1259900 玖、發明說明： 【發明戶斤屬之^技術領滅】 本發明涉及利用超聲波對媒氣等流體的流量進行計量 的流量計量裝置。 5 【】 現有的流里什1；裝置如第20圖中所示。在媒氣等流體 流經的流路31上設置有用於發射/接收超聲波的第丨超聲波 振盪器32及第2超聲波振盪器33。切換裝置34用於切換第1 超聲波振盪器32和第2超聲波振盪器33的超聲波發射/接收 10操作。發送裝置35驅動第1超聲波振盪器32或第2超聲波振 盡器33發射出超聲波。放大裝置36將從接收超聲波的超聲 波振盪器經切換裝置34送來的信號放大到規定的振幅。基 準比較裝置37將由放大裝置36放大後輸出的接收信號電壓 與一個基準電壓相比較。判斷裝置38如第21圖中所示在基 15準比較裝置37中接收信號超過基準電壓後的最初的過零點 Ta上送出輸出信號D。重複裝置39對來自判斷裝置38的信號 D進行計數’在計滿預先設定的次數後將信號〇輸出至控制 裝置42。計時裝置4〇_重複裝置39完成對信號〇進行預先設 定的上述次數的計數所花的時間進行計時。流量計算裝置 20 41根據計時裝置40計得的時間計算出流體的流量。控制裝 置42根據流量計算裝置41計算出的流量輪出和來自重複裝 置39的信號對發送裴置％進行控制。 下面描述該計量裝置的工作情況。首先，控制裝置42 使發迗裝置35和切換裝置科工作，使第丨超聲波振盪器32發 1259900 射出超聲波。該超聲波在流體中傳播，並由第2超聲波振盪 器33加以接收，由放大裝置36進行放大。基準比較裝置37 在放大裝置36的輸出大於基準電壓的時間點上輸出下降信 號C◦判斷裝置38在放大裝置36的輸出大於基準電壓後的最 5 初的過零點Ta上輸出下降信號D。重複裝置39將來自判斷裝 置38的信號D輸入到控制裝置42中。這一操作將重複進行預 先設定的N次，此間的時間由計時裝置40進行測定。接下 來，切換裝置34使第1超聲波振盪器32和第2超聲波振盪器 33中的超聲波的發射/接收操作發生交換，再進行同樣的操 10 作。流量計算裝置41測出由計時裝置40計得的從流體的上 游至下游（此方向為順流）和下游至上游（上方向為逆流）各 自的傳播時間，由下面的公式1求出流量Q。 / \ s . s ·乙/>昱―艺(公式1 )1259900 玖, invention description: [Technical invention] The present invention relates to a flow metering device that uses ultrasonic waves to measure the flow rate of a fluid such as a medium gas. 5 [] The existing flow is 1; the device is as shown in Fig. 20. The second ultrasonic oscillator 32 and the second ultrasonic oscillator 33 for transmitting/receiving ultrasonic waves are provided in the flow path 31 through which the fluid such as the medium flows. The switching means 34 is for switching the ultrasonic wave transmitting/receiving 10 operations of the first ultrasonic oscillator 32 and the second ultrasonic oscillator 33. The transmitting device 35 drives the first ultrasonic oscillator 32 or the second ultrasonic oscillator 33 to emit ultrasonic waves. The amplifying means 36 amplifies the signal sent from the ultrasonic oscillator receiving the ultrasonic wave via the switching means 34 to a predetermined amplitude. The reference comparing means 37 compares the received signal voltage outputted by the amplifying means 36 with a reference voltage. The judging means 38 sends out the output signal D on the first zero-crossing point Ta after the received signal exceeds the reference voltage as shown in Fig. 21, as shown in Fig. 21. The repeating means 39 counts the signal D from the judging means 38, and outputs the signal 至 to the control means 42 after counting the predetermined number of times. The timepiece 4〇_repetition device 39 counts the time taken to count the number of times the signal 预先 is set in advance. The flow rate calculating means 20 41 calculates the flow rate of the fluid based on the time counted by the time measuring means 40. The control unit 42 controls the transmission unit % based on the flow rounding calculated by the flow rate calculating means 41 and the signal from the repeating means 39. The operation of the metering device will be described below. First, the control device 42 operates the hairpin device 35 and the switching device to cause the second ultrasonic oscillator 32 to emit 1259900 ultrasonic waves. This ultrasonic wave propagates through the fluid, is received by the second ultrasonic oscillator 33, and is amplified by the amplifying device 36. The reference comparing means 37 outputs a falling signal C at a time point when the output of the amplifying means 36 is larger than the reference voltage. The determining means 38 outputs the falling signal D at the most zero-crossing point Ta after the output of the amplifying means 36 is larger than the reference voltage. The repeating means 39 inputs the signal D from the judging means 38 to the control means 42. This operation is repeated N times in advance, and the time between them is measured by the timing device 40. Next, the switching device 34 exchanges the transmission/reception operations of the ultrasonic waves in the first ultrasonic oscillator 32 and the second ultrasonic oscillator 33, and performs the same operation. The flow rate calculating means 41 measures the respective propagation times from the upstream to the downstream (the direction is the forward flow) and the downstream to the upstream (the upstream direction is the reverse flow) calculated by the time measuring means 40, and the flow rate Q is obtained by the following formula 1. / \ s . s · B /> 昱 ― Art (Formula 1)
\t 1 12 J 這裏，L為超聲波振盪器32，33之間的流體流動方向上的有 15 效距離，tl為從上游至下游的N次信號D的的時間，t2為從 下游至上游的N次信號D的的時間，v為被測定流體的流 速，S為流路的戴面積，φ為連結超聲波振盪器32，33的直 線和流體的流動方向之間的角度，K為與流量有關的係數。 為了使接收側的超聲波振盪器接收到的信號在一定振 20 幅上輸出，需對放大裝置36進行增益調整，將接收信號的 峰值電壓值調整到規定的電壓範圍内。具體說來，在對信 號D進行的重複裝置3 9中設定的次數的計數過程中，對第2 2 圖中的虛線所示的接收信號AL那樣接收信號的峰值電壓 1259900 值低於規定的電壓範圍的下限的次數和第22圖的虛線所示 的接收信號AH那樣接收信號的峰值電壓值超過規定的電 壓範圍的上限的次數進行計數，根據該結果調整下一次的 流量計量時的增益。例如，峰值電壓值低於下限的次數多 5 時提高增益，將接收信號調整到電壓的上限和下限之間， 如第22圖中的實線所表示的接收信號A那樣。 與放大裝置36的輸出電壓進行比較的基準比較裝置37 的基準電壓以判斷裝置38能檢測到過零點的位置為基準來 決定。在第21圖中，為了能使判斷裝置38檢測到接收信號 10 的第3個峰值P3後的最初的過零點Ta，基準電壓設定為接收 信號的第2和第3個峰值電壓之間的中間點電壓左右。這樣 一來，即使因流量的變化以及流體的溫度變化等因素導致 接收波形發生變化，接收信號的第2個波峰值電壓上升或者 第3個波峰值P3的電壓減少時，基準電壓相對於這兩個波峰 15 值都能確保一定的餘量，判斷裝置38能夠檢測到過零點丁a。 但是，在上述的現有流量計量裝置中，與放大到規定 振幅的接收信號進行比較的基準電壓是用固定電阻和半固 定電阻通過電阻分壓來設定的。採用此方法時，為了形成 規定的基準電壓，需要一邊監視基準電壓一邊通過手動方 20 式調節半固定電阻，故基準電壓設定比較費時間，且容易 發生調整誤差。另外，流量的計測過程冲基準電壓是固定 的，將接收信號進行放大的放大裝置的增益也是固定的。 因此，流量計量過程中超聲波的接收信號的振幅變化時， 基準電壓和接收信號的振幅之間的相對關係也發生變化。 1259900 例如，在接收信號的振幅電平變動較大的場合下，變化前 能超過基準電壓的接收波的第3個峰值P3的電壓就可能變 得低於基準電壓。其結果，基準比較裝置將會在接收信號 的第4個峰值P4之後才輸出信號C，判斷裝置將檢測出第4 5 個峰值P4以後的最初過零點。由此，計時裝置將會對該段 錯誤的時間進行計時，流量計算裝置將根據該時間計算出 錯誤的流量。 【發明内容】 本發明的流量計量裝置對在流路上流動的流體的流量 10 進行計量，它包括：設置在流路上的、發射和接收超聲波 信號的第1振盪器及第2振盪器；驅動第1和第2振盪器的發 送裝置；切換第1和第2振盪器的超聲波信號的發射/接收的 切換裝置；將第1和第2振盪器的接收信號進行放大的放大 裝置；根據超聲波信號在第1和第2振盪器之間的傳播時間 15 計算出流量的流量計算裝置；將經放大的接收信號電壓和 基準電壓進行比較，並且輸出表示接收信號的電壓與基準 電壓之間的大小關係發生變化的時間點的信號的基準比較 裝置；從基準比較裝置輸出的信號和放大裝置的輸出信號 判定超聲波信號到達第1或第2振盪器的時間點，並且輸出 20 表示到達該時間點的信號的判斷裝置；以及包括對從開始 發射超聲波信號到判斷裝置判定出到達時間點為至的超聲 波信號在流路上的傳播時間進行計時的傳播計時單元/及 根據上面計得的傳播時間確定基準電壓，並將基準電壓送 至基準比較裝置的電壓設定單元的基準設定裝置。 1259900 在本發明的流量計量裝置中，基準電壓被自動地設定 在相對於接㈣㈣振巾減夠確純大的餘量的位置 上’而且根據流量計量過程中接收信號的振幅變動能迅速 且高精度地設定基準電壓。㈣，判斷裝置能夠可靠地檢 測出接收波上的任意的時間點（如第3個+值之後的過零 流量計量裝置岐錢㈣號的純變糾也能保持 很咼的計測精度。 圖式簡單說明 10 圖。第！圖為本發明的W實施例中的流量計量襄置的方框 第2圖為用於說明第1實 情況的示意圖。 、以种的流赠量裝置的操作 15 圖 第3圖為本發明的第2實施例中的流量計量裝置的方框 ΓΛ為用於說明第2實施例中的流量計量裝置的操作 情況的示意圖。 第5圖為用於說明第2實施例中 的流量計量裝置的操作 20 圖 情況的特性圖。 第6圖為本發明的第3實施例中的流量計量裝置的方框 情況的第=於㈣㈣科«置的操作 第8圖為用於說明第3實施例旦 情況的流程圖。 、⑽里叶置裝置的操作 1259900 第9圖為本發明的第4實施例中的流量計量裝置的方框 圖。 第10圖為用於說明第4實施例中的流量計量裝置的操 作情況的示意圖。 5 第11圖為用於說明第4實施例中的流量計量裝置的操 作情況的流程圖。 第12圖為用於說明第4實施例中的流量計量裝置的操 作情況的流程圖。 第13圖為用於說明第4實施例中的流量計量裝置的操 10 作情況的示意圖。 第14圖為用於說明第4實施例中的流量計量裝置的其 他操作情況的流程圖。 第15圖為本發明的第5實施例中的流量計量裝置的方 框圖。 15 第16圖為用於說明第5實施例中的流量計量裝置的操 作情況的流程圖。 第17圖為用於說明本發明的第6實施例中的流量計量 裝置的方框圖。 第18圖為用於說明第6實施例中的流量計量裝置的操 20 作情況的示意圖。 第19圖為用於說明第6實施例中的流量計量裝置的操 作情況的示意圖。 第20圖為現有的流量計量裝置的方框圖。 第21圖為用於說明現有的流量計量裝置的操作情況的 10 1259900 示意圖。 第22®為用於說明現有的流量計量裝置的操作情況的 示意圖。 【實施冷式】 5 (實施例1) 第1圖為本發明的實施例1中的流量計量裝置的方框 圖’第2圖為說明流量計量裝置的操作情況的示意圖。流體 流經的流路1的途中配置有發射超聲波的第1超聲波振盪器 2和接收超聲波的第2超聲波振盪器3，它們被設置成與流體 10的流動方向成一個角度φ。發送裝置5驅動第丨超聲波振盪器 2或第2超聲波振盪器3發射出超聲波。切換裝置4使第1超聲 波振盪裔2和第2超聲波振盪器3中進行的超聲波發射/接收 操作發生交換。為使接收側的超聲波振盪器接收到的信號 在疋振巾田上輸出’放大裝置6的增益被進行調整。基準設 15定I置13將根據放大裝置ό的輸出設定的基準電壓送到基 準比較裝置7,基準比較裝置7將放大裝置6的輸出信號和該 基準兒塵進仃比較。#斷裝置8從基準比較裝置7的輸出和 大衣置6的輸出L咸判斷超聲波的到達時間點。重複裝置 9對判斷裝置8的輸出信號進行預先設定的次數的計數，並 2〇將來自觸裝置8的信號送到控制裝置12。計時裝置1〇對重 、复衣置9兀成對判斷裝置8的輸出信號進行預先設定的次數 的計數所需的時間進行計時。流量計算裝置U根據計時裝 置10计得的時間並在去 号慮流路的尺寸及流體的流動狀態之 後什异出流體的流| 里。控制裝置12根據流量計算裝置11、 1259900 5 10 15 设裝置9的輸出信號對發送裝置5和放大裝置6進行控 開^播計時單元i3b根據從控制裝置ί2送來的超聲波發射 禅時判斷裝^輸出對超聲波在流路上的傳 "間物計時。電麼設定單元仏根據傳播計時單元现 々輸出w基準m將其輸出職準比較裝置7。傳播 汁時單元⑶和㈣設定單元13a構絲準設定裝置13。 下面說明實施例！中的流量計量褒置中與基準塵設定 有關的操作情況。 、.第2圖為用於說明實施例1中的流量計量裝置的操作情 况的不意圖。流量計測開始時，控制裝置12使發送裝置^工 1乍’從超聲波缝器2發射出超聲波。第丨超聲波振盈器2發 射出的超聲波在流路！中的流體中傳播，並由第2超聲波振 盈器3加以接收。放大裝置6將與第2超聲波振蘯器3接收到 的超聲波相對應的輸出信號進行放大，使之達到一定的振 幅後送至基準比較裝置7和判斷裝置8。 " 傳播計時單元13b根據來自控制裝置12的表示超聲波 開始發射的信號和·裝置8的輸出對超聲波在流路上的 傳播時間進行計測。\t 1 12 J Here, L is the 15 effective distance in the direction of fluid flow between the ultrasonic oscillators 32, 33, t1 is the time from the upstream to the downstream N times signal D, and t2 is from downstream to upstream. The time of the Nth signal D, v is the flow velocity of the fluid to be measured, S is the wearing area of the flow path, φ is the angle between the straight line connecting the ultrasonic oscillators 32, 33 and the flow direction of the fluid, and K is related to the flow rate. Coefficient. In order to output the signal received by the ultrasonic oscillator on the receiving side over a constant amplitude of 20, it is necessary to adjust the gain of the amplifying means 36 to adjust the peak voltage value of the received signal to a predetermined voltage range. Specifically, in the counting process of the number of times set in the repeating means 39 for the signal D, the peak value of the received signal peak value 1259900 is lower than the predetermined voltage as the received signal AL indicated by the broken line in the second drawing. The number of times of the lower limit of the range and the number of times the peak voltage value of the received signal exceeds the upper limit of the predetermined voltage range as the received signal AH indicated by the broken line in Fig. 22 is counted, and the gain at the next flow rate is adjusted based on the result. For example, when the peak voltage value is less than the lower limit, the gain is increased by 5, and the received signal is adjusted between the upper limit and the lower limit of the voltage, as in the received signal A indicated by the solid line in Fig. 22. The