JP2012013711A - Flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flowmeter capable of eliminating excess consumption of power at starting vibration of system lock thereby reducing power consumption.SOLUTION: The flowmeter executes flow measurement at least once in each unit time, and calculates 1/n amount of flow per unit time based on the measurement result and adds the result to an integrated value n times. In each addition, it is checked if any digit carry occurs in the integrated value and pattern data of the detected carry is shift-output in the next unit time using a parallel input serial output shift register which shifts every unit time of 1/n. This is repeated every unit time to display the integrated value and output pulses in response to the output from the shift register.

Description

  The present invention relates to a flow meter for obtaining an integrated flow rate of a fluid. More specifically, the flow rate is periodically measured at least once during a unit time, and the passage amount per unit time obtained from the measurement result or the number of pulses corresponding thereto is accumulated or accumulated during the next unit time. It relates to the output flow meter.

Like an electromagnetic flow meter, a flow meter that measures the flow rate (instantaneous flow rate) at regular time intervals (unit time) and calculates the integrated flow rate based on that flow rate or outputs a flow rate pulse (pulse output) Assuming that the measured flow rate has flowed continuously for the fixed time (unit time), the passage amount (flow rate x unit time) during the fixed time (unit time) is obtained and the values are integrated. The integrated flow rate is obtained and displayed on the display unit. As for the output of the flow rate pulse (pulse output), for example, in the case of 1 m ³ / p, if there is a carry of 1 m ³ as a result of integration, a pulse is output.

  In this prior art, since the passing amount per unit time is added to the integrated value every unit time, when the flow rate increases and the passing amount per unit time becomes larger than the minimum digit of the integrated display, the display increases by one. Rather than that, there was a problem that it happened to fly and increase.

  In addition, in the case of a thermal flow rate sensor (also referred to as a flow sensor) using a heater that uses electric power as a drive source, the flow rate sensor is driven intermittently at regular time intervals in consideration of the economics of electric power. Then, the flow rate is measured (see, for example, Patent Document 1).

  However, in this known example, the sensor is driven every fixed time (unit time), that is, every 5 seconds, and the fluid passage amount for 5 seconds is calculated from the flow velocity measurement value every 5 seconds.

  For this reason, for example, when there is a flow rate of 100 L / h, the volume as the passing amount flowing in 5 seconds is 0.1389 L, so that the integrated flow rate is obtained by adding (integrating) the value 0.1389 L every 5 seconds. It will follow. Therefore, if a pulse output as a signal is output every time 1 L is integrated from this integrated value, the first signal is output 40 seconds after the start of measurement, and the second signal is the third signal after 75 seconds. Is output after 110 seconds. For this reason, even if a constant flow rate of 100 L / h flows, a pulse output that is a signal for every 1 L is not output at equal time intervals. Therefore, when trying to determine (monitor) the flow rate using this signal, even if a constant flow rate is flowing, it is determined that the flow rate has changed. In addition, the signal for every 1 L is received on the receiving side, and the flow rate cannot be correctly calculated from the reciprocal of the period of the signal (pulse output).

  Therefore, in view of such a point, the passage amount of the predetermined time (unit time) is 1 / n times, for example, divided into 100, and the fixed time (unit time) is divided into n times, for example, 100 times, and added. An intermittent drive integrating flow meter has been proposed (see, for example, Patent Document 2).

In this known example, the arithmetic circuit calculates the fluid passage amount for 5 seconds based on the sensor signal every 5 seconds. As an example, at a flow rate of 100 L / h, a volume of 0.1389 L of fluid flows in 5 seconds. The value of 0.1389L is divided into, for example, 100, and an integration amount of 0.001389L is sent to the integration counter every 0.05 seconds of 1/100 of the intermittent drive interval of 5 seconds, which is a constant unit time. The integration counter adds the received value to the integrated value so far to obtain the integrated flow rate. In the unit flow rate signal generating circuit that outputs a signal as a pulse output every 1 L, a unit flow rate signal is generated every time the integrated value reaches 1 L of the unit flow rate. By doing so, it is possible to output a pulse output every 1 L of the unit flow rate.
Japanese Patent Laid-Open No. 1-308921 (pages 3 to 4, FIG. 5) Japanese Patent Laid-Open No. 4-58114 (pages 1 to 3, FIGS. 1 and 2)

  In the prior art of Patent Document 2, the number of addition operations of the microcomputer used to obtain the integrated flow rate is n times, for example, 100 times that of the prior art of Patent Document 1, so the power consumption of the microcomputer Will increase. For this reason, a battery-driven flow meter using a battery as a power source has a problem in terms of battery life and has a difficulty in practical use.

