Abstrict This ultrasonic flow meter is provided for measuring flow volume
by determining the flow rate of a liquid from the difference in
propagation times of ultrasonic waves in both directions between
measuring units by providing measuring units having transducer at
an interval in the lengthwise direction on a measuring pipe through
which liquid flows. A pair of mounting members are provided in a
lower case of a case serving as a base at an interval wider than
that of measuring units. The measuring pipe is held by respective
retaining indentations to the outside in the axial direction of
measuring units by facing a left mounting member and a right mounting
member that compose the mounting members. In addition, an insulating
material is filled into the case so as to cover the measuring units
and the measuring pipe.
Claims What is claimed is:
1. An ultrasonic flow meter comprising: a measuring pipe through
which a liquid flows; and two measuring units provided on said measuring
pipe at an interval in its lengthwise direction, and which measures
flow volume by determining the flow rate of a liquid from the difference
in propagation times of ultrasonic waves in both directions between
these measuring units; wherein, said measuring pipe is supported
on a support stand, on which a pair of mounting units are provided
on a base at a wider interval than said measuring units, by retaining
said measuring pipe in said mounting units at the outside of said
measuring units in an axial direction of said measuring pipe.
2. An ultrasonic flow meter according to claim 1 wherein said
mounting units have a first mounting member and a second mounting
member that are fixed to be mutually facing, and retaining indentations
in the shape of a circular arc, which form an opening that holds
the outer periphery of said measuring pipe when mutually facing,
are formed in these first and second mounting members.
3. An ultrasonic flow meter according to claim 2 wherein the inner
diameter of said opening formed from said retaining indentations
is slightly smaller than the outer diameter of said measuring pipe.
4. An ultrasonic flow meter according to claim 3 wherein said
retaining indentations are formed to have a rugged surface, in order
to reduce external vibrations.
5. An ultrasonic flow meter according to claim 4 wherein the surface
of said retaining indentations has a rugged shape as a result of
forming engaging grooves along the peripheral direction.
6. An ultrasonic flow meter according to claim 5 wherein said
engaging grooves are V-shaped grooves.
7. An ultrasonic flow meter according to claim 6 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
8. An ultrasonic flow meter according to claim 5 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
9. An ultrasonic flow meter according to claim 2 wherein said
retaining indentations are formed to have a rugged surface, in order
to reduce external vibrations.
10. An ultrasonic flow meter according to claim 9 wherein the
surface of said retaining indentations has a rugged shape as a result
of forming engaging grooves along the peripheral direction.
11. An ultrasonic flow meter according to claim 10 wherein said
engaging grooves are V-shaped grooves.
12. An ultrasonic flow meter according to claim 11 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
13. An ultrasonic flow meter according to claim 10 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
14. An ultrasonic flow meter according to claim 1 wherein said
mounting units have a lower mounting member and an upper mounting
member fixed to be mutually facing above and below, and retaining
indentations in the shape of a circular arc, which form an opening
that holds the outer periphery of said measuring pipe when mutually
facing, are formed in these lower and upper mounting members.
15. An ultrasonic flow meter according to claim 14 wherein the
inner diameter of said opening formed from said retaining indentations
is slightly smaller than the outer diameter of said measuring pipe.
16. An ultrasonic flow meter according to claim 14 wherein said
retaining indentations are formed to have a rugged surface, in order
to reduce external vibrations.
17. An ultrasonic flow meter according to claim 16 wherein the
surface of said retaining indentations has a rugged shape as a result
of forming engaging grooves along the peripheral direction.
18. An ultrasonic flow meter according to claim 17 wherein said
engaging grooves are V-shaped grooves.
19. An ultrasonic flow meter according to claim 18 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
20. An ultrasonic flow meter according to claim 17 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
21. An ultrasonic flow meter according to any one of claims 1 to
7 wherein an insulating means that suppresses the transfer of heat
from the outside is provided covering said measuring units.
22. An ultrasonic flow meter according to claim 21 wherein said
insulating means is composed of an insulating material.
23. An ultrasonic flow meter according to claim 22 wherein said
insulating means is a case that houses said measuring units and
functions as said support stand.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ultrasonic flow meter that
measures the flow volume of a liquid flowing through a pipe using
ultrasonic waves.
