Note: Descriptions are shown in the official language in which they were submitted.
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MASS FLOW SENSOR
Technical Field
The present invention relates to the technical field of compressed natural
gas, and
particularly to a mass flow sensor used for measuring the mass flow of the
compressed
natural gas.
Background
As energy, the natural gas has the following advantages: firstly, the natural
gas is a kind
of high-quality green energy, its combustion emissions are far lower than
those of coal
and petroleum, so that the environmental pollution can be reduced; secondly,
the natural
gas is a kind of safe energy and contains no carbon monoxide, so that the harm
to people
and livestocks caused by leakage and other problems can be reduced, and
meanwhile,
the natural gas has a high ignition temperature and a narrow explosion limit,
so that the
safety is good; and thirdly, natural gas reserves are rich, and the
exploration and
development costs are low. Based on the above advantages, the natural gas
plays an
increasingly important role in the development of new energy. At present,
compressed
natural gas (Compressed Natural Gas, referred to as CNG) is widely used in the
fields
of electric power, chemical industry, city gas and the like, and particularly,
natural gas
powered vehicles are vigorously promoted in the United States, Russia, Japan,
New
Zealand, Australia, Canada and other countries. With the increasingly
extensive
application of the CNG, accurate measurement of the CNG in a trade process is
directly
related to the economic interests of both sides of the trade.
The gas pressure in a CNG dispenser is generally above 20MPa, the high
pressure will
change sensitive elements of a measurement tool, thereby affecting its
measurement
properties. In addition, because of the small density of the CNG, the
requirements on
the measurement precision of the measurement tool are higher. The above
characteristics of the CNG determine that its measurement way is different
from
ordinary fluid measurement. At present, the methods for measuring high
pressure gas
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flow mainly include an ultrasonic flowmeter, a thermal flowmeter and a
Coriolis mass
flowmeter:
the ultrasonic flowmeter is a meter which measures the flow by detecting the
effect of
fluid flow on an ultrasonic beam (or an ultrasonic pulse). As a meter
circulation channel
is not provided with any barrier, the ultrasonic flowmeter belongs to a
barrier-free
flowmeter and can carry out noncontact measurement, and no pressure loss is
generated. However, the ultrasonic measurement method is generally not
suitable for
pipeline flow measurement with an apertures of less than 25mm, so that the
application
is limited.
The thermal mass flowmeter is a meter that measures the flow via the principle
of heat
transfer, that is, the heat transfer relationship between flowing fluid and a
thermal
source (a heated object in the fluid or a heating body beyond a measurement
tube), and
has the characteristics of small pressure loss and simple structure, etc. But
its response
time is long, so it is not suitable for the fluid flow measurement which
changes rapidly.
The Coriolis mass flowmeter (Coriolis Mass Flowmeter, CMF) is a resonant
sensor that
measures the mass flow of the fluid flowing by the pipeline by the influence
of the
Coriolis effect generated by the fluid when flowing by the pipeline on the
vibration
phases or amplitudes on both ends of the pipeline, can directly sense the mass
flow of
the fluid, has the characteristics of high precision, small pressure loss,
multi-parameter
measurement and the like, and is widely used in the fields of industrial
measurement
and process control. Compared with the thermal mass flowmeter, its outstanding
advantage lies in large range ratio, and thus the demands of different
occasions can be
satisfied. At present, most of the domestic CNG dispensers adopt the Coriolis
mass
flowmeters for measurement.
In a CNG gas station, the pressure, the temperature, the density and the flow
rate of the
gas change quickly in a gas filling process, and the gas components of the
natural gas
are different at different time and different locations, therefore some
flowmeters are not
suitable for serving as the measurement tools in this case. At present, the
Coriolis mass
flowmeters are widely used as the measurement tools of the CNG dispensers at
home
and abroad. For example, typical applications include the CNG050 model
produced by
the American Micro Motion, the CNGmass series produced by the Germany Endress
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House (E + H), the SITRANS FCS200 model produced by the Siemens (SIEMENS),
etc.
