CN1777791A - Ultrasonic apparatus and method for measuring the concentration and flow rate of gas - Google Patents
Ultrasonic apparatus and method for measuring the concentration and flow rate of gas Download PDFInfo
- Publication number
- CN1777791A CN1777791A CN 200480010421 CN200480010421A CN1777791A CN 1777791 A CN1777791 A CN 1777791A CN 200480010421 CN200480010421 CN 200480010421 CN 200480010421 A CN200480010421 A CN 200480010421A CN 1777791 A CN1777791 A CN 1777791A
- Authority
- CN
- China
- Prior art keywords
- ultrasonic
- sample gas
- backward
- transmitter
- ultrasonic wave
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims description 18
- 238000012545 processing Methods 0.000 claims abstract description 10
- 239000007789 gas Substances 0.000 claims description 163
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 72
- 239000001301 oxygen Substances 0.000 claims description 72
- 229910052760 oxygen Inorganic materials 0.000 claims description 71
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 36
- 230000005540 biological transmission Effects 0.000 claims description 20
- 229910052757 nitrogen Inorganic materials 0.000 claims description 17
- 238000002604 ultrasonography Methods 0.000 claims description 10
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 8
- 230000001902 propagating effect Effects 0.000 description 10
- 239000000203 mixture Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- OLBVUFHMDRJKTK-UHFFFAOYSA-N [N].[O] Chemical compound [N].[O] OLBVUFHMDRJKTK-UHFFFAOYSA-N 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02818—Density, viscosity
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02836—Flow rate, liquid level
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02881—Temperature
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Measuring Volume Flow (AREA)
Abstract
The present invention provides an ultrasonic apparatus measures the concentration and flow rate of a sample gas by calculating a possible propagation time range on the basis of the gas temperature, determining whether or not the phases at which two first trigger signals, respectively generated on the basis of forward and backward waveforms of the ultrasonic waves, coincide with each other, processing the zero-cross signals so that the phases coincide with each other, obtaining reference zero-cross time instant by calculating mean value of the forward and backward zero-cross time instants, obtaining an ultrasonic reception point by subtracting an integral multiple of the cycle of the ultrasonic waves so that the results of the subtraction falls into a possible propagation time range and estimating the ultrasonic propagation time on the basis of the ultrasonic reception point.
Description
Technical Field
The present invention relates to an ultrasonic apparatus and a method for determining the concentration of oxygen in a sample gas and the flow rate of the sample gas, the sample gas being provided by an oxygen concentrator for medical purposes.
Background
It is well known that the propagation velocity of ultrasonic waves in a sample gas can be expressed as a function of the sample gas concentration and temperature. Assuming that the average molecular weight of the sample gas is M and the temperature is T (K), the ultrasonic velocity C (M/sec) passing through the static sample gas is expressed as the following equation (1)
C＝(κRT/M)1/2 ...(1)
Wherein,
kappa: ratio of molecular specific heat at constant volume to molecular specific heat at constant pressure
R: gas constant
Therefore, the average molecular weight M of the sample gas can be obtained by calculation by measuring the propagation velocity C (M/sec) of the ultrasonic wave passing through the sample gas and the temperature T (K) of the sample gas. For example, the average molecular weight M of a sample gas containing an oxygen-nitrogen gas mixture in a mixing ratio of P: (1-P) (0. ltoreq. P.ltoreq.1) can be calculated by the following equation (2).
M＝MO2P+MN2(1-P) ...(2)
Wherein:
MO2: molecular weight of oxygen
MN2: molecular weight of Nitrogen
Thus, the oxygen concentration P can be obtained by calculation from the measured average molecular weight M. When the sample gas is an oxygen-nitrogen mixture, it is reasonable to have k 1.4 over a wide range of oxygen to nitrogen mixing ratios.
If the propagation velocity of the ultrasonic wave in the sample gas is C (m/sec) and the flow velocity of the sample gas is V (m/sec), the velocity of the ultrasonic wave propagating forward with respect to the flow of the sample gas is C (m/sec)1(m/sec) is C1Velocity C of ultrasonic waves propagating backward with respect to the flow of sample gas2(m/sec) is C2Therefore, the flow velocity V (m/sec) of the sample gas can be obtained by the following equation (3).
V＝(C1-C2)/2 ...(3)
Multiplying the flow velocity of the sample gas by the cross-sectional area (m) of the sample gas flowing through the conduit2) That is to sayDetermining the flow rate (m) of the sample gas3/sec)。
Methods and apparatus have been developed to determine a specific gas concentration or sample gas flow rate based on the propagation velocity or propagation time of ultrasonic waves in the sample gas using the above-described principles. For example, in japanese unexamined patent publication (Kokai) No.6-213877, there is described an apparatus in which two ultrasonic transducers are oppositely disposed in a pipe through which a sample gas flows and the propagation time of ultrasonic waves propagating between the ultrasonic transducers is measured, thereby determining the concentration and flow rate of the sample gas. Further, in japanese unexamined patent publication (Kokai) nos. 7-209265 and 8-233718, there is described an apparatus for measuring the concentration of a specific gas contained in a sample gas by measuring the propagation speed or propagation time of an ultrasonic wave propagating in a volume using a reflection type apparatus including an ultrasonic transducer and a reflection plate disposed oppositely.
In such a method and apparatus for measuring concentration and flow rate using the propagation velocity of ultrasonic waves, it is necessary to accurately measure the propagation time of the ultrasonic waves. However, a signal generated from the received ultrasonic wave always contains a noise component, which makes it difficult to determine the timing at which the ultrasonic transducer receives the ultrasonic wave. Therefore, the propagation time of the ultrasonic wave is indirectly estimated by a complicated signal processing process or complicated hardware. For example, japanese unexamined patent publication (Kokai) No.9-318644 describes a method of measuring the ultrasonic wave propagation time in which the received ultrasonic wave waveform is integrated. When the result of the waveform integration reaches a predetermined trough, the first zero-crossing time can be determined as the travel time of the ultrasonic wave for measuring the flow rate. According to this method, even when the amplitude of the received wave fluctuates to some extent, the generation time of the zero-cross signal does not fluctuate. Therefore, the obtained zero-crossing timing is relatively close to the timing at which the ultrasonic wave actually reaches. However, the obtained zero-crossing time is not the true propagation time of the ultrasonic wave. Especially when measuring concentrations, the difference between the real propagation time and the zero crossing instant strongly influences the measurement error.
Further, japanese unexamined patent publication (Kokai) No.60-138422 describes a flow rate measurement device in which an envelope curve (envelopecurve) is calculated from a received ultrasonic waveform. The rise time of the envelope curve is calculated by an approximation equation to estimate the propagation time of the ultrasonic wave. However, the received ultrasonic waves must be extracted with hardware, and a complicated signal processing process is required to calculate an envelope curve from the extracted waveform. Therefore, according to the invention JPP' 422, it is difficult to provide a compact device at low cost.
Disclosure of Invention
An object of the present invention is to provide an ultrasonic apparatus and method for measuring a concentration and a flow rate of a gas, which can accurately measure a concentration and a flow rate of a sample gas without complicated signal processing and additional hardware.