2. Description of the Related Art
An ultrasonic flow meter is known in the prior art that uses ultrasonic
waves to function as a flow meter that measures the flow volume
of a liquid flowing through a pipe.
This ultrasonic flow meter provides two measuring units having
a transducer at an interval in the lengthwise direction on a measuring
pipe through which liquid flows. Ultrasonic waves are emitted from
one of the transducers which are then received by the other transducer.
Alternatively, ultrasonic waves are emitted from the other transducer
and then received by the first transducer. The flow rate of the
liquid in the measuring pipe is determined from the difference in
propagation times of these ultrasonic waves, and flow volume is
then measured from this flow rate.
However, if this ultrasonic flow meter is subjected to vibrations
from the outside between the respective measuring units, measurement
error occurring resulting in fluctuations in characteristics of
the measurement data and causing problems that the flow volume cannot
be measured accurately.
In addition, since the acoustic velocity, namely the velocity of
the ultrasonic waves, changes according to the temperature of the
liquid, it is necessary to measure flow volume using a conversion
value corresponding to the temperature of the liquid. However, if
ultrasonic waves emitted from the transducer are influenced by factors
other than the temperature of the liquid, such as the outside ambient
temperature, although the flow volume was corrected by converting
according to the temperature of the liquid, there is the problem
that the acoustic velocity is changed due to slight changes in temperature
and the flow volume cannot be measured accurately.
The following provides a detailed explanation of changes in the
acoustic velocity caused by changes in the temperature of the liquid
using the drawings.
FIG. 9 is a graph showing the relationship between the temperature
(.degree. C.) of water (liquid) and the acoustic velocity (m/s).
In addition, FIG. 10A is a graph showing the change in a reference
flow volume for each passage of time T in the case of a water temperature
of 20.degree. C., while FIG. 10B is a graph showing the output of
the transducers relative to the reference flow volume of FIG. 10A.
In addition, FIG. 11A is a graph showing the change in a reference
flow volume for each passage of time T in the case of a water temperature
of 29.degree. C., while FIG. 11B is a graph showing the output of
the transducers relative to the reference flow volume of FIG. 11A.
Furthermore, the units of flow volume Q and the reference flow
volume shown in FIGS. 10A and 11A indicate flow volume per minute
(mL/min), and the reference flow volume indicates the flow volume
flowing through the measuring pipe of the ultrasonic flow meter
obtained with a calibrated flow meter.
Conversion values of flow volume relative to the output of the
transducers are obtained from the graphs shown in FIGS. 9 through
11B.
It is generally known that the acoustic velocity of ultrasonic
waves output from the transducers changes considerably according
to the temperature of the liquid, and can be represented in the
graph showing the relationship between temperature and the acoustic
velocity of FIG. 9. According to the graph shown in FIG. 9 the
acoustic velocity can be seen to increase the higher the temperature
of the liquid.
In consideration of this change in the acoustic velocity due to
temperature, as shown in the graph of FIG. 10A, water at a temperature
of 20.degree. C. is allowed to flow in two stages of 1000 mL and
500 mL per minute from time 0 through the measuring pipe of the
ultrasonic flow meter using the reference flow meter. For the flow
volume of the former first stage, the water is allowed to flow for
time interval T1 and for the flow volume of the latter second stage,
water is allowed to flow for time interval T2 so as to be continued
from the first stage.
Whereupon, as shown in FIG. 10B, although the output of ultrasonic
waves outputted from the transducers at the ambient temperature
of 24.degree. C. remained nearly level prior to time 0 before the
water flows (see A), it can be seen to decrease suddenly by displacement
D1 (see B) corresponding to the start of water flow (time 0). When
the flow volume of the water changes from 1000 mL/min to 500 mL/min
(see C), the output can be seen to only change slightly by displacement
D2.
As shown in the drawings, the difference in the output between
displacement D1 and displacement D2 is such that D1.quadrature..quadrature.D2
and the change in the output due to the temperature change of the
difference of 4.degree. C. between the ambient temperature and the
water temperature can be understood to be larger than the change
in the output during the change in flow volume.
Next, an explanation is provided of the graphs in the case of allowing
water at a water temperature of 29.degree. C. to flow as shown in
FIG. 11 in comparison with the graph of FIG. 10. As shown in FIG.
