TWI817519B - Flow estimating method of rotary flowmeter under low flow-speed state - Google Patents

Abstract

A flow estimating method of a rotary flowmeter under a low flow-speed state is applied to a flowmeter having a blade wheel, a sensor, and an MCU, and includes following steps: generating pick-up signal and obtaining, when the sensor is triggered by the blade wheel, electrical signal for transforming into flow-speed information; recording flow-speed information for multiple cycles, wherein the flow-speed information includes multiple interval time in a full cycle; computing multiple estimated interval time for current cycle based on the multiple interval time of multiple cycles being recorded; and, computing and displaying multiple estimated pick-up signals of the current cycle based on the multiple estimated interval time, and estimating flows correspondingly based on the estimated pick-up signals incorporated with triggering time points.

Description

Flow estimation method for rotary flowmeter in low flow rate state

The present invention relates to a rotary flow meter, and in particular to a flow estimation method of the rotary flow meter.

Please refer to Figures 1 and 2. Figure 1 is a schematic diagram of a flow meter in related technology, and Figure 2 is a schematic diagram of access signal sensing in related technology. As shown in FIG. 1 , a general flow meter 1 has at least a fluid inlet 11 , a fluid outlet 12 , an impeller 13 , a sensor 14 and a display unit 15 . The flow meter 1 can be installed at a location where the flow rate/flow rate of a fluid needs to be calculated. Fluid (eg water) flows into the flow meter from the fluid inlet 11 and flows out of the flow meter from the fluid outlet 12 . When fluid flows into the flow meter 1, the impeller 13 is affected by the flow momentum of the fluid and rotates. The sensor 14 is arranged on one side of the impeller 13 . When the impeller 13 rotates and one of its blades passes the sensor 14, the sensor 14 is triggered to generate a pick-up signal 2.

The embodiment of FIG. 2 takes an impeller 13 with four blades as an example. The sensor 14 generates an access signal 2 when it senses the passage of a blade, and the flow meter 1 regards the time required for the sensor 14 to sense four complete access signals 2 as one cycle.

的計算公式，就可以得到流量當前的流速。接著，再經由特定公式的轉換，即可得到流量計1在這段時間內的累計流量。 When the flow rate of the fluid is normal, the rotation of the impeller will be very stable, so the time point of the above-mentioned access signal 2 will also be very stable, that is, the interval between each access signal 2 will be very stable. As shown in Figure 2, four access signals 2 can be stably obtained within a fixed measurement time (t) (that is, forming a complete cycle). And, through

The calculation formula can be used to obtain the current flow rate of the flow. Then, through conversion with a specific formula, the accumulated flow rate of flow meter 1 during this period of time can be obtained.

Please refer to Figure 3 again, which is a schematic diagram of access signal sensing in a low flow rate state. In a low flow rate state, the impeller 13 receives less momentum from the fluid, causing the impeller 13 to rotate slowly and unstable. Moreover, coupled with the factors of static friction and the structural limitations of the flow meter 1 itself, the interval time between each input signal 2 will be greatly different, thus forming an unstable cycle.

As shown in Figure 3, the number of access signals 2 that can be detected within the above fixed measurement time (t) may be less than one, which means that no signal may be measured at all. . Therefore, in a low flow rate state, the flow meter 1 must use the low flow dynamic acquisition time (T) to detect the access signal 2 . However, flow meter 1 does not generate or output any data between any two input signals 2. Therefore, flow meter 1 will produce inaccurate measurement results or poor measurement resolution when the flow rate is low. Too low problem.

The main purpose of the present invention is to provide a flow estimation method for a rotary flow meter in a low flow rate state, which can use previously recorded data to calculate and provide an estimated flow rate between two access signals.

In order to achieve the above purpose, the flow estimation method of the present invention can be mainly applied to a flow meter having an impeller, a sensor and a micro-control unit, and mainly includes the following steps: a) The sensor is triggered by the impeller. Generate multiple pick-up signals, wherein multiple intervals of multiple pick-up signals triggered by one rotation of the impeller form a cycle; b) The micro control unit controls the multiple intervals based on the Calculate the flow rate of a fluid in the flow meter over time; c) record the flow rate information of a plurality of cycles, wherein the flow rate information at least includes multiple intervals within one cycle; d) use the micro control unit based on the recorded A plurality of the interval times in the complex period are used to respectively calculate a plurality of estimated interval times in this cycle; and e) calculate a triggering time of multiple estimated access signals in this cycle based on the multiple estimated interval times. point, and calculate and display an estimated flow rate at each trigger time point.

Among them, the recorded multiple intervals in the complex period are used to calculate multiple estimated interval times in this cycle, and the estimation function established is expressed by the recorded data in the complex period. , using weighted moving average, median, mode, probability function, etc. as estimation methods.

Compared with related technologies, the present invention can calculate and provide an estimated flow rate between two real access signals. This can solve the problem that ordinary flow meters cannot determine the flow rate between two access signals, thereby improving the measurement accuracy of the flow meter in low flow conditions and improving the measurement resolution.

1: flow meter

11: Fluid inlet

12: Fluid outlet

13: Impeller

14: Sensor

15:Display unit

2: Access signal

21:Real cumulative traffic

3: Estimate cumulative traffic

4:Flowmeter

41: Impeller

411: First induction blade

412: Second induction blade

413:Third induction blade

414: The fourth induction blade

42: Sensor

43:Micro control unit

44:Display unit

51:The first real access signal

52:Second real access signal

53: The third real access signal

54:The fourth real access signal

71: First estimated access signal

62, 72: Second estimated access signal

63, 73: The third estimated access signal

64, 74: The fourth estimated access signal

8: Real access signal

81, 811: The first real access signal

S10~S22, S24~S30: estimation steps

S40~S46, S50~S56: Calculation steps

FIG. 1 is a schematic diagram of a related art flow meter.

