, 
and when raw material of the particulate material flowing through the flow 
passage in at least one of the flow meters is changed to a different one 
(for example, the lot of particulate material is changed), the centralized 
control unit feeds or supplies to the at least one flow meter a control 
signal so as to change the associated arithmetic and control unit from the 
normal operating mode to the correction mode. 
To achieve at least a part of the above object, according to a third aspect 
of the invention, there is provided a method of calibrating a flow meter 
comprising the steps of: 
measuring, by a load detector, a magnitude of a dynamic load, depending on 
a downward-flow impact of a particulate material flowing through a flow 
passage, and a magnitude of a static load corresponding to a total amount 
of the particulate material having been deposited or accumulated at a 
block position in a predetermined time period after the flow of the 
particulate material is blocked; 
finding or calculating a value of a dynamic load-type flow rate of the 
particulate material, corresponding to a measured value of the dynamic 
load, from the measured value of the dynamic load by a first calculation 
formula, and also finding or calculating a value of an actual flow rate of 
the particulate material from a measured value of the static load in the 
pre-determined time period by a second calculation formula; 
finding or obtaining a correction factor for bringing the dynamic load-type 
flow rate value, depending on difference of the particulate materials, 
into agreement with the actual flow rate value; and 
correcting the first calculation formula by the correction factor, and 
finding or calculating a corrected dynamic load-type flow rate value from 
the measured dynamic load value by the corrected first calculation 
formula. 
Preferably, the above flow meter calibration method comprises the steps of: 
forming the flow passage in a tubular member; 
connecting an opening-closing valve member, which opens and closes a 
downstream end opening of the tubular member, to the tubular member; 
detecting, by the load detector, the dynamic load represented by the 
downward-flow impact applied to the opening-closing valve member from the 
particulate material flowing through the flow passage in an open condition 
of the opening-closing valve member, the load detector being coupled to 
the tubular member connected to the opening-closing member; and 
detecting, by the load detector, the static load represented by the load 
corresponding to the total amount of the particulate material deposited 
within the tubular member during the predetermined time period when the 
opening-closing valve member is set at its closing or blocking position. 
Alternatively, the above flow meter correction method comprises the steps 
of: 
providing a load-receiving plate-like member in an inclined or oblique 
manner in the flow passage; 
providing a weir or block member at a downstream portion of the 
load-receiving plate-like member, the weir member being movable between a 
block position where the weir member blocks the flow of the particulate 
material at a position downstream of the load-receiving plate-like member 
and an open position where the weir member allows the flow of the 
particulate material; 
measuring, by the load detector, the static load representing the weight of 
the particulate material having been deposited on the load-receiving 
plate-like member in the predetermined time period after the weir member 
is set to the block position; and 
setting the weir member to the open position, and measuring, by the load 
detector, the dynamic load during the time when the particulate material 
is flowing through the flow passage. 
Since, in the flow meter calibration method of the invention, by the load 
detector, a magnitude of the dynamic load, depending on the downward-flow 
impact of the particulate material flowing through the flow passage, is 
measured, and also a magnitude of the static load, corresponding to the 
total amount of the particulate material having been flown through a 
predetermined position during a predetermined time period, is measured, 
and since a value of the dynamic load-type flow rate of the particulate 
material, corresponding to a measured value of the dynamic load, is 
calculated from the measured value of the dynamic load by the first 
calculation formula, and also a value of an actual flow rate of the 
particulate material is calculated from a measured value of the static 
load during the predetermined time period by the second calculation 
formula, it is possible to obtain, with respect to the actually-flowing 
particulate material, both of the dynamic load-type flow rate value, based 
on the measured value of the dynamic load depending on the downward-flow 
impact, and the actual flow rate value, and therefore it can be easily 
judged, whether or not the dynamic load-type flow rate value is accurate, 
by comparing it with the actual flow rate value. 
In the flow meter-calibration method of the invention, since the correction 
factor for bringing the dynamic load-type flow rate value, depending on 
the difference of the particulate materials, into agreement with the 
actual flow rate value is calculated, and the first calculation formula is 
corrected by the correction factor, and the corrected dynamic load-type 
flow rate value is calculated from the measured dynamic load value by the 
corrected first calculation formula, following advantageous effects can be 
obtained; if the dynamic load-type flow rate value deviates from the 
actual flow rate value, the first calculation formula is corrected so as 
to give a dynamic load-type flow rate-indicating value in agreement with 
the actual flow rate value, and by doing so, the calibration of the flow 
meter can be effected easily. Therefore, for example, when the lot of 
particulate material whose flow rate is to be measured is changed, so that 
a new particulate material, having a different nature, begins to flow 
through the flow passage, the correction of the flow rate of the flow 
meter or calibration thereof can be automatically effected in a short 
time. As a result, it becomes substantially unnecessary the correcting 
operation, which has been conventionally effected manually beforehand by 
the operator for each flow meter. 
As a matter of course, it is not necessary to measure or detect the actual 
flow rate constantly, but this is effected only when the correction of the 
flow rate or calibration becomes necessary. For example, this is effected 
twice a day, or when the raw material of the particulate material is 
changed, i.e. the particulate material of different origin is flown. 
Therefore, although the flow of the particulate material through the flow 
passage is interrupted when measuring the actual flow rate by a kind of 
batch process for the purpose of the correction, the time period of this 
interruption is short, and only temporary, and therefore the overall 
processing will not be affected significantly. 