11A, water at a temperature of 29.degree. C. is allowed to flow
in two stages at 1000 mL/min and 500 mL/min starting at time 0 through
the measuring pipe of the ultrasonic flow meter using the reference
flow meter. For the flow volume of the former first stage, the water
is allowed to flow for time interval T3 and for the flow volume
of the latter second stage, the water is allowed to flow for time
interval T4 so as to be continued from the first stage.
Whereupon, as shown in the graph of FIG. 11B, although the output
of ultrasonic waves output from the transducers at an ambient temperature
of 24.degree. C. was at the same position and remained nearly level
(see E) at the stage of time 0 before the water flowed in the same
manner as FIG. 10A, it can be seen increase suddenly by displacement
D3 (see F) corresponding to the start of the flow of water (time
0). When the flow volume of water changes from 1000 mL/min to 500
mL/min (see G), the output can be seen to only change slightly by
displacement D4.
As indicated in the drawings, the difference in output between
displacement D3 and displacement D4 is such that D3.quadrature..quadrature.D4
and the change in the output caused by a temperature change of the
difference of 5.degree. C. between the ambient temperature and water
temperature can be seen to be larger than the change in the output
for the change in flow volume.
In this manner, in the ultrasonic flow meter, changes in flow volume
are captured in an output region that is much smaller than the change
in the output of the transducers resulting from a change in the
liquid temperature. It can also be understood that the greater the
difference between ambient temperature and liquid temperature, the
larger the change in the output of the transducers.
Thus, if the liquid temperature is influenced even minimally by
the external ambient temperature, the output of the transducer changes
considerably, and measurement of flow volume at an extremely small
displacement for this output of the transducers has a high potential
to invite measurement error.
In this manner, in the conventional ultrasonic flow meter, there
were cases in which it was difficult to accurately measure flow
volume depending on the ambient temperature.
SUMMARY OF THE INVENTION
In consideration of the above circumstances, the object of the
present invention is to provide an ultrasonic flow meter that is
able to minimize effects caused by external vibrations, and accurately
measure flow volume without being affected by outside temperature.
In order to achieve the above object, the present invention provides
an ultrasonic flow meter comprising: a measuring pipe through which
a liquid flows, and two measuring units provided on the measuring
pipe at an interval in its lengthwise direction and which measures
flow volume by determining the flow rate of the liquid from the
difference in propagation times of ultrasonic waves in both directions
between these measuring units; wherein, the measuring pipe is supported
on a support stand, on which a pair of mounting units are provided
on a base at a wider interval than the measuring units, by retaining
the measuring pipe in the mounting units provided at an interval
to the outside of the measuring units in an axial direction of the
measuring pipe.
In this manner, since the measuring pipe is retained and supported
at the outside of the measuring units in the axial direction of
measuring pipe by mounting units provided on the base, external
vibrations can be blocked with the mounting units, thereby allowing
the reliability of measurement between the measuring units, which
are susceptible to the effects of external vibrations, to be enhanced.
In the ultrasonic flow meter of the present invention, it is preferable
that the mounting units have a first mounting member and a second
mounting member that are fixed to be mutually facing, and retaining
indentations in the shape of a circular arc, which form an opening
that holds the outer periphery of the measuring pipe when mutually
facing, are formed in these first and second mounting members.
In this manner, by mutually facing the first and second mounting
members in the state in which the measuring pipe is arranged in
retaining indentations formed in the first and second mounting members,
the outer periphery of the measuring pipe can be retained extremely
easily.
In the ultrasonic flow meter of the present invention, it is preferable
that the mounting members have a lower mounting member and an upper
mounting member fixed to be mutually facing above and below, and
retaining indentations in the shape of a circular arc, which form
an opening that holds the outer periphery of the measuring pipe
when mutually facing, are formed in these lower and upper mounting
members.
In this manner, by mutually facing the upper and lower mounting
members in the state in which the measuring pipe is arranged in
the retaining indentations formed on the upper and lower mounting
members, the outer periphery of the measuring pipe can be retained
extremely easily.
In the ultrasonic flow meter of the present invention, it is preferable
that the inner diameter of an diameter of an opening which is composed
by the retaining indentations is slightly smaller than the outer
diameter of the measuring pipe.