Figure 2 is a schematic diagram of access signal sensing in related technology.

Figure 3 is a schematic diagram of access signal sensing in a low flow rate state.

Figure 4 is a circuit block diagram of a flow meter according to a specific embodiment of the present invention.

Figure 5 is a schematic diagram of estimated traffic according to a specific embodiment of the present invention.

FIG. 6A is a first flowchart of an estimation method according to a specific embodiment of the present invention.

Figure 6B is a second flow chart of the estimation method according to a specific embodiment of the present invention.

FIG. 7 is a flow chart for calculating the estimated interval time according to the first specific embodiment of the present invention.

FIG. 8 is a flow chart for calculating the estimated interval time according to the second specific embodiment of the present invention.

Figure 9 is a schematic diagram of the estimated interval time according to a specific embodiment of the present invention.

A preferred embodiment of the present invention is described in detail below with reference to the drawings.

First, please refer to FIG. 4 , which is a circuit block diagram of a flow meter according to a specific embodiment of the present invention. The present invention discloses a flow estimation method for a rotary flow meter at low flow rates (hereinafter referred to as the estimation method in the description). The estimation method is mainly applied to the rotary flow meter as shown in Figure 4 ( Hereinafter referred to as flowmeter 4).

In the present invention, the flow meter 4 can be a webbed flow meter or a household electronic water meter, without limitation. As shown in FIG. 4 , the flow meter 4 mainly includes an impeller 41 , a sensor 42 , a micro control unit (Micro Control Unit, MCU) 43 and a display unit 44 . When fluid flows in through the fluid inlet (not shown in the figure) When the flow meter 4 flows out of the fluid outlet (not shown in the figure), the impeller 41 can be driven to rotate. The sensor 42 can be disposed on one side of the impeller 41 to sense the rotation of the impeller 41 .

In the embodiment of FIG. 4 , the impeller 41 has a total of four induction blades, including a first induction blade 411 , a second induction blade 412 , a third induction blade 413 and a fourth induction blade 414 . When the impeller 41 rotates and the first sensing blade 411 is sensed by the sensor 42, the sensor 14 can generate a first pick-up signal. When the second sensing blade 412 is sensed by the sensor 42, the sensor 14 can generate a second access signal. When the third sensing blade 413 is sensed by the sensor 42, the sensor 14 can generate a third access signal. When the fourth sensing blade 414 is sensed by the sensor 42, the sensor 14 may generate a fourth access signal. When the sensor 42 is triggered (pick-up) four times and generates four access signals, it can be regarded as a cycle. In the above embodiment, the impeller 41 has four induction blades. However, in practice, the impeller 41 may have n induction blades, where n≧1 is an integer, and is not limited to the embodiment of FIG. 4 .

Specifically, the impeller 41 can be mainly configured below the sensor 42 so that the induction blades 411 - 414 rotate below the sensor 42 . The sensor 42 may be, for example, a Hollen sensor that generates a magnetic field downward. When the impeller 41 disturbs the magnetic field through any of the induction blades 411-414, the sensor 42 can be triggered to generate a corresponding access signal.

The embodiment of FIG. 4 takes an impeller 41 with four induction blades 411-414 as an example, but the number of induction blades of the impeller 41 is not limited to four.

In the present invention, the microcontrol unit 43 of the flow meter 4 records executable program code. When the microcontrol unit 43 executes the executable program code, the estimation method of the present invention can be implemented. Moreover, the estimation method of the present invention is mainly started when the fluid in the flow meter 4 is in a low flow rate state (details will be described later).

The microcontrol unit 43 of the flow meter 4 can perform clock calculation, so it can record the trigger time point of each access signal, and can calculate the interval time between any two access signals (for example, as shown in Figure 3 Interval time (T)). After obtaining multiple interval times, the micro control unit 43 can calculate the flow rate of the fluid during this period of time by calculating the reciprocal of these interval times. Furthermore, the flow meter 4 can display the flow rate calculated by the micro control unit 43 on the display unit 44 of the flow meter 4 .

It is worth mentioning that the flow meter 4 can be tested and calibrated when it is produced by the original factory, and a calibrated compensation conversion factor (Convert coefficient, i.e. K coefficient) is generated for the low flow rate state. After the micro control unit 43 calculates the current flow rate of the fluid in the low flow rate state, the flow rate can be multiplied by the conversion factor to make the calculation result closer to reality.

In addition, the flow meter 4 can also record the corresponding parameters of flow rate and flow rate after undergoing the aforementioned testing and calibration. The microcontrol unit 43 multiplies the flow rate of the fluid in each interval time by the corresponding parameter to obtain the corresponding increase in flow rate in each interval time. Furthermore, the flow meter 4 can display the flow rate (increased flow rate or accumulated flow rate) calculated by the micro-control unit 43 on the display unit 44 .

Please also refer to FIG. 5 , which is a schematic diagram of estimated traffic according to a specific embodiment of the present invention. In the embodiment of FIG. 5 , the sensor 42 is triggered by one of the sensing blades at time point T _n-2 to generate the first access signal, and is triggered by another sensing blade at time point T _{n-1 .} Triggered to generate a second access signal. Based on the interval time (Δt ₀ ) between the two access signals, the micro control unit 43 can calculate the increased flow rate ΔQ during this period. Moreover, the micro control unit 43 adds the accumulated flow rate Q n _-2 at the trigger time point T _n-2 of the first access signal to the increased flow rate ΔQ during this period to obtain the flow rate at the time point T _n-1 Cumulative flow Q _n-1 . It is worth noting that the accumulated flow rates Q _n-1 and Q _n-2 here are both real accumulated flow rates 21.