Since the first type of flow meter of the invention comprises the tubular 
member forming the flow passage for the particulate material, the opening 
closing valve member, which is connected to the tubular member so as to 
open and close the downstream end opening of the tubular member, and 
receives a dynamic load corresponding to the flow rate of the particulate 
material, flowing through the flow passage, when the opening-closing valve 
member is in its open position to open the downstream end opening of the 
tubular member, and the load detector for detecting the total load acting 
on the tubular member, it is possible to detect, by one load detector the 
dynamic load and the static load or weight (of the particulate material 
deposited within the tubular member for a predetermined time period after 
the flow of the particulate material is interrupted by the opening-closing 
valve member), in the same flow meter structure having the opening-closing 
valve member at the tubular member. Therefore, this flow meter can be 
simple in structure or construction although it has the calibration 
function of correcting the flow rate value. 
In the flow meter of the invention, a dynamic load-type flow rate value, 
calculated by the dynamic load-type flow rate calculation means from a 
value of the load detector measured when the opening-closing valve member 
allows the flow of the particulate material so that the particulate 
material is flowing through the flow passage, is brought into agreement 
with the actual flow rate value which is obtained by the actual flow rate 
calculation means based on a measured value of the load detector, 
representing the static load or weight, and a value of the predetermined 
time period. Namely, if there is any difference between the two values, a 
correction factor for correcting the dynamic load-type flow rate value in 
such a manner as to eliminate the difference is obtained by the correction 
means, and the thus obtained correction factor is used for correcting the 
calculation of the dynamic load-type flow rate. 
Here, if a term or a factor, to be corrected, of the calculation formula of 
the dynamic load-type flow rate calculation means are beforehand 
determined, the correction can be effected easily. Therefore, when the 
actual flow rate or the static load or weight corresponding to the actual 
flow rate is measured, the correction processing is effected promptly. 
This correction can be processed by the arithmetic and control unit 
without requiring any substantial manual labor or operation, and therefore 
can be completed in a very short time. 
It will be readily appreciated that, in the second type of flow meter of 
the present invention, the calibration thereof or the correction of the 
flow rate can be made similarly to that described above with respect to 
the first type of flow meter. 
In the flow meter of the invention, preferably, the load detector has the 
range for detecting the dynamic load of the particulate material, and the 
range for detecting the static load of the particulate material. 
Therefore, in accordance with a magnitude of the load, the load can be 
always measured with the full range, and hence the accurate measurement 
can be effected. 
For example, in the first type of flow meter, it has been experimentally 
confirmed that the ratio between the dynamic load (composed mainly of the 
impact load) and the batch load is about 1:100, and that it is sufficient 
that the full range of the indication value of the load detector is set to 
about 1:100 in view of a resolution of the load cell etc. serving as the 
load detector. For example, when the flow rate was 5 tons/hour (where 1 
ton=1,000 kilograms), a dynamic load was about 150 g, whereas a static 
load or weight of rice grains as the particulate material, deposited or 
accumulated for 10 seconds (This will be hereinafter referred to as "batch 
load for ten seconds"), was about 14 kg. Therefore, by switching the 
range, the loads different in the ratio of 1:100 can be detected with the 
same precision (in terms of the number of effective digits or figures). It 
will be readily appreciated that by using the load detector such as a load 
cell with the full range, the accurate measurement can be achieved. In 
this example, actually, the dynamic load was measured with a load 
detection range whose full range was 200 g, and the batch load was 
measured with a load detection range whose full range was 20 kg. 
In the second type of flow meter of the invention, the magnitude of the 
impact load is relatively small. In this case, however, the ratio of the 
range may be, for example, about 1:100 if an additional static load is 
considered. 
In the flow meter system comprising a plurality of flow meters of the 
invention, preferably, the arithmetic and control unit of each of the 
plurality of flow meters has the normal operating mode for obtaining or 
finding the dynamic load-type flow rate, and the correction mode for 
obtaining or finding the correction factor, and the arithmetic and control 
units are connected to the centralized control unit which controls the 
arithmetic and control units in a centralized manner, and when the 
particulate material to be flown through the flow passage in at least one 
of the flow meters is changed to a different one, the centralized control 
unit supplies to the at least one flow meter a control signal so as to 
change the associated arithmetic and control unit from the normal 
operating mode to the correction mode. Therefore, there is no need to 
effect the correction operation by manually operating the corresponding 
flow meter each time the particulate material to be flown is changed to a 
different one. And besides, since the correction can be effected easily in 
a short time, the correction can be effected at least each time the 
particulate material to be flown is changed to a different one, and 
therefore the flow rate can always be measured correctly by all the flow 
meters in the system. Even when the particulate material to be flown is 
not changed to a different one, the flow rate (indication) correction of 
the flow meter or calibration thereof may be periodically effected in view 
of a change of environmental conditions and others. 
The foregoing and other objects, features and advantages of the invention 
will be made clearer hereafter from the description of preferred 
embodiments of the invention referring to attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A flow meter according to a first preferred embodiment of the invention 
will now be described with reference to FIGS. 1 to 7. 
In FIG. 1 showing a main portion of the flow meter 30, a 
vertically-extending, tubular member 3 of a desired length is supported, 
to be located below a lower end or downstream end of a stationary conduit 
2 forming a flow passage 1 for a particulate material G, by a stationary 
frame 21 of the flow meter 30 through load cells 4 and 5 serving as a load 
detector. A funnel-like reception portion 3a is formed at an upper end or 
upstream end of the tubular member 3. 
A movable valve device 10 in the form of a shut-off valve serving as an 
opening-closing valve is provided at a downstream end or discharge-side 
end 6 of the tubular member 3, and is operable to open and close a 
downstream end opening 7 at the downstream end of the tubular member 3. 