One of the common Coriolis mass sensors measures the mass flow via the
principle that
the fluid will generate a Coriolis force in direct proportion to the mass flow
when
flowing in a vibration tube. At present, people generally use a vibration tube
type
Coriolis mass flow sensor (as shown in Fig. 1), which mainly consists of a
sensitive
unit and a secondary meter, wherein the sensitive unit a includes measurement
tubes
al, a2, an exciter a5 and vibration pickups a3, a4; and the secondary meter b
includes a
closed loop control unit bl and a flow calculation unit b2, which are
respectively control
and signal processing systems of the sensitive unit. The sensitive unit
outputs a
vibration signal relevant to measured flow; the closed loop control unit bl
provides an
excitation signal for the exciter a5 to maintain the measurement tubes in a
resonant state
and track the vibration frequency of the measurement tubes al, a2 in real
time; and the
flow calculation unit b2 processes output signals of the vibration pickups a3,
a4 and
outputs measurement information, so as to determine the mass flow and the
density of
the measured fluid.
Since the aforementioned sensor adopts a U-shaped tube having a very large
curvature,
a larger resistance will be generated on the flow of the compressed natural
gas, and few
distance elements are provided, so it is difficult to guarantee higher
mechanical quality
factors, better stability and stronger seismic resistance.
Summary
The technical problem to be solved in the present invention is how to reduce
the
resistance generated on compressed natural gas, firmly realize distance
detection and
guarantee higher mechanical quality factors, better stability and stronger
seismic
resistance for circulation measurement tubes of the compressed natural gas,
when the
mass flow of the compressed natural gas is measured.
To this end, the present invention provides a mass flow sensor used for
measuring the
mass flow of the compressed natural gas, including: a first measurement tube
and a
second measurement tube, wherein the first measurement tube and the second
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measurement tube have the same structure and the same size and are arranged in
a shell
in parallel, each measurement tube includes a straight tube segment, a first
circular arc
segment, a second circular arc segment, a third circular arc segment, a fourth
circular
arc segment, a first inclined tube segment, a second inclined tube segment, a
first port
segment and a second port segment, wherein the first circular arc segment, the
first
inclined tube segment, the third circular arc segment and the first port
segment are
respectively symmetrical to the second circular arc segment, the second
inclined tube
segment, the fourth circular arc segment and the second port segment relative
to a plane
which is vertical to and equally divides the straight tube segment, the first
circular arc
segment is connected to the straight tube segment, the first inclined tube
segment is
connected to the first circular arc segment, the third circular arc segment is
connected
to the first inclined tube segment, the first port segment is connected to the
third circular
arc segment, the second circular arc segment is connected to the straight tube
segment,
the second inclined tube segment is connected to the second circular arc
segment, the
fourth circular arc segment is connected to the second inclined tube segment,
the second
port segment is connected to the fourth circular arc segment, an included
angle between
an axial line on which the straight tube segment is located and the axial line
on which
the first inclined tube segment is located, and the included angle between the
axial line
on which the first inclined tube segment is located and the axial line on
which the first
port segment is located are obtuse angles, and the included angle between the
axial line
on which the straight tube segment is located and the axial line on which the
second
inclined tube segment is located, and the included angle between the axial
line on which
the second inclined tube segment is located and the axial line on which the
second port
segment is located are both obtuse angles; exciters, arranged on the straight
tube
segment of the first measurement tube, the straight tube segment of the second
measurement tube and the planes which are vertical to and equally divide the
straight
tube segments; first detectors, arranged on connection parts of the first
circular arc
segments and the first inclined tube segments of the first measurement tube
and the
second measurement tube; second detectors, arranged on the connection parts of
the
second circular arc segments and the second inclined tube segments of the
first
measurement tube and the second measurement tube; a first shunt, arranged at
the
outside of the shell and connected with the first port segment; a second
shunt, arranged
at the outside of the shell and connected with the second port segment; a
first nut,
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arranged at the outside of the shell and connected to the first shunt; and a
second nut,
arranged at the outside of the shell and connected to the second shunt.