As shown in FIG. 5 , the sensor 42 is triggered by the next sensing blade at time point T _n to generate a third access signal. Based on the interval time (ΔT) between the second access signal and the third access signal, the micro control unit 43 can calculate the increased flow rate ΔQ during this period. Furthermore, the microcontrol unit 43 adds the increased flow rate ΔQ to the accumulated flow rate Qn _-1 at time point Tn- ₁ to obtain the accumulated flow rate _Qn at time point _Tn . Similarly, the cumulative flow rate _Qn here is the real cumulative flow rate 21.

When the flow meter 4 is in a low flow rate state, the interval between each access signal will become longer and unstable (for example, the interval ΔT in Figure 5). If the interval between two access signals is very long, the measurement results of the flow rate/flow rate of the flow meter 4 may be inaccurate, and the resolution will also become low.

As shown in Figure 5, the main purpose of the present invention is to calculate one or more estimated interval times between two real access signals when the flow meter 4 is in a low flow rate state, and based on these estimated interval times, One or more estimated cumulative flows 3 are provided between the two actual cumulative flows 21 .

In the embodiment of FIG. 5 , the flow meter 4 is in a low flow rate state after time point T _n-1 . In this embodiment, the micro control unit 43 will take the trigger time point T _n-1 of the last real access signal as a starting point, and calculate the first estimate based on multiple intervals in the previously recorded multiple cycles. The interval time Δt ₁ , the second estimation interval time Δt ₂ , and the mth estimation interval time Δt _m . Furthermore, the microcontrol unit 43 estimates the first estimated cumulative flow rate q ₁ , the second estimated cumulative flow rate q ₂ , and the mth estimated cumulative flow rate q _m at multiple time points based on these estimation interval times.

Through the calculation of the above-mentioned multiple estimated interval times and multiple estimated accumulated flow rates 3, the micro-control unit 43 can improve the measurement accuracy and resolution of the flow meter 4 in a low flow rate state.

Please continue to refer to FIG. 6A and FIG. 6B. FIG. 6A is a first flow chart of the estimation method according to a specific embodiment of the present invention, and FIG. 6B is a second flow chart of the estimation method according to a specific embodiment of the present invention. 6A and 6B disclose the specific execution steps of the estimation method of the present invention, and the estimation method can mainly be applied to the flow meter 4 shown in FIG. 4 , but is not limited thereto.

As shown in Figure 6A, after the flow meter 4 is installed and started, the sensor 42 can be continuously triggered by the impeller 41 to generate multiple access signals, and the micro control unit 43 can control the flow according to the internal clock (Clock). To sequentially calculate and record the intervals between multiple access signals. Furthermore, the micro control unit 43 can calculate the current flow rate of the fluid based on multiple intervals (step S10). Taking the impeller 41 with four sensing blades 411-414 as an example, one rotation of the impeller 41 can trigger the sensor 42 to generate four access signals. Each of these four access signals has an interval time relative to the previous access signal. The micro control unit 43 regards the four interval times (that is, the time when the sensor 42 generates four access signals) as a complete cycle. .

When the fluid flow rate is higher than a preset threshold, the flow meter 4 will operate in the normal mode. When the flow rate of the fluid is lower than the threshold value, the flow meter 4 will operate in the low flow rate estimation mode.

Specifically, when the flow rate of the fluid is higher than the threshold value, the fluid can cause the impeller 41 to rotate stably. In normal mode, the intervals between multiple access signals are quite stable and can form a stable cycle. Therefore, the flow meter 4 does not need to estimate the flow rate/flow rate in the normal mode.

It is worth mentioning that the estimation method of the present invention uses the data of multiple complete cycles that have already occurred to estimate the data of future periods (such as flow rate and flow rate). In order to allow the flow meter 4 to start the estimation process at any time, the micro control unit 43 needs to continuously record and update the flow rate information for a certain number of cycles when the sensor 42 is operating. Wherein, the flow rate information includes multiple intervals in a complete cycle.

In one embodiment, the microcontrol unit 43 can record three cycles of flow rate information, and delete the oldest data when new data is generated, thereby maintaining the accuracy of the reference material. In another embodiment, the microcontrol unit 43 can record the latest five cycles of flow rate information. However, the above are only some specific implementation examples of the present invention, but are not limited thereto.

As mentioned above, if the impeller 41 has four sensing blades 411-414, the sensor 42 can be triggered by the four sensing blades 411-414 to sequentially generate four access signals. Furthermore, the one cycle covers the intervals between these four access signals, and the flow rate information includes the four intervals within one cycle.

During the operation of the flow meter 4, the micro control unit 43 continues to determine whether the current flow rate of the fluid is lower than a preset threshold (step S12). If the current flow rate of the fluid is not lower than the threshold value (for example, 0.3 m ³ / s ), it means that the rotation of the impeller 41 is stable. At this time, the micro control unit 43 continues to execute step S10 so that the sensor 42 continues to sense and generate the access signal, and the micro control unit 43 continues to update the flow rate information.

In another embodiment, the micro control unit 43 may continue to calculate the clock, and when the time when the sensor 42 does not generate an access signal exceeds the threshold time, it may be determined that the current flow rate of the fluid is lower than the threshold value. However, the above are only some specific implementation examples of the present invention, but are not limited thereto.