The movable valve device 10 includes an opening-closing valve member 9 
pivotally movable about a pivot shaft 11 in directions D and E between a 
closing position B (see FIG. 2) where the valve member 9 closes the 
downstream end opening 7 to shut off the flow passage 1 and an open 
position A (see FIG. 1) where the valve member 9 opens the downstream end 
opening 7 to open the flow passage 1. During a period of time when the 
opening-closing valve member 9 is held in the closing position B, the 
particulate material G is continuously deposited or accumulated on the 
opening closing valve member 9 within the tubular member 3. On the other 
hand, the opening-closing valve member 9, when held in the open position 
A, is inclined, that is, disposed obliquely generally across the flow 
passage 1 as shown in FIG. 1, and therefore when the opening closing valve 
member 9 is in the open position A, a downward-flow impact load of the 
particulate material G is continuously or constantly applied to the 
opening-closing valve member 9. In so far as the opening-closing valve 
member 9 can be located in the open position A and the closing position B, 
the manner of movement of this valve member 9 intermediate the two 
positions A and B, as well as the manner of supporting this valve member 
9, may be different from the above manner. Further, in so far as the 
downward-flow impact load, received by the opening-closing valve member 9 
in its open position A, can be detected by the load cells 4 and 5 as the 
load detector, the tubular member 3 may be inclined instead of extending 
in the vertical direction, and also may be curved at its lower end portion 
instead of being straight. In so far as the load detector (load cells 4 
and 5) can detect the total load applied to the tubular member 3 in the 
vertical direction, their detection principle and structure may be any 
suitable ones. The load detector may be constituted by the single load 
cell instead of plural load cells if appropriate arrangement of the 
associated members is taken for detecting the load thereon. 
The opening-closing valve member 9 is driven by drive means 12, such as a 
pneumatic cylinder, to be moved or displaced in the directions D and E 
between the open position A and the closing position B. A stopper or 
spacer 13 supports the opening-closing valve member 9 at its open position 
A, and when the opening-closing valve member 9 is opened through a desired 
angle F to the open position A, the stopper or spacer 13 supports the 
valve member 9 so that the valve member 9 can be maintained in the open 
position A against the downward-flow impact load of the particulate 
material G. The stopper or spacer 13 may be provided with a cushioning or 
shock-absorbing material. 
A solenoid valve 14 controls to drive the pneumatic cylinder 12 by means of 
compressed or pressurized air. The solenoid valve 14, constituting a part 
of the movable valve device 10, is connected to a drive control device 16 
which delivers, in response to an output signal of an arithmetic and 
control unit 15 such as a microprocessor, a signal for controlling to 
drive the pneumatic cylinder 12, as shown in FIG. 3. The load cells 4 and 
5 serving as the load detector are connected to the arithmetic and control 
unit 15. Where the load detector is of such a type as the load cell for 
delivering an analog signal, the load cells 4 and 5 as the load detector 
are connected to the arithmetic and control unit 15 such as the 
microprocessor through an A/D converter 17. An output range or span of 
each of the load cells are adjusted appropriately by a so called "span 
adjustment". A memory or storage device 18 is connected to the arithmetic 
and control unit 15. The memory device or unit 18 stores therein programs, 
including calculation formulas necessary for converting the magnitudes of 
the loads, represented by output signal of the load detector (load cells 4 
and 5), into flow rate values, and constant values necessary for the 
calculation formulae, a correction formula and a correction value etc. 
Detected data of the load detector 4 and 5 and results of calculation in 
the arithmetic and control unit 15 are also stored in a time series manner 
in the memory device 18. The memory device 18 includes a RAM and a ROM. 
Reference numeral 19 denotes a display unit capable of displaying the 
calculation results in terms of a calculation degree. 
Basically, the flow meter 30 according to the first preferred embodiment of 
the invention has the above construction. 
In an actual job site (processing plant) where the flow rate of a 
particulate material, such as rice grains and wheat grains, is 
continuously measured, a plurality of flow meters are often provided or 
installed in one system. One example of such a system, forming a 
modification of the first embodiment, is shown in FIG. 4. In the system 31 
of FIG. 4, for example, four arithmetic and control units 15a to 15d are 
connected to a centralized or central control unit 20 such as a 
microcomputer or a minicomputer. The data of flow meters 30a to 30d been 
given to the central control unit 20, the degree of opening of an 
opening-closing valve member (not shown in FIG. 4, but has a function 
substantially the same as that of a flow rate control gate mechanism 
described later in an embodiment of FIGS. 10 to 14), provided at an 
upstream portion of each of the flow meters 30a to 30d, is adjusted by the 
central control unit 20, thereby controlling all the flow rates in the 
system 20. 
Data of various kinds of raw particulate materials (that is, particulate 
materials G to be treated or processed) upon arrival at the processing 
plant are stored in the central control unit 20, and also information of 
what kind of raw particulate material G is flowing through a respective 
one of the flow meters is held by the central control unit 20, and this 
information is used when processing each raw particulate material G. 
When the central control unit 20 supplies or delivers to any of the 
arithmetic and control units 15a to 15d of the flow meters 30a to 30d a 
signal indicating that the raw particulate material G is changed to a new 
one, the arithmetic and control unit 15 of the designated flow meter 30 
confirms that the new particulate material G has flown thereinto, and then 
effects a correction of the flow rate or calibration of the flow meter in 
accordance with the invention. Alternatively, the central control unit 20 
may deliver a flow rate correction or calibration operation initiation 
instruction signal to the relevant arithmetic and control unit 15 so that 
this arithmetic and control unit 15 can effect a correction of the flow 
rate or a calibration in accordance with the invention. In the latter 
case, regardless of whether or not the kind of particulate material G, 
flowing through the flow passage 1, is changed, the correction of the flow 
rate in the flow meter or calibration thereof is effected at predetermined 
timings (for example, at predetermined time intervals). 