reference voltage of the reference comparing means 37 which is compared with the output voltage of the amplifying means 36 is determined based on the position at which the determining means 38 can detect the zero-crossing point. In Fig. 21, in order to enable the determination means 38 to detect the first zero-crossing point Ta after the third peak P3 of the received signal 10, the reference voltage is set to be the middle between the second and third peak voltages of the received signal. The point voltage is around. In this way, even if the received waveform changes due to changes in the flow rate and temperature changes of the fluid, and the second peak voltage of the received signal rises or the voltage of the third peak P3 decreases, the reference voltage is relative to the two. Each peak 15 value can ensure a certain margin, and the judging device 38 can detect the zero crossing point a. However, in the above-described conventional flow rate measuring device, the reference voltage which is compared with the received signal amplified to a predetermined amplitude is set by the resistance division by the fixed resistor and the semi-fixed resistor. In this method, in order to form a predetermined reference voltage, it is necessary to adjust the semi-fixed resistor by the manual method while monitoring the reference voltage. Therefore, the reference voltage setting takes time and the adjustment error is likely to occur. In addition, the flow rate measurement process is fixed to the reference voltage, and the gain of the amplification device that amplifies the received signal is also fixed. Therefore, when the amplitude of the received signal of the ultrasonic wave changes during the flow measurement, the relative relationship between the reference voltage and the amplitude of the received signal also changes. 1259900 For example, when the amplitude level of the received signal fluctuates greatly, the voltage at the third peak P3 of the received wave that exceeds the reference voltage before the change may become lower than the reference voltage. As a result, the reference comparing means outputs the signal C after the fourth peak P4 of the received signal, and the judging means detects the first zero-crossing point after the 45th peak P4. Thus, the timing device will time the error period and the flow calculation device will calculate the wrong flow rate based on the time. SUMMARY OF THE INVENTION The flow metering device of the present invention measures a flow rate 10 of a fluid flowing on a flow path, and includes: a first oscillator and a second oscillator that are disposed on a flow path and that emit and receive ultrasonic signals; a transmitting device for the first and second oscillators; a switching device for switching the transmission and reception of the ultrasonic signals of the first and second oscillators; and an amplifying device for amplifying the received signals of the first and second oscillators; The propagation time between the first and second oscillators 15 is a flow rate calculating means for calculating the flow rate; comparing the amplified received signal voltage with the reference voltage, and outputting a magnitude relationship between the voltage indicating the received signal and the reference voltage a reference comparing means for the signal at the changed time point; the signal output from the reference comparing means and the output signal of the amplifying means determining the time point at which the ultrasonic signal reaches the first or second oscillator, and the output 20 indicating the signal arriving at the time point Determining the device; and including determining that the arrival time point is from the start of transmitting the ultrasonic signal to the determining device Acoustic wave propagation time counting unit for counting the signal propagation time in the flow path / meter and determined according to the above reference voltage obtained by the propagation time, and the reference voltage to the reference voltage setting unit to send the reference comparison means setting means. 1259900 In the flow metering device of the present invention, the reference voltage is automatically set at a position which is sufficiently large relative to the (four) (four) vibrating towel, and the amplitude variation of the received signal can be rapid and high according to the flow metering process. Set the reference voltage with accuracy. (4) The judging device can reliably detect an arbitrary time point on the received wave (for example, the purely variable correction of the zero-crossing flow metering device after the third + value can maintain a very high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 2 is a block diagram of a flow metering device in an embodiment of the present invention. FIG. 2 is a schematic view for explaining the first real case. Fig. 3 is a block diagram showing the operation of the flow rate measuring device in the second embodiment in the second embodiment of the present invention. Fig. 5 is a view for explaining the second embodiment. FIG. 6 is a characteristic diagram of the case of the flow metering device in the third embodiment of the present invention. FIG. 6 is a block diagram of the flow metering device in the third embodiment of the present invention. A flowchart of the case of the third embodiment will be described. (10) Operation of the inner blade device 1259900 Fig. 9 is a block diagram of the flow rate measuring device in the fourth embodiment of the present invention. Fig. 10 is a view for explaining the fourth embodiment. Operation of the flow metering device Fig. 11 is a flow chart for explaining the operation of the flow rate measuring device in the fourth embodiment. Fig. 12 is a flow chart for explaining the operation of the flow rate measuring device in the fourth embodiment. Fig. 13 is a schematic view for explaining the operation of the flow rate measuring device in the fourth embodiment. Fig. 14 is a flow chart for explaining another operation of the flow rate measuring device in the fourth embodiment. Fig. 16 is a flow chart for explaining the operation of the flow rate measuring device in the fifth embodiment. Fig. 17 is a view for explaining the operation of the flow metering device in the fifth embodiment. Fig. 18 is a block diagram for explaining the operation of the flow rate measuring device in the sixth embodiment. Fig. 19 is a view for explaining the flow rate in the sixth embodiment. A schematic diagram of the operation of the metering device. Fig. 20 is a block diagram of a conventional metering device. Fig. 21 is a schematic view of 10 1259900 for explaining the operation of the conventional metering device. A schematic diagram illustrating the operation of the conventional flow metering device. [Implemented Cooling Mode] 5 (Embodiment 1) FIG. 1 is a block diagram of a flow metering apparatus in Embodiment 1 of the present invention. FIG. 2 is a flow metering apparatus. A schematic diagram of an operation state in which a first ultrasonic oscillator 2 that emits ultrasonic waves and a second ultrasonic oscillator 3 that receives ultrasonic waves are disposed in the middle of the flow path 1 through which the fluid flows are disposed at an angle to the flow direction of the fluid 10. φ. The transmitting device 5 drives the second ultrasonic oscillator 2 or the second ultrasonic oscillator 3 to emit ultrasonic waves. The switching device 4 exchanges the ultrasonic transmitting/receiving operations performed by the first ultrasonic oscillating region 2 and the second ultrasonic oscillator 3. . In order to make the signal received by the ultrasonic oscillator on the receiving side output on the field of the vibrating towel, the gain of the amplifying means 6 is adjusted. The reference setting 15 sets the reference voltage set according to the output of the amplifying means 送到 to the reference comparing means 7, and the reference comparing means 7 compares the output signal of the amplifying means 6 with the reference dust. The #断装置8 determines the arrival time point of the ultrasonic wave from the output of the reference comparison device 7 and the output L of the coat set 6. The repeating device 9 counts the output signal of the judging device 8 a predetermined number of times, and sends a signal from the touch device 8 to the control device 12. The timepiece 1 〇 is used to count the time required for counting the number of times the output signal of the pair determination device 8 is set in advance. The flow rate calculation means U is based on the time counted by the timekeeping means 10 and is in the flow of the undesired fluid after the size of the flow path and the flow state of the fluid. The control device 12 controls the transmitting device 5 and the amplifying device 6 according to the output signal of the flow calculating device 11, 1259900 5 10 15 , and controls the opening and closing timing unit i3b to determine the mounting time according to the ultrasonic wave sent from the control device ί2. Outputs the timing of the ultrasonic waves on the flow path. The setting unit 输出 outputs the reference unit 仏 according to the current output w reference m of the propagation timing unit. The juice-time unit (3) and (four) setting unit 13a are configured to set the wire alignment device 13. The embodiment is explained below! The operation related to the reference dust setting in the flow metering device. Fig. 2 is a schematic view for explaining the operation of the flow rate measuring device in the first embodiment. At the start of the flow metering, the control unit 12 causes the transmitting unit to emit ultrasonic waves from the ultrasonic stitcher 2. The ultrasonic wave emitted by the second ultrasonic vibrator 2 is in the flow path! The fluid in the medium propagates and is received by the second ultrasonic vibrator 3. The amplifying device 6 amplifies the output signal corresponding to the ultrasonic wave received by the second ultrasonic vibrator 3, reaches a constant amplitude, and sends it to the reference comparing device 7 and the judging device 8. " The propagation timing unit 13b measures the propagation time of the ultrasonic wave on the flow path based on the signal from the control device 12 indicating that the ultrasonic wave starts to be emitted and the output of the device 8.