  Furthermore, in general, in order to reduce the power consumption of the microcomputer, the system clock is stopped when the microcomputer is not working. However, when the system clock is stopped, when the operation is started again, it is necessary to set an oscillation stabilization standby time for the system clock oscillator to be stabilized every time. Therefore, every time the system clock is stopped and then restarted, the oscillation stabilization standby time consumes extra power even though the microcomputer is not doing anything, so operations such as addition are repeated at short intervals. Therefore, there is a problem in that the microcomputer is inefficient and power consumption is increased.

  Accordingly, an object of the present invention is to provide a flow meter that can solve these problems, particularly a flow meter that obtains an integrated flow rate or outputs a unit flow rate signal (pulse output).

  In order to achieve the above object, the invention of claim 1 performs at least one flow rate measurement during each unit time, and integrates 1 / n of the passage amount per unit time obtained from the result n times. A parallel that adds to the value, detects the presence or absence of a carry to a specific digit of the integrated value in each addition, and shifts the detected carry or not pattern data every 1 / n unit time in the next unit time The flowmeter is characterized in that the shift output is performed using an input serial output type shift register, and this is repeated every unit time, and the integrated value is displayed and the pulse is output according to the output of the shift register. .

  According to a second aspect of the present invention, in the flowmeter according to the first aspect, a passing amount per unit time is obtained from an average value of a plurality of flow rate measurement results performed within a unit time.

  According to a third aspect of the present invention, in the flowmeter according to the first or second aspect, the amount of passage per unit time is obtained from the flow rate measurement results within a plurality of past unit times.

  According to a fourth aspect of the present invention, in the flowmeter according to any one of the first to third aspects, when the passing amount per unit time is negative, the negative amount is canceled out with the positive amount, and pulse output is performed. It is what.

  According to the first aspect of the present invention, the addition operation of adding 1 / n of the passage amount per unit time obtained at the time of measuring the flow rate n times at a time without stopping the system clock, and the obtained pulse output, that is, the pattern data By using the shift register as a shift output signal, the microcomputer does not need to operate with the system clock stopped, so there is no extra current consumption at the start of system clock oscillation and overall low power consumption. be able to. In addition, when the passage amount per unit time is first added, if the pulse output is not necessary, the operation of adding 1 / n of the passage amount per unit time n times is not performed, and the shift register is not operated. it can.

  In the invention of claim 2, since the average value of the flow rate measurement values is used, a flow meter with little variation can be realized.

  The invention according to claim 3 also uses an average value of the flow rate measurement values for several unit times, so that a highly accurate flow meter with less variation can be realized.

  In the invention of claim 4, a flow meter with high accuracy and low power consumption that does not cause a discrepancy between the actual flow amount and the integrated value or the number of pulse outputs can be realized by offsetting the passing amount at the time of reverse flow.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the first embodiment of FIG. 1, the flow rate measuring unit 1 measures the flow rate of the fluid flowing through a flow path (not shown) during a unit time interval output from the timing output unit 2, for example, a 1-second interval break signal at least once. To do. The measured value of the flow rate is multiplied by the unit time in the passage amount calculation unit 3 per unit time to calculate the passage amount per unit time, that is, (flow rate × unit time), and is compared with a predetermined value in the comparison unit 4. When the passing amount per unit time is equal to or less than a predetermined value, for example, zero, the passing amount per unit time is added to the integrated value of the integrating unit 5 during the next unit time. When the passage amount per unit time exceeds a predetermined value, the passage amount obtained by the passage amount calculation unit 3 per unit time is 1 / n by the passage amount calculation unit 6 per 1 / n, and 1 / n The passing amount per unit time is calculated and added to the accumulating unit 5 every 1 / n of the unit time during the next unit time. Note that n is an integer equal to or greater than 2, and can be set to 100, for example, as in the prior art.