Next, a load conversion operation, and principles of calculation of a 
dynamic load-type flow rate and an actual flow rate, which are necessary 
for the correction of the flow rate in the flow meter 30 shown in FIGS. 1 
to 3 or the calibration thereof, will be described. 
When the opening-closing valve member 9 of the movable valve device 10 is 
in its open position A as shown in FIG. 1, a downward-flow impact load of 
the falling (or downwardly-flowing) particulate material G acts on the 
opening-closing valve member 9. This downward-flow impact load is detected 
by the load cells 4 and 5 in the form of a sum of loads applied to the 
load cells 4 and 5, and this downward-flow impact load, that is, the 
dynamic load, is converted into a flow rate, by a predetermined 
calculation formula. 
The mode or condition or state shown in FIG. 1 is a normal operating mode 
or condition or state (that is, a normal mode or condition or state of 
use) in which the flow rate of the particulate material G is measured 
while the particulate material G is flowing or passing through the flow 
meter 30, and this condition is a particulate material-flowing/flow 
rate-measuring mode. Analog signals, delivered from the load cells 4 and 5 
in accordance with the downward-flow impact load corresponding to the flow 
rate of the particulate material G, are converted by the A/D converter 17 
(FIG. 3), and are supplied as an impact load signal EA serving as the 
dynamic load signal to the arithmetic and control unit 15 (FIG. 3) and is 
converted therein into a flow rate value QA according to the impact load 
(dynamic load), by means of the following calculation formula 1: 
EQU QA=EA*a calculation 
formula 1 
where a represents a conversion factor for converting the impact load 
(dynamic load) into the flow rate. 
In FIG. 6 in which the abscissa axis represents time t, and the ordinate 
axis represents the dynamic load W acting on the load cells 4 and 5, 
regions indicated by "RA" are regions where the dynamic load consists 
essentially of the impact load, and a region indicated by "RB" is a region 
where the dynamic load consists essentially of the static load or weight. 
When the flow rate of the particulate material G is kept substantially 
constant, the dynamic load signal W from the load cells 4 and 5 hardly 
varies with time. Therefore, for example, if the output of the flow meter 
30 is adjusted such that a predetermined bias is beforehand applied to the 
output W of the load cells 4 and 5 so that the output W (=EA) of the load 
cells 4 and 5 can become zero in a condition where the opening-closing 
valve member 9 is in the open position A, and where the particulate 
material G is not flowing (that is, in a condition in which only the 
constantly acting static loads or weights of the tubular member 3, the 
opening-closing valve member 9, the pneumatic cylinder 12, etc., act on 
the load cells 4 and 5), the output W coincides with the impact load EA, 
and the flow rate value QA can be obtained merely by multiplying the 
impact load signal EA (corresponding to the output W representing the 
impact load (dynamic load)) by the conversion factor a. 
When the opening-closing valve member 9 of the movable valve device 10 is 
set to the closing position B as shown in FIG. 2, the falling (or 
downwardly-flowing) particulate material G is deposited or accumulated on 
the opening-closing valve member 9 within the tubular member 3. The total 
weight of the thus deposited particulate material G is sampled and 
detected at desired time intervals, and a change of the weight per unit 
time is found or calculated to obtain the actual flow rate. Namely, the 
condition or state shown in FIG. 2 is a condition or state in which the 
flow of the particulate material G is temporarily blocked or intercepted 
within the flow meter 30 so as to effect the correction of the flow rate 
or calibration, while keeping the flow rate of the particulate material G 
constant at the upstream side of the flow meter 30. Thus, this mode or 
condition or state is a flow rate correction or flow meter calibration 
mode. As in the normal mode, the analog signals from the load cells 4 and 
5 are converted by the A/D converter 17 (FIG. 3) into a static load or 
weight signal EB, representing the total weight of the deposited 
particulate material G, which signal is sent to the arithmetic and control 
unit 15 (FIG. 3) where the signal EB is converted into a weight Y by means 
of the following calculation formula 2: 
EQU Y=EB*b calculation 
formula 2 
where b represents a conversion factor for converting the output in the 
static load or weight measurement range of the load cells 4 and 5 into the 
actual weight. 
The actual flow rate QB is obtained from weight values Y1 and Y2, measured 
respectively at consecutive sampling times X1 and X2, by means of the 
following calculation formula 3: 
EQU QB=(Y2-Y1)/(X2-X1) calculation 
formula 3 
During the time period indicated by the region RB in FIG. 6, the weight W 
(expressed by Y in terms of a scale) increases as the amount of deposition 
or accumulation of the falling particulate material G increases. 
Therefore, based on the information of the weight Y1 at time X1 and the 
information of the weight Y2 at time X2, the actual flow rate QB is 
obtained by the calculation formula 3. 
Before describing details of the correction of the flow rate in the flow 
meter 30 or the calibration thereof, basic principles of the correcting or 
calibrating operation will first be described briefly. 
