JPH06160137A - Flow measuring device - Google Patents

Abstract

PURPOSE:To provide a flow measuring device capable of precisely adjusting the analog current in a short time. CONSTITUTION:A flow measuring device is provided with the first correction data generating circuit 41 outputting the first correction data J when the digital signal Dmin corresponding to the analog current C (4mA) and the first specified value Q do not coincide at the flow of 0, a request signal generating circuit 42 outputting the request signal L when both of them coincide, a flow signal generating circuit 27 outputting the flow signal A corresponding to the maximum flow by the request signal L, and the second correction data generating circuit 43 comparing the digital signal Dmax corresponding to the analog current C outputted based on the request signal L and the second specified value R (equivalent to 20mA) and outputting the second correction data K when they do not coincide. The first and second width data Tb, Tc are re-written by the outputs of the first and second correction data J, K. The visual work is omitted, the adjusting time is shortened, and the adjusting precision can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device used for measuring a flow rate of a fluid.

[0002]

2. Description of the Related Art An example of a conventional flow rate measuring device is shown in FIG. This flow measuring device includes a flow measuring unit 1,
The flow rate measuring unit 1 is connected to the flow rate measuring unit 1 via a signal line 2 so as to be able to send and receive signals.

The flow rate measuring section 1 includes a sensor section 4 for detecting a flow rate of a fluid, a flow rate measuring section control section 5 for converting a flow rate signal A from the sensor section 4 into a PWM signal B, and a PWM signal B for an analog current. C is converted to C and this analog current C is converted to signal line 2
Current conversion circuit 6 for outputting to the adjusting device 3 via
And a flow rate measuring unit communication circuit 7 interposed between the signal line 2 connected to the analog current conversion circuit 6 and the flow rate measuring unit control unit 5.

The flow rate measuring section control section 5 includes a cycle setting register 8 for storing cycle data of the PWM signal B, a width setting register 9 for storing width data of the PWM signal B, and a flow rate signal A from the sensor section 4. Based on the period data of the period setting register 8 and the width data of the PWM signal B.
It is composed of an arithmetic circuit 10 which converts the data into a signal and outputs it.

The adjusting device 3 includes an adjusting device control section 11 and
An operating unit 14 including an increasing switch 12 for outputting an increasing command signal D to the adjusting device control unit 11 and a decreasing switch 13 for outputting a decreasing command signal E to the adjusting device control unit 11, and an adjusting device control unit 11 There is provided a communication circuit 15 for the adjusting device, which is interposed between the signal line 2 and one end of the signal line 2. An ammeter 16 is provided so as to branch to the signal line 2.

In this flow rate measuring device, when the flow rate signal A is input from the sensor unit 4 to the arithmetic circuit 10, the flow rate signal A is converted into a PWM signal B by the arithmetic circuit 10, and the PWM signal B is converted into an analog current conversion circuit. At 6, the data is converted into an analog current C in the used current range, and this data is output to a display (not shown) connected to the signal line 2 for display, or output to a printer for printing.

In this flow rate measuring device, when the fluid is not flowing (flow rate = 0), the lower limit value of the working current range of the analog current C is not set to 0 from the viewpoint of design margin and the like.
mA, and when the flow rate of the fluid shows the maximum value, the upper limit value of the working current range of the analog current C is set to 20 mA, for example.

By the way, in the flow rate measuring device, the flow rate = 0 depending on the type of the flow rate measuring unit 1 or its change over time.
At the time of and at the maximum flow rate, the lower limit value (eg 4mA) and upper limit value (eg 20m) of the working current range specified in advance
A) may not be indicated. In order to deal with this, the flow rate measuring device is configured to make the following adjustments.

That is, by visually observing the ammeter 16, the analog current C
When the value is <4 mA, an increase command signal D is output by operating the increase switch 12, and the arithmetic operation circuit 10 of the flow rate measuring unit control unit 5 stores it in the width setting register 9 according to the increase command signal D. If the first adjustment data corresponding to the lower limit value is increased by +1 and the analog current C value is> 4 mA, a decrease command signal E is output by operating the decrease switch 13, and the decrease command signal E is output. In accordance with E, the arithmetic circuit 10 of the flow rate measuring unit control unit 10 decrements the first adjustment data corresponding to the lower limit value stored in the width setting register 9 by 1 and the analog current C value becomes 4 mA. Ends the adjustment for the lower limit value (4 mA) with. In addition, the upper limit (20m
The adjustment for A) was performed by rewriting the second adjustment data corresponding to the upper limit value stored in the width setting register 9 while visually observing the ammeter 16 as in the adjustment for the lower limit value (4 mA).