  The integrated flow rate calculated by the integrating unit 5 is displayed on the display unit 7. Further, a pulse signal is output from the pulse output unit 8 for each unit flow rate of the integrated flow rate. As described above, the timing output unit 2 outputs the unit time interval delimiter signal to the flow rate measuring unit 1 and outputs the 1 / n unit time signal to the integrating unit. At the timing of the 1 / n unit time signal, the passing amount per 1 / n unit time is added to the integrated value of the integrating unit 5. Based on the timing at which the specific digit of the integrated value changes, the display of the integrated value is updated and the pulse is output.

  In FIG. 1, a portion surrounded by a two-dot chain line and denoted by reference numeral 9 indicates a portion constituted by a microcomputer. Further, the change-over switches S1 and S2 are interlocked with each other and are switched according to the output of the comparison unit 4. When the passage amount per unit time is less than or equal to the predetermined value, the changeover switches S1 and S2 are in the state shown in the figure, and when the passage amount per unit time exceeds the predetermined value, the switch is switched from the state shown in the figure. .

  FIG. 2 is a block diagram of the second embodiment, FIG. 3 is a flowchart of addition overflow detection in the second embodiment of FIG. 2, and FIG. 4 is a timing diagram showing the relationship between the break signal and the added signal in the second embodiment. In the block diagram of FIG. 2, elements having the same functions as those of the first embodiment of FIG.

  The timing output unit 2A in FIG. 2 outputs a delimiter signal to the flow rate measuring unit 1 every second of a fixed time (unit time) interval, and outputs an addition signal to the integrating unit 5 at intervals equal to n. To do. This addition signal is the same as the 1 / n unit time signal in the embodiment of FIG.

  The flow rate measuring unit 1 receives the separation signal from the timing output unit 2A and measures the flow rate of the fluid flowing through a flow path (not shown). The flow rate measurement is configured to end before the next break signal. When the flow rate measurement is completed, from the measurement results, the passage amount per unit time and the passage amount per 1 unit time and the passage amount per 1 unit time are respectively determined by the passage amount calculation unit 3 and the passage amount calculation unit 6 per unit time. calculate.

  At the time of the delimiter signal, the addition overflow detection unit 10 performs an operation of temporarily adding the passing amount per unit time to the integrated value held by the integrating unit 5 (step 101 in FIG. 3). Since provisional addition is not addition to the integrated value itself, the integrated value itself does not change at this point. When the display minimum digit (the pulse output unit has the same structure as the display minimum digit in this embodiment) is changed by the provisional addition operation, that is, the carry to the display minimum digit (that is, from the digit one digit below the display minimum digit) 1), the 1 / n period addition from the next delimiter signal is turned ON (step 105 in FIG. 3). When the display minimum digit does not change, the integration unit 5 displays the addition result in the provisional addition operation. The accumulated value to be held is written (step 107 in FIG. 3), and 1 / n period addition is turned off (step 109 in FIG. 3). In the second embodiment, addition by the addition overflow detection unit 10 is performed for less than the display minimum digit of the integrated value. Therefore, writing (updating) to the integrated value when there is no overflow is performed for less than the minimum display digit. FIG. 3 shows the flow of these processes.

  The 1 / n period addition means adding the passing amount per 1 / n unit time to the integrated value at 1 / n unit time intervals.

  FIG. 4 shows the relationship between the break signal and the addition signal. The delimiter signal is generated by a method of outputting an addition signal of 1 / n unit time interval once every n times. In the second embodiment, the integrating unit 5 adds the passage amount per 1 / n unit time based on the flow rate measurement value per unit time for each addition signal during the next unit time. After that, that is, at the start of the next unit time, the addition overflow detection unit 10 performs a process at the time of the break signal (the operation of temporarily adding the passing amount per unit time to the integrated value held by the integrating unit 5 and When 1 changes, the 1 / n cycle addition function from the next delimiter signal is turned ON, and when the minimum display digit does not change, the temporary addition result is written to the integration value held by the integration unit 5, and the 1 / n cycle addition function Is turned off).