接下來，傳播計時單元Db-邊對傳播時間進行計時， 電壓設定單元13a-邊將鮮電壓下降至電壓$在該電壓 %上判斷裝置8能夠檢測到接收波的第2個峰值打後最= 過零點T卜這樣，基料較裝置7和判斷裝置辦分別輸出 信號B1和信號B2。這樣-來，在判斷裝置8檢測第3個峰值 P3後最初的過零點的情況下’由傳播計時單元⑶計時的傳 12 1259900 播k間將縮短超聲波的丨周期，超聲波如為5 〇 〇 kHz的情況下 將縮短2 ps。 第1傳播計時單元13b計測到的傳播時間縮短超聲波頻 f的1個周期的時間時，電壓設定單元l3a會將基準電壓提 π到Vc’在該電壓上能夠檢測到接收波的第4個峰值P4後最 初的過零點17。這樣，基準比較裝置7和判斷裝置8將分別 ，出UC1和WC2。傳播計時單元別進行計時的傳播 時間由此將比判斷裝置8檢測第3個峰值⑽最初的過零點 的場合下延長超聲波的丨周期的時間。 ” 10 15 吏土準私>£像上述那樣發生變化時，基準電塵將如第^ 圖中所不的那樣在接收波的第2個峰值Μ附近至第3個每值 P3附近之間發生變化設定單元^將基準電壓設定在 其中間點上，並將設定好的電壓向基準比較裝置7輸出。A 率比較裝置7將該基準電壓與放大裝置6的輸出相比較，並 =放大裝置6的輸出大於基準電壓的時間點的信號輸 出至判斷㈣。判斷裝置8將上述的時間點以後的放大裝 的輸出广"虎從正變負的最初的過零點丁3判斷為超聲 >的到達日_ ’並將表示該日㈣點的信號輸出到重複裝Next, the propagation timing unit Db-side counts the propagation time, and the voltage setting unit 13a-side drops the fresh voltage to the voltage $. On the voltage %, the determining means 8 can detect the second peak of the received wave after hitting the most = In this way, the base material outputs the signal B1 and the signal B2 separately from the device 7 and the judging device. In this way, in the case where the judging means 8 detects the first zero-crossing point after the third peak P3, the transmission of the 12th 129959900 counted by the propagation timing unit (3) shortens the chirp period of the ultrasonic wave, and the ultrasonic wave is 5 〇〇 kHz. In case of 2 ps will be shortened. When the propagation time measured by the first propagation timing unit 13b is shortened by one cycle of the ultrasonic frequency f, the voltage setting unit 13a raises the reference voltage by π to Vc' at which the fourth peak of the received wave can be detected. The initial zero crossing after P4 is 17. Thus, the reference comparing means 7 and the judging means 8 will respectively output UC1 and WC2. The propagation time by which the propagation timing unit performs timing is thus extended by the time when the determination means 8 detects the first zero crossing of the third peak (10). 10 15 准 准 & £ £ When the change occurs as described above, the reference dust will be between the second peak 接收 of the received wave and the third value per P3 as in the figure The occurrence change setting unit sets the reference voltage at its intermediate point, and outputs the set voltage to the reference comparison means 7. The A rate comparison means 7 compares the reference voltage with the output of the amplification means 6, and = the amplification means The signal outputted at a time point greater than the reference voltage is output to the judgment (4). The judging means 8 judges that the output of the amplifier package after the above-mentioned time point is wide and "the tiger is judged to be ultrasonic from the initial zero-crossing point D which is positively negative". Arrival date _ 'and output the signal indicating the day (four) point to the reload
置9中 „ r π岍衷置S能夠檢測出;^ 衣置6犧（接收波）中的特定時間點(如第騎㈣ 點）的基準電壓範㈣基準設找置13-邊名 又破—中間點上，故計測裝置爛 13 1259900 測出接收波中的特定時間點。由於計測裝置中能夠每進行 一次流量計量或者定期地像上面所述的那樣快速、高精度 地設定基準電壓，基準電壓總是能保持在最合適的值上。 (實施例2) 5 第3圖為本發明的實施例2中的流量計量裝置的方框 圖，第4及5圖為說明該流量計量裝置的操作情況的示意 圖。時間差計時單元13c對基準比較裝置7的輸出和判斷裝 置8的輸出之間的時間差進行計時。電壓設定早元13 a根據 時間差計時單元13c的輸出設定基準電壓，並將設定好電壓 10 輸出至基準比較裝置7。電壓設定單元13a和時間差計時單 元13c構成基準設定裝置131。其他構成部分由於實施例1和 相同，故省略對其的說明。 下面說明具有上述構成的流量計量裝置的操作情況。 流量計量開始時，控制裝置12使發送裝置5工作，從超聲波 15 振盪器2發射出超聲波。由第1超聲波振盪器2發射出的超聲 波在流路1中傳播，並由第2超聲波振盪器3所接收，再由放 大裝置6放大後，輸出到基準比較裝置7。放大裝置6的增益 由控制裝置12進行控制，使接收信號達到一定的振幅。基 準比較裝置7將放大裝置6的輸出和基準壓Vc進行比較，並 20 與實施例1中同樣，在放大裝置6的輸出大於基準電壓Vc時 的時間點上向判斷裝置8和時間差計時單元13c輸出第4圖 中所示的信號C1。 判斷裝置8以基準比較裝置7的輸出為參考，將第4圖中 所示的放大裝置6的輸出在上述時間點後的最初過零點Ta 14 1259900 判定超聲波的到達時間點，並向時間差計時單元13c輸出信 號C2。時間差計時單元13c從基準比較裝置7的輸出信號C1 和判斷裝置8的輸出信號C2對第4圖中所示的時間差td進行 計時。電壓設定單元13a—邊輸入時間差計時單元13c計測 5 的時間差td，一邊使基準電壓Vc上下變化。如第5圖中所 示，時間差td因基準電壓Vc的變化而變化。 基準電壓Vc設定為與判斷裝置8能夠檢測接收波的第2 個峰值P2後的最初的過零點Tb的電平即峰值P2的值幾乎相 同的電壓V2時，時間差tdo是接收波的1/4個周期，即500ns。 10 然後，增大基準電壓使之超過V2後再由判斷裝置8檢測第3 個峰值P3後最初的過零點Ta時，時間差td如第5圖中所示將 成為最大值。這以後，隨著基準電壓的增加，時間差td將 減小；當基準電壓達到與第3個峰值P3的電壓值幾乎相同的 電壓V3時，時間差td再次成為tdo。 15 然後，電壓設定單元13a把時間差td將成為基準電壓變 化時的時間差td的最大值和最小值（周期的1/4)之間的中間 點電壓設定為基準電壓。通過進行這樣的設定，時間差計 時單元13c計得的時間差td將被設定在根據基準電壓的變化 而變化的範圍的中間點上，這樣，基準電壓將被保持在能 20 夠穩定地檢測接收波的特定過零點Ta的電平上，且基準電 壓可被迅速並且高精度地設定好。由於計測裝置可以快 速、高精度地在每次進行流量計量時或者定期地進行上述 的基準電壓的設定，故基準電壓總是能夠保持在最合適的 電平上。 15 !2599〇〇 (貫施例3) 10 15 20 第6圖為本發明的實施例3中的流量計量裝置的方框 圖。第7圖為用來說明該流量計量裝置的操作情況的示意 圖，第8圖為表示其操作情況的流程圖。流路丨上相對於流 體的流動方向成一定角度Φ設置有用於發射/接收超聲波的 第1超聲波振盪器2和第2超聲波振盪器3。發送裝置5使第i 超聲波振盪器2或第2超聲波振盪器3發射出超聲波。切換裝 置4用於使第1超聲波振盪器2和第2超聲波振盪器3中的超 聲波發射/接收操作發生交換。放大裝置6按照由控制裝置 12所控制的增益對接收側的超聲波振盪器所接收到的信號 進行放大，基準比較裝置7將經放大裝置6放大了的信號與 基準電壓進行比較。判斷裝置8從基準比較裝置7的輸出和 由放大裝置6放大了的信號判斷超聲波的到達時刻。重複裝 置9對判斷裝置8的輸出信號進行計數，在計滿預先設定的 次數的時間點上向控制裝置12發出信號。計時裝置1 〇對重 複裝置9完成對判斷裝置8的輸出信號計滿預先設定的次為 至的時間進行計時。流量計算裝置11根據計時裝置1〇計得 的時間並在考慮了管路的尺寸及流體的流動狀態後，叶管 出流體的流量。控制裝置12接收流量計算寰置丨丨、重複| 置9發出的信號，對發送裝置5和放大裝置6進行控制。基準 設定裝置14由數/模（D/A)變換器或數控衰減$ (Digital-Controlled Attenuator)等構成，用於設定基準比争、 裝置7中的基準電壓。基準設定裝置14根據基準電壓變化時 的基準比較裝置的輸出來確定基準電壓。 16 1259900 下面參照第8圖對具有上述構成的流量計量裝置的操 作情況進行說明。電源接通之後，控制裝置12首先進行初 始設定操作，即調整放大裝置6的增益，設定基準電壓。增 益調整好以後，接收信號被放大成如第7圖中所示那樣的 5 (比方說）第5圖峰值P5的電壓達到規定的範圍内。如第7圖所 示，在接收信號高於上述範圍的下限期間，放大裝置6向控 制裝置12和基準設定裝置14中輸出峰值檢測信號PD。為了 使接收側的超聲波振盪器接收到的信號達到一定振幅，首 先對放大裝置6的增益進行調整，將其設定為第1增益（步驟 10 1)。其後，對判斷接收信號的到達時期而需檢測的峰值（比 方說）第3個峰值P3前面的第2個峰值P2的電壓在流量計量 過程中的變化幅度加以考慮，用比最初調整好的放大裝置6 的第1增益大的第2增益對接收波進行放大（步驟2)。被放大 後的接收信號如第7圖中所示。 15 第7圖中的虛線為以第1增益放大的接收信號，實線為 以第2增益放大的接收信號。基準設定裝置14將用於與在第 2增益上被放大的接收信號A相比較的第7圖中所示的基準 電壓Vref從最低基準電壓增加1個控制單位（例如5mV)(步 驟3)。在實施例3中，最低的基準電壓Vref被設定為比接收 20 信號A的第1個峰值P1的電壓高但比第2個峰值P2的電壓 低。控制裝置12將重複裝置9的重複次數設定成1次後，使 發送裝置5工作，從第1超聲波振盪器2發射出超聲波信號 (步驟4)。由第1超聲波振盪器2發射出的超聲波信號在流路1 中傳播，由第2超聲波振盪器3加以接收，再經放大裝置6放 17 1259900 大後輸出到基準比較裝置7。如第7圖中所示，基準比較裝 置7將放大裝置6的輸出（接收信號A)和基準電壓V1· e f進行比 較，當放大裝置6的輸出大於基準電壓Vref時向基準設定裝 置14和判斷裴置8輸出信號C2，C3，C4，C5(步驟5)。基準 5 設定裝置14對基準比較裝置7的輸山信號C2至C5的個數進 行計數（步驟6)，在放大裝置6輸出峰值檢測信號（步驟7)之 前重複執行上述的步驟5和步驟6。從放大裝置6有峰值檢測 信號送來時，基準設定裝置14判斷基準比較裝置7輸出的信 號的個數是不是為3個（步驟8)。如果信號的個數不是3個， 10 將基準電壓Vref增加1個控制單位（步驟3)，其後再重複執行 步驟4至8。基準比較裝置7輸出的信號的個數達到3個時， 將放大裝置6的增益設置回第1增益（步驟9)。 即，當基準電壓Vref處於接收信號的第2個峰值P2的電 壓以下時，基準比較裝置7將輸出4個信號C2〜C5，直至放 15 大裝置6輸出峰值檢測信號為止。基準電壓Vref超過接收波 的第2個峰值P2的電壓時，基準比較裝置7將不輸出信號 C2，只輸出3個信號C3〜C5。在基準比較裝置14的輸出信 號的個數從4變成3這一時間點上，基準設定裝置14停止增 加基準電壓Vref。並且，在放大裝置6的增益回到調整前的 20 第1增益時，基準設定裝置14的基準電壓Vref比接收信號的 第2個峰值P2的電壓稍高一點點。基準電壓Vref和第2個峰 值P2的電壓之間的差是考慮了第2個峰值P2的電壓在流量 計量過程中的變化幅度後設定的，使得流量計量過程中接 收信號的振幅即使發生變動，第2個峰值P2的電壓也不會超 18 1259900 過基準電壓Vref。這樣，在此刻的基準電壓Vref上，與第3 個峰值P3的電壓之間可以有很大的餘量，判斷裝置8相對於 接收信號的振幅變動能最穩定地檢測出超聲波接收信號的 到達時刻。 5 如上所述，在本實施例中’基準設定裝置14根據基準 比較裝置7的輸出來設定基準電壓，並在設定該基準電壓時 考慮到了為檢測接收信號的到達時期而需檢測的峰值的前 1個峰值在流量計量過程中的振幅變動最大值。這樣一來， 為檢測接收信號的到達時期而需檢測的那個峰值的前1個 10 峰值不會超過基準電壓，為檢測接收信號的到達時期而需 檢測的那個峰值和基準電壓之間將有很大的餘量。因此， 在實施例3的流量計量裝置中，計測過程不易受到接收信號 的振幅變動的影響，能夠高精度地對流量進行計量。另外， 在實施例3中，係對放大裝置6的增益調整後，再用比其大 15 的規定的增益對接收信號進行放大，進行基準電壓設定， 考慮到要檢測接收信號的到達時期而需檢測的峰值（例如 第3個峰值P3)的前1個峰值（即第2個峰值P2)的電壓在流量 計測過程中的變動幅度，首先將基準電壓Ref設定成比最大 變動時的第2個峰值P2的電壓要高，則基準電壓發生變更時 20 基準比較裝置7的輸出信號的個數會表示出接收信號的各 峰值的電壓，因此，控制裝置12能夠從基準比較裝置7的輸 出信號的個數識別出接收信號和基準電壓之間的相對關 係。在對流量計量過程中發出的振幅變動加以考慮後，控 制裝置12也可以將基準電壓Vref設定在要檢測接收信號的 19 !2599〇〇 、I τΉ而k测的第〕個峰值ρ3和前i個的第2個峰值 的電壓之間的任意電壓上。 (貫施例4) _ & ”圖為本發_第4實_巾的流量計量裝置的方框 >圖。弟10圖以及第13圖為表示該流量計量裝置中的操作情 況的=意圖，第11及12圖為其操作情況的流程圖。 士弟9圖中，時間差計時裝置㈣基準比較裝置7和判斷 ^置8的輸出之間的時間差進行計時。與實施例3不同的 疋基準叹疋I置14根據時間差計時裝置15的輸出來設$ φ 10基❸匕較裝置7的基準電壓。其他構成部分與第6圖中所示 的貫施例3相同，在此就省略對它們的說明。 下面借助第11圖來說明具有上述構成的流量計量裝置 的操作情況。電源接通後，控制裝置12首先進行的初始咬 定操作是調整放大裝置6的增益，設定基準電壓。實施例4 b中的放大裝置6的增益調整方式與實施例3中的相同，故在 此就省略對其說明。 首先由控制I置12调整放大裝置6的增益（步驟1 〇 1)， · 使接收側的超聲波振盪器接收到的信號達到規定的振幅。 之後，基準設定裝置Μ將基準電壓設定在可設定範圍中的 20最低電壓上（步驟102)。接下來，控制裝置12將重複裝置9 的重複次數設定為1次後，使發送裝置5工作，從第丨超聲波 · 振盪器2發射出超聲波信號（步驟丨〇 3)。 由第1超耸波振盪器2發射出的超聲波信號在流路i中 傳播，並由第2超聲波振盪器3加以接收，再由放大裝置6加 20 1259900 以放大後’輪出到基準比較裝置7甲。 第_中示出了放大後的接收信號。基準比較裝置7 將放大衣置6的輪出（接收信號A)和基準糕進行比較(步驟 1〇4)，在信號A超過基準電壓的時間點Te上向時間差計時壯 5置15和判斷裝置8輪出信號c。時間差計時裝置i5接收到: 號C後開始計時(步驟1 〇5)，判斷裝置8將時間點Tc以後的传 號A的最初的過零點Ta判斷為超聲波的到達時間點（步驟 1〇6)，將信號〇輪出至重複裝置9和時間差計時裝置15中。 輸出時間差計時裝置15在接收到信肋時停止計時（步驟 )並將。十得的時間差Td輸出至基準設定裝置Μ。基準 叹疋I置14將基準電壓增加可變範圍中的1個控制單位(例 如(㈣，。由於重複裝置9中設定的重複次數為！ ^控制裝置12從重複裝置9接收到表示重複操作已完成的 信息的信號’再次使發送裝置5工作，從第1超聲波振盈器2 《射出超喊彳§^接下來，重複進行步_3至步驟⑽， 直至基準„又定I置M將基準電壓設定到設定範圍中的最大 電壓上為止。 壯使基準電壓由最小變化到最大這段時間内時間差計時 2〇衣置Μ計算之時間差中，有複數個與緊接前-個時間差相 車乂下大巾田·交化之變曲點。基準設定裝置14將基準電壓設定 =例如與緊鄰著的前一個的時間差相比較有1.3倍以上的 ,定化的多個拐點中具有最大間隔的拐點之間的中間點上 (步驟110)。 下面用第13圖來說明步驟11〇中的操作情況。第13圖中 21 1259900 定在第13圖中第2個峰值P2和第3個峰值P3的電壓的中間點 電壓Vref上。這樣一來，基準電壓和第2個峰值及第3個峰 值的電壓之間將有很大的餘量，對於接收信號的電壓變動 而吕判斷裝置8可以隶穩定地檢測出超聲波的接收彳吕號的 5 到達時期。 基準設定裝置14如上面所述的那樣上設定好基準電壓 時，控制裝置12在重複裝置9中設定正式的重複次數（例如 256次），流量計量即告開始。 下面利用第12圖說明流量計量開始後的基準設定裝置 · 10 14中的操作情況。流量計量開始後，控制裝置12使發送裝 置5工作，從第1超聲波振盪器2發射出超聲波信號（步驟 12)，第2超聲波振盪器3接收到的超聲波信號由放大裝置6 放大後輸出至基準比較裝置7及判斷裝置8。