[0010]

However, in the above-described flow rate measuring device, when adjusting the analog current C, the operation unit 14 of the adjusting device 3 is operated while watching the ammeter 16, and the correction data is obtained by this operation. Is transmitted to the flow rate measurement unit 1, so it takes a lot of adjustment time and
Due to the visual inspection of the ammeter 16, a reading error occurred and the adjustment accuracy was low.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flow rate measuring device capable of achieving adjustment of an analog current in a short time and with high accuracy.

[0012]

In order to achieve the above object, the present invention is directed to a sensor unit for detecting a flow rate of a fluid, and a flow rate signal from the sensor unit stored in an adjustment data storage circuit. , A flow rate measuring section having a current converting section for converting and outputting to an analog current in a working current range in which a lower limit value and an upper limit value are defined by the second adjustment data, and the first and second flow rate measuring sections. In a flow rate measuring device comprising an adjusting device that rewrites the first and second adjusting data stored in the adjusting data storage circuit by transmitting the correcting data according to the contents of the first and second correcting data, The specified value storage circuit for storing the first and second specified values corresponding to the lower limit value and the upper limit value of the operating current range, and the analog current value from the flow rate measuring unit when the flow rate of the fluid is 0 Comparing with the specified value of 1 And it generates a coincidence signal when being a comparator circuit for generating a mismatch signal when they do not coincide,
Request to the first correction data generation circuit that generates the first correction data having the content corresponding to the first specified value when the comparison circuit generates the non-coincidence signal, and the flow rate measurement unit when the comparison circuit generates the coincidence signal. A flow rate signal generating circuit for outputting a signal is provided in the adjusting device, and a flow rate signal corresponding to the maximum flow rate of the fluid is output to the current conversion section instead of the flow rate signal from the sensor section that receives the request signal. When a signal generation circuit is provided in the flow rate measurement unit and receives an analog current output from the current conversion unit in response to a signal input from the flow rate signal generation circuit, the analog current value is compared with a second specified value and they do not match. A second correction data generation circuit for generating the second correction data having the content corresponding to the second specified value is provided in the adjustment device.

[0013]

With this structure, when the analog current from the flow rate measuring unit when the flow rate of the fluid is 0 is input to the adjusting device when the power supply is turned on, the comparison circuit causes the analog current value and the first regulation value. When the values do not match, the first correction data generation circuit outputs the first correction data to the flow rate measurement unit and the first adjustment data in the adjustment data storage circuit is rewritten to change the operating current range. While the adjustment for the lower limit value is performed, if the analog current and the first specified value match due to this adjustment, the request signal generation circuit outputs the request signal and the flow rate signal generation circuit corresponds to the maximum flow rate of the fluid. The flow rate signal is output to the current conversion unit, and the current conversion unit
An analog current corresponding to the flow rate signal is output to the adjusting device, and the second correction data generation circuit compares the analog current value with the second specified value and when they do not match, the second specified value is set. The second correction data having the corresponding content is output to the flow rate measuring unit, the second adjustment data in the adjustment data storage circuit is rewritten, and the adjustment is completed with respect to the upper limit value of the operating current range.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A flow rate measuring device according to an embodiment of the present invention will be described below with reference to FIGS. This flow rate measuring device uses a flow rate signal A of fluid with a lower limit value of 4 mA and an upper limit value of 20 mA.
Flow rate measuring section 20 for converting into an analog current C in the working current range to be output, and this flow rate measuring section 20 via the signal line 2.
And an adjusting device 21 which is connected to and capable of transmitting and receiving a signal to and from.

The flow rate measuring section 20 includes a sensor section 4 for detecting the flow rate of the fluid, a flow rate measuring section control section 22 for converting the flow rate signal A from the sensor section 4 into a PWM signal B, and an analog current for the PWM signal B. C is converted to C and this analog current C is converted to signal line 2
Analog current conversion circuit 6 that outputs to the adjusting device 21 via the
And a flow rate measuring section communication circuit 7 interposed between the signal line 2 connected to the analog current conversion circuit 6 and the flow rate measuring section control section 22.