Preferably, the exciters include coils, magnetic steel and fixing brackets,
the coils and
the magnetic steel are coaxially arranged, and the fixing brackets are
respectively
welded on the first measurement tube and the second measurement tube by braze
welding.
Preferably, the first detectors and the second detectors respectively include
coils,
magnetic steel and fixing brackets, the coils and the magnetic steel are
coaxially
arranged, and the fixing brackets are respectively welded on the first
measurement tube
and the second measurement tube by braze welding.
Preferably, the mass flow sensor further includes: first distance plates,
arranged on the
connection parts of the first port segments and the third circular arc
segments on the
first measurement tube and the second measurement tube; second distance
plates,
arranged on the connection parts of the third circular arc segments and the
first inclined
tube segments on the first measurement tube and the second measurement tube;
third
distance plates, arranged on the connection parts of the second port segments
and the
fourth circular arc segments on the first measurement tube and the second
measurement
tube; and fourth distance plates, arranged on the connection parts of the
fourth circular
arc segments and the second inclined tube segments on the first measurement
tube and
the second measurement tube.
Preferably, the mass flow sensor further includes: a first reinforcing sleeve,
arranged
on the connection part of the first port segment of the first measurement tube
and the
first shunt; a second reinforcing sleeve, arranged on the connection part of
the second
port segment of the first measurement tube and the second shunt; a third
reinforcing
sleeve, arranged on the connection part of the first port segment of the
second
measurement tube and the first shunt; and a fourth reinforcing sleeve,
arranged on the
connection part of the second port segment of the second measurement tube and
the
second shunt.
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Preferably, the first shunt is connected with the first reinforcing sleeve and
the third
reinforcing sleeve by argon arc welding, the second shunt is connected with
the second
reinforcing sleeve and the fourth reinforcing sleeve by argon arc welding, the
first
reinforcing sleeve and the second reinforcing sleeve are welded on the first
measurement tube by braze welding, the third reinforcing sleeve and the fourth
reinforcing sleeve are welded on the second measurement tube by braze welding,
and
the first shunt and the second shunt are welded on the shell by argon arc
welding.
Preferably, the mass flow sensor further includes: temperature sensors and
fixing parts,
and the fixing parts are used for fixing the temperature sensors to the first
distance
plates.
Preferably, the mass flow sensor further includes: a supporting beam arranged
between
the first measurement tube and the second measurement tube, and both ends of
the
supporting beam are welded on the first shunt and the second shunt by argon
arc
welding and are parallel to the first measurement tube and the second
measurement tube
for fixing and supporting conducting wires in the shell.
Preferably, the mass flow sensor further includes: a connection tube and an
adapting
flange, the connection tube is used for connecting the shell and the adapting
flange, and
the adapting flange is sealed with an adapting bolt through a rubber column.
Preferably, the mass flow sensor further includes: a pressure switch, arranged
on an
upper surface of the shell and used for detecting the pressure in the shell
and sending a
prompt message when the pressure is greater than an early warning threshold.
Preferably, a groove is formed in a side face of the shell.
By means of the aforementioned technical solutions, when the mass flow of the
compressed natural gas is measured, the resistance generated on the compressed
natural
gas can be reduced, and firm distance detection can be realized to guarantee
higher
mechanical quality factors, better stability and stronger seismic resistance
for the
circulation measurement tubes of the compressed natural gas.