Since the flow of the same particulate material G through the same flow 
passage 1 is measured, the impact load flow rate value (dynamic load-type 
flow rate value) QA should essentially or inherently coincide with the 
actual flow rate value QB obtained from the static load or weight. The 
actual flow rate value QB is obtained by the measurement according to the 
definition of the weight flow rate or mass flow rate, and therefore it is 
thought that in so far as the calibration of each associated apparatus 
itself is effected properly, the actual flow rate value QB is an accurate 
value independent of the material to be measured. On the other hand, the 
dynamic load-type flow rate value QA can vary depending on various 
factors, of the material to be measured, such as bulk specific gravity and 
resiliency; however, so far as the same material to be measured is 
concerned, the dynamic load-type flow rate value QA increases as the 
actual flow rate increases. Namely, the dynamic load-type flow rate value 
QA has a positive correlation with to the actual flow rate QB, and also is 
virtually proportional to the actual flow rate QB as shown in FIG. 5. 
Therefore, the relation, indicated by the following equation or 
calculation formula 4, can be established: 
EQU QA=k*QB calculation 
formula 4 
where k represents a correction factor. 
A dynamic load-type or impact load-type flow rate value QAc after the 
correction or calibration can be obtained from the following calculation 
formula 5 derived from the calculation formulae 1 and 4: 
EQU QAc=QA*k 
EQU QAc=EA*a*k calculation 
formula 5 
where k represents the flow rate correction factor, a represents the 
conversion factor, and EA represents the impact load signal, as described 
above. 
Therefore, if it is desired to provide a correction processing loop to be 
continuously executed according to a computer program, a is replaced by 
"a*ku". 
Now, the flow rate correction or flow meter calibration operation in the 
flow meter 30 will be described in detail with reference to FIGS. 6 and 7. 
Normally, the flow meter 30 is operating in the mode to continuously detect 
the impact load as the dynamic load. Therefore, the impact load signal EA 
is constantly inputted as shown in Step S1, and the dynamic load-type flow 
rate QA is constantly calculated or found by the calculation formula 1 as 
shown in Step S2. 
In Step S3, it is always checked by the arithmetic and control unit 15 of 
the flow meter 30 whether or not the raw particulate material G is changed 
and also whether or not there is an instruction that the correction 
calculation should be effected, and as long as these events or situations 
do not occur, the program or processing returns to Step 1, i.e. Step Sl 
and Step S2 are repeated. Where the plurality of flow meters 30a, 30b,. . 
. are connected to the central control unit 20 as described above with 
reference to FIG. 4, information indicating the occurrence of the 
above-mentioned events or situations can be given from the central control 
unit 20 to corresponding one or ones of the flow meters 30a -30d. If the 
signal representative of the change of the raw particulate material G, or 
the flow rate correction calculation initiation instruction signal is 
produced, the program proceeds to a flow rate correction or calibration 
processing routine of infra Step S4. 
When the program processing proceeds to the correction processing routine, 
the detection of the dynamic load or impact load is not effected, and 
therefore during a period of time (corresponding to a time period T3 in 
FIG. 6) before the program exits from the correction processing routine, 
that is, when the correction processing is being effected, there is used 
the impact load signal EA obtained immediately before the program enters 
the correction processing routine, whereby even when the plurality of flow 
meters are monitored and controlled by the central control unit 20, the 
central control unit 20 can continue to control all of the flow rates in 
the system. 
In a case where the flow meter 30 is so constructed that the ratio of the 
impact load to the batch load is substantially 1:100 as described above, 
and for example, if the impact load is about 150 g, i.e. 150 gram-force, 
with the flow rate of 5 tons/hour, then the batch load amounts to about 14 
kg for ten seconds. When trying to process the signal of such a wide range 
by one amplifier, there is a possibility that the precision of measurement 
of the impact load is lowered. Therefore, in Step S5, the measurement 
range is switched from a gram unit for the impact load to a kilogram unit 
for the batch load. Namely, the measurement range is switched from the 
measurement range for the region RA (FIG. 6) to the measurement range for 
the region RB. 
In Step S6, the opening-closing valve member 9 of the movable valve member 
10 is switched from the open position A to the closing position B, and 
simultaneously with this switching operation, time T is reset to 0, and 
time (time period) T after setting the opening-closing valve member 9 to 
the closing position B is measured. 
When the opening-closing valve member 9 is set to the closing position B, 
the total load of the falling particulate material G acts on the 
opening-closing valve member 9, and the output of the load detector 4 and 
5 are not stable at first due to vibrations etc. In an example in Step S7, 
it is estimated that stability time period or stabilizing time period T1 
required for extinction or elimination of the disturbance such as the 
vibrations is 3 seconds. 
In Step S8, based on a first point of time X1 for weight measurement, after 
the elapse of time T1 and the output EB1 of the load cells 4 and 5 at the 
time point X1, the time point X1 and a weight value Y1 at this time point 
X1 are obtained. 
With the elapse of time T, the amount of deposited or accumulated the 
particulate material G (having flown through the flow passage 1) on the 
opening-closing valve member 9 within the tubular member 3 increases, so 
that the load acting on the load cells 4 and 5 increases. If the flow rate 
is constant, the flow rate can be found by measuring the weight of the 
deposited or accumulated particulate material G. In Step S9, it is judged 
whether or not the elapse of time T is 8 seconds. 
In Step S10, a time point X2 after time T elapses 8 seconds (X2=8 if X1 is 
set to 0 in Step S8), as well as a weight value Y2 derived from the output 
EB2 of the load cells 4 and 5 at this time point X2, is obtained. 
In Step S11, the actual flow rate QB is derived or calculated from the 
calculation formula 3. If desired, a zero or reference point for the 
output EB1, EB2 of the load cells 4 and 5, from which the actual flow rate 
QB is derived, may not be adjusted because only the difference of 
therebetween is effective as apparent from the calculation formula 3. 