The control unit 22 for the flow rate measuring unit has an arithmetic circuit 23 for the flow rate measuring unit for inputting the flow rate signal A and the adjustment completion signal H,
A period setting register / comparator 24 for rewritably storing the period data T _a of the PWM signal B, and the PWM signal B
Width setting register / comparator 25 for rewritably storing the width data, a correction circuit 26 for inputting the first and second correction data J and K, a flow rate signal generating circuit 27 for inputting the request signal L, and a clock. 28, a timer counter 29, a timer starting circuit 30, and a signal output circuit 31 for outputting the PWM signal B
It consists of and. In this case, the width data of the PWM signal B stored in the width setting register / comparator 25 is
First and second width data (first and second adjustment data) T _b ,
It is composed of T _{c and the} like.

The arithmetic circuit 23 for the flow rate measuring section is composed of a cycle setting, width setting register / comparators 24 and 25, and a timer counter.
In cooperation with 29, the flow rate signal A based on the cycle data _Ta and the first and second width data _Tb and _Tc of the PWM signal B stored in the cycle setting / width setting register / comparators 24 and 25. Is converted into a PWM signal B and output to the analog current conversion circuit 6 via the signal output circuit 31. In the present embodiment, the flow rate measuring unit control unit 22 and the signal output circuit 31
Constitute a current conversion section.

The flow rate signal generating circuit 27 receives the request signal L and outputs the flow rate signal A corresponding to the maximum flow rate of the fluid to the flow rate measuring section arithmetic circuit 23 in place of the flow rate signal A from the sensor section 4. It is supposed to do.

The timer counter 29 inputs the clock signal generated by the clock 28, and starts counting the number of pulses of this clock signal from the time when the start signal issued by the timer start circuit 30 is input. The timer counter 29 clears the value when the count number of the timer counter 29 and the cycle data T _a set in the cycle setting register / comparator 24 match, and restarts counting from 0.

In the cycle setting register / comparator 24, the count number of the timer counter 29 is
When it coincides with the cycle data T _a set in the comparator 24, a signal indicating this is output to the signal output circuit 31.

The width setting register / comparator 25 is provided with the first and second width data T in which the count number of the timer counter 29 is set in the width setting register / comparator 25.
_{When b} and T _c match, a signal indicating that is output to the signal output circuit 31.

The signal output circuit 31 receives the signal from the period setting register / comparator 24 and controls the level of the PWM signal B so as to change it from a low level (L) to a high level (H). Receiving the signal from the comparator 25, the level of the PWM signal B is set to high level (H)
Control to change from low level (L),
The amplitude is also determined and the PWM signal B is output.

The adjusting device 21 includes an adjusting device control unit 32, an operating unit 35 having a start switch 33 and a reset switch 34 for outputting a start signal M and a reset signal N to the adjusting device control unit 32, and an adjusting unit 35. The adjustment device communication circuit 15 interposed between the device controller 32 and one end of the signal line 2 and the analog current C connected to the lead-in part of the signal line 2 are connected.
Resistor 36 for converting the
Corresponding to the lower limit value (4 mA) and the upper limit value (20 mA) of the working current range, which is interposed between the control unit 32 and the controller 32 for adjusting device and converts an analog signal into a digital signal. It is composed of a prescribed value storage circuit 38 for storing the first and second prescribed values Q and R as digital signals, and a display section 39 for displaying the completion of adjustment and the like.

The adjusting device control section 32 compares the analog current C value from the flow rate measuring section 20 when the flow rate of the fluid is 0 with the first specified value (4 mA), and when they are in agreement, outputs a coincidence signal. , A comparison circuit 40 which generates a mismatch signal when they do not match, and a first correction data J which has a content corresponding to a first specified value (4 mA) when the comparison circuit 40 generates a mismatch signal Of the correction data generating circuit 41, the request signal generating circuit 42 that outputs the request signal L to the flow rate measuring unit 20 when the comparison circuit 40 generates the coincidence signal, and the flow rate signal generating circuit 27.
The analog current C output from the signal output circuit 31 is received by the signal input from, and the analog current C value is compared with the second specified value R (20 mA). If they do not match, the second specified value R ( 20 mA) and a second correction data generation circuit 43 for generating the second correction data K having a content corresponding to 20 mA).

FIG. 2 is a flow chart showing the arithmetic processing and control contents of the flow rate measuring unit control section 22 and the adjusting apparatus control section 32, and the operation of the flow rate measuring apparatus will be described below along this flow chart. .