If the current flow rate of the fluid is lower than the threshold value, it means that the flow meter 4 is currently in a low flow rate state, so the rotation of the impeller 41 is relatively unstable. At this time, the microcontrol unit 43 can start the low flow rate estimation mode (step S14). In the low flow rate estimation mode, the microcontrol unit 43 implements the estimation process by executing the executable program code (for example, steps S16 to S30 shown in FIG. 6A and FIG. 6B , but is not limited thereto).

After entering the low flow rate estimation mode, the micro control unit 43 determines whether the recorded data reaches the target amount (step S16). In one embodiment, the microcontrol unit 43 determines whether the flow rate information of a target number of cycles (eg, three cycles, five cycles, etc.) has been recorded. In another embodiment , the micro control unit 43 determines whether a target number of interval times (for example, fifteen or twenty, etc.) has been recorded.

If the recorded flow rate information has not reached the target quantity, the micro control unit 43 does not execute the flow estimation process temporarily. However, although the flow meter 4 is in a low flow rate state and the micro control unit 43 does not execute the flow estimation process, the flow meter 4 still senses the impeller 41 through the sensor 42 and generates a corresponding access signal, and through the micro The control unit 43 calculates the interval time of the access signal (step S18). Thereby, the micro control unit 43 can continuously record and accumulate flow rate information sufficient for performing the estimation process.

If the recorded flow rate information reaches the target quantity, the microcontrol unit 43 can execute a flow estimation process. Specifically, the micro control unit 43 first calculates the estimated interval time of each corresponding section in this cycle based on the recorded interval time of each section in the plurality of cycles (step S20).

Specifically, the micro control unit 43 mainly calculates the estimated interval time of the same segment in the current cycle based on the interval time of the same segment in the past multiple cycles.

Please also refer to FIG. 9 , which is a schematic diagram of the estimated interval time according to a specific embodiment of the present invention. In the embodiment of FIG. 9 , the impeller 41 has four sensing blades 411 - 414 , and one rotation can trigger the sensor 42 to generate four access signals.

In the embodiment of FIG. 9 , because the flow rate of the fluid is lower than the threshold value, the micro control unit 43 starts after the sensor 42 generates the first real access signal 81 at time point T _n and enters a new period C _n . Perform traffic estimation. At time point _Tn , the microcontrol unit 43 has recorded the flow rate information of the previous three periods Cn _-3 , Cn _-2 and _Cn-1 . In the embodiment of FIG _. 9 , the flow rate _information recorded by _the micro-control unit 43 includes the interval time Δt _{( n -3,1)} , △ t _{( n -2,1)} and △ t _{( n -1,1)} , the interval time of the second section △ t _{( n -3,2)} , △ t _{( n -2 ,2)} and t _{( n -1,2)} , the interval time of the third section △ t _{( n -3,3)} , △ t _{( n -2,3)} and △ t _{( n -1,3)} , And the interval time t _{( n -3,4)} , △ t _{( n -2,4)} and △ t _{( n -1,4)} of the fourth section.

In the period C _n-3 , the sensor 42 generates the second real access signal 52 after the interval time Δt _{( n -3,1)} of the first section ends. During the interval time Δt of the second section, The third real access signal 53 is generated after the end of _{( n -3,2)} , the fourth real access signal 54 is generated after the interval time Δt _{( n -3,3)} of the third section ends, and in the fourth After the interval time t _{( n -3,4)} of the section ends, the cycle enters C _{n - 2} and the first real access signal 51 of cycle C _{n - 2} is generated. The rules for the flow rate information of period C _n-2 and period C _n-1 are the same as those of period C _n-3 and will not be described again below.

In order for the microcontrol unit 43 to calculate the flow rates at multiple time points in this cycle (eg, cycle C _n in FIG. 9 ), it needs to first calculate multiple estimated interval times in this cycle. In the above step S20, the micro control unit 43 can obtain the interval time Δt _{( n -3,1),} Δt of the first section in the period Cn _-3 , the period Cn _-2 and the period Cn _{-1. ( n -2,1)} and the interval time △ t _{( n -1,1)} , and use these three data to calculate the estimated interval Pre of the corresponding section (ie, the first section) in this cycle C _{n t ( n ,1)} .

According to the triggering time point of the first real access signal 81 in this cycle and the estimated interval time Pret _{( n ,1)} of the first section, the micro control unit 43 can estimate the second estimated access signal 62 Trigger time point.

Similarly, in step S20, the micro control unit 43 can also obtain the interval time Δt _{( n -3,2)} of the second section in the period C _n-3 , the period C _n-2 and the period C _n-1. , △ t _{( n -2,2)} and the interval time △ t _{( n -1,2)} , and use these three data to calculate the estimate of the corresponding section (i.e., the second section) in this cycle C _n Interval time Pret _{( n ,2)} . Furthermore, based on the trigger time point of the second estimated access signal 62 and the estimated interval time Pret _{( n ,2)} of the second section, the micro control unit 43 can estimate the third estimated access signal 63 Trigger time point.

Moreover, based on the same method as above, the micro control unit 43 can estimate the estimated interval time Pret _{( n ,3)} of the third section and the trigger time point of the fourth estimated access signal 64, and the estimated trigger time point of the fourth section. The estimation interval time Pre _{t ( n , 4)} of the segment and the triggering time point of the first estimation access signal 71 in the next period Cn+1.

It is worth mentioning that the present invention mainly uses the triggering time point of the first real access signal after the flow meter 4 enters the low flow rate state as the starting point of estimation, and estimates backward. Therefore, any real access signal in a complete cycle may be used as the starting point for estimation.