In Step S12, the flow rate correction factor k is derived or calculated 
from one form of the calculation formula 5, and the dynamic load-type flow 
rate QAc after the correction or calibration is derived or calculated from 
another form of the calculation formula 5 by using this flow rate 
correction factor k. 
If the same flow rate correction is utilized until the next flow rate 
correction operation is effected, the conversion factor a is replaced by 
a*k in the program processing operation as shown in Step S13. 
When the flow rate correction calculation is completed, the opening-closing 
valve member 9 of the movable valve device 10 is returned to the open 
position A as shown in Step S14. As a result, the particulate material G, 
having been deposited or accumulated on the opening-closing valve member 9 
within the tubular member 3, drops, so that the flow meter 30 is returned 
to the condition in which the opening-closing valve member 9 receives the 
normal impact load. In this case, also, the output of the load cells 4 and 
5 becomes unstable at first because of an abrupt load change, and 
therefore although not shown in the flow chart of FIG. 7, preferably 
stability time or stabilizing time T2 as shown in FIG. 6 is preserved. 
After the output of the load cells 4 and 5 becomes stable, the load 
detection range is returned from the measurement region RB, corresponding 
to the kg-unit range, to the measurement region RA corresponding to the 
gram-unit range, and the operation control is returned to the normal mode 
or routine (that is, to Step S1) in which the impact load (dynamic load) 
is detected. 
In the above arithmetic and control unit 15 such as a microprocessor, the 
processing Step S2 of the program therein corresponds to a function of 
dynamic load flow rate calculation means of the flow meter 30, and the 
processing Steps S5 to Sll of the program correspond as a whole to a 
function of actual flow rate calculation means of the flow meter 30, and 
the processing Step S12 of the program corresponds to a function of means 
for calculating the correction factor of the flow meter 30. These are 
quantitative calculations of physical quantities, and therefore in so far 
as mathematically- or algebraically-equivalent quantities can be derived, 
their specific calculation procedures may be changed as desired. 
In the flow meter 30 of the above construction and the system 31 including 
the plurality of flow meters 30, when correction of the dynamic load-type 
flow rate value QA in the impact load detection-type flow meter, i.e. flow 
meter 30 in the normal mode, to make it equal to the actual flow rate OB 
determined from the measured weight can be effected automatically without 
requiring any manual labor or operation. And besides, when it becomes 
necessary to correct the flow rate indication or calibrate the flow meter 
as a result of change of the raw particulate material G, this correction 
or calibration can be effected substantially promptly. Therefore, the more 
precise flow rate measurement can be made constantly as compared with the 
conventional impact load detection-type flow meters. Moreover, in the flow 
meter 30, the movable valve device 10, having the opening-closing valve 
member 9, the load detector constituted by the load cell 4 and 5, and the 
arithmetic and control unit 15 are combined together as if an impact load 
detection-type flow meter and an actual flow rate meter are formed on the 
common tubular member 3, and the construction of the flow meter is 
relatively simple. 
In addition, as the measurement ranges for the load cells 4 and 5 as a load 
detector, there are provided two ranges, that is, the larger range for the 
detection of the static load or weight and the smaller range for the 
detection of the impact load, and therefore the detection of the load can 
be always effected over substantially the full range or span of the load 
cells 4 and 5, so that the accurate load output can be obtained. 
Furthermore, the plurality of arithmetic and control units 15a, 15b, . . ., 
of the plurality of flow meters 30a, 30b, . . . installed in a processing 
plant, are connected to the central control unit 20, and the flow rate of 
each of the flow meters is automatically corrected in response to the 
signal from the central control unit 20. Therefore, in accordance with the 
change of the raw particulate material G or with a predetermined condition 
(for example, at predetermined time intervals), the correction operation 
initiation instruction signal etc. can be delivered to a respective one of 
the flow meters 30a, 30b, . . ., and therefore there is no need to control 
the flow meters 30a, 30b, . . . individually of one another by a manual 
labor or operation, and the continuous detection of the flow rate by the 
detection of the dynamic load can be constantly made accurately. 
Next, a flow meter according to a second preferred embodiment of the 
invention will be described with reference to FIGS. 8 and 9. 
In FIGS. 8 and 9, the flow meter 60 comprises a particulate material supply 
portion 41, a particulate material flow rate detection portion 42, a 
particulate material flow rate calculation and correction control portion 
43, and a particulate material discharge portion 44. A flow passage 45 for 
a particulate material G is formed in the flow meter 60 to extend from the 
supply portion 41 through the particulate material detection portion 42 
down to the particulate material discharge portion 44. 
A first inclined flow passage portion 46 for guiding the particulate 
material G supplied from a hopper etc. (not shown) is provided in the 
particulate material supply portion 41, and also a second inclined flow 
passage portion 48 is formed in the supply portion 41. The second inclined 
flow passage portion 48 extending in a direction substantially 
perpendicular to the first inclined flow passage portion 46 is connected 
to the first inclined flow passage portion 46 by a gently-curved flow 
passage portion 47. An inclined guide plate or flow-down plate 49 is 
mounted in a stationary manner on a flow meter frame 59 to form the second 
inclined flow passage portion 48. 
The flow rate detection portion 42 comprises a load-receiving plate-like 
member 50, which is provided in an inclined manner in the flow passage 45 
for the particulate material G so as to receive a dynamic load 
corresponding to the flow rate of the particulate material G passing 
through the flow passage 45, a load cell 51 serving as a load detector for 
detecting a magnitude of the load received by or applied to the 
load-receiving plate-like member 50, and a weir member 52 movable between 
a block position H where the weir member 52 intercepts or blocks the flow 
of the particulate material G at a downstream region of the load-receiving 
plate-like member 50 and an open position J where the weir member 52 
allows the particulate material G to flow or pass. 