First, when the power supply of the flow rate measuring unit 20 and the adjusting device 21 is turned on (step S61), the flow rate is measured from the flow rate signal generating unit at a flow rate of 0 (not shown) with no fluid flow (flow rate = 0). A flow rate signal A corresponding to a flow rate of 0 is input to the control section 22 for the section, and the analog current conversion circuit 6 via the flow rate measuring section control section 22 outputs an analog current C (4
(mA equivalent) will be sent to the adjusting device 21 (step
S62), in this state, when the start switch 33 is turned on (step S63), a predetermined analog current C input from the analog current conversion circuit 6 via the A / D conversion circuit 37.
The adjusting device controller 32 reads the digital signal D _min corresponding to (corresponding to 4 mA) (step S64).

Then, the comparison circuit 40 compares the digital signal D _min with the first specified value Q (step S65). If they match, a match signal is generated, and if they do not match, a mismatch signal is generated and a match is generated. When a signal is generated, the process proceeds to step S66, while when a mismatch signal is generated, the process proceeds to step S69 to execute the process.

In step S69, the first correction data generation circuit 41 sets the first specified value Q as the first correction data J via the adjustment device communication circuit 15, the signal line 2 and the flow rate measurement unit communication circuit 7. And sends it to the flow rate measuring unit control unit 22.

The control unit 22 for the flow rate measuring unit inputs the first correction data J and sets the first width data T _b stored in the width setting register / comparator 25 to correspond to the first specified value Q. Rewrite to the value (corresponding to 4mA) (step
S70), after this process, the process returns to step S64 to execute the process.

When the process returns from step S70 to step S64 and the process is executed, the process of rewriting the first width data T _b to the value (4 mA) corresponding to the first specified value Q was performed in step S70. As a result, YES is determined in step S65 following step S64, and the process proceeds to step S64, and the request signal generation circuit 42 outputs the request signal L in step S66. Then, the flow rate signal generating circuit 27 receives the request signal L and outputs the flow rate signal A corresponding to the maximum flow rate of the fluid to the flow rate measuring section arithmetic circuit 23 in place of the flow rate signal A from the sensor section 4. As a result, the flow rate measuring unit 20 causes the analog current C (corresponding to 20 mA) corresponding to the flow rate signal A.
Is output (step S67).

Then, this analog current C (equivalent to 20 mA)
Is input to the A / D conversion circuit 37 as a voltage signal via the resistor 36, and the A / D conversion circuit 37 outputs a digital signal D _max (corresponding to 20 mA) corresponding to the input signal to the adjustment device control unit 32, The controller 32 for the adjusting device controls the digital signal D _max (20
(equivalent to mA) is read (step S68).

Subsequent to step S68, the second correction data generation circuit 43 compares the digital signal D _max with the second specified value R (step S71). If they match, the process proceeds to step S72, and again. If they do not match, step S7
Proceed to step 4 to perform processing.

In step S74, the second correction data generation circuit 43 transmits the second specified value R as the second correction data K to the flow rate measuring section 20. Then, the arithmetic circuit for the flow rate measurement unit
23 is the second value stored in the width setting register / comparator 25
The width data T _c of the second prescribed value R is rewritten according to the contents of the second prescribed value R (step S75), and after the processing of this step S75, the processing returns to step S68 and is performed.

When the process returns from step S75 to step S68 and the process is executed, the process of rewriting the second width data T _c in accordance with the content (20 mA) of the second specified value R is performed in step S75. As a result, YES is determined in step S71 subsequent to step S68, and the process proceeds to step S72 to perform the process. In this step S72, the reset switch 34 is turned on, which causes the adjustment device control unit 32 to operate.
From the adjustment completion signal H is transmitted from the flow rate measuring section 20 to the flow rate measuring section 20, the display indicating the completion is displayed on the display section 39, and the lower limit value (4 mA) and the upper limit value (20 mA) of the working current range are displayed.
The adjustment process for is completed.

