Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2001-02-28
2003-07-01
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
Reexamination Certificate
active
06587797
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid consumption amount-measuring method and an apparatus for the same, for measuring a consumption amount of a fluid such as compressed air in a fluid-operated apparatus.
2. Description of the Related Art
The fluid-operated apparatus is widely used, for example, in the production steps. Usually, the fluid-operated apparatus is constructed such that the pressure fluid is not consumed when the operation is stopped. However, in some cases, the pressure fluid leaks, for example, due to any damage of piping and packing.
A flow rate-measuring apparatus has been hitherto used in order to measure the consumption amount brought about by the leakage of the pressure fluid as described above. The flow rate-measuring apparatus includes, for example, differential pressure flow meters, ultrasonic flow meters, turbine flow meters, hot-wire flow meters, orifice flow meters, and float flow meters.
Explanation will now be made for a case in which the consumption amount of the pressure fluid is measured by using the differential pressure flow meter. As shown in
FIG. 8
, the flow rate-measuring apparatus
10
comprises a throttle
16
having a known cross-sectional area arranged between a pressure fluid supply source
12
for constructing a fluid pressure system
11
and a fluid-operated apparatus
14
as a measurement objective. Pressure gauges
18
,
20
are connected on the upstream and downstream sides of the throttle
16
respectively. The amount of the pressure fluid passing through a throttle
22
arranged in the fluid-operated apparatus
14
corresponds to the consumption amount of the pressure fluid consumed by the fluid-operated apparatus
14
.
When the consumption amount of the pressure fluid consumed by the fluid-operated apparatus
14
is measured, the pressure fluid supply source
12
is firstly operated to supply the pressure fluid via the throttle
16
to the fluid-operated apparatus
14
. During this process, the pressure of the pressure fluid, which is measured by the downstream pressure gauge
20
, is inversely proportional to the effective cross-sectional area of the throttle
22
of the fluid-operated apparatus
14
. All of the pressure fluid, which flows through the fluid-operated apparatus
14
, is supplied via the throttle
16
. Therefore, the flow rate of the pressure fluid flowing through the throttle
16
is equal to the flow rate of the pressure fluid supplied to the fluid-operated apparatus
14
.
Accordingly, the flow rate of the pressure fluid flowing through the throttle
16
is determined from the pressures of the pressure fluid measured by the pressure gauges
18
,
20
respectively and the effective cross-sectional area of the throttle
16
. The effective cross-sectional area of the throttle
22
is determined from the flow rate and the pressure of the pressure fluid measured by the downstream pressure gauge
20
. Thus, it is possible to determine the flow rate, i.e., the consumption amount of the pressure fluid flowing through the throttle
22
of the fluid-operated apparatus
14
, from the effective cross-sectional area of the throttle
22
and the pressure of the pressure fluid measured by the upstream pressure gauge
18
.
However, it is considerably difficult to measure the consumption amount brought about by the leakage, by using the flow rate-measuring apparatus
10
as described above. That is, in order to measure the consumption amount of the fluid-operated apparatus
14
highly accurately, it is necessary to select the flow rate-measuring apparatus
10
which has a measuring range in conformity with the degree of the consumption amount. However, the degree of the consumption amount, which is brought about by the leakage of the fluid to be measured, is usually unclear.
Therefore, in order to select the flow rate-measuring apparatus
10
having an optimum measuring range, it is also considered that a trial and error process is performed to attach and detach one selected from a plurality of flow rate-measuring apparatuses
10
having different measuring ranges with respect to the fluid pressure system
11
. However, the attachment and detachment operation is extremely complicated. Further, the flow rate-measuring apparatus
10
itself is considerably expensive. Therefore, such a process is not considered to be an appropriate practical method.
Further, as shown in
FIG. 8
, when the flow rate-measuring apparatus
10
is constructed and connected in series on the upstream stage of the fluid-operated apparatus
14
for constructing the fluid pressure system
11
to measure the consumption amount brought about by the fluid-operated apparatus
14
, for example, it is necessary to set a small effective cross-sectional area of the throttle
16
of the flow rate-measuring apparatus
10
in order to measure a small consumption amount highly accurately. As a result, the flow resistance of the pressure fluid becomes large. Therefore, it is difficult to perform the driving operation by supplying a predetermined amount of the pressure fluid to the fluid-operated apparatus
14
while still installing such a flow rate-measuring apparatus
10
after the measurement of the consumption amount.
Another arrangement is known as shown in FIG.
9
. That is, a stop valve
24
is provided between a pressure fluid supply source
12
and a fluid-operated apparatus
14
. A bypass, which comprises a stop valve
26
, a flow rate-measuring apparatus
10
, and a stop valve
28
, is provided between upstream and downstream portions with respect to the stop valve
24
. In this arrangement, the stop valves
24
,
26
,
28
are switched so that the pressure fluid may be supplied to the fluid-operated apparatus
14
via the flow rate-measuring apparatus
10
when the consumption amount is measured, while a predetermined amount of the pressure fluid may be directly supplied to the fluid-operated apparatus
14
while still installing the flow rate-measuring apparatus
10
when the fluid-operated apparatus
14
is driven and operated.
However, even in the case of this arrangement, it is necessary to perform the operation for selecting the flow rate-measuring apparatus
10
having an optimum measuring range in order to measure the consumption amount highly accurately. Therefore, the problem described above cannot be solved.
The present invention has been made in order to solve the problems as described above, an object of which is to provide a fluid consumption amount-measuring method and an apparatus for the same in which the operation including, for example, attachment and detachment to a fluid pressure system is easy, and the consumption amount due to the leakage of a pressure fluid or the like can be easily measured, making it possible to perform highly accurate measurement irrelevant to the measuring range of the consumption amount.
SUMMARY OF THE INVENTION
According to the present invention, even when the measuring range of the consumption amount in the fluid-operated apparatus is unknown, the pressure values P
1
, P
2
, P
3
on the downstream side of a stop valve are measured and calculated respectively. Thus, it is possible to conveniently measure the consumption amount of the pressure fluid flowing through the fluid-operated apparatus.
Any one of the pressure value P
2
and the pressure value P
3
may be determined earlier. When the pressure values P
1
, P
2
, P
3
on the downstream side of the stop valve are measured respectively, then the pressure drop is increased, and the measurement time is shortened by previously releasing a part of the pressure fluid in a forcible manner by the aid of another valve having a known effective cross-sectional area.
According to another aspect of the present invention, it is unnecessary that the fluid consumption amount-measuring apparatus is provided at an intermediate portion of a piping tube extending from a pressure fluid supply source to the fluid-operated apparatus. Therefore, it is easy to attach and detach the fluid consumption amount-measuring apparatus.
Hayakawa Nozomi
Kamada Yuji
Nakamura Kazuo
Sato Nobue
Sato Wataru
Barlow John
Guss Paul A.
Lau Tung
Sato Nobue
SMC Kabushiki Kaisha
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