The load-receiving plate-like member 50 is supported by the load cell 51 in 
such a manner that the plate-like member 50 is spaced by a predetermined 
distance or height L vertically downwardly from the inclined guide plate 
49 of the supply portion 41 in generally or substantially parallel 
relation thereto. Therefore, the particulate material G, flowing over the 
inclined guide plate 49 along the second inclined flow passage portion 48 
of the flow passage 45, falls a distance not smaller than L from a 
downstream end 49a of the guide plate 49 to the plate-like member 50, so 
that the plate-like member 50 is subjected to a drop impact corresponding 
to the flow rate of the particulate material G. 
When the weir member 52 is disposed in the open position J indicated by 
phantom lines in FIG. 8, the particulate material G, having dropped on the 
load-receiving plate-like member 50, flows down over the plate-like member 
50 along a flow passage 53 defined by the plate-like member 50, and is 
discharged to the exterior through the discharge portion 44, at a bottom 
portion of the frame 59 of the flow meter 60, constituted by a discharge 
tube and a bellows 58 for preventing the particulate material G from 
dissipation. At this time, similarly to the load cells 4 and 5 of the flow 
meter 30 of the first embodiment as described above, the load cell 51 
serving as the load detector receives not only an impact load EAf1 
proportional to the flow rate of the particulate material G dropping on 
the plate-like member 50, but also a substantially static load EAf2 
corresponding to the amount of the particulate material G present on the 
plate-like member 50 upon flowing down thereover. Therefore, when the 
particulate material G is flowing continuously, the load cell 51 receives 
a total load EAf of a magnitude equal to (EAf1+EAf2). The magnitude of the 
dynamic impact load EAf1 depends on various factors such as the weight 
flow rate (mass flow rate) of the particulate material G, the height L and 
the angle M of inclination of the load-receiving plate-like member 50. On 
the other hand, the magnitude of the static load EAf2 depends not only on 
an inclined angle T of the load-receiving plate-like member 50 but also on 
the weight of the particulate material G present on the plate-like member 
50 upon flowing thereover. This weight of the particulate material G, in 
turn, depends on a length of the plate-like member 50, and a thickness of 
a layer of the particulate material G on the plate-like member 50 (in 
other words, a stacked height of the particulate material G at the flow 
passage portion 48) etc. The ratio between magnitudes of these two kinds 
of loads EAf1 and EAf2 is determined appropriately, and may be determined 
in view of the technique disclosed in Japanese Patent Unexamined 
Publication No. 63-195524 described above as the prior art and 
incorporated herein by reference thereto, if necessary. If a suitable zero 
point adjustment is made for the dynamic load EAf, this dynamic load EAf 
can be treated in the similar manner to the dynamic load EA (impact load) 
in the flow meter 30 according to the first embodiment. The inclination 
angle T of the plate-like member 50 is about 45 degrees in the example 
illustrated in FIG. 8, while this angle T may be selected freely as 
desired so long as the particulate material G can flow down thereover or 
therealong, i.e. this angle T may be greater or smaller than 45 degrees, 
and may be greater or smaller than the angle of inclination of the 
flow-down plate 49. 
On the other hand, when the weir member 52 is disposed in the closing 
position H indicated by solid lines in FIG. 8, the particulate material G, 
having fallen on the load-receiving plate-like member 50, is blocked or 
intercepted by the weir member 52, and is therefore deposited or 
accumulated on the plate-like member 52. A change of a load EBf, acting on 
the load cell 51 in accordance with this deposition or accumulation, is 
substantially similar to a change of the load EB acting on the load cells 
4 and 5 in the closing position of the opening-closing valve member 9 of 
the flow meter 30 according to the first embodiment. 
Reference numeral 54 denotes guide members, such as rollers, for guiding 
the vertical (upward and downward) movement or displacement of the weir 
member 52 between the open position J and the closing position H. 
Similarly to the opening-closing valve member 9 of the flow meter 30 
according to the first embodiment, the weir member 52 is connected to 
drive means 55 (which comprises a solenoid valve and a pneumatic cylinder) 
driven under the control of the arithmetic and control unit 43, and the 
weir member 52 is moved upward or downward when a piston rod of the 
pneumatic cylinder of the drive means 55 is contracted or extended. In the 
flow meter 60 according to this embodiment, so long as the opening and 
closing of the flow passage is concerned, the weir member 52 replaces the 
opening-closing valve member 9 of the flow meter 30 according to the first 
embodiment. The pneumatic cylinder drive means 55 may be replaced by any 
other appropriate drive means such as an electric motor which drives and 
rotates at least one of the guide rollers 54. 
The arithmetic and control portion 43, constituted by a microprocessor 
etc., serving as the arithmetic and control unit is designed substantially 
similarly to the arithmetic and control unit 15 of the flow meter 30 
according to the first embodiment, and utilizing the relations and 
characteristics shown in FIGS. 5 and 6, a dynamic load-type flow rate QA, 
an actual flow rate QB and a flow rate correction factor k are calculated 
or obtained from the dynamic load EAf (corresponding to EA) and the static 
load or weight EBf (corresponding to EB) in accordance with a procedure 
similar to that shown in FIG. 7. Therefore, this flow meter 60 can be also 
configured as in FIG. 3, and can support a system including a plurality of 
flow meters as in FIG. 4. In FIGS. 8 and 9, reference numeral 56 denotes a 
display portion corresponding to the display unit 19 of the flow meter 30. 