Return to Figure 6A. After step S20, the micro control unit 43 has calculated multiple estimation interval times in this cycle (for example, multiple estimation interval times Pret _{( n ,1) ,} Pret in the cycle _Cn shown in Figure 9 _{( n ,2)} , Pre _{t ( n ,3)} and Pre _{t ( n ,4)} ). Thereby, the micro control unit 43 can further calculate the trigger time points of multiple estimated access signals in this cycle based on the multiple estimated interval times, and calculate and display the estimated traffic at each trigger time point (step S22 ).

As shown in FIG. 9 , the micro control unit 43 can calculate the second estimation based on the triggering time point of the first real access signal 81 of this period C _n and the estimation interval time Pre _{t ( n , 1)} of the first section. The trigger time point of the second estimated access signal 62 is estimated, and the third estimated access signal 63 is calculated based on the trigger time point of the second estimated access signal 62 and the estimated interval time Pret _{( n , 2)} of the second section. The trigger time point of the fourth estimated access signal 64 is calculated based on the trigger time point of the third estimated access signal 63 and the estimated interval time Pret _{( n ,3)} of the third section, And based on the triggering time point of the fourth estimated access signal 64 and the estimated interval time Pret _{( n , 4)} of the fourth section, the first estimated access signal 71 of the next period C _n-1 is calculated. Trigger time point, and so on.

。並且，微控制單元43將所推估的流速乘上流量計4預設的對應參數，即可推估出各個區段中增加的對應流量。藉此，微控制單元43可進一步推估流體在各個時間點上的累計流量。並且，上述由微控制單元43所推估的流速及累計流量都可被流量計4顯示於顯示單元44上，以供使用者查看。藉由上述流速及累計流量的推估及顯示，流量計4的量測結果與量測解析度可以被有效地提昇。 Furthermore, as mentioned above, the microcontrol unit 43 can obtain the flow rate of the fluid at each time point by calculating the reciprocal of the estimated interval time of each section. More specifically, the microcontrol unit 43 can calculate the flow rate according to the following formula:

. Furthermore, the microcontrol unit 43 multiplies the estimated flow rate by the corresponding parameters preset by the flow meter 4 to estimate the corresponding increased flow rate in each section. Thereby, the micro control unit 43 can further estimate the accumulated flow rate of the fluid at each time point. Moreover, the above-mentioned flow rate and accumulated flow rate estimated by the micro-control unit 43 can be displayed on the display unit 44 by the flow meter 4 for the user to view. Through the estimation and display of the above flow velocity and accumulated flow rate, the measurement results and measurement resolution of the flow meter 4 can be effectively improved.

It is worth mentioning that although the rotation of the impeller 41 is relatively unstable at low flow rates, while the micro control unit 43 executes the estimation program, the sensor 42 will continue to sense the rotation of the impeller 41 and generate corresponding signals. Real access signal (such as real access signal 8 in Figure 9). As shown in FIG. 6B , when the sensor 42 generates a new real access signal 8 , the micro control unit 43 can also calculate the corresponding interval time, flow rate, and flow rate based on the previous real access signal and the current real access signal. The flow rate is displayed through the display unit 44 (step S24).

In the above estimation procedure, the micro control unit 43 continues to determine whether the current cycle ends (step S26), and continues to execute steps S22 and S24 before the end of the current cycle. In this way, the flow meter 4 can not only calculate and provide the flow rate and flow rate based on the real access signal, but also provide the estimated flow rate and flow rate between two real access signals, making the measurement results of the flow meter 4 more accurate. Be accurate and improve the resolution of the information provided.

In the present invention, after activating the low flow rate estimation mode, the microcontrol unit 43 can continuously determine whether the current flow rate of the fluid is not lower than the threshold value. In other words, the microcontrol unit 43 may continue to determine whether to leave the low flow estimation mode after activating the low flow estimation mode (step S28).

In one embodiment, in step S14, the microcontrol unit 43 activates the low flow velocity estimation mode when it determines that the flow velocity is lower than the first threshold (eg, 0.3 m ³ /3). In step S28, when the micro control unit 43 determines that the flow rate is not lower than the first threshold, it leaves the low flow rate estimation mode.

In another embodiment, in step S14, the microcontrol unit 43 activates the low flow velocity estimation mode when it determines that the flow velocity is lower than the first threshold (eg, 0.3 m ³ /3). In step S28, the micro control unit 43 leaves the low flow velocity estimation mode when it determines that the flow velocity is not lower than the second threshold value (for example, 0.5 m ³ /3) slightly higher than the first threshold value. By setting a second threshold value slightly higher than the first threshold value, it is possible to avoid misjudgments of the micro control unit 43 caused by instantaneous changes in the flow rate of the fluid.

In another embodiment, the microcontrol unit 43 may leave the low flow rate estimation when it determines that the flow rate is not lower than the first threshold or the second threshold and the number of determinations is higher than a set value (such as three or five times). model. By setting the above set value, misjudgments of the micro control unit 43 caused by instantaneous changes in the fluid can be avoided.

After leaving the low flow rate estimation mode, the micro control unit 43 returns to step S10 to allow the sensor 42 to continue sensing the impeller 41 and generate a corresponding access signal without executing the estimation process.

If it is determined in step S28 that the low flow rate estimation mode is not left (that is, the current flow rate is still lower than the threshold), then after the end of this cycle, the micro control unit 43 then calculates multiple estimation interval times for the next cycle. As mentioned above, when estimating multiple estimation interval times in the previous cycle, the sensor 42 will still generate a real access signal (only the triggering time point is unstable and the interval time is longer). In order to make the estimation data closer to reality, after executing an estimation procedure, the microprocessing unit 43 can calculate the next step based on the estimated interval time of multiple sections in the previous cycle and the real interval time of multiple sections. The estimated interval time of multiple sections in one cycle (step S30).