In this manner, since the opening comprised by the retaining indentations
formed by mutually facing each mounting member is formed to have
a diameter that is slightly smaller than the outer diameter of the
measuring pipe, the measuring pipe can be reliably retained by both
mounting members.
In the ultrasonic flow meter of the present invention, it is preferable
that the retaining indentations are formed to have a rugged surface.
In this manner, since the retaining indentations are formed to
have a rugged surface, the measuring pipe can be reliably retained,
and the effects of external vibrations can be further reduced.
In the ultrasonic flow meter of the present invention, it is preferable
that the surface of the retaining indentations has a rugged shape
as a result of forming engaging grooves along the peripheral direction.
In this manner, since the surface of the retaining indentations
is formed to have a rugged shape as a result of forming engaging
grooves along the peripheral direction, vibrations in the measuring
pipe in the axial direction can be reliably blocked by the engaging
grooves.
In the ultrasonic flow meter of the present invention, it is preferable
that the engaging grooves are V-shaped grooves.
In this manner, since the engaging grooves are V-shaped grooves,
the outer peripheral surface of the measuring pipe reliably engages
with the engaging grooves, thereby reliably retaining the measuring
pipe in the mounting members.
In the ultrasonic flow meter of the present invention, it is further
preferable that a plurality of the engaging grooves are formed in
the retaining indentations at intervals in the axial direction of
the measuring pipe that is retained.
In this manner, since a plurality of engaging grooves are provided
arranged in the axial direction, vibrations transmitted to the measuring
pipe can be blocked even more reliably.
In the ultrasonic flow meter of the present invention, it is preferable
that an insulating means that covers the measuring units and suppresses
the transfer of heat from the outside is provided.
In this manner, since the measuring units are covered by the insulating
means, it is difficult for external heat to transfer to the measuring
units, and the temperature of the measuring units is maintained.
In other words, the temperature of the liquid flowing through the
measuring pipe constitutes the main effect on the measuring units.
Therefore, the temperature of the liquid flowing through the measuring
units is no longer affected by the external ambient temperature,
and flow volume can be measured accurately from changes in the acoustic
velocity of ultrasonic waves in accordance with the liquid temperature.
In the ultrasonic flow meter of the present invention, it is further
preferable that the insulating means is composed of an insulating
material.
In this manner, since the insulating means is composed of the insulating
material, heat insulation is carried out more effectively, and for
example, the measuring units can be covered according to the shape
of the measuring units to promote more effective heat insulation.
Therefore, it is possible to accurately measure flow volume without
the liquid temperature being affected by the external temperature.
In the ultrasonic flow meter of the present invention, it is further
preferable that the insulating means is a case that houses the measuring
units.
In this manner, the measuring units are removed from transfer of
heat from the outside by being housed, and therefore, flow volume
can be measured accurately by blocking the effects of the external
ambient temperature. In addition, the measuring units can be protected
by the case, and the reliability and durability of the ultrasonic
flow meter are improved. The case preferably uses a material having
insulating action and a low coefficient of heat transfer, and preferably
uses a material such as SUS.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a perspective view for explaining the structure of the
ultrasonic flow meter in a first embodiment of the present invention.
FIG. 2 is a side view for explaining the structure of the ultrasonic
flow meter in the first embodiment of the present invention.
FIG. 3 is an exploded cross-sectional view for explaining the structure
of the mounting unit that fixes the ultrasonic flow meter in the
first embodiment of the present invention to the support stand.
FIG. 4 is an overhead view for explaining the structure of the
mounting member of the mounting unit of FIG. 3.
FIG. 5 is a partial cross-sectional view for explaining the structure
of the fixing portion of the mounting unit of FIG. 3.
FIG. 6 is a partially enlarged cross-sectional view for explaining
the structure of the fixing portion of the mounting unit of FIG.
3.
FIG. 7A is an exploded view for explaining the structure of the
ultrasonic flow meter in a second embodiment of the present invention
FIG. 7B is a cross-sectional view of the ultrasonic flow meter
of FIG. 7A as viewed from the cross-section taking along the axis
of a measuring pipe.
FIG. 8A is a perspective view for explaining the structure of the
ultrasonic flow meter showing a variation of the second embodiment.
FIG. 8B is a cross-sectional view of the ultrasonic flow meter
of FIG. 8A as viewed from cross-section H--H taken along the axis
of the measuring pipe.