The flow meter 60 may be provided with a supply control portion for 
adjusting or controlling the flow rate of the particulate material G to be 
supplied or fed to the flow rate detection portion 42. 
Next, with reference to FIGS. 10 to 13, description will be made of a flow 
meter 90 in which a particulate material flow rate-adjusting gate is 
further provided in the particulate material supply portion of the flow 
meter shown in FIGS. 8 and 9. 
The flow meter 90, schematically shown in FIGS. 10 and 11, includes a flow 
rate-adjusting gate mechanism 63 in a particulate material supply portion 
61 corresponding to the particulate material supply portion 41 of the flow 
meter 60, and this gate mechanism 63 controls the flow or supply of a 
particulate material G into a flow passage portion 62 corresponding to the 
flow passage portion 48. The flow meter 90 is substantially identical in 
construction or structure to the flow meter 60 except that the particulate 
material supply portion 61 with the flow rate-adjusting gate mechanism 63 
replaces the particulate material supply portion 41 and that an arithmetic 
and control unit 43 has a control processing function of controlling the 
supply of the particulate material G by the flow rate-adjusting gate 
mechanism 63. Therefore, only these differences will be described below in 
detail. 
As schematically shown in FIGS. 10 and 11, the flow rate-adjusting gate 
mechanism 63 comprises an electric motor 64, and a pivotally movable gate 
member 67 which is pivotally moved or displaced in directions M and N by 
the electric motor 64 to change a degree S of opening (or flow area) of a 
flow passage portion 66 so as to adjust the flow rate of the particulate 
material G from a particulate material reservoir 65 to the flow passage 
portion 62. 
More specifically, the flow rate-adjusting gate mechanism 63 has, for 
example, a construction or structure shown in FIGS. 12 and 13. 
In FIGS. 12 and 13, a frame 68 of the flow rate-adjusting gate mechanism 63 
is fixedly mounted on the frame 59 of the flow meter 90, and has a lower 
end 70 open to the flow passage portion 62. A particulate 
material-supplying, tubular portion 71 having a square cross-section, 
decreasing in cross-sectional area progressively toward a lower end 
thereof, is fixedly secured to the frame 68. An outlet opening 73 is 
formed at the lower end of the particulate material-supplying, square 
tubular portion 71, and has an arcuate lower edge 72 forming a part of a 
circle around a center P (FIG. 13). The gate member 67, having a generally 
sector-shape as viewed from the side thereof and U-shaped bridge-like 
configuration, is mounted to be outside of the lower edge or end portion 
72 and an outer side edge portion 75 of the square tubular portion 71 so 
that the gate member 67 can be pivotally moved in the directions M and N 
about a shaft 74 with an axis passing through the center point (or center 
line) P. The gate member 67 has a gate plate portion 77 at a generally 
partially cylindrical portion 76 having an arcuate shape as seen in FIG. 
13. Radially extending portions 78 and 79, at upper and lower edges, of 
the gate member 67 are opened. Link members 80 and 81 are adapted to 
displace the gate member 67 pivotally in the directions M and N around the 
shaft 74 in response to forward and backward rotation of an output shat of 
the motor 64. When the gate member 67 is fully displaced in the direction 
N to be disposed to a position Q shown by solid lines in FIG. 13, the 
opening 73 is completely closed by the gate plate portion 77 of the gate 
member 67, so that the particulate material G will not flow out of the 
supply portion 61. On the other hand, when the gate member 67 is fully 
displaced in the direction M to be disposed in a position R shown by 
phantom lines in FIG. 13, the opening 73 is completely opened, so that the 
flow rate of the particulate material G through the opening 73 becomes 
maximal. A magnitude S of the opening or aperture 73 which is not closed 
or blocked by the gate member 67 can be changed, according to the 
position, of the gate member 67, between the positions Q and P to be 
defined in response to forward (normal)/backward (reverse) rotation of the 
motor 64, to thereby change or adjust the flow rate of the particulate 
material G from the not-closed or blocked part of the opening 73. 
The flow rate adjustment gate mechanism 63 may be of any shape other than 
that shown in FIGS. 10 to 13, so long as the flow rate of the particulate 
material G from the supply portion can be adjusted or controlled. 
It will be apparent that the flow meter 90 with the supply gate can be 
operated in the similar manner to the flow meter 60 shown in FIGS. 8 and 9 
in a case where the degree S of opening at the opening or aperture 73 to 
be defined by the gate member 67 of the gate mechanism is set to a fixed 
level or magnitude. 
In this flow meter 90, the following control may be employed. As shown in 
FIG. 14, a flow rate QA in accordance with a dynamic load, i.e., dynamic 
load-type flow rate QA, detected by a load cell 51 serving as the load 
detector, is corrected in accordance with the procedure shown in FIG. 7, 
and then the opening degree S at the opening 73 of the flow rate-adjusting 
gate mechanism 63 in the open condition of this flow rate-adjusting gate 
mechanism 63 is controlled, so that the corrected dynamic load-type flow 
rate QAc can coincide with a predetermined target flow rate value Qt. by a 
flow rate-setting control portion 85 additionally provided in the 
arithmetic and control unit 43 in association with a corrected flow rate 
calculation portion 84. 
The flow rate-adjusting gate mechanism 63 may be also provided in the flow 
meter 30 of the first embodiment shown in FIGS. 1 and 2 as having 
described above with reference to FIG. 4, so that the flow rate (opening 
degree S) can be controlled as described with reference to FIG. 14.