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Brief Description of the Drawings
The features and advantages of the present invention will be understood more
clearly
with reference to the accompanying drawings, the accompanying drawings are
schematic and cannot be understood as any limitation to the present invention,
and in
the accompany drawings:
Fig. 1 shows a structural schematic diagram of a mass flow sensor in the prior
art;
Fig. 2 shows a structural schematic diagram of a mass flow sensor according to
one
embodiment of the present invention;
Fig. 3 shows a front view of a mass flow sensor according to one embodiment of
the
present invention;
Fig. 4 shows a top view of a mass flow sensor according to one embodiment of
the
present invention;
Fig. 5 shows a structural schematic diagram of a measurement tube in a mass
flow
sensor according to one embodiment of the present invention;
Fig. 6 shows a schematic diagram of a detector and an exciter in a mass flow
sensor
according to one embodiment of the present invention;
Fig. 7 shows a schematic diagram of a distance plate in a mass flow sensor
according
to one embodiment of the present invention;
Fig. 8 shows a schematic diagram of a mounting relationship between a distance
plate
and a measurement tube in a mass flow sensor according to one embodiment of
the
present invention;
Fig. 9 shows a schematic diagram of a fixing part in a mass flow sensor
according to
one embodiment of the present invention;
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Fig. 10 shows a schematic diagram of a mounting relationship between a fixing
part
and a distance plate in a mass flow sensor according to one embodiment of the
present
invention;
Fig. 11 shows a schematic diagram of a side face of a shell of a mass flow
sensor
according to one embodiment of the present invention.
Illustration to reference signs:
1-first measurement tube; 2-second measurement tube; 3-exciter; 4-first
detector; 5-
second detector; 6-first distance plate; 7-second distance plate; 8-third
distance plate;
9-fourth distance plate; 10-first nut; 11-second nut; 12-first shunt; 13-
second shunt; 14-
first reinforcing sleeve; 15-second reinforcing sleeve; 16-third reinforcing
sleeve; 17-
fourth reinforcing sleeve; 18-supporting beam; 19-connection tube; 20-adapting
flange;
21-fixing part; 22-shell; 23-presure switch; 24-straight tube segment; 25-
first circular
arc segment; 26-second circular arc segment; 27-first inclined tube segment;
28-second
inclined tube segment; 29-third circular arc segment; 30-fourth circular arc
segment;
31-first port segment; 32-second port segment; and 34-shell.
Detailed Description
To understand the aforementioned purposes, features and advantages of the
present
invention more clearly, the present invention will be further described below
in detail
in combination with the accompanying drawings and specific implementations. It
should be noted that the embodiments and the features in the embodiments of
the
present application can be mutually combined without generating conflict.
Many specific details are illustrated in the description below to fully
understand the
present invention, but the present invention can also be implemented in other
manners
different from what is described herein, and thus the protection scope of the
present
invention is not limited by the specific embodiments disclosed below.
As shown in Fig. 2 and Fig. 3, a mass flow sensor according to one embodiment
of the
present invention is used for measuring the mass flow of the compressed
natural gas,
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and includes: a first measurement tube 1 and a second measurement tube 2,
wherein the
first measurement tube 1 and the second measurement tube 2 have the same
structure
and the same size and are arranged in a shell 34 in parallel, as shown in Fig.
5, each
measurement tube includes a straight tube segment 24, a first circular arc
segment 25,
a second circular arc segment 26, a third circular arc segment 29, a fourth
circular arc
segment 30, a first inclined tube segment 27, a second inclined tube segment
28, a first
port segment 31 and a second port segment 32, wherein the first circular arc
segment
25, the first inclined tube segment 27, the third circular arc segment 29 and
the first port
segment 31 are respectively symmetrical to the second circular arc segment 26,
the
second inclined tube segment 28, the fourth circular arc segment 30 and the
second port
segment 32 relative to a plane which is vertical to and equally divides the
straight tube
segment 24, the first circular arc segment 25 is connected to the straight
tube segment
24, the first inclined tube segment 27 is connected to the first circular arc
segment 25,
the third circular arc segment 29 is connected to the first inclined tube
segment 27, the
first port segment 31 is connected to the third circular arc segment 29, the
second
circular arc segment 26 is connected to the straight tube segment 24, the
second inclined
tube segment 28 is connected to the second circular arc segment 26, the fourth
circular
arc segment 30 is connected to the second inclined tube segment 28, the second
port
segment 32 is connected to the fourth circular arc segment 30, an included
angle
between an axial line on which the straight tube segment 24 is located and the
axial line
on which the first inclined tube segment 27 is located, and the included angle
between
the axial line on which the first inclined tube segment 27 is located and the
axial line
on which the first port segment 31 is located are obtuse angles, and the
included angle
between the axial line on which the straight tube segment 24 is located and
the axial
line on which the second inclined tube segment 28 is located, and the included
angle
between the axial line on which the second inclined tube segment 28 is located
and the
axial line on which the second port segment 32 is located are both obtuse
angles; as
shown in Fig. 6, the mass flow sensor further includes: exciters 3, arranged
on the
straight tube segment 24 of the first measurement tube 1, the straight tube
segment of
the second measurement tube 2 and the planes which are vertical to and equally
divide
the straight tube segments 24; first detectors 4, arranged on connection parts
of the first
circular arc segments 25 and the first inclined tube segments 27 of the first
measurement
tube 1 and the second measurement tube 2; second detectors 5, arranged on the
connection parts of the second circular arc segments 26 and the second
inclined tube
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segments 28 of the first measurement tube 1 and the second measurement tube 2;
a first
shunt 12, arranged at the outside of the shell 34 and connected with the first
port
segment 31; a second shunt 13, arranged at the outside of the shell 34 and
connected
with the second port segment 32; a first nut 10, arranged at the outside of
the shell 34
and connected to the first shunt 12; and a second nut 11, arranged at the
outside of the
shell 34 and connected to the second shunt 13.