FIG. 9 is a graph showing the relationship between water temperature
and acoustic velocity.
FIG. 10A is a graph of experimental data showing the change in
reference flow volume during time T at a water temperature of 20.degree.
C.
FIG. 10B is a graph of experimental data showing the change in
the output of the transducer relative to the reference flow volume
shown in FIG. 10A.
FIG. 11A is a graph of experimental data showing the change in
reference flow volume during time T at a water temperature of 29.degree.
C.
FIG. 11B is a graph of experimental data showing the change in
the output of the transducer relative to the reference flow volume
shown in FIG. 11A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following provides an explanation of the ultrasonic flow meter
of the embodiments of the present invention with reference to the
drawings.
[First Embodiment]
The following provides an explanation of a first embodiment of
the ultrasonic flow meter as claimed in the present invention.
In FIGS. 1 and 2 reference symbol 1 indicates an ultrasonic flow
meter. This ultrasonic flow meter 1 is formed from a synthetic resin
having superior chemical resistance such as vinyl chloride or fluororesin,
and has a measuring pipe 2 through which a liquid flows, and two
measuring units 3 provided at an interval in the lengthwise direction
on this measuring pipe 2.
The measuring units 3 employ a structure in which a transducer
5 is tightly adhered to the outer periphery of the measuring pipe
2 and its outer periphery is covered by the retaining tube 6. Furthermore,
reference symbol 8 in the drawings indicates lead wires of transducer
5.
The ultrasonic flow meter 1 composed in the manner described above
is supported on a support stand 11. This support stand 11 has a
base 13 provided with legs 12 extending downward, and mounting units
14 provided on the upper surface of base 13 near both ends, and
ultrasonic flow meter 1 is respectively supported by these mounting
units 14 at locations farther to the outside of the measuring unit
3 in the an axial direction of the measuring pipe 2.
As shown in FIG. 3 each mounting unit 14 has a lower mounting
member 14a fixed on base 13 and an upper mounting member 14b fixed
to the upper portion of this lower mounting member 14a.
Retaining indentations 21 in the shape of a circular are are formed
on the respective opposing faces of the lower mounting member 14a
and the upper mounting member 14b, and by mutually facing the lower
mounting member 14a and the upper mounting member 14b, a opening
22 having circular shape is formed by each retaining indentation
21.
A pair of threaded holes 23 are formed in the lower surface of
lower mounting member 14a, and by screwing bolts 25 that are inserted
from the lower surface of the base 13 through mounting holes 24
formed in the base 13 into these threaded holes 23 the lower mounting
member 14a is fastened to the base 13.
In addition, a pair of coupling threaded holes 26 are formed in
the upper surface of the lower mounting member 14a, and insertion
holes 27 are formed in the upper mounting member 14b that are continuous
with the coupling threaded holes 26 when installed on the upper
portion of the lower mounting member 14a.
By installing the upper mounting member 14b on the upper portion
of the lower mounting member 14a, inserting mounting bolts 28 into
the insertion holes 27 of upper mounting member 14b in the state
in which the measuring pipe 2 of the ultrasonic flow meter 1 is
arranged in the opening 22 comprised by the retaining indentations
21 and screwing the mounting bolts 28 into the coupling threaded
holes 26 the lower mounting member 14a and the upper mounting member
14b are fastened together, and then the measuring pipe 2 of the
ultrasonic flow meter 1 is held in the opening 22 comprised by the
retaining indentations 21.
Here, the inner diameter of the opening 22 comprised by the retaining
indentations 21 of the lower mounting member 14a and the upper mounting
member 14b is made to be slightly smaller than the outer diameter
of the measuring pipe 2.
Moreover, as shown in FIGS. 4 and 5 a plurality of V-shaped engaging
grooves 31 are formed along the peripheral direction at intervals
in the axial direction in the retaining indentations 21 of the lower
mounting member 14a and the upper mounting member 14b.
As a result, when the measuring pipe 2 of the ultrasonic flow meter
1 is fixed by these mounting units 14 as a result of the outer
periphery of the measuring pipe 2 engaging with the engaging grooves
31 of the retaining indentations 21 of the lower mounting member
14a and the upper mounting member 14b as shown in FIG. 6 the measuring
pipe 2 is reliably held, and displacement of the measuring pipe
2 in the axial direction of the measuring pipe 2 or in any of the
other four directions is reliably prevented.