As described above, when the analog current C (corresponding to 4 mA) from the flow rate measuring unit 20 when the power is turned on and the flow rate of the fluid is 0 is input to the adjusting device 21, this analog current C (corresponding to 4 mA). The comparison circuit 40 compares the digital signal D _min converted with the first specified value Q with each other, and when they do not match, the first correction data generation circuit 41 outputs the first correction data J to the flow rate measurement unit 20. Then, the first width data T _b of the width setting register / comparator 25 is rewritten to adjust the lower limit value of the operating current range, and when the analog current C and the first specified value Q coincide with each other by this adjustment. The request signal generation circuit 42 outputs the request signal L, and the flow rate signal generation circuit 27 outputs the flow rate signal A corresponding to the maximum flow rate of the fluid to the current conversion unit (flow rate measurement unit control unit 22), and the current conversion unit ( The signal output circuit 31) is The amount signal A analog current corresponding to the C (20 mA or equivalent) is output to the adjusting device 21, the digital signal D _max obtained by converting the same analog current C (20 mA equivalent)
The second correction data generation circuit 43 compares the value with the second specified value R, and when the values do not match, the second width data T _c of the width setting register / comparator 25 is rewritten to change the operating current range. The upper limit is adjusted and the adjustment is completed. Therefore, when adjusting the lower limit value (4 mA) and the upper limit value (20 mA) of the operating current range, the visual work is omitted as compared with the conventional flow rate measuring device that requires visual work. It is possible to shorten the time and improve the adjustment accuracy.

[0036]

Since the present invention is the flow rate measuring device configured as described above, the analog current from the flow rate measuring portion when the flow rate of the fluid is 0 is input to the adjusting device, and the comparison circuit The analog current value and the first specified value are compared, and when they do not match, the first correction data generation circuit outputs the first correction data to rewrite the first adjustment data in the adjustment data storage circuit. When the adjustment of the lower limit value of the operating current range is completed and the adjustment to this lower limit value is completed, the flow rate signal generation circuit receives the request signal output from the request signal generation circuit and converts the flow rate signal corresponding to the maximum flow rate of the fluid into current. And the current converter outputs an analog current corresponding to the flow rate signal to the adjusting device, and the second correction data generation circuit compares the analog current value with the second specified value to determine that they match. Tena At this time, the second correction data having the content corresponding to the second specified value is output to the flow rate measurement unit, the second adjustment data in the adjustment data storage circuit is rewritten, and the adjustment for the upper limit value of the used current range is completed. Therefore, when adjusting the lower and upper limits of the operating current range, visual work is omitted as compared with the conventional flow rate measuring device that involves visual work, which shortens the adjustment time and improves the adjustment accuracy. Can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing a flow rate measuring device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing arithmetic processing and control contents of the same flow rate measuring device.

FIG. 3 is a timing chart of signals used in the flow rate measuring device.

FIG. 4 is a block diagram schematically showing an example of a conventional flow rate measuring device.

[Explanation of symbols]

 2 Signal line 4 Sensor section 6 Analog current conversion circuit 20 Flow rate measuring section 21 Adjusting device 22 Flow rate measuring section control section 25 Width setting register / comparator 27 Flow rate signal generating circuit 31 Signal output circuit 32 Adjusting apparatus control section 38 Specified value Storage circuit 40 Comparison circuit 41 First correction data generation circuit 42 Request signal generation circuit 43 Second correction data generation circuit

Claims (1)

[Claims] 1. A lower limit value and an upper limit value are defined by a sensor section for detecting a flow rate of a fluid, and first and second adjustment data stored in an adjustment data storage circuit for a flow rate signal from the sensor section. Flow rate measuring section having a current converting section for converting into an analog current in a used current range and outputting the analog current, and the first and second correction data are transmitted to the flow rate measuring section to be stored in the adjustment data storage circuit. A flow rate measuring device comprising an adjusting device that rewrites the first and second adjustment data in accordance with the contents of the first and second correction data, in which a first value corresponding to a lower limit value and an upper limit value of the working current range, A specified value storage circuit that stores a second specified value and an analog current value from the flow rate measuring unit when the flow rate of the fluid is 0 are compared with the first specified value. If they occur and do not match, A comparison circuit that generates a mismatch signal,
Request to the first correction data generation circuit that generates the first correction data having the content corresponding to the first specified value when the comparison circuit generates the non-coincidence signal, and the flow rate measurement unit when the comparison circuit generates the coincidence signal. A flow rate signal generating circuit for outputting a signal is provided in the adjusting device, and a flow rate signal corresponding to the maximum flow rate of the fluid is output to the current conversion section instead of the flow rate signal from the sensor section that receives the request signal. When a signal generation circuit is provided in the flow rate measurement unit and receives an analog current output from the current conversion unit in response to a signal input from the flow rate signal generation circuit, the analog current value is compared with a second specified value and they do not match. A flow rate measuring device characterized in that a second correction data generating circuit for generating second correction data having a content corresponding to a second specified value is provided in the adjusting device.