基準比較裝置7 將接收信號與基準電壓進行比較（步驟13)，從接收信號大於 15 基準電壓的時間點起時間差計時裝置13開始計時（步驟 14)，這樣的計時一直進行到判斷裝置8檢測到其後最初的 過零點為止（步驟15，16)。 籲 判斷裝置8檢測到過零點（超聲波的到達時間點）後，控 制裝置12再次使發送裝置5工作，從超聲波振盪器2發射出 20 超聲波信號。從步驟12至16的一系列操作將重複進行預先 設定的次數（步驟11)。初始設定操作中設定基準電壓時，第 13圖中的拐點TP2至拐點TP3之間的時間差（500ns〜800ns) 被設定為規定的範圍。例如，可以將上述的規定範圍設在 上述時間差的20%從80%之間，即560ns(二800ns — 23 1259900 500ns)x0.2+500)至740ns(二800ns— 500ns)x0.8+500)之間。規 定的重複次數完成之後，基準設定裝置14判斷在步驟12至 16的操作重複執行預先設定的次數期間由時間差計時裝置 15計得的時間差中是否存在上述規定的範圍以外的時間 5 差’根據時間差的分布決定是否再設定基準電壓。亦即^ 基準設定裝置14判斷是否存在比規定的範圍短的時間差 (不到560ns)(步驟17)，如果存在則像初始設定操作一樣地 再次設定基準電壓（步驟19)。如果不存在更短的時間差，則 基準設定裝置14同樣地判斷否存在比上述規定範圍長的時 10 間差（超過740ns)(步驟18)，如果存在，則像初始設定操作 中那樣再次設定基準電壓（步驟19)。如果超出上述規定的範 圍之外的短時間差和長時間差都存在的話，控制裝置12則 重新進行初始設定操作。如不存在上述規定的範圍外的時 間差，則結束流量計量，由計時裝置10對流量計量開始至 15 完成規定的重複次數的時間進行測定。之後，第1超聲波振 盪器2和第2超聲波振盪器3中進行的超聲波信號的發射/接 收操作由切換裝置4進行切換，計測裝置執行和上面同樣的 操作，測定出被測定流體從上游至下游的超聲波傳播時間 和從下游至上游的傳播時間，流量計算裝置11根據這些時 20 間差並在考慮到流路的尺寸和流動狀悲的基礎上求出流 量。 下面說明基準設定裝置14的其他操作情況。第14圖為 用於描述基準設定裝置14的其他操作情況的流程圖。步驟 11〜16的操作情況與第12圖的步驟11〜16的操作情況相 24 1259900 同。 超聲波信號的發射/接收操作在完成重複裝置9中預先 設定的次數後，基準設定裝置14對從時間差計時裝置15在 重複次數期間計得的時間差中是否存在初始設定操作中設 5 定基準電壓時2個拐點之間的時間差的幅度的規定的比率 (與上述一樣為20%)的範圍的上限、下限雙方向的範圍之外 的時間差進行判斷（步驟21)。如果存在這樣的時間差，基礎 設定裝置14和初始設定操作中一樣再次設定基準電壓（步 驟22) 。 # 10 在不存在這樣的時間差的場合下，基準設定裝置14判 斷是否只存在比範圍的上限(740ns)長的時間差（步驟23)。 當存在較長的時間差時，判斷其次數是否超過規定的次數 (例如10次)(步驟24)。當其次數超過規定的次數時，基準設 定裝置14根據其次數增加基準電壓，即1次增加1個控制單 15 位（2mV)，2次增力口2個控制單位（步驟25，26);其次數不到 規定的次數時，基準設定裝置14使基準電壓只增加1個控制 單位(2mV)(步驟26)。 · 接下來，判斷是否只存在比基準設定裝置14範圍的下 限(560ns)短的時間差（步驟27)，在只存在較短的時間差的 20 場合下，判斷其次數是否在規定的次數（例如10次）以上（步 驟28)。如果其次數在規定的次數以上，則基準設定裝置14 根據其次數減少基準電壓，即1次減少1個控制單位(2mV)， 2次則減少2個控制單位（步驟29，30)。如其次數不到規定的 次數，則基準設定裝置14使基準電壓只減少1個控制單位 25 1259900 (2mV)(步驟30)。然後，根據與範圍的上限相比較（步驟23) 以及和下限相比較（步驟27)的結果，如果計測到的所有的時 間差在規定範圍内的話，則不改變基準電壓，過程結束。 這樣，進行流量計量時，根據時間差計時裝置15的計 5 得的時間差脫離設定基準電壓時的時間差決定的規定的時 間差幅度的次數對基準電壓進行再次設定。 實施例4中，將時間差計時裝置15計得的時間差發生大 幅度變化的多個拐點中具有最大間隔的拐點間的中間點設 定為基準電壓。如果接收信號的電壓變動方向（增加或減少） 10 上有偏向，如接收信號的電壓變動不增加只減少，則基準 電壓可以不是設在時間差的拐點間的中點上，而是設在比 其低的電壓上。這樣一來，對於接收信號的電壓變動（減少） 而言，與基準電壓之間可以有很大的餘量。在這樣的場合 下，基準電壓即使設定在例如時間差的最大間隔的拐點間 15 的1/3的電壓上也可以，將基準電壓根據接收信號的電壓變 動之特性設定在任意的點上也是可以的。 通過上述的處理，可以將基準電壓設定在超聲波的接 收波中相對於接收信號的電壓變動最能穩定地檢測超聲波 信號的到達時期的電壓上。並且，基準電壓的設定之後， 20 當流量計量時由時間差計時裝置15計得的時間差從根據基 準電壓設定好的時間差決定的規定時間差的範圍脫離時基 準電壓將被進行再設定。這樣一來，基準電壓能被自動、 迅速地設定好，設定好之後在流量計量裝置進行流量計量 時也可以將基準電壓繼續保持在最適合的電壓上。 26 1259900 (實施例5) 第15圖為本發明的每 圖。第16圖μ -甘 中的流量計量裝置的方框 Θ…不〜计測裝置的操作情況的流程圖。 ，、中，基準設定裝置丨4從控 M t ^ Ά - 則衣置匕接收表不從第！ 弟2振爾射出的超聲波方向的信號後會定 的基準電壓進行改變。山於甘 〜俊對叹疋 由方匕、他構成要素與實施例4中相 冋’故省略其說明。 下面對具有上述構成的流量 同的基準設定裝置14的摔作俨 《一施例4不 10 W知作Μ况進行說明。電源接通後， 控制裝置12首先進行的初& 丁扪仞始5又疋刼作是調整放大裝置6的 :皿、X疋基準電壓。和實施例4中—樣，在基準電壓設定 揉作中’基準設定裝置14使基準電壓從最小向最大變化， 並將基準電壓設定在時間差計時裝置ls計得的時間差發生 15 20 很大變化的多個拐點中具有最大間隔的拐點間的中點上。 然後’與實施例2t-樣’控制裝置12以重複褒置9中設定 的次數進行超聲波时射和純，㈣量進料量（步驟 51)。流量計量之後，控制裝置12計算出時間差計時裝幻5 計得的时間差的平均值(步驟52)。然後，控制裝置12通過切 換裝置4使第1聲波振盈器2和第2超聲波振盈器3進行切換 (步驟53)，再以同樣的過程對流量進行計量（步驟$句，其 後’計算出時間差計時裝置b計得的時間差的平均值(步驟 55)。基準設定裝置Μ將第i超聲波振盪器2及第2超聲波振 盪1§'3的各個發射方向的平均時間差進行比較（步驟允）。平 均時間差大於規定的值时，例如—方的時間差為6〇〇ns，另 27 1259900 一方的時間差為670ns，存在10%以上的差時，基準設定裝 置14設定每個發射方向上的基準電壓（步驟57)，以後根據不 同的方向分別採用不同的基準電壓。 如上所述，從上游向下游方向以及從下游向上游方向 5 發射超聲波信號時，在各個發射方向上因流過流路的流體 流量不同接收信號的靈敏度也不同，接收波的電壓和基準 電壓的關係也將發生變化。因此，實施例5中，時間差計時 裝置計得的時間差在超聲波信號發射方向不同的場合下， 能夠在各個方向上設定最適的基準電壓。採用實施例5中的 10 流量計量裝置的話，即便因超聲波信號的發射方向不同引 起上述的接收信號電壓上的差異，也能將基準電壓保持在 最合適的電壓上。 第17圖為本發明的實施例6中的流量計量裝置的方框 圖。第18，19圖為說明流量計量裝置的操作情況即基準電 15 壓的決定操作的示意圖。第17圖中，基準設定單元7a由預 先設定基準電壓或者改變基準電壓的設定的數控衰減器等 構成。比較單元7b將基準設定單元7a中設定的基準電壓和 接收側振盪器的接收信號電壓進行比較。時間差計時單元 7c對比較單元7b的輸出和判斷裝置8的輸出之間的時間差 20 進行計時。與其他實施例不一樣的是，在實施例6中的流量 計量裝置中，基準比較裝置7由基準設定單元7a、比較單元 7b和時間差計時單元7c構成。信號幅度檢測裝置16用於計 算出基準比較裝置7的輸出之後放大裝置6的輸出的任意的 時間點之間的時間。其他構成要素由於與實施例3中相同， 28 1259900 故省略對其的說明。 下面δ兄明具有上述構成的流量計量裝置的操作情況。 基準比較裝置7通過以下的方式決定基準電壓。控制裝置12 在電源接通时的初始設定操作、流量計算裝置⑽算出了 5異常值及判斷袭置8不能判別出超聲波信號的到達時期的 場合下向基準比較裝置7發出設定基準電壓的指示，將基準 比車乂衣置7σ又疋[基準電壓決定操作]模式。當基準比較裝置7 在控制裝置12的指示下進入[基準電壓決定操作]模式時，基 準。又疋單元7a將基準電壓設定在經放大裝置6放大後的超 10聲波接收信號的峰值電壓附近。例如，如第關中所示， 第4们峰值P4為整個接收波的峰值的場合下，基準設定單元 7a將基準電壓設定在峰值Μ的電壓力也上。然後，基準設 定單元％ 一邊將基準電壓I電壓Vrefs逐漸降低，時間差計 時單元7c-邊對比較單元凡的輸出信號和判斷裝置8的輸 15出信號之間的時間差進行計時。 舉例來說，基準電壓位於第18圖的虛線中所示的Vrefp 的％合下，判斷裝置8在放大裝置6輸出的接收波達到電壓 Vrefp以後最初的過零點Ta處輸出下降信號£。此時，時間 差计時單70 7 C對比較單元7 b的輸出信號c和判斷裝置8的輸 20出信號E之間的時間差td進行計時。 第19圖中不出了基準電壓如上面所述的那樣下降時時 間差什日守單元7C中計得的時間差^。當基準電壓處在超聲波 接收佗號的各個峰值（第2個峰值p2，第3個峰值P3···)上 時，時間差td為超聲波頻率的1/4周期，處於其他部分上時 29 1259900 則隨著基準電壓的下降時間差將變長。 如上所述，時間差td和基準電壓之間存在一定相關關 係，時間差td為超聲波的1/4周期時的基準電壓為超聲波接 收信號的各峰值電壓。基準設定單元7a將第3個峰值和第2 5 個峰值的電壓中間的基準電壓Vr2及第2個峰值和第1個峰 值P1的電壓中間的基準電壓Vrl存貯起來後，基準比較裝置 7的「基準電壓決定操作模式」即告結束。 為了檢測接收信號的到達時期要檢測比方說第3個峰 值P3時，控制裝置12將峰值P3的電壓和其前1個峰值即第2 · 10 個峰值P2的電壓之間的中間電壓Vr2設定為基準電壓後，進 行流量計量。另外，在實施例6中，對放大裝置6的增益進 行調整後，在「基準電壓決定操作模式」中最初設定成將 基準電壓從接收信號的整體上的峰值電壓開始逐漸減少。 但是，與此相反，從接收信號振幅最小的第1個峰值pi附近 15 開始逐漸增加電壓，根據時間差計時早元7c計得的時間差 將基準電壓設定在規定的峰值之間（如峰值P2，P3之間）的 中間電壓上的話也可以達到同樣的效果。 · 此外，雖然在實施例6中像上面所述的那樣基準電壓是 被設置在接收信號中的岭值電壓的中間點上的，但是，像 20 實施例2中所述的那樣，接收信號的電壓（振幅）變動方向（增 加或減少）有偏向時，也可以將基準電壓設定在相對於接收 信號的電壓變動在特定的峰值電壓間能和基準電壓取得很 大差值的任意電壓上。比方說，可以如實施例2中所述的那 樣，將基準電壓設定在規定的特定峰值間的電壓的1/3上。 30 1259900 如上所述，在實施例6中，在電源接通時的初始設定操 作及其後的基準電壓設定操作時，時間差計時單元7c從進 行計時的比較單元7b和判斷裝置8的輸出信號之間的時間 差決定基準設定單元7a的基準電壓並將其存貯起來。由於 5 該基準電壓是根據實際的超聲波信號的接收波來決定的。 故實施例6中的流量計量裝置能夠在最合適的基準電壓上 對流量進行計量。 L圖式簡單說明3 第1圖為本發明的第1實施例中的流量計量裝置的方框 10 圖。 第2圖為用於說明第1實施例中的流量計量裝置的操作 情況的示意圖。 第3圖為本發明的第2實施例中的流量計量裝置的方框 圖。 15 第4圖為用於說明第2實施例中的流量計量裝置的操作 情況的示意圖。 第5圖為用於說明第2實施例中的流量計量裝置的操作 情況的特性圖。 第6圖為本發明的第3實施例中的流量計量裝置的方框 20 圖。 第7圖為用於說明第3實施例中的流量計量裝置的操作 情況的示意圖。 第8圖為用於說明第3實施例中的流量計量裝置的操作 情況的流程圖。 31 12599〇〇 圖。 苐9圖為本發明的第4實施例中的产 量叶量裝置的方框 作情=Γ”4實，的流量計.裝置的操 第11圖為用於說明第 m %例中的流量旦 识沾治您国„ I nt里 作情況的流程圖 第12圖為用於說明第4實施例 作情況的流程圖。 裝置的操 中的流量計量裝置的操 i叶量裝置的操 i"情Ι=Γ—的流 第14圖為用於說明第 量裝置的其 只方也例中的流|斗 他操作情況的流程圖。 冲 第15圖為本發明的篦 框圖。 弟、施例中的流量計量裝置的方 15 IU6圖為用於說明第5實施例 作情況的流程圖。 里叶里I置的才呆 第17圖為用 裝置的方框圖。 於說明本發明的第6實施例中的流 量計量 量計量裝置的操 第18圖為用於說明筮 主 貫施例中的流 20作情況的示意圖。 第19圖為用於說明第 作情況的示意圖。 ^例中的流量計量裝置的操 _圖為現有料量計量裝置的方框圖。 第21圖為用於說％ # 月現有的流量計量裝置的操作情況的 32 1259900 示意圖。 第2 2圖為用於說明現有的流量計量裝置的操作情況的 示意圖。 【圖式之主要元件代表符號表 1…流路 13b…傳播計時單元 2···第1超聲波振盪器 13c…時間差計時單元 3···第2超聲波振盪器 14···基準設定裝置 4···切換裝置 15…時間差計時裝置 5…發送裝置 16···信號幅度檢測裝置 6···放大裝置 31···流路 7···基準比較裝置 32…第1超聲波振盪器 7a…基準設定單元 33…第2超聲波振盪器 7b…比較單元 34···切換裝置 7c…時間差計時單元 35···發送裝置 8···判斷裝置 36···放大裝置 9···重複裝置 37…基準比較裝置 10…計時裝置 38…判斷裝置 11…流量計算裝置 39···重複裝置 12…控制裝置 40…計時裝置 13…基準設定裝置 41…流量計算裝置 13a···電壓設定單元 42···控制裝置Set -9 r π 岍 置 S can detect; ^ clothing 6 sacrifice (receiving wave) at a specific time point (such as the first ride (four) point) of the reference voltage (four) benchmark set to find 13 - At the intermediate point, the measuring device is ok 13 1259900. The specific time point in the received wave is measured. Since the measuring device can set the flow rate every time or periodically, the reference voltage can be set quickly and accurately as described above. The voltage can always be kept at the most suitable value. (Embodiment 2) 5 FIG. 3 is a block diagram of the flow metering device in Embodiment 2 of the present invention, and FIGS. 4 and 5 are diagrams illustrating the operation of the flow metering device. The time difference timing unit 13c counts the time difference between the output of the reference comparison means 7 and the output of the determination means 8. The voltage setting early 13a sets the reference voltage based on the output of the time difference timing unit 13c, and sets the voltage 10 The voltage is supplied to the reference comparing means 7. The voltage setting means 13a and the time difference measuring means 13c constitute the reference setting means 131. The other components are the same as those of the first embodiment, and the description thereof will be omitted. Next, the operation of the flow rate measuring device having the above configuration will be described. When the flow rate is started, the control device 12 operates the transmitting device 5 to emit ultrasonic waves from the ultrasonic wave 15 oscillator 2. The ultrasonic waves emitted from the first ultrasonic oscillator 2 are The flow path 1 propagates and is received by the second ultrasonic oscillator 3, amplified by the amplification device 6, and output to the reference comparison device 7. The gain of the amplification device 6 is controlled by the control device 12 to make the reception signal constant. The amplitude comparison unit 7 compares the output of the amplifying device 6 with the reference pressure Vc, and in the same manner as in the first embodiment, the timing device 6 and the time difference are counted at the time when the output of the amplifying device 6 is larger than the reference voltage Vc. The unit 13c outputs the signal C1 shown in Fig. 4. The judging means 8 refers to the output of the reference comparing means 7, and the output of the amplifying means 6 shown in Fig. 4 is at the initial zero-crossing point Ta 14 after the above time point. 