According to the present invention, there is provided an ultrasonic apparatus for measuring a concentration and a flow rate of a sample gas, comprising:
a conduit for flow of sample gas;
a first ultrasonic transmitter-receiver installed in the pipe;
a second ultrasonic transmitter-receiver installed in the pipe opposite to the first ultrasonic transmitter-receiver;
a transmission/reception switch for switching operation modes of the first and second ultrasonic wave transmitter/receivers between a transmission mode of transmitting ultrasonic waves and a reception mode of receiving ultrasonic waves;
a temperature sensor disposed within the conduit for measuring the temperature of the sample gas flowing through the conduit;
the first ultrasonic transmitter-receiver generating an ultrasonic wave forward with respect to the flow direction of the sample gas in its transmission mode, and generating a backward waveform based on the received ultrasonic wave generated by the second ultrasonic transmitter-receiver when it is in the reception mode;
the second ultrasonic transmitter-receiver generates an ultrasonic wave backward with respect to the flow direction of the sample gas in its transmission mode, and generates a forward waveform based on the received ultrasonic wave generated by the first ultrasonic transmitter-receiver when it is in the reception mode;
means for generating a trigger signal when the forward and backward waveforms exceed a predetermined level;
means for generating forward and backward zero-crossing signals when the forward and backward waveforms exceed zero level;
propagation time calculation means, which is connected to the temperature sensor, the trigger signal generation means, and the zero-crossing signal generation means, for (1) calculating a possible propagation time range based on the gas temperature measured by the temperature sensor, (2) determining whether phases of two first trigger signals, which are generated on the basis of forward and backward waveforms, respectively, (3) processing the zero-crossing signals so that the phases thereof coincide with each other if they do not coincide with each other, (4) obtaining a reference zero-crossing time by calculating an average of the forward and backward zero-crossing times, (5) subtracting an integral multiple of the ultrasonic wave period so that the subtracted result falls within the possible propagation time range, thereby obtaining an ultrasonic wave reception point, and (6) estimating the ultrasonic wave propagation time based on the ultrasonic wave reception point.
Further, according to another feature of the present invention, there is provided a method of measuring a concentration of a sample gas flowing through a pipe, comprising the steps of:
generating an ultrasonic wave forward with respect to a flow direction of the sample gas;
generating an ultrasonic wave backward with respect to a flow direction of the sample gas;
measuring the temperature of the sample gas flowing through the conduit;
generating a trigger signal when the forward and backward waveforms exceed a predetermined level;
generating forward and backward zero-crossing signals when the forward and backward waveforms exceed zero level;
calculating a range of possible travel times based on the gas temperature measured by the temperature sensor;
determining whether phases of two first trigger signals, which are generated on a forward and backward waveform basis, respectively, coincide with each other;
processing the zero-crossing signals to make their phases coincide with each other if they do not coincide with each other;
obtaining a reference zero-crossing time by calculating an average of the forward and backward zero-crossing times;
subtracting integral multiple of the ultrasonic period to make the subtracted result fall into a possible propagation time range, thereby obtaining an ultrasonic receiving point; and
estimating the propagation time of the ultrasonic wave on the basis of the ultrasonic wave reception point.
Further, according to another feature of the present invention, there is provided an oxygen concentration system that generates an oxygen-enriched gas, including:
an oxygen concentration device for generating an oxygen-rich gas by absorbing nitrogen to remove nitrogen from air; and
an ultrasonic apparatus for measuring an oxygen concentration in an oxygen-enriched gas and a flow rate of the oxygen-enriched gas, the ultrasonic apparatus comprising:
a conduit for receiving and flowing an oxygen-enriched gas;
a first ultrasonic transmitter-receiver installed in the pipe;
a second ultrasonic transmitter-receiver installed in the pipe opposite to the first ultrasonic transmitter-receiver;
a transmission/reception switch for switching operation modes of the first and second ultrasonic wave transmitter/receivers between a transmission mode of transmitting ultrasonic waves and a reception mode of receiving ultrasonic waves;
a temperature sensor disposed within the conduit for measuring the temperature of the oxygen-enriched gas flowing through the conduit;
the first ultrasonic wave transmitter-receiver generates an ultrasonic wave forward with respect to the flow of the oxygen-enriched gas in its transmission mode, and generates a backward waveform based on the received ultrasonic wave generated by the second ultrasonic wave transmitter-receiver when it is in the reception mode;
the second ultrasonic wave transmitter-receiver generates an ultrasonic wave backward with respect to the oxygen-enriched gas flow in its transmission mode, and generates a forward waveform based on the received ultrasonic wave generated by the first ultrasonic wave transmitter-receiver when it is in the reception mode;
means for generating a trigger signal when the forward and backward waveforms exceed a predetermined level;
means for generating forward and backward zero-crossing signals when the forward and backward waveforms exceed zero level;
propagation time calculation means, which is connected to the temperature sensor, the trigger signal generation means, and the zero-crossing signal generation means, for (1) calculating a possible propagation time range based on the gas temperature measured by the temperature sensor, (2) determining whether phases of two first trigger signals, which are generated on the basis of forward and backward waveforms, respectively, (3) processing the zero-crossing signals so that the phases thereof coincide with each other if they do not coincide with each other, (4) obtaining a reference zero-crossing time by calculating an average of the forward and backward zero-crossing times, (5) subtracting an integral multiple of the ultrasonic wave period so that the subtracted result falls within the possible propagation time range, thereby obtaining an ultrasonic wave reception point, and (6) estimating the ultrasonic wave propagation time based on the ultrasonic wave reception point.
Further, according to another feature of the present invention, there is provided an oxygen concentration system for generating an oxygen-enriched gas, comprising
An oxygen concentration device for generating an oxygen-rich gas by absorbing nitrogen to remove nitrogen from air; and
an ultrasonic apparatus for measuring an oxygen concentration in the oxygen-enriched gas and a flow rate of the oxygen-enriched gas, the ultrasonic apparatus comprising:
a conduit for flowing a target gas of measured concentration;
a first ultrasonic transmitter-receiver installed in the pipe;
a second ultrasonic transmitter-receiver installed in the pipe opposite to the first ultrasonic transmitter-receiver;
the pipe comprises a straight part and a vertical part vertically connected with the straight part;
the first and second ultrasonic wave transmitter-receivers are disposed at the vertical portion so as to face the end of the linear portion; and is
The distances between the first and second ultrasonic transmitter-receivers and the respective ends of the straight portions of the pipe satisfy the following relationship.
0＜D＜f-r2/C
Wherein:
d: a distance (m) between the first and second ultrasonic transmitter-receivers and respective ends of the straight portion
f: frequency (Hz) of ultrasonic waves in sample gas
r: inner diameter of pipe (m)
C: velocity of ultrasonic wave (m/sec)
Brief Description of Drawings
FIG. 1 is a schematic diagram of an oxygen concentration apparatus according to the present invention;
FIG. 2 is a schematic view of an ultrasound apparatus of the present invention;
FIG. 3A is a waveform based on received ultrasonic waves;
FIG. 3B is a partially enlarged illustration of the waveforms shown in FIG. 3A;
FIG. 4 shows a graphical representation of an ultrasonic waveform with a trigger signal and a zero crossing signal;
FIG. 5 is a graph showing the relationship between the velocity of ultrasonic waves and temperature;
fig. 6 is a diagram showing forward and backward ultrasonic waveforms, in which case the phases of the generated trigger signals coincide with each other.
FIG. 7 is a view similar to FIG. 6, in which case the phases do not coincide with each other;
FIG. 8 is a view similar to FIG. 6, in which case the phases are not coincident with each other;
fig. 9 is an explanatory diagram for showing a manner of obtaining the zero-crossing timing on the assumption that the sample gas is in a stationary state;
fig. 10 is an explanatory diagram for showing a manner of obtaining ultrasonic wave reception points;
FIG. 11 is a cross-section of an ultrasound device according to another embodiment of the invention;
fig. 12 is an explanatory diagram showing a sound field formed in front of the ultrasonic transducer;
FIG. 13 shows experimental results of ultrasonic waveforms obtained by the apparatus of FIG. 11;
FIG. 14 shows experimental results of ultrasonic waveforms obtained by the apparatus of FIG. 11; and is
Fig. 15 shows experimental results of ultrasonic waveforms obtained by the apparatus of fig. 11.