Taking the embodiment of FIG. 9 as an example, after time point T _n , the micro control unit 43 generates four sections of estimated interval times Pre _t(n,1) , Pre _t(n,2) , Pre _{t( n,3)} and Pre _t(n,4) . When the period _Cn ends, the micro control unit 43 receives the first real access signal 811 of the next period at time point Tn ₊₁ . At this time, the micro control unit 43 can use time point T _n+1 as the starting point to start estimating multiple estimation interval times of the next period C _n+1 .

Specifically, in step S30, the micro control unit 43 can mainly calculate the next period based on the interval time Δt ( n , 1) of the first section of the previous period and the estimated interval time Pre _{t (n, 1)} The estimated interval Pre _t(n+1,1) of the corresponding section (i.e., the first section), the interval time Δt ( n ,2) of the second section based on the previous period, and the estimated interval Time Pre _t(n,2) is used to calculate the estimated interval time Pre _t(n+1,2) of the corresponding section (ie, the second section) of the next cycle, based on the time of the third section of the previous cycle. The interval time Δt ( n ,3) and the estimated interval time _Pret(n,3) are used to calculate the estimated interval time Pret _(n+1, ) of the corresponding section of the next period (ie, the third section) ₃₎ , and calculate the corresponding section of the next cycle (i.e., the fourth section) based on the interval time Δt ( n ,4) of the fourth section of the previous cycle and the estimated interval time _Pret(n,4) segment) estimated interval time Pre _t(n+1,4) .

In other words, when the flow meter 4 starts the low flow velocity estimation mode and performs the first estimation process, the micro control unit 43 only uses the real data of the past multiple cycles to calculate the estimation data of the next period. After the first estimation process, the micro control unit 43 will simultaneously use the real data of the previous period and the estimation data of the previous week basis to calculate the estimation data of the next period.

After step S30, the micro control unit 43 has calculated a plurality of estimation interval times in the next cycle (for example, a plurality of estimation interval times Pre t ( _{n +1 , 1)} , Pre _{t ( n +1,2)} , Pre _{t ( n +1,3)} and Pre _{t ( n +1,4)} ). Thereby, the micro control unit 43 executes step S22 again to calculate the trigger time points of the multiple estimated access signals 72, 73, and 74 in the next cycle based on the multiple estimated interval times, and calculates and displays each trigger. The estimated flow rate at the time point (step S22).

In the present invention, the microcontrol unit 43 continues to execute steps S22 to S30 until the flow meter 4 leaves the low flow rate estimation mode. Furthermore, the microcontrol unit 43 of the present invention will continue to execute steps S10 to S30 after the flow meter 4 is activated, until the flow meter 4 no longer needs to detect the flow rate/flow rate of the fluid.

Please continue to refer to FIG. 6A, FIG. 6B and FIG. 7 at the same time. FIG. 7 is a calculation flow chart of the estimated interval time according to the first specific embodiment of the present invention. Figure 7 is used to further explain step S20 of Figure 6A.

As shown in the figure, when the sensor 42 generates a real access signal and starts a new cycle, the micro control unit 43 retrieves multiple intervals of the n-th section from the recorded plural cycles (step S40). Next, the micro control unit 43 calculates the estimated interval time of the n-th section in this cycle based on the multiple interval times of the n-th section (step S42). In this embodiment, n is a positive integer starting from 1.

After step S42, the micro control unit 43 determines whether the calculation of the estimated interval time of all sections in this cycle is completed (step S44). In one embodiment, the number of segments in one cycle is equal to the number of induction blades 411-414 on the impeller 41, but is not limited thereto.

If it is determined in step S40 that the estimated interval time in this cycle has not been calculated, the micro control unit 43 will n+1 (step S46), and execute steps S40 and S42 again to calculate the estimated interval time in the current cycle based on the recorded The estimated interval time of the n+1th section in this cycle is calculated based on multiple intervals of the n+1th section.

If it is determined in step S44 that all estimation interval times in this cycle have been calculated, the microcontrol unit 43 can end this estimation process, and then execute step S22 shown in FIG. 6A .

In the embodiment of FIG. 9 , the micro control unit 43 can obtain the first value of the period C _n-3 from the recorded data when the sensor 42 generates the first real access signal 81 and starts a new period C _n . The interval time Δt _(n-3,1) of the segments, the interval time Δt _(n-2,1) of the first segment of the period C _n-2 and the interval of the first segment of the period C _n-1 Time △t _(n-1,1) , and calculate the interval time Pret _{( n ,1)} of the first section of this cycle _Cn accordingly. Moreover, the micro control unit 43 can determine the interval time Δt _(n-3,2) of the second section of the period C _n-3 and the interval time Δt _{(n-2) of the second section of the period C n -2. ,2)} and the interval time Δt _(n-1,2) of the second section of cycle C _n-1 to calculate the interval time Pre _{t ( n ,2)} of the second section of this cycle C _n , based on Analogy.

In one embodiment, the micro control unit 43 can use a moving average method to calculate the moving average of multiple recorded intervals of the same section, and use this moving average as the corresponding value in this cycle. The estimated interval for the segment.

In one embodiment, the microcontrol unit 43 may calculate the median of multiple recorded interval times of the same segment as the estimated interval time of the corresponding segment in this cycle. For example, if the three interval times of the same section are 1 second, 2 seconds and 7 seconds respectively, the micro control unit 43 uses the median 2 seconds as the estimated interval time of the corresponding section in this cycle.