1259900 determines the arrival time point of the ultrasonic wave, and outputs a signal C2 to the time difference timing unit 13c. The output signal of the time difference timing unit 13c from the reference comparison means 7 C1 and the output signal C2 of the judging device 8 count the time difference td shown in Fig. 4. The voltage setting unit 13a detects the time difference td of the time difference unit 13c, and changes the reference voltage Vc up and down. As shown in the figure, the time difference td changes due to the change of the reference voltage Vc. The reference voltage Vc is set to a value of the peak value P2 which is the level of the first zero-crossing point Tb after the determination device 8 can detect the second peak P2 of the received wave. At almost the same voltage V2, the time difference tdo is 1/4 cycle of the received wave, that is, 500 ns. 10 Then, after the reference voltage is increased to exceed V2, the first zero-crossing point after the third peak P3 is detected by the judging device 8 In the case of Ta, the time difference td will become the maximum as shown in Fig. 5. Thereafter, as the reference voltage increases, the time difference td decreases; when the reference voltage reaches the voltage V3 which is almost the same as the voltage value of the third peak P3, the time difference td becomes tdo again. Then, the voltage setting unit 13a sets the intermediate point voltage between the maximum value and the minimum value (1/4 of the period) of the time difference td when the time difference td becomes the reference voltage as the reference voltage. By performing such setting, the time difference td calculated by the time difference counting unit 13c is set at an intermediate point of a range that varies according to the change of the reference voltage, so that the reference voltage is held at the energy level 20 to stably detect the received wave. The level of the specific zero crossing point Ta is set, and the reference voltage can be set quickly and with high precision. Since the measuring device can quickly and accurately perform the above-described reference voltage setting every time the flow rate is measured or periodically, the reference voltage can always be maintained at the optimum level. 15 !2599 〇〇 (Example 3) 10 15 20 Fig. 6 is a block diagram of the flow rate measuring device in Embodiment 3 of the present invention. Fig. 7 is a schematic view for explaining the operation of the flow rate measuring device, and Fig. 8 is a flow chart showing the operation of the flow metering device. The first ultrasonic oscillator 2 and the second ultrasonic oscillator 3 for transmitting/receiving ultrasonic waves are provided on the flow path at a constant angle Φ with respect to the flow direction of the fluid. The transmitting device 5 causes the i-th ultrasonic oscillator 2 or the second ultrasonic oscillator 3 to emit ultrasonic waves. The switching device 4 is for exchanging ultrasonic wave transmitting/receiving operations in the first ultrasonic oscillator 2 and the second ultrasonic oscillator 3. The amplifying means 6 amplifies the signal received by the ultrasonic oscillator on the receiving side in accordance with the gain controlled by the control means 12, and the reference comparing means 7 compares the signal amplified by the amplifying means 6 with the reference voltage. The judging means 8 judges the arrival time of the ultrasonic wave from the output of the reference comparing means 7 and the signal amplified by the amplifying means 6. The repeating device 9 counts the output signal of the judging device 8, and sends a signal to the control device 12 at the time when the predetermined number of times is counted. The timekeeping device 1 〇 the reset device 9 completes counting the time until the output signal of the determination device 8 is counted up to a predetermined time. The flow rate calculating means 11 calculates the flow rate of the fluid from the leaf tube based on the time counted by the time measuring means 1 and considering the size of the pipe and the flow state of the fluid. The control device 12 receives the signals from the flow rate calculation device 重复, 重复, and 9, and controls the transmission device 5 and the amplification device 6. The reference setting means 14 is constituted by a digital/analog (D/A) converter or a digital-controlled led $ (Digital-Controlled Attenuator) or the like for setting the reference ratio and the reference voltage in the device 7. The reference setting means 14 determines the reference voltage based on the output of the reference comparison means when the reference voltage changes. 16 1259900 Next, an operation of the flow rate measuring apparatus having the above configuration will be described with reference to Fig. 8. After the power is turned on, the control device 12 first performs an initial setting operation, i.e., adjusts the gain of the amplifying device 6, and sets the reference voltage. After the gain adjustment is made, the received signal is amplified to 5 (say), the voltage of the peak P5 of the fifth graph is within a prescribed range as shown in Fig. 7. As shown in Fig. 7, the amplifying means 6 outputs the peak detecting signal PD to the control means 12 and the reference setting means 14 while the received signal is higher than the lower limit of the above range. In order to bring the signal received by the ultrasonic oscillator on the receiving side to a constant amplitude, the gain of the amplifying device 6 is first adjusted to be set to the first gain (step 10 1). Thereafter, the peak value to be detected for judging the arrival period of the received signal (say, the voltage of the second peak P2 before the third peak P3) is considered in the flow metering process, and is adjusted better than the initial adjustment. The second gain having the first gain of the amplifying device 6 amplifies the received wave (step 2). The amplified received signal is as shown in Figure 7. 15 The broken line in Fig. 7 is a received signal amplified by the first gain, and the solid line is a received signal amplified by the second gain. The reference setting means 14 increases the reference voltage Vref shown in Fig. 7 for comparison with the received signal A amplified on the second gain by one control unit (e.g., 5 mV) from the lowest reference voltage (step 3). In the third embodiment, the lowest reference voltage Vref is set to be higher than the voltage of the first peak P1 of the reception 20 signal A but lower than the voltage of the second peak P2. The control device 12 sets the number of repetitions of the repeating device 9 to once, and then operates the transmitting device 5 to emit an ultrasonic signal from the first ultrasonic oscillator 2 (step 4). The ultrasonic signal emitted from the first ultrasonic oscillator 2 propagates through the flow path 1, is received by the second ultrasonic oscillator 3, and is output to the reference comparison device 7 via the amplification device 6. As shown in Fig. 7, the reference comparing means 7 compares the output (received signal A) of the amplifying means 6 with the reference voltage V1·ef, and judges to the reference setting means 14 when the output of the amplifying means 6 is larger than the reference voltage Vref The device 8 outputs signals C2, C3, C4, C5 (step 5). The reference 5 setting means 14 counts the number of the mountain-transfer signals C2 to C5 of the reference comparing means 7 (step 6), and repeats the above-described steps 5 and 6 before the amplifying means 6 outputs the peak detecting signal (step 7). When the peak detecting signal is sent from the amplifying device 6, the reference setting means 14 determines whether or not the number of signals output from the reference comparing means 7 is three (step 8). If the number of signals is not three, 10 increases the reference voltage Vref by one control unit (step 3), and then repeats steps 4 to 8. When the number of signals output from the reference comparing means 7 reaches three, the gain of the amplifying means 6 is set back to the first gain (step 9). That is, when the reference voltage Vref is equal to or lower than the voltage of the second peak P2 of the received signal, the reference comparing means 7 outputs four signals C2 to C5 until the peak device 6 outputs the peak detecting signal. When the reference voltage Vref exceeds the voltage of the second peak P2 of the received wave, the reference comparator 7 outputs only the signals C2 and outputs only three signals C3 to C5. When the number of output signals of the reference comparing means 14 is changed from 4 to 3, the reference setting means 14 stops increasing the reference voltage Vref. Further, when the gain of the amplifying means 6 returns to the first gain of 20 before the adjustment, the reference voltage Vref of the reference setting means 14 is slightly higher than the voltage of the second peak P2 of the received signal. The difference between the voltage of the reference voltage Vref and the voltage of the second peak P2 is set in consideration of the magnitude of change of the voltage of the second peak P2 during the flow metering process, so that even if the amplitude of the received signal changes during the flow metering process, The voltage at the second peak P2 will not exceed 18 1259900 over the reference voltage Vref. Thus, there is a large margin between the reference voltage Vref and the voltage of the third peak P3 at this time, and the determination device 8 can detect the arrival time of the ultrasonic reception signal most stably with respect to the amplitude variation of the received signal. . 