  The accumulator 5 performs 1 / n cycle addition when 1 / n cycle addition (also referred to as 1 / n cycle addition function) is ON, and does not perform 1 / n cycle addition when 1 / n cycle addition is OFF. The switching between the ON and OFF operations is performed after the nth 1 / n cycle addition and at the next delimiter signal processing. In the case of ON, the previous passage amount per 1 / n unit time is simultaneously switched to the current passage amount per 1 / n unit time.

  Therefore, the measurement results in the flow rate measurement unit are integrated during a unit time starting from the next delimiter signal. That is, when 1 / n period addition is ON, the flow rate measured by the flow rate measurement unit is converted into a passing amount per unit time, and every n addition signals following the first delimiter signal after the end of the flow rate measurement. 1 / n of the passing amount per unit time.

  The display unit 7 updates the display when the display minimum digit is updated by the 1 / n period addition in the integration unit 5. In the second embodiment, only the updated digits are displayed and updated.

  The pulse output unit 8 outputs a pulse at the same time when the display unit digit that is also a pulse unit amount is updated (carry) in the integrating unit 5.

  In the second embodiment, the minimum display digit and the pulse unit amount (also referred to as pulse output unit) are the same, but it is also possible to output a pulse when there is a carry that is one digit above the minimum display digit. Is possible. In this case, for example, the display shows 1 L or more, and the pulse output can be 10 L / p.

  In the second embodiment as well, the part excluding the flow rate measuring unit 1 and the display unit 7 is configured by a microcomputer.

FIG. 5 is a block diagram of Embodiment 3 of the present invention.
The timing output unit 2B outputs a delimiter signal to the flow rate measuring unit 1 at intervals of unit time (1 second in the embodiment), and shift signals to the shift register unit at intervals of n (16 in the embodiment). Output to.

  The flow rate measuring unit 1 receives the separation signal from the timing output unit 2B and measures the instantaneous flow rate. The measurement is configured to end before the next break signal.

  When the measurement of the flow rate is completed, the measurement result is output to the passage amount calculation unit 6 per 1 / n unit time, and the passage amount calculation unit 6 per 1 / n unit time calculates the passage amount per 1 / n unit time.

  When the delimiter signal is received, the pulse output pattern detection unit 11 adds the passage amount per 1 / n unit time to the integrated value M (less than the pulse output unit) held therein, and how many times overflow occurs. Remembers what happened with the addition. In this embodiment, 1 is set when there is an overflow during 16 additions where n is 16, and 0 is set when there is no overflow, and the data is output to the shift register unit 12 as 16-bit data (hereinafter also referred to as pattern data). 1 is High and 0 is Low.

  A shift signal having a period of 1 / n unit time (in the embodiment, a 16 Hz clock) is input to the shift register unit 12 from the timing output unit 2B, and the pattern data input from the pulse output pattern detection unit 11 is received. Shifting with a shift signal is performed. In the embodiment, 16-bit pattern data is shifted by a clock of 16 Hz, and all is output in one second as a unit time.

  For example, as a result of measuring the flow rate, when the passage amount per second, which is a unit time, is 3.56 L, the passage amount per 1 / n unit time is 0.225 L because n = 16. Here, if the integrated value M is 0.6300L, data to be output to the shift register unit 12 is obtained as follows.

  That is, the act of adding 0.2225L, which is a passing amount per 1 / n unit time, to the integrated value M is repeated 16 times, and the presence or absence of overflow to 1L is stored as 1 and 0 data at each addition. Since it is sufficient that an overflow to 1L can be detected, the integral value M is set to 0 for the integer part and 4 digits for the decimal part. Therefore, there is no 1L digit (it was set to 0 in the following calculation), and only the presence or absence of overflow, which is a carry to the 1L digit, can be detected. That is, when there is no overflow, the overflow information data is 0, and when there is an overflow, the overflow information data is 1.

  The overflow information data of the addition result is the parallel input data to the shift register. That is, pattern data 0100001000100001 in which 16 pieces of data from the first time to the 16th time are arranged in order is input to the shift register.

  The shift register unit 12 outputs this pattern data to the integrating unit 5 and the pulse output unit 8 as a shift output signal in order from the first calculation result to the 16th time every 1/16 second by a 16 Hz shift signal (FIG. 6). reference).