In this manner, according to the above-mentioned ultrasonic flow
meter, since the measuring pipe 2 is held and supported by the mounting
units 14 provided on the base 13 at locations farther to the outside
in the axial direction than measuring units 3 provided at an interval,
external vibrations can be blocked with the mounting members 14.
Therefore, it is possible to enhance the reliability of measurement
between the measuring units 3 which are susceptible to the effects
of external vibrations.
Moreover, by facing the lower mounting member 14a and the upper
mounting member 14b in the state in which the measuring pipe 2 is
arranged in the retaining indentations 21 formed in the lower mounting
member 14a and the upper mounting member 14b, the outer periphery
of the measuring pipe 2 can be held extremely easily.
In addition, since the opening 22 comprised by the retaining indentations
21 formed by the facing lower mounting member 14a and the upper
mounting member 14b is formed to have a slightly smaller diameter
than the outer diameter of the measuring pipe 2 the measuring pipe
2 can be reliably held by the lower mounting member 14a and the
upper mounting member 14b.
Moreover, since the surface of the retaining indentations 21 is
formed in a rugged shape by a plurality of engaging grooves 31 arranged
in the axial direction along their peripheral direction, vibrations
to the axial direction in the measuring pipe 2 can be reliably blocked
by the engaging grooves 31.
Moreover, since the engaging grooves 31 are in the form of V-shaped
grooves, the outer peripheral surface of the measuring pipe 2 can
reliably engage with engaging grooves 31 thereby allowing measuring
pipe 2 to be even more reliably held in mounting units 14.
[Second Embodiment]
The following provides an explanation of a second embodiment of
the ultrasonic flow meter as claimed in the present invention using
FIGS. 7A and 7B.
FIGS. 7A and 7B are drawings showing an ultrasonic flow meter 1a
in the present embodiment, with FIG. 7A being an exploded view of
the ultrasonic flow meter 1a, and FIG. 7B being a cross-sectional
view as viewed from the cross-sectional parallel to the axis of
a measuring pipe 2 of the ultrasonic flow meter 1a.
In the drawing, reference symbol 4 indicates a tightly adhered
tube, 14 indicates a mounting unit composed of a lower mounting
member 14a and an upper mounting member 14b, 50 indicates a case
(insulating means) composed of a lower case 51 serving as a base
and an upper case 52 and 53 and 54 indicate respective insulating
materials (insulating means).
Furthermore, since other reference symbols are the same as in the
ultrasonic flow meter explained in the above first embodiment, their
explanation is omitted.
The case 50 shown in FIG. 7B is composed by the combining lower
case 51 formed into the shape of a "U" by bending, and
the upper case 52 formed into the shape of a flat plate to match
the opening in the top of the lower case 51. This case 50 is made
of SUS (Stainless Steel) material having a comparatively poor heat
transfer rate, and its total length has a length that is equal to
or greater than the interval between the measuring units 3 provided
at a prescribed interval.
The lower mounting members 14a, which are formed at roughly half
the height of the case 50 are fixed at both ends in the lengthwise
direction of the lowercase 51 so as to each be housed within the
lower case 51 in the same manner as the attachment to the base 13
shown in the first embodiment. The retaining indentations 21 in
the shape of a circular are are formed in the upper surface of the
lower mounting members 14a, and by mutually facing the opposing
retaining indentations 21 of the upper mounting member 14a, openings
are formed by the respective retaining indentations 21.
A pair of bolt insertion holes 27 for the mounting bolts 28 that
fasten the upper mounting members 14b and the lower mounting members
14a are formed in the upper surface of the upper mounting member
14a in the same manner as the first embodiment, and a pair of bolt
insertion holes 55a for upper cover mounting bolts 55 for attaching
the upper cover 52 are also formed in the upper surface of the upper
mounting member 14a. Furthermore, a pair of insertion holes 55b
to pass the upper cover mounting bolts 55 are each formed in the
upper cover 52 as well.