5 As described above, in the present embodiment, the 'reference setting means 14 sets the reference voltage based on the output of the reference comparison means 7, and sets the reference voltage to take into account the peak to be detected for detecting the arrival time of the received signal. The maximum value of the amplitude variation of one peak during the flow metering process. In this way, the first 10 peaks of the peak to be detected for detecting the arrival period of the received signal do not exceed the reference voltage, and there is a very large relationship between the peak and the reference voltage to be detected for detecting the arrival period of the received signal. A large margin. Therefore, in the flow rate measuring device of the third embodiment, the measurement process is less susceptible to fluctuations in the amplitude of the received signal, and the flow rate can be accurately measured. Further, in the third embodiment, after the gain of the amplifying device 6 is adjusted, the received signal is amplified by a predetermined gain larger than 15 to set the reference voltage, and it is necessary to detect the arrival time of the received signal. The fluctuation range of the voltage of the first peak (for example, the second peak P2) of the detected peak (for example, the third peak P3) during the measurement of the flow rate is first set to the second voltage at the time of the maximum fluctuation. When the voltage of the peak P2 is high, when the reference voltage is changed, the number of output signals of the reference comparator 7 indicates the voltage of each peak of the received signal. Therefore, the control device 12 can output the signal from the reference comparator 7. The number identifies the relative relationship between the received signal and the reference voltage. After considering the amplitude variation emitted during the flow measurement, the control device 12 can also set the reference voltage Vref to the first peak ρ3 and the front i of the 19 to 2599 〇〇, I τ Ή and k to be detected. The voltage of the second peak is between any voltage. (Example 4) The _ & ” diagram is a block diagram of the flow metering device of the present invention. The figure 10 and the figure 13 show the operation of the flow metering device. Intent, Fig. 11 and Fig. 12 are flowcharts showing the operation of the case. In Fig. 9, the time difference device (4) compares the time difference between the reference comparison device 7 and the output of the judgment device 8. The difference from the third embodiment is as follows. The reference sigh I 14 sets the reference voltage of the device φ 10 based on the output of the time difference timer device 15. The other components are the same as the third embodiment shown in Fig. 6, and the description is omitted here. Next, the operation of the flow rate measuring device having the above configuration will be described with reference to Fig. 11. After the power is turned on, the initial initial operation performed by the control device 12 is to adjust the gain of the amplifying device 6 and set the reference voltage. The gain adjustment mode of the amplifying means 6 in 4b is the same as that in the third embodiment, so the description thereof will be omitted here. First, the gain of the amplifying means 6 is adjusted by the control I set 12 (step 1 〇 1), Side ultrasonic oscillator reception The received signal reaches a predetermined amplitude. Thereafter, the reference setting means sets the reference voltage to the lowest voltage of 20 in the settable range (step 102). Next, the control means 12 sets the number of repetitions of the repeating means 9 to one time. Thereafter, the transmitting device 5 is operated to transmit an ultrasonic signal from the second ultrasonic wave oscillator 2 (step 丨〇3). The ultrasonic signal emitted from the first supersonic wave oscillator 2 propagates in the flow path i, and is The second ultrasonic oscillator 3 receives the second ultrasonic oscillator 3, and then adds 20 12599900 to the amplifying device 6 to amplify and then rotates to the reference comparing device 7A. The amplified receiving signal is shown in the _. The reference comparing device 7 will enlarge the clothes. The rounding (receiving signal A) of 6 is compared with the reference cake (step 1〇4), and the time difference is set to 5 at the time point Te at which the signal A exceeds the reference voltage, and the judging device 8 rotates the signal c. When the device i5 receives the number C and starts counting (step 1 〇 5), the determining device 8 determines the first zero-crossing point Ta of the mark A after the time point Tc as the arrival time point of the ultrasonic wave (step 1〇6), and Signal turn to repeat 9 and the time difference timing device 15. The output time difference timing device 15 stops timing (step) when receiving the rib, and outputs the time difference Td of ten to the reference setting device Μ. The reference sigh I sets 14 to increase the reference voltage One control unit in the variable range (for example, ((4), because the number of repetitions set in the repeating device 9 is ! ^ the control device 12 receives a signal indicating that the repeated operation has been completed from the repeating device 9') again causes the transmitting device 5 work, from the first ultrasonic vibrator 2 "shot super shout 彳 ^ next, repeat step _3 to step (10), until the reference „ again set I set M to set the reference voltage to the maximum voltage in the set range until. The time difference between the minimum and the maximum of the reference voltage is calculated. In the time difference between the calculation and the calculation of the time difference, there are a plurality of time points that are different from the previous time difference. The reference setting means 14 sets the reference voltage =, for example, 1.3 times or more compared with the time difference of the immediately preceding one, and the intermediate point between the inflection points having the largest interval among the plurality of normalized inflection points (step 110). The operation in step 11A will be described below using Fig. 13. In Fig. 13, 21 1259900 is set at the intermediate point voltage Vref of the voltages of the second peak P2 and the third peak P3 in Fig. 13. In this way, there is a large margin between the reference voltage and the voltage of the second peak and the third peak. For the voltage variation of the received signal, the apparatus 8 can stably detect the reception of the ultrasonic wave. Number 5 arrives at the time. When the reference setting device 14 sets the reference voltage as described above, the control device 12 sets the official number of repetitions (for example, 256 times) in the repeating device 9, and the flow rate starts. Next, the operation of the reference setting means 1014 after the start of the flow rate will be described using FIG. After the flow rate is started, the control device 12 operates the transmitting device 5 to emit an ultrasonic signal from the first ultrasonic oscillator 2 (step 12), and the ultrasonic signal received by the second ultrasonic oscillator 3 is amplified by the amplifying device 6 and output to the reference. Comparison device 7 and determination device 8. The reference comparing means 7 compares the received signal with the reference voltage (step 13), and starts time counting means 13 from the time point when the received signal is greater than 15 reference voltage (step 14), and such counting continues until the determining means 8 detects The initial zero crossing thereafter (steps 15, 16). When the judging means 8 detects the zero-crossing point (the arrival time point of the ultrasonic wave), the control device 12 operates the transmitting device 5 again to emit 20 ultrasonic signals from the ultrasonic oscillator 2. The series of operations from steps 12 to 16 will be repeated a predetermined number of times (step 11). When the reference voltage is set in the initial setting operation, the time difference (500 ns to 800 ns) between the inflection point TP2 and the inflection point TP3 in Fig. 13 is set to a predetermined range. For example, the above specified range can be set between 20% of the above time difference from 80%, that is, 560 ns (two 800 ns - 23 12 599 00 500 ns) x 0.2 + 500) to 740 ns (two 800 ns - 500 ns) x 0.8 + 500 )between. After the predetermined number of repetitions is completed, the reference setting means 14 determines whether or not the time difference other than the predetermined range is present among the time differences counted by the time difference timer means 15 during the execution of the operations of steps 12 to 16 repeatedly. The distribution determines whether or not to set the reference voltage. That is, the reference setting means 14 judges whether or not there is a time difference (less than 560 ns) shorter than the predetermined range (step 176 ns), and if so, sets the reference voltage again as in the initial setting operation (step 19). If there is no shorter time difference, the reference setting device 14 similarly determines whether there is a difference (over 740 ns) between the time 10 longer than the predetermined range (step 18), and if so, sets the reference again as in the initial setting operation. Voltage (step 19). If a short time difference and a long time difference outside the range specified above exist, the control device 12 performs the initial setting operation again. If there is no time difference outside the above-specified range, the flow rate is ended, and the time measuring device 10 measures the time from the start of the flow rate to the completion of the predetermined number of repetitions. Thereafter, the