According to the Coriolis effect, for the two measurement tubes, double
distance plates
are fixed and welded on both sides of the measurement tubes, and the two
measurement
tubes are firmly welded on outer end faces of the shunts in parallel to form a
tuning
fork to eliminate the influence of external vibration. The two measurement
tubes vibrate
at their inherent frequency under the excitation of electromagnetic exciters,
and the
vibration phases are reverse. Due to the vibration effect of the measurement
tubes, each
fluid micelle flowing in the tubes obtains a Coriolis acceleration, and the
measurement
tubes are applied with distribution Coriolis forces reverse to the
acceleration direction.
Since the directions of the Coriolis forces applied to the inlet and outlet
sides of the
measurement tubes are reverse, the measurement tubes twist, and the torsion
degree is
in direct proportion to instantaneous mass flow in the tubes. Two
electromagnetic
detectors on an inflow side and an outflow side of the measurement tube detect
two
paths of vibration signals in the process of each vibration circle of the
tuning fork, the
phase difference of the two paths of signals is in direct proportion to the
torsion degree
of the measurement tube, namely the instantaneous flow. The mass flow can be
calculated by calculating the phase difference between the signals.
Since the included angles between the axial lines of the straight tube
segments and the
inclined tube segments are obtuse angles, the included angles between the
axial lines of
the inclined tube segments and the port segments are obtuse angles, and the
segments
are connected by the circular arc segments, so that the transition is smooth,
when the
compressed natural gas flows in the measurement tubes, no larger resistance
will be
generated on the compressed natural gas, the performance and the mechanical
quality
factor of the resonant sensor are effectively improved, the flow field effect
is greatly
reduced, the flow resistance is small, the pressure loss is low, the mass flow
of the gas
can be measured, the processing is simple, and the cost is low.
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The tube material of the two measurement tubes can be 316L stainless steel,
holmium
and hastelloy, and of course, other tube materials can also be selected
according to
demands. The measurement tubes can be integrally formed and can also be
assembled
by the straight tube segments, the circular arc segments and the inclined tube
segments.
When the fluid does not flow by the sensor, the exciters excite the
measurement tubes
to vibrate at their inherent frequencies, at this time, sinusoidal signal
frequency and
phases detected by the two detectors at the inlet sides and the outlet sides
of the
measurement tubes are completely the same, with no phase difference generated.
At
this time, the measurement tubes are hollow tubes, the resonant frequency of
the
measurement tubes are density reference frequency, that is, the frequency when
there
is no fluid, and the numerical values of measured real-time density and the
mass flow
of the fluid are 0. When the fluid flows by the sensor, firstly, the flow of
the fluid in the
measurement tubes induces the Coriolis effect, both ends of the measurement
tubes are
applied with Coriolis forces having the same magnitude and reverse direction
due to
the influence of moments, which is embodied in that the sinusoidal signals
detected by
the two detectors have a phase difference, the phase difference is in direct
proportion
to the mass flow of the fluid, and the real-time mass flow of the fluid can be
obtained
by detecting the magnitude of the phase difference.