The insulating materials 53 and 54 divided into two parts above
and below each other, use foaming polystyrol for their material,
and are formed to a size such that they can be housed in the space
inside the case 50 when combined. Indentation 53b in the shape of
a circular arc is formed in the upper surface of lower insulating
material 53 to match the shape of measuring pipe 2 while indentations
53a in the shape of a circular are having a large radius are formed
in the upper surface of lower insulating material 53 to match the
positions of both measuring units 3.
In addition, indentations are formed in upper insulating member
54 as well to match the shapes of the measuring pipe 2 and the measuring
units 3 in the same manner as lower insulating member 53.
In the measuring unit 3 differs from the measuring unit 3 shown
in the first embodiment, the transducer 5 is fixed to the outside
of the measuring pipe 2 over the tightly adhered tube 4. In this
case, ultrasonic waves emitted or received from the transducer 5
are transmitted through the tightly adhered tube 4 fixed by being
tightly adhered to the outside of the measuring pipe 2. The tightly
adhered tube 4 is fixed by, for example, a gel-like adhesive.
The ultrasonic flow meter 1a assembled as shown in FIG. 7B is formed
to have an external shape such that both the measuring units 3 of
the measuring pipe 2 are covered by the case 50 and is further
composed so that both the measuring units 3 and the measuring pipe
2 between them housed inside the case 50 are covered by the insulating
materials 53 and 54.
As a result, the inside and outside of the ultrasonic flow meter
1a are isolated by the case 50 making them thermally insulated,
and the space between the measuring units 3 is further isolated
from the outside by insulating material, thereby making them thermally
insulated.
According to the ultrasonic flow meter 1a in the present embodiment
explained above, since the measuring pipe 2 is held and supported
by the mounting units 14 provided inside the case 50 father to the
outside in the axial direction than the measuring units 3 provided
at an interval, vibrations from the outside can be blocked by the
mounting units 14 and as a result, the reliability of measurement
between the measuring units 3 which are susceptible to the effects
of external vibrations, can be enhanced.
In addition, since liquid flowing inside the measuring pipe 2 is
no longer affected by external ambient temperature due to the case
50 and the insulating materials 53 and 54 the temperature of the
liquid no longer changes in both measuring units 3 thereby making
it possible to accurately measure flow volume corresponding to the
temperature of the liquid.
Furthermore, although a constitution in which the insulating materials
53 and 54 are provided inside the case 50 has been explained for
the ultrasonic flow meter 1a explained in the present embodiment,
this should not be interpreted as being limited to this, but rather
only the case 50 may be provided as an insulating means of measuring
pipe 2. According to this, although insulating effects decrease
as compared with the present embodiment, if installed in a location
where there is little change in ambient temperature, this ultrasonic
flow meter is still capable of fulfilling its function. Furthermore,
since the insulating materials 53 and 54 are not used, production
costs can be reduced.
In addition, an ultrasonic flow meter 1b shown in FIGS. 8A and
8B may be used as a variation of the present embodiment. FIGS. 8A
and 8B are drawings explaining the structure of the ultrasonic flow
meter 1b showing a variation of the present embodiment, with FIG.
8A being a perspective view showing its external form, and FIG.
8B being a cross-sectional view taking along the axial direction
the of measuring pipe 2 in cross-section H--H of FIG. 8A.
Reference symbol 51' indicates a lower case in the shape of the
letter "U" similar to the first embodiment, 52' indicates
an upper cover in the shape of the letter "L", 60 indicates
a protective cover installed so as to cover the measuring units
3 and the outer periphery of the measuring pipe 2 between the both
measuring units 3 and 61 indicates an insulating material (insulating
means) filled inside lower case 51'. In addition, reference symbol
S indicates a space for processing wiring connections formed by
the upper cover 52', while reference symbols J indicate wiring connections
between lead wires 8 and cables 8a.
The lower case 51' has a opening (see reference symbol K) formed
on the right side so as to cover the axis of the measuring pipe
2 in the drawings, and a wall 52b' that composes the upper cover
52' is attached to as to cover this opening.
In addition, the mounting units 14' are provided on both ends of
the lower case 51' similar to the ultrasonic flow meter 1a explained
in FIGS. 7A and 7B. As shown in FIG. 8A, the mounting units 14'
are divided into two sections to match the direction of orientation
of the opening of the lower case 51', with a right mounting member
14b' (second mounting member) being provided on the side of the
opening of the lower case 51', and a left mounting member 14a' (first
mounting member) being provided at the position that faces the right
mounting member 14b ' with measuring pipe 2 interposed between.