  As described above, the pulse output pattern detection unit 11 performs n times to add the passage amount per 1 / n unit time to the accumulated value M (less than the pulse output unit) held internally at the time of the delimiter signal, The presence / absence of overflow to the 1L digit is detected at each addition. Then, the obtained 16-bit pattern data is set in the shift register of the shift register unit 12. These n times (16 times) addition action and setting of 16-bit pattern data are performed during the period indicated by the symbol T in FIG. 7, that is, from the time of the delimiter signal to the rise of the next shift signal (the delimiter signal is Since it is synchronized with the rise of the shift signal, it is performed for 1/16 second). Therefore, the shift output signal of the pattern data, which is a serial output from the shift register, is started after a time indicated by the symbol T, that is, 1/16 second from the delimiter signal as shown in FIG.

  In the next segmentation, the pattern data is obtained by adding the passage amount per 1 / n unit times n times to 0.1900 that is the 16th integrated value M (actually n = 16). When the passage amount per second does not change at 3.56L, the passage amount per 1 / n unit time is similarly 0.2225L. In this case, there are overflows in the 16 additions at the 4th, 9th and 13th times. Therefore, the pattern data that is output data from the pulse output pattern detection unit 11 is 0001000010001000.

  In the case of a passing amount of 3.56 L per second, it takes 0.2809 seconds to flow 1 L, and when expressed in a 1/16 second period, it is 4.49 periods. The two pattern data shown in this embodiment are arranged as follows.

01000010001000010001000010001000
The period in which “1”, which can be said to represent the pulse output timing, appears in the range of 5 to 4, which coincides with the aforementioned 4.49 period expressed in 1/16 second period.

  In the third embodiment, the integrating unit 5 and the display unit 7 are provided so that the shift output signal from the shift register unit 12 is counted and displayed. The accumulating unit 5 can be configured by a simple counting operation. This time, the output from the shift register unit 12 is used as an interrupt to the microcomputer, and the integrating unit 12 is configured by the microcomputer, counting the interrupts, and displaying the integrated value as the count result from the first digit. It is also possible to display from the upper digit. Since the microcomputer only performs the count operation only at the rising edge by the shift output signal from the shift register, the current consumption is small. Further, when there is no overflow to the 1L digit, the signal from the shift register unit does not become High, so the integrating unit 12 (also the pulse output unit) does not operate and there is no wasteful power consumption.

  The pulse output unit 8 is configured to output a pulse when the shift output signal from the shift register unit 12 becomes High (the High signal of the shift output signal from the shift register unit is directly output as a pulse). The pulse output unit 8 can be handled by a microcomputer, and can be configured to have an internal counter and to count the output from the shift register unit 12, and for example, invert every 5 counts at High and Low. In this case, a pulse output close to a duty of 50% is possible.

  In this embodiment, the passage amount per unit time is first added to the integrated value M. When the specific digit does not change, that is, when pulse output is not required, the passage amount per unit time is 1 It is also possible to prevent the shift register from operating without performing the operation of adding / n n times continuously.

  FIG. 8 is a block diagram of Embodiment 4 of the present invention. The timing output unit 2C outputs a delimiter signal to the flow rate measurement unit 1 and the event output unit 13 at unit time intervals (1 second interval in this embodiment). When the separation signal is input, the flow rate measuring unit 1 measures the flow rate, and outputs the measured value to the passage amount calculating unit 3 per unit time. The passing amount calculation unit 3 per unit time calculates the passing amount per unit time by multiplying the flow rate by unit time, and outputs it to the calculation unit 14.

  The computing unit 14 obtains the number of output events by receiving the passage amount per unit time and dividing it by the event amount. The event amount refers to a constant passage amount, and it is assumed that flow rate integration is performed or pulse output is performed based on a signal (event signal) output for each event amount. Therefore, the number of output events indicates a multiple of how many times the amount of fluid flows per unit time of the event amount (the constant passing amount). In this embodiment, assuming that the output is inverted every 5 L for the purpose of pulse output of 10 L / p, the event amount (fixed passage amount) is set to 5 L.