transmission/reception operation of the ultrasonic signals performed by the first ultrasonic oscillator 2 and the second ultrasonic oscillator 3 is switched by the switching device 4, and the measuring device performs the same operation as above to measure the fluid to be measured from upstream to downstream. The ultrasonic wave propagation time and the propagation time from the downstream to the upstream, the flow rate calculating means 11 obtains the flow rate based on the difference between these times and 20 in consideration of the size of the flow path and the flow sorrow. Next, other operation of the reference setting device 14 will be described. Fig. 14 is a flow chart for describing other operational situations of the reference setting means 14. The operation of steps 11 to 16 is the same as the operation of steps 11 to 16 of Fig. 12, which is the same as 24 1259900. After the transmission/reception operation of the ultrasonic signal is completed a predetermined number of times in the repeating device 9, the reference setting device 14 sets a reference voltage for the initial setting operation from the time difference measured by the time difference counting device 15 during the number of repetitions. The time difference between the upper limit and the lower limit of the range of the predetermined ratio of the time difference between the two inflection points (20% as described above) is determined (step 21). If there is such a time difference, the basic setting means 14 sets the reference voltage again as in the initial setting operation (step 22). #10 When there is no such time difference, the reference setting means 14 determines whether or not there is only a time difference longer than the upper limit (740 ns) of the range (step 23). When there is a long time difference, it is judged whether the number of times exceeds a prescribed number of times (for example, 10 times) (step 24). When the number of times exceeds a predetermined number of times, the reference setting means 14 increases the reference voltage according to the number of times, that is, one control unit 15 bits (2 mV) is added once, and the second boosting port has two control units (steps 25, 26); When the number is less than the predetermined number of times, the reference setting means 14 increases the reference voltage by only one control unit (2 mV) (step 26). Next, it is judged whether or not there is only a time difference shorter than the lower limit (560 ns) of the range of the reference setting means 14 (step 27), and in the case where there is only a short time difference of 20, it is judged whether or not the number of times is a predetermined number of times (for example, 10) Times) above (step 28). When the number of times is equal to or greater than the predetermined number of times, the reference setting means 14 decreases the reference voltage according to the number of times, that is, decreases one control unit (2 mV) once, and reduces two control units twice (steps 29, 30). If the number of times is less than the predetermined number of times, the reference setting means 14 reduces the reference voltage by only one control unit 25 1259900 (2 mV) (step 30). Then, based on the result of comparison with the upper limit of the range (step 23) and the comparison with the lower limit (step 27), if all the measured time differences are within the prescribed range, the reference voltage is not changed, and the process ends. As described above, when the flow rate is measured, the reference voltage is reset by the number of times of the predetermined time difference determined by the time difference when the time difference measuring device 15 is out of the set reference voltage. In the fourth embodiment, the intermediate point between the inflection points having the largest interval among the plurality of inflection points in which the time difference counted by the time difference counting means 15 is largely changed is set as the reference voltage. If the direction of voltage variation (increase or decrease) of the received signal is biased, if the voltage fluctuation of the received signal does not increase and only decreases, the reference voltage may not be set at the midpoint between the inflection points of the time difference, but rather Low voltage. In this way, there is a large margin between the voltage variation (decrease) of the received signal and the reference voltage. In such a case, the reference voltage may be set to, for example, 1/3 of the voltage between the inflection points 15 of the maximum interval of the time difference, and it is also possible to set the reference voltage to an arbitrary point according to the characteristic of the voltage fluctuation of the received signal. . According to the above processing, the reference voltage can be set to the voltage at which the ultrasonic wave is detected in the ultrasonic wave with respect to the voltage fluctuation of the received signal, and the voltage at the arrival time of the ultrasonic signal can be stably detected. Then, after the reference voltage is set, the reference voltage is reset when the time difference calculated by the time difference timer device 15 is deviated from the range of the predetermined time difference determined by the time difference set by the reference voltage. In this way, the reference voltage can be automatically and quickly set, and the reference voltage can be maintained at the most suitable voltage when the flow metering device performs the flow metering. 26 1259900 (Embodiment 5) Figure 15 is a diagram of each of the present invention. Fig. 16 is a block diagram of the flow metering device in the -- 甘... not a flow chart of the operation of the measuring device. , , and , the reference setting device 丨 4 slave control M t ^ Ά - then the clothing is not received from the first! The signal from the ultrasonic direction emitted by the 2nd Zhener will change the reference voltage. Shan Yugan ~ Jun to sigh 疋 匕 匕 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋 疋Next, the case where the flow rate of the above-described configuration is the same as that of the reference setting device 14 will be described. After the power is turned on, the first & initial start 5 of the control device 12 is also used to adjust the amplification device 6 : the dish, the X 疋 reference voltage. As in the fourth embodiment, the reference setting device 14 changes the reference voltage from the minimum to the maximum during the reference voltage setting, and sets the reference voltage to the time difference of the time difference counting device ls to greatly change 15 20 . The midpoint between the inflection points having the largest interval among the plurality of inflection points. Then, the 'and the second embodiment' control device 12 performs the ultrasonic injection and the pure (four) amount of feed amount (step 51) in the number of times set in the repeating device 9. After the flow rate is measured, the control device 12 calculates the average of the time differences calculated by the time difference timer (step 52). Then, the control device 12 switches the first acoustic vibrator 2 and the second ultrasonic vibrator 3 by the switching device 4 (step 53), and then measures the flow rate by the same procedure (step $ sentence, followed by 'calculation The average value of the time difference calculated by the time difference timer device b (step 55). The reference setting device 比较 compares the average time difference between the respective transmission directions of the i-th ultrasonic oscillator 2 and the second ultrasonic oscillation 1 § '3 (step permission) When the average time difference is larger than the predetermined value, for example, the time difference of the square is 6 ns, and the time difference of the other 27 12599900 is 670 ns, and when there is a difference of 10% or more, the reference setting device 14 sets the reference voltage in each of the emission directions. (Step 57), respectively, different reference voltages are respectively used according to different directions. As described above, when the ultrasonic signal is transmitted from the upstream to the downstream direction and from the downstream to the upstream direction 5, the fluid flowing through the flow path in each of the emission directions The sensitivity of the received signal differs depending on the flow rate, and the relationship between the voltage of the received wave and the reference voltage also changes. Therefore, in the fifth embodiment, the time difference is timed. When the time difference of the ultrasonic signals is different, the optimum reference voltage can be set in each direction. With the 10 flow metering device of the fifth embodiment, the above-mentioned reception is caused even by the difference in the emission direction of the ultrasonic signals. The difference in signal voltage can also maintain the reference voltage at the most suitable voltage. Figure 17 is a block diagram of the flow metering device in Embodiment 6 of the present invention, and Figures 18 and 19 show the operation of the flow metering device. In other words, the reference setting unit 7a is constituted by a numerically controlled attenuator or the like that sets a reference voltage or a setting of a reference voltage in advance, and the comparison unit 7b sets the reference set in the reference setting unit 7a. The voltage is compared with the received signal voltage of the receiving side oscillator. The time difference counting unit 7c counts the time difference 20 between the output of the comparing unit 7b and the output of the judging device 8. Unlike the other embodiments, in the sixth embodiment In the flow metering device, the reference comparing device 7 is composed of the reference setting unit 7a and the comparison table. 