Preferably, the exciters 3 include coils, magnetic steel and fixing brackets,
the coils and
the magnetic steel are coaxially arranged, and the fixing brackets are
respectively
welded on the first measurement tube 1 and the second measurement tube 2 by
braze
welding. The exciters are used for exciting the measurement tubes to vibrate,
and the
measurement tubes are in a simple harmonic vibration state by closed loop
control
systems to cause the sensor to vibrate at its inherent frequency.
Preferably, the first detectors 4 and the second detectors 6 respectively
include coils,
magnetic steel and fixing brackets, the coils and the magnetic steel are
coaxially
arranged, and the fixing brackets are respectively welded on the first
measurement tube
1 and the second measurement tube 2 by braze welding.
For the exciters and the detectors, the coils and the magnetic steel are
cooperatively
used, the exciters are mounted at the central axes of the straight tube
segments at the
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middle of the two opposite measurement tubes, the detectors are located at the
connection sites of smooth transition of the first parts of circular arc tube
segments and
the inclined tube segments of the measurement tubes, and the detectors are
mounted
outward to form a good closed loop system together, so that the detection tube
of the
sensor has a stable working state, the influence of external disturbance is
reduced, and
the self-regulation ability is improved.
As shown in Fig. 8, preferably, the mass flow sensor further includes: first
distance
plates 6, arranged on the connection parts of the first port segments 31 and
the third
circular arc segments 29 on the first measurement tube 1 and the second
measurement
tube 2; second distance plates 7, arranged on the connection parts of the
third circular
arc segments 29 and the first inclined tube segments 27 on the first
measurement tube
1 and the second measurement tube 2; third distance plates 8, arranged on the
connection parts of the second port segments 32 and the fourth circular arc
segments
30 on the first measurement tube 1 and the second measurement tube 2; and
fourth
distance plates 9, arranged on the connection parts of the fourth circular arc
segments
30 and the second inclined tube segments 28 on the first measurement tube 1
and the
second measurement tube 2.
As shown in Fig. 7, four distance plates are respectively composed of two E-
shaped
plates, two distance plates are located at smooth connection sites of the
circular arc
segments and the port segments of the measurement tube, two distance plates
are
located at the smooth connection sites of the inclined tube segments and the
circular arc
segments of the measurement tube, and a double distance mode is realized by
two
groups of distance plates, so that the resonant frequency of the measurement
tube is
higher, the stability is good, and the seismic resistance is strong. Moreover,
a plurality
of through holes are formed in each distance plate to enable the internal
circuit of the
shell to penetrate through, which is conducive to the layout of the internal
circuit.
The two measurement tubes are simultaneously fixed by the distance plates in a
vacuum
braze welding manner, so that the measurement tubes are unlikely to deform,
the
properties of the two measurement tubes are completely the same as much as
possible,
meanwhile limited twisting and bending necessary for flow measurement are
provided,
and the positions of the double distance plates on the straight tube segments
can be
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changed to change the resonant frequency of the sensor, so that the positions
of the
double distance plates on the straight tube segments can be determined
according to the
designed frequency to reduce the vibration coupling of the internal
measurement tubes
and reinforce the seismic resistance of the measurement tubes.
Preferably, the mass flow sensor further includes: a first reinforcing sleeve
14, arranged
on the connection part of the first port segment 31 of the first measurement
tube 1 and
the first shunt 12; a second reinforcing sleeve 15, arranged on the connection
part of
the second port segment 32 of the first measurement tube 1 and the second
shunt 13; a
third reinforcing sleeve 16, arranged on the connection part of the first port
segment 31
of the second measurement tube 2 and the first shunt 12; and a fourth
reinforcing sleeve
17, arranged on the connection part of the second port segment 32 of the
second
measurement tube 2 and the second shunt 13.