  Further, the calculation unit 14 divides the unit time by the calculated number of output events, and calculates the event time corresponding to the time during which the event amount that is the constant passing amount flows. Furthermore, the offset time is subtracted from the event time by subtracting the previous product of the remaining number of events and event time, and the event output count and the new remaining event count are calculated from the sum of the output event count and the remaining event count. . The event time, the offset time, and the event output count are output to the event output unit 13, and the number of remaining events is stored for the next unit time.

  These calculations are performed following the flow rate measurement in the flow rate measuring unit 1, and are determined and prepared by the start of the next unit time.

Next, it demonstrates in detail using FIG. The time from the break signal to the break signal is the unit time. As described above, the number of output events is a number (a multiple) indicating how many times the fluid has flowed a certain passage amount (that is, the event amount) determined within a unit time. The flow rate is measured at least once within a unit time, and the passage amount per unit time is calculated by multiplying the measured flow rate by the unit time, and that amount flows evenly (at a constant flow rate) within the next unit time. The flow rate is integrated or pulse output is performed. In other words, an event signal having the number of output events calculated from the measured flow rate is output (including output in the form of integration) during the next unit time. And the event signal output for every said fixed passage amount is output for every event amount. Since the number of output events per unit time is not limited to an integer and may include a fractional part, it may be less than one event amount at the time of a delimiter signal. In the first unit time in FIG. 9 (1) For example, 1 the number of minutes less than the number of events the output event, that is, "number of remaining events" S ₁₂ is 0.7. In this case, in the next unit time (2), the number of events when adding an event number 0.3 min _{S 21} after the _{S 12} is _S 21 _{+ S 12} = 1, and the where the event signal is output. The number of events in a unit time (1) was called the number of remaining events the number S ₁₂ of less than one.

Although not shown in the example of FIG. 9, as a result of the flow rate measurement, the output event number S1 is 3.0 in the unit time (1) following the first break signal, and in the unit time (2) following the next break signal. The number of output events S2 is 2.5. Since the event amount is 5L, the flow rate integration and pulse output are performed every 5L for 15L for 1 second of the first unit time (1) and for 12.5L for 1 second of the next unit time (2). Since the flow rate integration and pulse output are performed assuming that a uniform and constant flow rate is flowing within one unit time, the time for which one event amount flows, that is, the event time, is divided by the number of output events for each unit time. It is calculated by that. For example,
The event time T ₁ in the first unit time (1) is T ₁ = 1 ÷ 3 = 0.333 seconds The event time T ₂ in the next unit time (2) is T ₂ = 1 ÷ 2.5 = 0.4 seconds It becomes. further,
In the first unit time (1), the time corresponding to S ₁₁ (= 0.3) is 0.333 × 0.3 = 0.01 seconds.

In the next unit time (2), the time corresponding to S ₂₁ (= 0.3) is 0.4 × 0.3 = 0.12 seconds.

These times S ₁₁ and S ₂₁ are referred to as offset times, and using the remaining event numbers S ₀₂ = 0.7 and S ₁₂ = 0.7 as described above,
From offset time t ₁₁ = T ₁ − (T ₁ × S ₀₂ )
From t ₁₁ = 0.333− (0.333 × 0.7) = 0.10 seconds, offset time t ₂₁ = T ₂ − (T ₂ × S ₁₂ )
It is also possible to obtain by calculation of t ₂₁ = 0.4 × (0.4 × 0.7) = 0.12 seconds.

Since the number of event signals output within the unit time is the number of event outputs, the integer part of the number of output events plus the number of remaining events is the event output count, and the decimal part is carried forward for the next unit time. Stored as the number of remaining events. This value is used to calculate each data for the next unit time. In the first unit time (1) of this embodiment,
Number of remaining events S ₀₂ + number of output events S 1 = 0.7 + 3.0 = 3.7
From event output number 3 of the integer part of 3.7, the remaining number of events _{S 12} is 0.7 in the fractional part of 3.7.

In the next unit time (2),
Number of remaining events S ₁₂ + number of output events S 2 = 0.7 + 2.5 = 3.2
From event output number 3, the remaining number of events _{S 22} carried forward to the next unit period (3) is 0.2.

  After all, at each unit time, starting from the delimiter signal, the event signal is output after the offset time has elapsed, and then the event signal is output for the number of event outputs at the event time interval. In addition, an event signal can be output every 5 L of one event amount (a constant passing amount).