In other words, the ultrasonic flow meter 1b referred to here is
arranged nearly equivalent to the state in which the ultrasonic
flow meter 1a shown in FIG. 7 is rotated by 90 degrees about the
axis of the measuring pipe 2 as the center, and the measuring pipe
2 is fixed by the mounting units 14'.
In addition, lead wire guide holes 51a' are formed in an upper
wall 51b' that composes lower case 51', respectively arranged nearly
directly above the measuring units 3 on both sides. As a result,
the lead wires 8 of the transducer 5 are wired outside of the lower
case 51' through the lead wire guide holes 51a', and the ends of
the lead wires 8 are positioned in the space S formed by the upper
cover 52' for processing the wiring connections.
The upper cover 52' has an L-shaped cross-section that intersects
the axis of the measuring pipe 2 with one section being composed
by a wall 52b' in the shape of a flat plate, and the other section
being composed by a wall 52c' that is perpendicular to the wall
52b' and in the shape of a vat. A case 50' is then assembled by
the plate-shaped wall 52b' being fixed to the right mounting member
14b ' of the lower case 51' by a plurality of upper cover fastening
bolts 55'.
Cable guide holes 52a' are formed in the vat-shaped wall 52c' so
as to oppose the lead wire guide holes 51a' formed in the lowercase
51'. In addition, the space S for processing wiring connections
is formed inside the vat-shaped wall 52c' as a result of combining
the lower case 51'.
The space S is an empty space that houses wiring connections J
that are formed by processing the wiring connections of the lead
wires 8.
The lead wires 8 have a prescribed length from the transducer 5
and are required to be extended in processes of composing the ultrasonic
flow meter 1b. Consequently, the lead wires 8 are connected with
cables 8a capable of reliably incorporating weak signals to a measuring
amplifier and so forth with the wiring connections J, and are wired
outside of the case 50' from the cable guide holes 52a' after being
fixed in the vicinity of the lead wire 18 guide holes 51a'.
Thus, the wiring connections J of the lead wires 8 are located
within the space S for processing wiring connections. Naturally,
the upper cover 52' is attached to the lower case 51' after having
filled the insulating material 61 to be described later, and at
the time of completion of connection processing of the lead wires
8 and the cables 8a.
In addition, the present variation also employs a structure in
which the insulating material 61 is provided within the case 50'.
In this variation, a structure is shown in which the insulating
material 61 is filled after fixing the measuring pipe 2 with the
mounting units 14' in the lower case 51', and partly covering the
measuring units 3 and the measuring pipe 2 with protective cover
60 made of plastic and so forth.
The following provides a more detailed explanation of the constitution
of the insulating material 61 and the filling work. Since the measuring
units 3 and the measuring pipe 2 are important components for measuring
flow volume, it is necessary that they be protected from the filling
work of the insulating material 61 described later. In order to
protect these components, the measuring units 3 and the measuring
pipe 2 are covered by a protective cover 60 made of, for example,
polypropylene resin. A similar resin may be used to cover the area
around the lead wires 8 and the gaps of the case 50'.
After providing the protective cover 60 on the measuring units
3 the insulating material 61 in the form of foaming polystyrol
and so forth is filled into the lower case 51'. As a result, the
insulating material 61 is filled throughout all portions of the
lower case 51', and thermal insulating action is obtained for the
measuring units 3 and the measuring pipe 2 between the both measuring
units 3.
Furthermore, the insulating material 61 may be partly filled into
one side of the case 50' formed to match the shape of the protective
cover 60 in advance, and then the protective cover 60 provided with
the remaining insulating material 61 may be inserted inside the
case 50'.
According to such an ultrasonic flow meter 1b, in addition to improving
the rigidity of the case 50' and enhancing its strength, the thermal
insulation properties can also be further improved. In addition,
since the insulating material 61 can be easily provided within the
case 50', it is not necessary to form insulating material to match
the shapes of the measuring units 3 and the measuring pipe 2 thereby
making it possible to suppress production costs. In addition, the
wiring connections J of the lead wires 8 are located between the
outside of the insulating material 61 and the inside of upper cover
52', thereby making it possible to realize simplification of connection
processing and protection of the wiring connections J. |