In one embodiment, the microcontrol unit 43 can calculate the mode of multiple recorded intervals of the same segment as the estimated interval of the corresponding segment in this cycle. For example, if the three interval times of the same section are 1 second, 5 seconds and 1 second respectively, the micro control unit 43 uses 1 second as the estimated interval time of the corresponding section in this cycle.

In one embodiment, the microcontrol unit 43 can calculate a probability density function (PDF) based on multiple recorded intervals of the same segment, and use this probability density function to guess the corresponding segment in this cycle. estimated interval.

However, the above are only some specific implementation examples of the present invention, but are not limited to the above.

It is worth mentioning that, in order to avoid drastic changes in flow rate from affecting the estimation results of the micro-control unit 43, the micro-control unit 43 of the present invention can perform weighting calculations on multiple reference intervals when executing the estimation program. Specifically, the microcontrol unit 43 can make the calculation weight of the interval time of the last cycle smaller than the calculation weight of the interval time of other cycles, thereby reducing the influence of the data of the last cycle on the overall calculation.

For example, if the three recorded intervals of the same section are 4 seconds, 2 seconds and 12 seconds respectively, then when calculating the average value, the micro control unit 43 can add the three interval times and divide them by three. , to obtain the average value of 6 seconds, and use 6 seconds as the estimated interval time of the same segment in this cycle.

In order to achieve the above purpose, the micro control unit 43 can make the calculation weight of the last interval time smaller than the calculation weights of the other two interval times (for example, 0.4, 0.4 and 0.2 in sequence). In this embodiment, the micro control unit 43 can obtain the average value of 4.8 seconds by calculating the formula: (4×0.4+2×0.4+12×0.2), and use 4.8 seconds as the prediction of the same section in this cycle. Estimate the interval. Thereby, the micro control unit 43 can avoid estimation errors caused when the flow rate changes instantaneously.

Please continue to refer to FIG. 6A, FIG. 6B and FIG. 8 at the same time. FIG. 8 is a calculation flow chart of the estimated interval time according to the first specific embodiment of the present invention. Figure 8 is used to further explain step S30 of Figure 6B.

As shown in the figure, after the sensor 42 generates a real access signal and starts a new cycle, the micro control unit 43 obtains the interval time of the n-th section in the previous cycle and the previous cycle from the recorded data. The estimated interval time of the nth section in the cycle (step S50). Next, the micro control unit 43 calculates the estimated interval time of the n-th section in the next cycle based on the interval time of the n-th section and the estimated interval time of the n-th section (step S52). In this embodiment, n is a positive integer starting from 1.

After step S52, the micro control unit 43 determines whether all estimation interval times in this cycle have been calculated (step S54).

If it is determined in step S54 that the estimated interval time in this cycle has not been calculated, the micro control unit 43 will n+1 (step S56), and execute steps S50 and S52 again to calculate the estimated interval time based on the nth value in the previous cycle. The interval time of the +1 section and the estimated interval time of the n+1th section are used to calculate the estimated interval time of the n+1th section in the next cycle.

If it is determined in step S54 that all the estimation interval times for the next period have been calculated, the microcontrol unit 43 may end the current estimation process, and then execute step S22 shown in FIG. 6A .

In the embodiment of FIG. 9 , the micro control unit 43 can obtain the first value of the period C _n from the recorded data when the sensor 42 generates the first real access signal 811 and starts a new period C _n+1. The interval time Δt _(n,1) of the section and the estimated interval time Pre _{t ( n ,1)} are used to calculate the interval time Pre _t of the corresponding section (ie, the first section) of this cycle C _{n+1 ( n +1,1)} . Moreover, the micro control unit 43 can calculate the second area of the current period C n ₊₁ based on the interval time Δt _{(n, 2)} of the second area of the period C _n and the estimated interval time Pre _{t ( n , 2).} The interval time between segments is Pre _{t ( n +1,2)} , and so on.

It is worth mentioning that the micro control unit 43 in this embodiment calculates the estimated data for the next period based on the real interval time and the estimated interval time of the previous period, so it can calculate the estimated data for the next period based on the real interval time and the estimated interval time. Different calculation weights are set for each interval.

In one embodiment, the micro control unit 43 can calculate the estimated interval time of the m-th section in the next cycle mainly based on the following formula: Pre _{t ( n +1, m )} = α × Pre _{t ( n , m )} +(1-α)×△ t _{( n , m )} , where α <1, Pre _{t ( n +1, m )} is the estimated interval time of the m-th section in the next cycle, Pre _{t ( n , m )} is the estimated interval time of the m-th section in the previous cycle, △ t _{( n , m )} is the interval time of the m-th section in the previous cycle. Thereby, the micro control unit 43 can adjust the calculation weights of the real interval time and the estimated interval time in the estimation process by setting the α value.

More specifically, when executing the estimation program, the microcontrol unit 43 can calculate the estimation interval time of the first section in the next cycle according to the following first formula: Pre _{t ( n +1,1)} = α × Pre _{t ( n ,1)} + (1-α)×△ t _{( n ,1)} , where Pre _{t ( n +1,1)} is the estimated interval time of the first section in the next cycle, Pre _{t ( n ,1)} is the estimated interval time of the first section in the previous cycle, △ t _{( n ,1)} is the interval time of the first section in the previous cycle. Furthermore, the micro control unit 43 can calculate the estimated interval time of the second section in the next cycle according to the following second formula: Pre _{t ( n +1,2)} = α × Pre _{t ( n ,2)} +( 1-α)×△ t _{( n ,2)} , where Pre _{t ( n +1,2)} is the estimated interval time of the second section in the next cycle, and Pre _{t ( n ,2)} is the previous cycle The estimated interval time of the second section in , △ t _{( n ,2)} is the interval time of the second section in the previous cycle, and so on.