The above calculations in the calculation unit 14 are summarized as shown in FIG.
In FIG. 8, when the delimiter signal is input from the timing output unit 2C, the event output unit 13 first outputs the first event signal (event output) after the offset time has elapsed, and thereafter repeats the output at the event time interval. The event output count is output and stopped. Thereafter, event output is continued with a new offset time, event time, and number of event outputs for each delimiter signal. This event output unit 13 is configured by using a timer of a microcomputer (time is measured using a timer configured by a down counter, and time comes (the set time is counted down to 0). And a timer interrupt). That is, when a delimiter signal is input, the offset time is first set in the timer. Then, when the first timer interruption occurs after that time, an event time is set in the timer (after that, an interruption occurs every event time). This interrupt is an event signal.

  The integration display unit 15 counts and displays the event signal from the event output unit 13. In the embodiment, since an event signal is output every 5L, the frequency is first divided by 1/2 and counted to display a digit of 10L or more.

  The pulse output unit 8 is configured to output a pulse of an open collector output, and is configured to invert the output ON and OFF every time an event signal output every 5L is input. Since it is inverted every 5L, a 10L / p pulse output with 50% duty equal to the ON time and OFF time is realized (see FIG. 11).

  As described above, in this embodiment, the event output unit 13 is realized by using a timer in the microcomputer for time measurement. The event output is output in the form of a timer interrupt. The integration display unit 15 and the pulse output unit 8 are configured by a microcomputer so that the above operation is performed by the interruption (the microcomputer is responsible for the operation).

  When the event output count becomes zero, no event is output in the next unit time. Only the decimal part is stored as the new number of remaining events.

  The event output count is not necessarily used. Since a new setting is made to the timer at the time of the delimiter signal, the next unit time is shifted to when the number of event outputs is automatically output.

  According to this method, the addition operation is not required every 1 / n unit time, and the microcomputer may be operated when the pulse output is required or when the integration is required. Therefore, power consumption can be reduced. Further, the pulse period in this method is not a multiple of 1 / n unit time, and is accurate because of the resolution of the timer. In the embodiment, 32768 Hz is used as the timer clock. Therefore, event output is possible with a resolution of about 30 microseconds, which is one clock. Therefore, it is possible to accurately calculate the flow rate from the pulse period in a device that receives this pulse output.

  In the case of the present embodiment, when the reference time break timing and the event output are close in timing, the offset time is adjusted so that the event output timing is not too close to the break timing. This prevents unexpected malfunctions. As an operation of the flow meter, the first configuration is to surely keep the number of event outputs per unit time. As a specific adjustment method, when the number of new remaining events is close to zero, the offset time at the time of output from the calculation unit is reduced (5 msec in the embodiment), and when the number of new remaining events is close to 1, the offset time (Same as above) Another method is to adjust the event interval. These are adjustments at the output level from the calculation unit, and the new remaining event number stores the calculation result as it is.

  In the fourth embodiment, the number of remaining events can be used as a minus buffer by slightly changing the processing in the calculation unit of FIG. FIG. 12 shows processing in the calculation unit in the embodiment. When the flow rate is negative, the passing amount per unit time and the number of output events are also negative. Next, add the calculated number of output events and the number of remaining events (the number of remaining events may also be negative). If this result is 1 or more, the operation has already been explained. The addition result of the number of events is stored as a new number of remaining events. By this method, the amount of negative flow is stored as the number of remaining events, and when it turns to positive, no event is output until the negative number of remaining events is canceled and becomes positive. Therefore, an event output corresponding to the total amount of flow on the positive side is possible, and a flow meter that performs correct output can be realized.

  This embodiment is different only in the function of the flow rate measuring unit in the block diagrams of FIGS. 1, 2, 5, and 8 of the first to fourth embodiments. That is, as shown in FIG. 13, the flow measurement is performed a plurality of times (n times in this embodiment) and the measurement results are stored every unit time, and the first to n-th measurements are performed after the completion of the plurality of flow measurements. The average value of the flow rate measurement results is calculated to obtain the average flow rate. Based on this average flow rate, the passage amount per unit time is calculated by the passage amount calculation unit per unit time. The plurality of n can be, for example, 4 times. By doing so, a low power consumption flow meter with little variation can be realized. It is also possible to omit the maximum and minimum values from multiple flow measurements, and use the average of the remaining measurements as the average flow value. Even if this occurs, a flow meter with high accuracy can be realized by omitting it.