Best Mode for Carrying Out The Invention
Preferred embodiments of the present invention are described below. In the embodiments described below, the sample gas consists of oxygen and nitrogen. However, the measurable sample gas is not limited to a gas sample of oxygen and nitrogen, and the present invention can also be applied to a mixture containing other gases.
FIG. 1 shows a schematic diagram of an oxygen concentration system with an ultrasonic gas concentration and flow measurement device according to a preferred embodiment of the present invention.
The plant 100 includes an oxygen concentration plant 102 that produces an oxygen-enriched gas by removing nitrogen from air, which is provided from outside the system by a compressor 104 through a filter 106. The oxygen-enriched gas produced by the oxygen concentration device 102 is supplied to the ultrasonic device 200 of the present invention through a flow setting means 108, such as a pressure reducing valve. The resulting oxygen-enriched gas is then provided to the user or patient through product filter 110.
The oxygen concentration apparatus includes a plurality of columns (not shown) for containing a nitrogen adsorbent such as zeolite, piping (not shown) including piping for directing compressed air from the compressor 104 to each of the plurality of columns and for directing the generated oxygen-enriched gas from the columns to the flow setting device 108, and valves (not shown) disposed in the piping for selectively opening and closing the piping so that the adsorbent contained in one of the columns absorbs nitrogen to generate the oxygen-enriched gas, while the adsorbent contained in the other of the columns releases the adsorbed nitrogen to regenerate the adsorbent.
Referring to fig. 2, an ultrasonic apparatus 200 for measuring the concentration and flow rate of a sample gas according to the present invention will be described.
The gas concentration and flow measurement device 200 includes a conduit 202 for the flow of sample gas or oxygen-enriched gas generated by the oxygen concentration device 102. The pipe 202 has a straight portion 208 and vertical portions 204 and 206 connecting the ends of the straight portion. The straight portion 208 comprises a pipe element having a circular cross-section, the diameter of which does not vary with the longitudinal axis.A first ultrasonic transducer 218 providing a first ultrasonic transmitter-receiver is fixed at one end in the straight portion, and a second ultrasonic transducer 222 providing a second ultrasonic transmitter-receiver is fixed at the other end in the straight portion 208, opposite to the first ultrasonic transducer 218. In this embodiment, the distance between first and second ultrasonic transducers 218 and 222 is referred to as the propagation length LS。
The vertical portion 204 is disposed relatively upstream in the gas flow direction through the pipe 202, and has an inlet 204 a. The oxygen concentration device 102 is connected to the inlet 204a by a supply line 210 as a source of sample gas 212.
The vertical portion 206 is disposed relatively downstream in the direction of gas flow through the conduit 202 and has an outlet 206a that is connected to the product filter 110.
A transmit-receive switch 224 is coupled to the first and second ultrasonic transducers 218 and 222. The transmit-receive switch 224 independently switches the operating mode of the first and second ultrasonic transducers 218 and 222 between a transmit mode in which the first and second ultrasonic transducers 218 and 222 transmit ultrasonic waves and a receive mode in which the first and second ultrasonic transducers 218 and 222 receive ultrasonic waves. The transmit-receive switch 224 is connected to a microcomputer 226 so that the switching operation of the transmit-receive switch 224 is controlled by the microcomputer 226.
A driver 228 for driving the first and second ultrasonic transducers 218 and 222, a zero crossing detection circuit 230 for detecting zero crossing times of signals from the first and second ultrasonic transducers 218 and 222, a display unit 234 for displaying, for example, an operation state and a measurement result of the apparatus 200, and a memory 232 for storing an operating system of the microcomputer 226 and various parameters, including a fixed memory or a magnetic disk device, are connected to the microcomputer 226.
The operation of the ultrasonic concentration and flow rate measuring device 200 of the present embodiment will be described below.
A sample gas, such as a nitrogen-oxygen gas mixture, is supplied to the conduit 202 in a mixture ratio of P: (1-P) (0. ltoreq. P.ltoreq.1). At this time, the temperature of the sample gas is measured by the temperature sensors 216 and 220, and the average value thereof is stored in the memory 232 as a reference temperature T0 (K). According to this embodiment, the operating temperature range of the system 100 is preferably, for example, 5-35 degrees Celsius.
In supplying the sample gas, a pulse for generating an ultrasonic wave is sent from the microcomputer 226 to the driver 228. A pulsed voltage is applied from driver 228 to first ultrasonic transducer 218 through transmit-receive switch 224. The first ultrasonic transducer 218 emits ultrasonic waves corresponding to the pulse voltage. The ultrasonic waves emitted by the first ultrasonic transducer 218 propagate in the sample gas flowing through the straight portion 208 of the pipe 202 and are received by the second ultrasonic transducer 222. The second ultrasonic transducer 222 generates an electric signal corresponding to the received ultrasonic wave, and transmits the electric signal to the microcomputer 226 through the transmission/reception switch 224 and the zero-crossing detection circuit 230. The microcomputer 226 calculates the forward propagation time t based on the time at which the transmitted pulse is generated to the driver 228 and the time at which the electrical signal is received from the second ultrasonic transducer 222S1(sec)。
Subsequently, upon receiving the electrical signal from the second ultrasonic transducer 222, the transmit-receive switch 224 switches the operation mode of the first ultrasonic transducer 218 from the transmission mode to the reception mode immediately while switching the operation mode of the second ultrasonic transducer 222 from the reception mode to the transmission mode. Then, the microcomputer 226 transmits a pulse for generating an ultrasonic wave to the driver 228. The pulsed voltage from the driver 228 is supplied to the second ultrasonic transducer 222 through the transmit-receive switch 224. The second ultrasonic transducer 222 generates ultrasonic waves corresponding to the pulse voltage. The ultrasonic waves are received by the first ultrasonic transducer 218. The first ultrasonic transducer 218 generates an electric signal corresponding to the received ultrasonic wave, and transmits the electric signal to the microcomputer 226 through the transmission/reception switch 224 and the zero-crossing detection circuit 230. The microcomputer 226 calculates the backward propagation time t based on the time of the generation of the transmit pulse to the driver 228 and the time of the reception of the electrical signal from the first ultrasonic transducer 218S2(sec)。
Obtaining tS1And tS2Can be eliminated from the influence of the sample gas flow in the pipe 202. Propagation time t of ultrasonic waves in a stationary sample gasSDefined by the following equation (4).
tS＝(tS1+tS2)/2 ....(4)
The microcomputer 226 then calculates the propagation velocity C of the ultrasonic wave in the stationary sample gas by the following equation (5)S(m/sec)。
CS＝LS/tS...(5)
Oxygen concentration PSThis is obtained by the following equation (6) on the basis of equations (1) and (2).