Preferably, the first shunt 12 is connected with the first reinforcing sleeve
14 and the
third reinforcing sleeve 16 by argon arc welding, the second shunt 13 is
connected with
the second reinforcing sleeve 15 and the fourth reinforcing sleeve 17 by argon
arc
welding, the first reinforcing sleeve 14 and the second reinforcing sleeve 15
are welded
on the first measurement tube 1 by braze welding, the third reinforcing sleeve
16 and
the fourth reinforcing sleeve 17 are welded on the second measurement tube 2
by braze
welding, and the first shunt 12 and the second shunt 13 are welded on the
shell 34 by
argon arc welding.
As shown in Fig. 9 and Fig. 10, preferably, the mass flow sensor further
includes:
temperature sensors (not shown in the figures) and fixing parts 21, and the
fixing parts
21 are used for fixing the temperature sensors to the first distance plates 6.
The temperature sensors can be directly fixed on the distance plates by the
fixing parts
of the temperature sensors to sense the temperature change in the sensors more
directly,
so as to obtain a sensing value closer to an actual temperature in the
detection tube to
improve the subsequent processing precision.
As shown in Fig. 4, preferably, the mass flow sensor further includes: a
supporting
beam 18 arranged between the first measurement tube 1 and the second
measurement
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tube 2, and both ends of the supporting beam are welded on the first shunt 12
and the
second shunt 13 by argon arc welding and are parallel to the first measurement
tube 1
and the second measurement tube 2 for fixing and supporting conducting wires
in the
shell 34. The supporting beam is used for fixing and supporting the conducting
wires,
so that the wiring is more convenient, and the internal structure of the shell
is trimmed
and simplified conveniently.
Preferably, the mass flow sensor further includes: a connection tube 19 and an
adapting
flange 20, the connection tube 19 is used for connecting the shell 34 and the
adapting
flange 20, and the adapting flange 20 is sealed with an adapting bolt through
a rubber
column. The adapting flange is sealed by an extrusion manner of the rubber
column and
the adapting bolt, so that the sealing effect and the mounting convenience can
be
improved.
Preferably, the mass flow sensor further includes: a pressure switch 23,
arranged on an
upper surface of the shell 34 and used for detecting the pressure in the shell
34 and
sending a prompt message when the pressure is greater than an early warning
threshold.
The pressure switch is mounted on the shell of the sensor to detect the
pressure change
in the shell of the sensor, and timely early warning can be carried out when
the internal
pressure is greater to prevent the sensor from being damaged.
As shown in Fig. 11, preferably, a groove is formed in a side face of the
shell 34 to
improve the overall strength of the shell. The shell 34 is specifically
divided into an
upper shell and a lower shell to be conveniently dismounted and mounted.
The technical solutions of the present invention have been described above in
detail
with reference to the accompanying drawings. Considering that a U-shaped tube
having
a very large curvature is adopted in related technology to generate a larger
resistance to
the flow of the compressed natural gas, and that the distance elements are
few, a higher
mechanical quality factor, better stability and stronger seismic resistance
are difficult
to guarantee. By means of the technical solutions of the present application,
when the
mass flow of the compressed natural gas is measured, the resistance generated
on the
compressed natural gas can be reduced, and firm distance detection can be
realized to
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guarantee higher mechanical quality factors, better stability and stronger
seismic
resistance for the circulation measurement tubes of the compressed natural
gas.
Industrial Applicability
According to the mass flow sensor provided by the present invention, the
included
angles between the axial lines of the straight tube segments and the inclined
tube
segments are set to be obtuse angles, the included angles between the axial
lines of the
inclined tube segments and the port segments are set to be obtuse angles, and
the
segments are connected by the circular arc segments, so that the transition is
smooth,
when the compressed natural gas flows in the measurement tubes, no larger
resistance
will be generated on the compressed natural gas, when the mass flow of the
compressed
natural gas is measured, the resistance generated on the compressed natural
gas can be
reduced, and firm distance detection can be realized to guarantee higher
mechanical
quality factors, better stability and stronger seismic resistance for the
circulation
measurement tubes of the compressed natural gas.