  This embodiment is different only in the function of the flow rate measuring unit of each of the above embodiments. That is, as shown in FIG. 14, the average value for n times of the current flow measurement result, the previous result, and the (n−1) previous result is obtained as the average flow rate. A passage amount per unit time is calculated from the average flow rate by a passage amount calculation unit per unit time. In this manner, a low power consumption flow meter with little variation can be realized.

  FIG. 15 is a flowchart illustrating the operation of the flow rate measurement unit according to the eighth embodiment. A block diagram of the entire flow meter can be configured in the same manner as in FIG. 8, for example. In this embodiment, the flow rate measurement unit first measures the flow rate, and when the result is negative, it adds to the negative buffer and outputs the flow rate as zero. If the measurement result is positive, check the negative buffer. When the minus buffer is zero, the measurement result is output as is. If the minus buffer is negative rather than zero, add the plus measurement to it. As a result, when it is less than or equal to zero, the flow rate is set to zero. When the negative buffer becomes positive as a result of adding the positive measurement value, the positive value is output as a flow rate, and the negative buffer is set to zero.

  With the above operation, even if there is a back flow of water, when the flow turns positive, the flow rate becomes zero until the positive flow amount flows until the reverse flow portion flows. There is no discrepancy in the number of outputs. Therefore, an accurate and low current consumption flow meter can be realized.

  The present invention is applicable to measuring instruments such as water meters and gas meters.

The block diagram of the flowmeter which concerns on Example 1 of this invention. The block diagram of the flowmeter which concerns on Example 2 of this invention. The flowchart of the addition overflow detection of the flowmeter which concerns on Example 2 of this invention. The timing diagram which shows the relationship between the division | segmentation signal and addition signal of the flowmeter which concerns on Example 2 of this invention. The block diagram of the flowmeter which concerns on Example 3 of this invention. The figure explaining the shift register of the flowmeter which concerns on Example 3 of this invention. The timing diagram explaining operation | movement of the shift register of the flowmeter which concerns on Example 3 of this invention. The block diagram of the flowmeter which concerns on Example 4 of this invention. The figure explaining the effect | action of the flowmeter which concerns on Example 4 of this invention. The figure explaining the calculation content of the calculating part of the flowmeter which concerns on Example 4 of this invention. The timing diagram of the flowmeter which concerns on Example 4 of this invention. The flowchart of the flowmeter which concerns on Example 5 of this invention. The principal part functional block diagram of the flowmeter which concerns on Example 6 of this invention. The principal part functional block diagram of the flowmeter which concerns on Example 7 of this invention. The flowchart of the flow measurement part of the flowmeter which concerns on Example 8 of this invention.

DESCRIPTION OF SYMBOLS 1 Flow measurement part 2, 2A, 2B, 2C Timing output part 3 Passing amount calculation part per unit time 4 Comparison part 5 Accumulation part 6 1 / n Passing amount calculation part per unit time 7 Display part 8 Pulse output part 9 Microcomputer 10 Addition Overflow detection unit 11 Pulse output pattern detection unit 12 Shift register unit 13 Event output unit 14 Calculation unit 15 Integration display unit

Claims (4)

  Measure flow rate at least once during each unit time, add 1 / n of the amount of passage per unit time obtained from the result to the integrated value n times, and at each addition to a specific digit of the integrated value The pattern data of the presence / absence of the carry is detected using a parallel input serial output type shift register that shifts every 1 / n unit time in the next unit time, and this is output. The flow meter is characterized in that the integrated value is displayed and the pulse is output according to the output of the shift register so that the above is repeated every unit time.   2. The flowmeter according to claim 1, wherein a passing amount per unit time is obtained from an average value of a plurality of flow rate measurement results performed within the unit time.   The flowmeter according to claim 1 or 2, wherein a passage amount per unit time is obtained from a flow rate measurement result within a plurality of unit times in the past.   4. The flowmeter according to claim 1, wherein when the passing amount per unit time is negative, the negative amount is canceled out with the positive amount and pulse output is performed.

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