7b and the time difference timing unit 7c. The signal amplitude detecting means 16 is for calculating the time between the arbitrary time points of the output of the amplifying means 6 after the output of the reference comparing means 7. The other constituent elements are the same as in the third embodiment, 28 1259900, the description thereof will be omitted. The following is a description of the operation of the flow rate measuring device having the above configuration. The reference comparing device 7 determines the reference voltage by the following method: The initial setting operation and flow rate of the control device 12 when the power is turned on When the calculation device (10) calculates the abnormal value of 5 and determines that the arrival time of the ultrasonic signal is not determined, the instruction 8 sets an instruction to set the reference voltage to the reference comparison device 7, and sets the reference ratio to the vehicle 77σ and 疋[the reference voltage is determined. Operation] mode. When the reference comparing means 7 enters the [reference voltage decision operation] mode under the instruction of the control means 12, the reference is made. Further, the unit 7a sets the reference voltage in the vicinity of the peak voltage of the super 10 sound wave reception signal amplified by the amplification means 6. For example, when the fourth peak value P4 is the peak value of the entire received wave as shown in the second level, the reference setting unit 7a sets the reference voltage to the voltage Μ of the peak Μ. Then, the reference setting unit % gradually decreases the reference voltage I voltage Vrefs, and the time difference counter unit 7c-phases the time difference between the output signal of the comparison unit and the output signal of the judging means 8. For example, the reference voltage is located at the % of Vrefp shown in the broken line of Fig. 18, and the judging means 8 outputs the falling signal £ at the first zero-crossing point Ta after the received wave output from the amplifying means 6 reaches the voltage Vrefp. At this time, the time difference chronograph 70 7 C counts the time difference td between the output signal c of the comparing unit 7 b and the output signal E of the judging means 8. In Fig. 19, the time difference in which the reference voltage is decreased as described above in the time-of-day unit 7C is not shown. When the reference voltage is at each peak of the ultrasonic reception apostrophe (the second peak p2, the third peak P3···), the time difference td is 1/4 cycle of the ultrasonic frequency, and when it is in other parts, 29 1259900 As the reference voltage falls, the time difference will become longer. As described above, there is a certain correlation between the time difference td and the reference voltage, and the reference voltage when the time difference td is 1/4 of the ultrasonic wave is the peak voltage of the ultrasonic wave receiving signal. The reference setting unit 7a stores the reference voltage Vr2 between the third peak and the voltage of the 25th peak and the reference voltage Vrl between the second peak and the voltage of the first peak P1, and then the reference comparator 7 The "reference voltage determines the operating mode" is over. In order to detect the arrival time of the received signal, for example, when the third peak P3 is detected, the control device 12 sets the intermediate voltage Vr2 between the voltage of the peak P3 and the voltage of the first peak, that is, the second to ten peaks P2. After the reference voltage, the flow rate is measured. Further, in the sixth embodiment, after the gain of the amplifying device 6 is adjusted, in the "reference voltage determining operation mode", the reference voltage is initially set to gradually decrease from the peak voltage of the entire received signal. However, on the contrary, the voltage is gradually increased from the vicinity of the first peak pi 15 where the amplitude of the received signal is the smallest, and the reference voltage is set between the predetermined peaks according to the time difference calculated by the time difference 7c (e.g., peak P2, P3). The same effect can be achieved with the intermediate voltage between. Further, although in the sixth embodiment, the reference voltage is set at the intermediate point of the ridge voltage in the received signal as described above, the signal is received as described in Embodiment 2 of FIG. When the voltage (amplitude) fluctuation direction (increased or decreased) is biased, the reference voltage may be set to an arbitrary voltage that can largely differ from the reference voltage with respect to the voltage fluctuation of the received signal between the specific peak voltages. For example, the reference voltage can be set to 1/3 of the voltage between the specified specific peaks as described in the second embodiment. 30 1259900 As described above, in the sixth embodiment, at the time of the initial setting operation at the time of power-on and the subsequent reference voltage setting operation, the time difference counting unit 7c outputs the output signals from the comparison unit 7b and the judging device 8 that perform the counting. The time difference between them determines the reference voltage of the reference setting unit 7a and stores it. Since 5 the reference voltage is determined based on the received wave of the actual ultrasonic signal. Therefore, the flow metering device of Embodiment 6 can measure the flow rate at the most suitable reference voltage. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a flow rate measuring device in a first embodiment of the present invention. Fig. 2 is a schematic view for explaining the operation of the flow rate measuring device in the first embodiment. Fig. 3 is a block diagram showing a flow rate measuring device in a second embodiment of the invention. Fig. 4 is a schematic view for explaining the operation of the flow rate measuring device in the second embodiment. Fig. 5 is a characteristic diagram for explaining the operation of the flow rate measuring device in the second embodiment. Figure 6 is a block diagram of the flow rate measuring device in the third embodiment of the present invention. Fig. 7 is a schematic view for explaining the operation of the flow rate measuring device in the third embodiment. Fig. 8 is a flow chart for explaining the operation of the flow rate measuring device in the third embodiment. 31 12599〇〇 Picture. Figure 9 is a flow chart of the production leaf amount device of the fourth embodiment of the present invention. The flow chart of the device is shown in Fig. 11 for explaining the flow rate in the m-th example. A flowchart for explaining the situation in your country is shown in Fig. 12 as a flowchart for explaining the case of the fourth embodiment. The flow of the operation of the flow metering device of the device is shown in Fig. 14 for explaining the flow of the first device and the flow of the device. flow chart. Figure 15 is a block diagram of the present invention. The diagram of the flow metering device in the embodiment, the IU6 diagram is a flowchart for explaining the case of the fifth embodiment. I have stayed in the middle of the Ili. Figure 17 is a block diagram of the device. Fig. 18, which is a flow chart for explaining the flow rate measuring device in the sixth embodiment of the present invention, is a schematic view for explaining the flow of the flow in the main embodiment. Fig. 19 is a schematic view for explaining the first case. The operation of the flow metering device in the example is a block diagram of the existing metering device. Figure 21 is a schematic diagram of 32 1259900 for the operation of the existing flow metering device of % #月. Fig. 2 is a schematic view for explaining the operation of the conventional flow metering device. [Main component representative symbol table of the figure: channel 13b... propagation timing unit 2... first ultrasonic oscillator 13c... time difference counting unit 3... second ultrasonic oscillator 14···reference setting device 4· ·Switching device 15...Time difference measuring device 5...Transmitting device 16···Signal amplitude detecting device 6···Amplifying device 31···Flow path 7···Comparative comparison device 32...First ultrasonic oscillator 7a...reference Setting unit 33...second ultrasonic oscillator 7b...comparing unit 34···switching device 7c...time difference counting unit 35···transmitting device 8···determining device 36···amplifying device 9···repetitive device 37... Reference comparison device 10: chronograph device 38...determination device 11...flow rate calculation device 39···repetition device 12...control device 40...timer device 13...reference setting device 41...flow rate calculation device 13a···voltage setting unit 42·· ·Control device