PS＝(κRTS/CS 2-MN2)/(MO2-MN2) ...(6)
Further, the oxygen concentration in the sample gas can be determined from the ratio of the propagation velocity of the ultrasonic wave in the sample gas to the propagation velocities of the ultrasonic wave in 100% oxygen and 100% nitrogen. That is, the temperature T can be easily obtained by equation (1)S(K) Propagation velocity C of ultrasonic waves in 100% oxygenO2(m/sec), and temperature TS(K) Propagation velocity C of ultrasonic waves in 100% nitrogenN2(m/sec). Therefore, let C be the propagation velocity of the ultrasonic wave in the sample gasS(m/sec), P can be calculated by the following equation (7)S。
PS＝(1/CS 2-1/CN2 2)/(1/CO2 2-1/CN2 2) ...(7)
The operation may be performed by the microcomputer 126 and the result displayed by the display unit 134.
Next, obtaining t will be explainedS1And tS2The method of (1). In this relation, the timing at which the first or second ultrasonic transducer 218 or 222 transmits the ultrasonic wave is referred to as a transmission time, and the timing at which the first or second ultrasonic transducer 218 or 222 receives the ultrasonic wave is referred to as an ultrasonic wave reception point in the present application.
Fig. 3A shows a typical ultrasonic waveform received by the microcomputer 226, and fig. 3B is an enlargement of the waveform portion shown in cycle 3B. As shown in fig. 3A and 3B, the waveform contains a plurality of noise components, so that it is difficult to detect the ultrasonic wave receiving point of the ultrasonic wave propagating in the sample gas. Therefore, according to the present invention, the ultrasonic wave reception point can be estimated based on the zero-crossing timing of the measured waveform after the amplitude of the waveform has sufficiently increased to some extent. To this end, the zero-crossing detection circuit 230 includes a zero-crossing comparator and a flip-flop comparator.
Referring to fig. 4, the flip-flop comparator outputs a trigger signal S when the waveform exceeds a predetermined level upwardtiTo the microcomputer 226. The zero-crossing comparator outputs a zero-crossing signal Z when the waveform crosses zero level upwardciTo the microcomputer 226. When the microcomputer 226 receives the first trigger signal StiThe microcomputer 226 then determines each zero crossing signal ZciAs the zero crossing time. Preferably, the microcomputer 226 determines the first three zero-crossing signals as the first to third zero-crossing times Zc1、Zc2And Zc3。
The interval between the respective zero-crossing instants is theoretically related to the period of the ultrasonic wave. Thus, from the first zero-crossing time Z along the time axisc1Tracing back, multiplying by integral multiple of ultrasonic wave period to estimate ultrasonic wave receiving pointThe travel time can be estimated by subtracting the transmit time and an integer multiple of the ultrasound period from the ultrasound receive point.
As described above, the propagation velocity C (m/sec) of the ultrasonic wave in the stationary gas can be obtained by equation (1). For example, the propagation velocity of the ultrasonic wave in pure nitrogen gas at 20 degrees Celsius is 349.1m/sec, and the velocity in pure oxygen gas at 20 degrees Celsius is 326.6 m/sec. Therefore, the propagation speed of the ultrasonic wave in the oxygen-nitrogen gas mixture at 20 degrees centigrade falls within the range of 326.6 to 349.1 m/sec. FIG. 5 is a graph showing the relationship between the speed of ultrasonic waves and the gas temperature, in which the upper limit and the lower limit of the propagation speed of ultrasonic waves in an oxygen-nitrogen gas mixture are respectively represented by Cmax(T) and Cmin(T). Possible propagation time range is LS/Cmax(T) to LS/Cmin(T). Thus, if the propagation length L is chosenSThe following relationship (8) is satisfied, and only one integer may be selected so that the ultrasonic wave reception point falls within the possible propagation time range.
(LS/Cmin(T)-LS/Cmax(T))＜1/f ...(8)
Wherein:
f: frequency of ultrasonic waves in sample gas
Make (L)S/Cmax(T)-LS/Cmin(T)) the gas temperature T having the maximum value is the lower limit of the operating temperature. If the operating temperature is 5 degrees Celsius and the ultrasonic frequency is 40KHz, the propagation length L of the relation (8) is satisfiedSThe calculation is as follows.
LS＜12.3cm ...(9)
According to this embodiment, L is usedS0.1m as an example.
In order to obtain the propagation time t of the ultrasonic waveSThe forward and backward propagation times t are measured in advanceS1And tS2. See the figureWhen the second of the forward and backward waveforms exceeds the trigger level, a trigger signal is generated. In this case, the trigger signal is generated at the same time or phase relative to the waveform, and at the difference between the zero crossing times between the forward and backward waves, a ═ ZcBi-ZcFiSubstantially equal to the propagation time t between the forward and backward wavesS1And tS2Difference t ofd(ZcFi: zero crossing time of the forward waveform, ZcBi: the zero-crossing time, i, of the backward waveform is 1, 2, 3. (number of waves)).
However, even when the same trigger level is used, the trigger signal StiBut also typically at different waveform phases between the forward and backward waves. Referring to fig. 7, for a forward wave, the trigger signal is generated when the third wave exceeds the trigger level, and for a backward wave, the trigger signal is generated when the second wave exceeds the trigger level. Therefore, the trigger signal of the backward wave is generated one cycle earlier than the trigger signal of the forward wave. In this case, the difference between zero crossing times between the forward and backward waves, a ═ ZcBi-ZcFiAnd is a negative value. If sample gas flows through the conduit 102, A ═ ZcBi-ZcFiMust not be negative. Thus, if A ═ ZcBi-ZcFiNegative values, it is clear that the trigger signal for the backward wave is generated earlier than the trigger signal for the forward wave.
On the other hand, referring to fig. 8, for a forward wave, the trigger signal is generated when the second wave exceeds the trigger level. For backward waves, the trigger signal is generated when the third wave exceeds the trigger level. In this case, the zero-crossing time difference between the forward and backward waves, a ═ ZcBi-ZcFiGreater than one cycle of the ultrasonic wave, indicating that the trigger signal for the forward wave is generated earlier than the trigger signal for the backward wave.
According to an embodiment of the invention, the pipe 102 is designed such that the difference t between the propagation time between the forward and backward wavesdAlways fall within one ultrasound cycle. This feature enables the microcomputer 226 to distinguish the cases shown in fig. 7 and 8 from each other, andcalculating the difference t between the propagation timesd. That is, if A ═ ZcBi-ZcFiNegative, it is the case shown in fig. 7, and if a ═ ZcBi-ZcFiGreater than one ultrasonic cycle is the case shown in fig. 8.
Thus, the structure of the duct 102 having the above-described features will be described below.
The possible range of the sample gas flow velocity V (m/sec) is shown by the following inequality (10).
0≤V≤Q/(60000π/r2) ..(10)
Wherein:
q: flow rate of sample gas (liter/min)
r: inner diameter of pipe (cm)
As mentioned above, the velocity of the ultrasonic wave propagating forward with respect to the sample gas flow is C1C + V, the ultrasonic velocity propagating backwards with respect to the sample gas flow is C2＝C-V。
Wherein:
c: velocity of ultrasonic waves (m/sec) propagating in a stationary gas
C1: forward propagating ultrasonic velocity (m/sec) with respect to sample gas flow
C2: velocity of ultrasonic wave (m/sec) propagating backward with respect to sample gas flow
V: flow velocity (m/sec)
Difference in propagation time tdCalculated by the following equation.
td＝LS/C2-LS/C1
＝LS/(C-V)-LS/(C+V) ...(11)
Therefore, if the inner diameter of the pipe 102 satisfies the following relational expression(12) The difference t of propagation timedWill be less than the ultrasonic period.