Through the technical solution of the present invention, the flow meter can provide an estimated value of flow rate or flow rate between two real access signals, thereby solving the problem of poor measurement accuracy and measurement resolution of the flow meter in a low flow rate state. low question.

The above descriptions are only preferred specific examples of the present invention, which do not limit the patent scope of the present invention. Therefore, all equivalent changes made by applying the content of the present invention are equally included in the scope of the present invention, and are hereby stated. bright.

S10~S22: Estimation steps

Claims (9)

A flow estimation method for a rotary flow meter in a low flow rate state, applied to a flow meter having an impeller, a sensor and a microcontrol unit, wherein the low flow rate state means that the flow rate of the fluid is lower than a preset threshold value. This results in a relatively unstable state of rotation of the impeller, and the flow estimation method includes: a) The sensor is triggered by the impeller to generate multiple pick-up signals, wherein the impeller rotates for a The multiple intervals of multiple access signals generated by the circle trigger form a cycle; b) the micro control unit calculates the flow rate of a fluid in the flow meter based on the multiple intervals; c) records multiple cycles A flow rate information, wherein the flow rate information at least includes a plurality of the interval times in a cycle; d) the micro control unit calculates a moving average, a center value of a plurality of the interval times in the plurality of cycles recorded number of digits, a mode or a probability density function to respectively calculate multiple estimated interval times in this cycle; and e) obtain a first real interface generated by the sensor being triggered by the impeller in this cycle. input signal, calculate a trigger time point of multiple estimated access signals in this cycle sequentially based on the first real access signal and the multiple estimated interval times, and calculate the reciprocal of each estimated interval time to obtain An estimated flow rate at each trigger time point is obtained, and the estimated flow rate at each trigger time point is multiplied by a corresponding parameter of the flow meter to obtain and display an estimated flow rate at each trigger time point. The flow estimation method as described in claim 1, further comprising: f1) determining whether the flow rate is lower than a first threshold by the micro-control unit; f2) Repeat step a), step b) and step c) when the flow rate is not lower than the first threshold; f3) Start a low flow push when the flow rate is lower than the first threshold estimation mode; and f4) perform step d) and step e) in the low flow estimation mode. The flow estimation method as described in claim 2, wherein the impeller includes n sensing blades, the sensor is triggered by the n sensing blades and sequentially generates n access signals, and the flow velocity information includes a The interval time of n segments within the cycle, where n is an integer ≧1. The flow estimation method as described in claim 2, wherein the step d) includes: d1) obtaining the recorded interval time of a first section in the plurality of cycles from the micro control unit; d2) based on the first Calculate the estimated interval time of the first segment in this cycle for multiple intervals of one segment; d3) obtain the recorded interval time of the next segment in the plurality of cycles by the micro control unit ; d4) Calculate the estimated interval time of the next section in this cycle based on multiple intervals of the next section; and d5) Before the calculation of the estimated interval time of multiple sections in this cycle is completed , repeat step d3) and step d4). The traffic estimation method as described in claim 4, wherein in the step d2) and the step d4), a calculation weight of the interval time in the last cycle is smaller than the calculation weight of the interval time in other cycles. The traffic estimation method as described in request item 2, which further includes: g) Determine whether this cycle is over; h) Continue to perform this step e) before the end of this cycle; i) After the end of this cycle, based on the multiple estimated intervals of the previous cycle and the multiple estimated intervals of the previous cycle The interval time calculates multiple estimated interval times of the next period, and performs step e) based on the multiple estimated interval times of the next period. The flow estimation method as described in claim 6, wherein the step i) includes: i1) obtaining the estimated interval time and the interval time of the first section of the previous cycle from the micro control unit; i2) based on The estimated interval time and the interval time of the first section in the previous cycle are used to calculate the estimated interval time of the first section in the next cycle; i3) The micro control unit obtains the next cycle time of the previous cycle. The estimated interval time and the interval time of a section; i4) Calculate the estimated interval time of the next section in the next cycle based on the estimated interval time and the interval time of the next section in the previous cycle ; and i5) Repeat step i3) and step i4) before the estimated interval time of the plurality of segments in the next period is calculated. The traffic estimation method as described in request item 7, wherein the step i2) calculates the estimation interval time of the first section of the next period according to a first formula: Pre _{t ( n +1,1)} = α × Pre _{t ( n ,1)} + (1-α)×△ t _{( n ,1)} , where α <1, Pre _{t ( n +1,1)} is the prediction of the first section of the next cycle Estimated interval time, Pre _{t ( n ,1)} is the estimated interval time of the first section in the previous cycle, △ t _{( n ,1)} is the estimated interval time of the first section in the previous cycle; The step i4) calculates the estimated interval time of the next section of the next cycle based on a second formula: Pre _{t ( n +1, m )} = α × Pre _{t ( n , m )} + (1-α )×△ t _{( n , m )} , where α <1, Pre _{t ( n +1, m )} is the estimated interval time of the next section of the next cycle, Pre _{t ( n , m )} is the previous The estimated interval time of the next section of the cycle, △ t _{( n , m )} is the interval time of the next section of the previous cycle. The flow estimation method as described in claim 6, further comprising: j) the microcontrol unit continuously determines whether the flow rate is not lower than a second threshold in the low flow rate estimation mode; and k) in the flow rate The low flow rate estimation mode is exited when the flow rate is not lower than the second threshold, wherein the second threshold is greater than the first threshold.

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