LS/(C-Q/(60000π/r2))-LS/(C+Q/(60000π/r2))＜1/f ...(12)
When the ultrasonic velocity through the pipe 102 is minimum (C ═ C)min(5 degrees celsius) 318.1m/sec, the left term of the inequality (12) takes the maximum value. Thus, for example, if the ultrasonic frequency passing through the pipe 102 is 40(KHz), the flow Q is 10(litter/min) and the length of the pipe 102 is 10(cm), the inner diameter r (mm) of the pipe 102 is r > 2.05 (mm). According to the present embodiment, r is selected to be 2.5(mm) as an example.
Next, a method of measuring the concentration and flow rate of the sample gas will be described in detail below.
First, in the case shown in fig. 6, the propagation time difference t between the forward and backward wavesdAccording to formula A ═ ZcBi-ZcFiIs obtained because, as mentioned above, the propagation time difference tdIs substantially equal to the difference A ═ ZcBi-ZcFiIs. In the case shown in FIG. 7, the propagation time difference tdAccording to B ═ ZcBi+1-ZcFiThus obtaining the product. In the case shown in fig. 8, the propagation time difference is Z as indicated by BcBi-ZcFi+1Thus obtaining the product. Preferably, a plurality of a or B values are obtained for arithmetic averaging.
Next, the ultrasonic velocity in the sample gas is estimated assuming that the sample gas is static. For this purpose, the phase difference in the trigger signal output result is determined in advance based on the value a. If there is no phase difference, the average Z of the first zero-crossing times of the forward and backward waveforms is shown in FIG. 6c_aveCalculated by the following equation.
Zc_ave＝(ZcF1+ZcB1)/2 ...(13)
In the case shown in fig. 7, the average value Z of the first zero-crossing instants of the forward and backward waveformsc_aveCalculated by the following equationAnd (4) calculating.
Zc_ave＝(ZcF1+ZcB2)/2 ...(14)
In the case shown in fig. 8, the average value Z of the first zero-crossing instants of the forward and backward waveformsc_aveCalculated by the following equation.
Zc_ave＝(ZcF2+ZcB1)/2 ...(15)
Assuming that the ultrasonic wave passes through a static sample gas, the average value Zc_aveCan be seen as the first zero-crossing instant obtained. Zc_aveReferred to in this application as the reference zero-crossing instant.
As described above, the length of the pipe 102 is designed so that only an integer can be selected so that the ultrasonic wave reception point falls within the range of possible propagation times (fig. 9). Thus, from the first zero-crossing time Z along the time axisc_aveTracing back, multiplying by integral multiple of ultrasonic wave period until the ultrasonic wave receiving point falls into possible range, and estimating the ultrasonic wave propagation time tS。
Ultrasonic velocity C in static sample gasSEstimated by the following equation (16).
CS＝LS/tS ...(16)
Oxygen concentration PSC calculated by equation (6) or (7)SCan be obtained.
Forward and backward propagation times t in the sample gas flowing through the pipe 102S1And tS2Estimated by the following equations (17) and (18).
tS1＝tS-td/2 ...(17)
tS2＝tS+td/2 ...(18)
Forward and backward velocity C of ultrasonic waves in sample gas flowing through the pipe 1021And C2Estimated by the following equations (19) and (20).
C1＝LS/tS1 ...(19)
C2＝LS/tS2 ...(20)
Then, the sample gas flow rate V through the pipe 102 is obtained by equations (3), (19) and (20). Further, the flow rate Q of the sample gas is calculated by the following equation (21).
Q＝6000πr2V ....(21)
Next, referring to fig. 11 to 15, an ultrasonic concentration and flow rate measuring apparatus of a preferred embodiment will be described below.
Ultrasonic concentration and flow measurement device 10 includes conduit 27 which provides conduit 102 of the embodiment of FIG. 2. The housings 25 and 26, which enclose the first and second ultrasonic transducers 20 and 21, are fixed to both ends of the pipe 27 by welding portions 41 and 42. The housings 25 and 26 include ports 28 and 29 extending perpendicular to the conduit 27 to provide inlet and outlet portions 204a and 206a in the embodiment of fig. 2. The conduit 27 and the housings 25 and 26 are preferably made of the same metal material, such as an aluminum alloy.
The pipe 27 and the housings 25 and 26 are fixed to the base plate 30 or the housing of the oxygen concentration apparatus at one position by bolts 45. This configuration allows the tube 27 to freely deform longitudinally when subjected to external forces that may occur when the tube 27 thermally deforms.
The covers 23 and 24 are connected to the housings 25 and 26 by bolts 43 and 44 so that the O-rings 39 and 40 are sandwiched between the housings 25 and 26 and the covers 23 and 24, thereby closing the end openings of the housings. The first and second ultrasonic transducers 20 and 21 are attached to the inner surfaces of the covers 23 and 24. The first and second ultrasonic transducers 20 and 21 generate ultrasonic waves of 40 KHz.
In addition, temperature sensors 37 and 38 for detecting the temperature of the gas are attached to the inner surfaces of the covers 23 and 24. The first and second ultrasonic transducers 20 and 21 and the temperature sensors 37 and 38 are connected to the microcomputer 226 through connectors 31 and 34 attached to the outer surfaces of the covers 23 and 24, and cables 33 and 36 and connectors 32 and 35 are mounted on the substrate 30.
The distance D between the end faces of the first and second ultrasonic transducers 20 and 21 and the corresponding end of the pipe 27 is an important design consideration. Generally, the sound field formed by the ultrasonic waves from the ultrasonic transducer includes a near sound field and a far sound field, as shown in fig. 12. Ultrasonic waves propagate linearly through the near-sound field, while on the other hand, in the far-sound field, they propagate in the form of spherical waves. Thus, if the end of the pipe 27 exceeds the near field, the ultrasonic energy transmitted in the pipe 27 will be reduced compared to a pipe whose end is disposed in the near field, and thus the sound/noise ratio of the signal from the transducer will be reduced.
It is well known that the division between the near and far sound fields is at point Z0Expressed, its distance D from the end face of the ultrasonic transducer along the center line of the transducer is expressed by the following equation (22).
D＝f-r2/C ...(22)
Wherein:
f: frequency of ultrasonic waves (Hz) in sample gas
r: inner diameter of pipe (m)
C: ultrasonic velocity (m/sec)
As described above, the velocity C in the sample gas is represented by equation (1). Thus, the higher the gas temperature and the smaller the molecular weight, the higher the velocity C. According to this embodiment, Z is0The maximum value is that, for example, the sample gas is 35 degrees Celsius air, and Z is0Approximately 1.4 mm.
FIGS. 13-15 show the results of ultrasonic waveform experiments obtained by the apparatus of FIG. 11, in which the distances d are 0.3mm, 1.0mm and 1.8 mm. The experimental results show that when the distance d is 1.8mm, the ultrasonic energy received by the ultrasonic transducer is significantly reduced compared to the case where the distance d is 0.3mm and 1.0 mm.
Claims (22)
1. An ultrasonic apparatus for measuring sample gas concentration and flow, comprising:
a conduit for flow of sample gas;
a first ultrasonic transmitter-receiver installed in the pipe;
a second ultrasonic transmitter-receiver installed in the pipe opposite to the first ultrasonic transmitter-receiver;
a transmission-reception switch for switching an operation mode of the first and second ultrasonic transmission-receivers between a transmission mode of transmitting ultrasonic waves and a reception mode of receiving ultrasonic waves;
a temperature sensor disposed within the conduit for measuring the temperature of the sample gas flowing through the conduit;
the first ultrasonic transmitter-receiver generating an ultrasonic wave forward with respect to the flow direction of the sample gas in its transmission mode, and generating a backward waveform based on the received ultrasonic wave generated by the second ultrasonic transmitter-receiver when it is in the reception mode;
the second ultrasonic transmitter-receiver generates an ultrasonic wave backward with respect to the flow direction of the sample gas in its transmission mode, and generates a forward waveform based on the received ultrasonic wave generated by the first ultrasonic transmitter-receiver when it is in the reception mode;
means for generating a trigger signal when the forward and backward waveforms exceed a predetermined level;
means for generating forward and backward zero-crossing signals when the forward and backward waveforms exceed zero level;
propagation time calculation means, which is connected to the temperature sensor, the trigger signal generation means, and the zero-crossing signal generation means, for (1) calculating a possible propagation time range based on the gas temperature measured by the temperature sensor, (2) determining whether phases of two first trigger signals, which are generated on the basis of forward and backward waveforms, respectively, (3) processing the zero-crossing signals so that the phases thereof coincide with each other if they do not coincide with each other, (4) obtaining a reference zero-crossing time by calculating an average of the forward and backward zero-crossing times, (5) subtracting an integral multiple of the ultrasonic wave period so that the subtracted result falls within the possible propagation time range, thereby obtaining an ultrasonic wave reception point, and (6) estimating the ultrasonic wave propagation time based on the ultrasonic wave reception point.
2. An ultrasound device according to claim 1, wherein the distance between the first and second ultrasound transmitter-receiver along the pipe is chosen such that, under possible operating conditions of the ultrasound device, only one subtracted result falls within the determined range of possible propagation times.
3. The ultrasonic apparatus according to claim 2, wherein the distance between the first and second ultrasonic transmitter-receivers along said pipe is selected so as to satisfy the following relationship
(LS/Cmin(Tmin)-LS/Cmax(Tmin))＜1/f
Wherein:
f: frequency of ultrasonic waves in sample gas
Cmin(Tmin): at the lowest operating temperature TminA lower limit of ultrasonic velocity (m/sec) in the lower (centigrade) sample gas;
Cmax(Tmin): at the lowest operating temperature TminUpper limit of ultrasonic velocity (m/sec) in sample gas below (centigrade).
4. The ultrasonic apparatus of claim 1, wherein the inner diameter of the conduit is selected such that the difference between the forward and backward propagation times is less than the period of the ultrasonic wave under operating conditions of the sample gas.
5. The ultrasonic apparatus of claim 1, wherein the inner diameter of the conduit is selected to satisfy the following relationship
L/(Cmin(Tmin)-Qmax/(60000π/r2))
-L/(Cmin(Tmin)+Qmax/(60000π/r2))＜1/f
Wherein:
f: frequency of ultrasonic waves in sample gas
Cmin(Tmin): at the lowest operating temperature TminLower limit of ultrasonic velocity (m/sec) in lower (degree centigrade) sample gas
Qmax: upper limit of sample gas flow (liter/min).
6. The ultrasonic apparatus of claim 1, wherein the conduit comprises a straight portion and a vertical portion connected perpendicularly to the straight portion;
the first and second ultrasonic wave transmitter-receivers are disposed at the vertical portion so as to face the end of the linear portion; and is
The distances between the first and second ultrasonic transmitter-receivers and the respective ends of the linear portions of the pipe satisfy the following relationship
0＜D＜f-r2/C
Wherein:
d: a distance (m) between the first and second ultrasonic transmitter-receivers and respective ends of the straight portion
f: frequency (Hz) of ultrasonic waves in sample gas
r: inner diameter of pipe (m)
C: velocity of ultrasonic waves (m/sec).
7. A method of measuring the concentration of a sample gas flowing through a conduit, comprising the steps of:
generating an ultrasonic wave forward with respect to a flow direction of the sample gas;
generating an ultrasonic wave backward with respect to a flow direction of the sample gas;
measuring the temperature of the sample gas flowing through the conduit;
generating a trigger signal when the forward and backward waveforms exceed a predetermined level;
generating forward and backward zero-crossing signals when the forward and backward waveforms exceed zero level;
calculating a range of possible travel times based on the gas temperature measured by the temperature sensor;
determining whether phases of two first trigger signals, which are generated on a forward and backward waveform basis, respectively, coincide with each other;
processing the zero-crossing signals to make their phases coincide with each other if they do not coincide with each other;
obtaining a reference zero-crossing time by calculating an average of the forward and backward zero-crossing times;
subtracting integral multiple of the ultrasonic period to make the subtracted result fall into a possible propagation time range, thereby obtaining an ultrasonic receiving point; and
the ultrasonic propagation time is estimated on the basis of the ultrasonic reception point.
8. The method of claim 7, wherein said forward and backward ultrasonic waves are transmitted and received by first and second ultrasonic transmitter-receivers disposed in said pipe, the distance between the first and second ultrasonic transmitter-receivers along said pipe being selected such that, under possible operating conditions of said ultrasonic device, only one subtracted result falls within said determined range of possible travel times.
9. The method of claim 8, wherein the distance along the pipe between the first and second ultrasonic transmitter-receivers is selected to satisfy the following relationship
(LS/Cmin(Tmin)-LS/Cmax(Tmin))＜1/f
Wherein:
f: frequency of ultrasonic waves in sample gas
Cmin(Tmin): at the lowest operating temperature TminLower limit of ultrasonic velocity (m/sec) in lower (degree centigrade) sample gas
Cmax(Tmin): at the lowest operating temperature TminUpper limit of ultrasonic velocity (m/sec) in sample gas below (centigrade).
10. The method of claim 7, wherein the inner diameter of the conduit is selected such that the difference between the forward and backward propagation times is less than the period of the ultrasonic wave under operating conditions of the sample gas.
11. The method of claim 7, wherein the inner diameter of the pipe is selected to satisfy the following relationship
L/(Cmin(Tmin)-Qmax/(60000π/r2))
-L/(Cmin(Tmin)+Qmax/(60000π/r2))＜1/f
Wherein:
f: frequency of ultrasonic waves in sample gas
Cmin(Tmin): at the lowest operating temperature TminLower limit of ultrasonic velocity (m/sec) in lower (degree centigrade) sample gas
Qmax: upper limit of sample gas flow (liter/min).
12. An oxygen concentration system for generating an oxygen-enriched gas, comprising:
an oxygen concentration device for generating an oxygen-rich gas by absorbing nitrogen to remove nitrogen from air; and
an ultrasonic apparatus for measuring an oxygen concentration in the oxygen-enriched gas and a flow rate of the oxygen-enriched gas, the ultrasonic apparatus comprising:
a conduit for receiving and flowing an oxygen-enriched gas;
a first ultrasonic transmitter-receiver installed in the pipe;
a second ultrasonic transmitter-receiver installed in the pipe opposite to the first ultrasonic transmitter-receiver;
a transmission/reception switch for switching operation modes of the first and second ultrasonic wave transmitter/receivers between a transmission mode of transmitting ultrasonic waves and a reception mode of receiving ultrasonic waves;
a temperature sensor disposed within the conduit for measuring the temperature of the oxygen-enriched gas flowing through the conduit;
the first ultrasonic wave transmitter-receiver generates an ultrasonic wave forward with respect to the flow of the oxygen-enriched gas in its transmission mode, and generates a backward waveform based on the received ultrasonic wave generated by the second ultrasonic wave transmitter-receiver when it is in the reception mode;
the second ultrasonic wave transmitter-receiver generates an ultrasonic wave backward with respect to the oxygen-enriched gas flow in its transmission mode, and generates a forward waveform based on the received ultrasonic wave generated by the first ultrasonic wave transmitter-receiver when it is in the reception mode;
means for generating a trigger signal when the forward and backward waveforms exceed a predetermined level;
means for generating forward and backward zero-crossing signals when the forward and backward waveforms exceed zero level;
propagation time calculation means, which is connected to the temperature sensor, the trigger signal generation means, and the zero-crossing signal generation means, for (1) calculating a possible propagation time range based on the gas temperature measured by the temperature sensor, (2) determining whether phases of two first trigger signals, which are generated on the basis of forward and backward waveforms, respectively, (3) processing the zero-crossing signals so that the phases thereof coincide with each other if they do not coincide with each other, (4) obtaining a reference zero-crossing time by calculating an average of the forward and backward zero-crossing times, (5) subtracting an integral multiple of the ultrasonic wave period so that the subtracted result falls within the possible propagation time range, thereby obtaining an ultrasonic wave reception point, and (6) estimating the ultrasonic wave propagation time based on the ultrasonic wave reception point.
13. The ultrasonic apparatus of claim 12 wherein the distance along the conduit between the first and second ultrasonic transmitter-receivers is selected such that, under possible operating conditions of the ultrasonic apparatus, only one subtracted result falls within the determined range of possible travel times.
14. The ultrasonic apparatus of claim 13, wherein the distance along the conduit between the first and second ultrasonic transmitter-receivers is selected to satisfy the following relationship
(LS/Cmin(Tmin)-LS/Cmax(Tmin))＜1/f
Wherein:
f: frequency of ultrasonic waves in sample gas
Cmin(Tmin): at the lowest operating temperature TminOxygen-enriched gas at lower degree centigradeLower limit of ultrasonic velocity (m/sec) in volume
Cmax(Tmin): at the lowest operating temperature TminThe upper limit of the ultrasonic velocity (m/sec) in the oxygen-enriched gas is given below (degrees centigrade).
15. Ultrasound device according to claim 12, wherein the inner diameter of said conduit is chosen such that the difference between said forward and backward propagation times is smaller than the period of the ultrasound waves in operating conditions with oxygen-enriched gas.
16. The ultrasonic apparatus of claim 12, wherein the inner diameter of the conduit is selected to satisfy the following relationship
L/(Cmin(Tmin)-Qmax/(60000π/r2))
-L/(Cmin(Tmin)+Qmax/(60000π/r2))＜1/f
Wherein:
f: frequency of ultrasonic waves in sample gas
Cmin(Tmin): at the lowest operating temperature TminLower limit of ultrasonic velocity (m/sec) in oxygen-enriched gas
Qmax: upper limit of sample gas flow (liter/min).
17. The ultrasonic apparatus of claim 12, wherein the conduit comprises a straight portion and a vertical portion connected perpendicularly to the straight portion;
the first and second ultrasonic wave transmitter-receivers are disposed at the vertical portion so as to face the end of the linear portion; and is
The distances between the first and second ultrasonic transmitter-receivers and the respective ends of the linear portions of the pipe satisfy the following relationship
0＜D＜f-r2/C
Wherein:
d: a distance (m) between the first and second ultrasonic transmitter-receivers and respective ends of the straight portion
f: frequency (Hz) of ultrasonic waves in sample gas
r: inner diameter of pipe (m)
C: velocity of ultrasonic wave (m/sec)
18. The ultrasonic apparatus according to claim 12, wherein said tube is fixed to the oxygen concentrating device at a position such that the tube can be freely thermally expanded in a longitudinal direction of said straight portion when subjected to an external force which may be generated when the tube is thermally deformed.
19. An oxygen concentration system for generating oxygen-enriched gas, comprising
An oxygen concentration device for generating an oxygen-rich gas by absorbing nitrogen to remove nitrogen from air; and
an ultrasonic apparatus for measuring an oxygen concentration in the oxygen-enriched gas and a flow rate of the oxygen-enriched gas, the ultrasonic apparatus comprising:
a conduit for flowing a target gas of measured concentration;
a first ultrasonic transmitter-receiver installed in the pipe;
a second ultrasonic transmitter-receiver installed in the pipe opposite to the first ultrasonic transmitter-receiver;
the pipe comprises a straight part and a vertical part vertically connected with the straight part;
the first and second ultrasonic wave transmitter-receivers are disposed at the vertical portion so as to face the end of the linear portion; and is
The distances between the first and second ultrasonic transmitter-receivers and the respective ends of the linear portions of the pipe satisfy the following relationship
0＜D＜f-r2/C
Wherein:
d: a distance (m) between the first and second ultrasonic transmitter-receivers and respective ends of the straight portion
f: frequency (Hz) of ultrasonic waves in sample gas
r: inner diameter of pipe (m)
C: velocity of ultrasonic waves (m/sec).
20. The oxygen concentration system of claim 19 wherein the inner diameter of the straight portion is less than the outer diameter of the first and second ultrasonic transducers.
21. An oxygen concentration system according to claim 19 wherein the conduit is secured to the oxygen concentration apparatus by means which allow the straight portion to be freely longitudinally deformed when subjected to external forces which may be generated when the conduit is thermally deformed.
22. The oxygen concentration system according to claim 19, wherein said pipe is fixed to the oxygen concentration device at a position such that the pipe can be freely thermally expanded in a longitudinal direction of said straight portion when subjected to an external force which may be generated when the pipe is thermally deformed.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP115333/2003 | 2003-04-21 | ||
| JP2003115333A JP4271979B2 (en) | 2003-04-21 | 2003-04-21 | Ultrasonic gas concentration flow measurement method and apparatus |
| JP168911/2003 | 2003-06-13 | ||
| JP271779/2003 | 2003-07-08 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1777791A true CN1777791A (en) | 2006-05-24 |
| CN100374826C CN100374826C (en) | 2008-03-12 |
Family
ID=33474563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004800104217A Expired - Lifetime CN100374826C (en) | 2003-04-21 | 2004-04-20 | Ultrasonic apparatus and method for measuring the concentration and flow rate of gas |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP4271979B2 (en) |
| CN (1) | CN100374826C (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102830164A (en) * | 2012-08-23 | 2012-12-19 | 郑州光力科技股份有限公司 | On-line detection method and apparatus of methane concentration |
| CN101680859B (en) * | 2007-05-31 | 2013-01-02 | 帝人制药株式会社 | Ultrasonic gas concentration measuring method and device using the same |
| CN107064295A (en) * | 2017-01-14 | 2017-08-18 | 西安科技大学 | A kind of methane gas concentration measurement system and method |
| CN111164421A (en) * | 2017-10-04 | 2020-05-15 | 上田日本无线株式会社 | Ultrasonic transmitter, propagation time measuring device, gas concentration measuring device, propagation time measuring program, and propagation time measuring method |
| CN111238587A (en) * | 2020-01-20 | 2020-06-05 | 浙江威星智能仪表股份有限公司 | Ultrasonic transducer transmission time calibration method |
| CN113063467A (en) * | 2021-04-28 | 2021-07-02 | 哈勃智能传感(深圳)有限公司 | Sensor-based oxygen concentration and effective flow measuring method and storage medium |
| CN118394142A (en) * | 2024-06-26 | 2024-07-26 | 深圳市东吉联医疗科技有限公司 | Oxygen concentration control method, equipment and storage medium of portable oxygenerator |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006162458A (en) * | 2004-12-08 | 2006-06-22 | Matsushita Electric Ind Co Ltd | Ultrasonic-type flow measuring apparatus |
| JP4588508B2 (en) * | 2005-03-28 | 2010-12-01 | 帝人ファーマ株式会社 | Gas flow rate and gas concentration measurement device using ultrasonic propagation time measurement method |
| JP2007322194A (en) * | 2006-05-31 | 2007-12-13 | Matsushita Electric Ind Co Ltd | Fluid flow measuring instrument |
| JP2008014800A (en) * | 2006-07-06 | 2008-01-24 | Matsushita Electric Ind Co Ltd | Flow measuring instrument |
| EP2496136B1 (en) | 2009-11-03 | 2015-04-08 | Koninklijke Philips N.V. | Apparatus for measuring a level of a specific gas in exhaled breath |
| WO2017134828A1 (en) * | 2016-02-05 | 2017-08-10 | 富士電機株式会社 | Measuring device, measuring method and measuring program |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4955004A (en) * | 1988-09-06 | 1990-09-04 | Westinghouse Electric Corp. | Liquid acoustic waveguide tube |
| FI87493C (en) * | 1991-12-23 | 1993-01-11 | Kytoelae Instrumenttitehdas | OVER ANCHORING FOR OVER MAINTENANCE AV STROEMNINGSHASTIGHETEN AV GASER OCH / ELLER STORHETER SOM KAN HAERLEDAS FRAON DENNA |
| CN1078552A (en) * | 1992-04-01 | 1993-11-17 | 瓦尔蒂翁特克尼里伦图基穆斯克斯库斯公司 | The assay method and the device of gas velocity in the pipe |
| FR2749652B1 (en) * | 1996-06-07 | 1998-08-21 | Schlumberger Ind Sa | METHOD FOR MEASURING THE PROPAGATION TIME OF AN ACOUSTIC SIGNAL IN A FLUID BY PASSING TO ZERO OF SAID ACOUSTIC SIGNAL |
-
2003
- 2003-04-21 JP JP2003115333A patent/JP4271979B2/en not_active Expired - Lifetime
-
2004
- 2004-04-20 CN CNB2004800104217A patent/CN100374826C/en not_active Expired - Lifetime
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101680859B (en) * | 2007-05-31 | 2013-01-02 | 帝人制药株式会社 | Ultrasonic gas concentration measuring method and device using the same |
| US8746037B2 (en) | 2007-05-31 | 2014-06-10 | Teijin Pharma Limited | Ultrasonic apparatus and method for measuring the concentration of gas |
| CN102830164A (en) * | 2012-08-23 | 2012-12-19 | 郑州光力科技股份有限公司 | On-line detection method and apparatus of methane concentration |
| CN102830164B (en) * | 2012-08-23 | 2015-07-08 | 郑州光力科技股份有限公司 | On-line detection method and apparatus of methane concentration |
| CN107064295A (en) * | 2017-01-14 | 2017-08-18 | 西安科技大学 | A kind of methane gas concentration measurement system and method |
| CN107064295B (en) * | 2017-01-14 | 2019-07-02 | 西安科技大学 | A kind of methane gas concentration measurement system and method |
| CN111164421A (en) * | 2017-10-04 | 2020-05-15 | 上田日本无线株式会社 | Ultrasonic transmitter, propagation time measuring device, gas concentration measuring device, propagation time measuring program, and propagation time measuring method |
| US11499939B2 (en) | 2017-10-04 | 2022-11-15 | Ueda Japan Radio Co., Ltd. | Ultrasonic wave transmitter, propagation time measurement device, gas concentration measurement device, propagation time measurement program, and propagation time measurement method |
| CN111238587A (en) * | 2020-01-20 | 2020-06-05 | 浙江威星智能仪表股份有限公司 | Ultrasonic transducer transmission time calibration method |
| CN113063467A (en) * | 2021-04-28 | 2021-07-02 | 哈勃智能传感(深圳)有限公司 | Sensor-based oxygen concentration and effective flow measuring method and storage medium |
| CN118394142A (en) * | 2024-06-26 | 2024-07-26 | 深圳市东吉联医疗科技有限公司 | Oxygen concentration control method, equipment and storage medium of portable oxygenerator |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004317459A (en) | 2004-11-11 |
| CN100374826C (en) | 2008-03-12 |
| JP4271979B2 (en) | 2009-06-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1217161C (en) | Simultaneous determination of multiphase flowrates and concentrations | |
| CN1777791A (en) | Ultrasonic apparatus and method for measuring the concentration and flow rate of gas | |
| CN1055542C (en) | Ultrasonic fluid vibrating flowmeter | |
| CN1285906C (en) | Equipment and method for measuring concentration and flow rate of gas ultrasonically | |
| CN1668895A (en) | Ultrasonic flowmeter and ultrasonic flowmetering method | |
| CN1211641C (en) | Flow-rate measurement method and ultrasonic flowmeter | |
| AU2004233273B2 (en) | Ultrasonic apparatus and method for measuring the concentration and flow rate of gas | |
| CN1135366C (en) | Flowmeter | |
| CN1190654C (en) | Gas leak detection system | |
| CN1714279A (en) | Ultrasonic flowmeter and ultrasonic flow rate measuring method | |
| CN1155831C (en) | Method for measuring ultrasonic flow speed | |
| CN1648614A (en) | Wedge and wedge unit for use in ultrasonic doppler flow meter | |
| CN1091519A (en) | Measure the device that fluid flows | |
| CN1821724A (en) | Flow meter | |
| CN1153295A (en) | Coriolis-type mass flow meter with at least one measuring tube | |
| CN1227512C (en) | Flowmeter | |
| CN1198088A (en) | Ultrasonic diagnosis apparatus | |
| CN1223510C (en) | Oxygen concentrating apparatus | |
| CN1179200C (en) | Apparatus and method for detecting vibrations, e.g. in a coriolis mass-flowmeter, using noise filtering | |
| JP4473535B2 (en) | Oxygen concentrator | |
| CN1546981A (en) | Three phase mixed fluid on-line parameter measuring method and device | |
| CN1056691C (en) | Vortex flowmeter with a double obstruction | |
| CN1166925C (en) | method and device for converting physical quantity measured by measuring appts. | |
| CN1194689A (en) | Fluid meter of the ultrasonic type for attenuation of parasitic ultrasonic waves | |
| TW200949261A (en) | A device and method for testing natural frequency of acoustic speakers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| REG | Reference to a national code |
Ref country code: HK Ref legal event code: DE Ref document number: 1089813 Country of ref document: HK |
|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| REG | Reference to a national code |
Ref country code: HK Ref legal event code: GR Ref document number: 1089813 Country of ref document: HK |
|
| ASS | Succession or assignment of patent right |
Owner name: TEIJIN LIMITED Free format text: FORMER OWNER: TEIJIN PHARMA LTD. Effective date: 20130412 |
|
| C41 | Transfer of patent application or patent right or utility model | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20130412 Address after: Osaka City, Osaka of Japan Patentee after: TEIJIN Ltd. Address before: Tokyo, Japan Patentee before: Teijin Pharma Ltd. |
|
| EE01 | Entry into force of recordation of patent licensing contract | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Application publication date: 20060524 Assignee: Imperial Medical Devices (Shanghai) Co.,Ltd. Assignor: TEIJIN PHARMA Ltd. Contract record no.: X2023990000273 Denomination of invention: Ultrasonic equipment and method for measuring gas concentration and flow Granted publication date: 20080312 License type: Common License Record date: 20230227 |
|
| CX01 | Expiry of patent term |
Granted publication date: 20080312 |
|
| CX01 | Expiry of patent term |