JP2902233B2 - Flow compensation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow correction device, and more particularly, to a flow correction device that multiplies a pulse constant of a flow pulse by various correction coefficients and outputs a correction pulse.

[0002]

2. Description of the Related Art A flow signal of a flow meter is often transmitted remotely, and is generally output as a flow pulse having a weight of flow rate. However, flow meters are selected according to the type and accuracy of the fluid to be measured.The flow pulses output from these flow meters are flow rates according to process variables, and the pulse frequency is also wide. Calculation processing is performed. The arithmetic processing means for this is preferably used commonly for the diversified flow rate pulse signals. Since the fluid to be measured has the same density and viscosity conditions as liquid and process variables such as temperature and pressure from the liquid, the pulse constant of the flow rate pulse also needs to be corrected to the pulse constant of the reference state by the above-mentioned liquid condition. Therefore, it is ideal that the arithmetic processing means for the flow rate pulse can be processed in accordance with the state of all the fluids.

[0003] The applicant of the present invention discloses a "flow rate correction device" in Japanese Patent Publication No. 3-15684, in which a process variable such as temperature and pressure of a fluid in a measurement state is inputted from a flow rate pulse to a constant temperature and a predetermined temperature. It is proposed to output the corrected flow pulse under the pressure condition.

The flow rate correction device first inputs a flow rate pulse to a counter that repeatedly counts the pulses at a fixed period, and calculates a corrected flow rate based on a process variable based on the flow rate accumulated in the counter during this period. At this time, the flow rate correction coefficient S is further normalized to S 'proportional to S by a positive number smaller than "1", and is multiplied by the number n of the flow rate pulses in the period T and input to the adder / subtractor. The correction flow pulse is output in synchronization with the flow pulse input from the integrated value added to the addition / subtraction counter, and the operation is performed until the addition / subtraction value in the addition / subtraction unit becomes zero. The above operation is repeated. However, in the above-mentioned conventional flow compensator, it is necessary to accumulate the flow pulse in the counter for a certain period of time. During this period, it is assumed that the process variable does not change, and a constant period T is set in accordance with the operation speed of the flow compensator. Was established. When the flow rate is constant, the integrated value n of the flow pulse is a constant value, but when the flow rate fluctuation is large, there is a disadvantage that n also changes greatly. That is, it is considered that a process variable changes at a small flow rate at a small flow pulse frequency, and there is a problem that a calculation speed determined by a CPU of a flow rate calculation device does not follow at a large flow rate at a high flow pulse frequency. . Moreover, the pulse speed of the correction pulse higher than the pulse frequency of the flow pulse could not be obtained.

[0005]

The present invention has been made in view of the above circumstances, and does not require a counter for a flow pulse, and outputs a double pulse using the rising and falling edges of a flow pulse to perform correction in real time. Accordingly, it is an object of the present invention to provide a flow rate correction device capable of performing a flow rate correction with high responsiveness.

[0006]

To achieve the above object, the present invention provides (1)
A double pulse circuit that outputs a flow pulse as a double pulse,
Pulse processing means for sequentially outputting the pulse train of the doubled pulse as an odd-numbered pulse and an even-numbered pulse train, and correction means for correcting a flow rate for each output pulse of the doubled pulse output from the pulse processing means. The correction means multiplies the pulse constant of the flow rate pulse, a correction coefficient for the pulse constant, and a multiplication coefficient m ^-1 and multiplies an operation coefficient K by 2
Arithmetic processing means for normalizing to a smaller positive value and storing the same, odd pulse comparing means for comparing the operation coefficient K with "1" each time the odd pulse is interrupted, and a comparison value of the odd pulse comparing means. Is greater than "1", outputs a corrected flow rate pulse, and adds a surplus value less than "1". Each time the even-numbered pulse interrupts, the counter outputs a corrected flow rate pulse. It is constituted by an even-number pulse comparing means for subtracting "1" from the added value and outputting a corrected flow rate pulse. Further, (2) dividing the double pulse inputted to the pulse processing means, It is characterized by multiplying the operation coefficient K by a frequency division value.

First, the principle of the flow rate correction device according to the present invention will be described. The flow rate pulse has a pulse constant that varies depending on the type and diameter of the flow meter and has a constant flow rate weight. Therefore, the pulse frequency of the flow pulse is a value proportional to the flow rate in the same flow meter. Further, when the type of the flow meter is different, the pulse constant is also different, and the pulse frequency at the same flow rate is different according to the magnitude of the pulse constant. In order to standardize this, it is necessary to determine a reference for a pulse frequency serving as a base and divide the frequency by a frequency division value n determined to be the reference frequency.

In the present invention, as will be described later, the rising and falling of the flow pulse is converted into a double pulse, the resolution is doubled, each flow pulse is corrected, and a corrected flow pulse is output. Coefficient K for normalizing
And the operation coefficient K is defined as 0.2 <K <2. Here, the operation coefficient K is determined as follows: K = A ₀ × COMP × n × 1 / m (1) Here, A ₀ : pulse constant COMP: correction coefficient m: correction coefficient The pulse constant _A0 is a _value having a flow rate weight, for example, a flow rate unit such as 1 (liter) per pulse or cm ³ (cubic centimeter), and a correction coefficient (COMP).
Is the pulse constants A _0, for example, a coefficient for performing temperature compensation of the pressure or the like. The correction coefficient m is a dimensionless number for normalizing the operation coefficient K so that K <2 so that (operation coefficient) K is infinitely close to 2, and the correction coefficient m is expressed by the above equation (1). The calculated calculation coefficient K is calculated and stored in the calculation processing device.

FIG. 1 shows a flow rate pulse shaping device of a flow rate correction device according to the present invention. In FIG.
Reference numerals 2 and 4 denote a mono-multi (MM), 3 denotes an inverter, 5 denotes an OR circuit, and 6 denotes a frequency dividing circuit (CTC). FIG.
(A), (b) is a pulse waveform of a flow rate pulse and an interruption pulse of the circuit part of FIG.

A shaped flow pulse as shown in FIG. 2A is input to the flow pulse input terminal 1, and the mono-multi 2 is activated by the rising pulse of the pulse.
Interrupt pulse 1 of FIG. 2B having a pulse width determined by
Output. On the other hand, the falling pulse of the flow pulse is inverted by the inverter 3 to operate the mono-multi 4, and the interrupt pulse 2 is output. The interrupt pulse 1 and the interrupt pulse 2 are input to the frequency dividing circuit 6 via the OR gate 5. This frequency dividing circuit 6 is not necessary and is removed if the flow pulse frequency is lower than the maximum frequency of the achievable pulse speed of the flow pulse determined by the processing speed of the CPU of the flow correction device. The interrupt pulses 1 and 2 are output as a pulse train of an odd pulse (1) and an even pulse (2) as shown in FIG. The OR gate 5 is not always necessary, and the interrupt pulses 1 and 2 can be directly input to the frequency dividing circuit 6 to obtain odd and even pulse trains.

FIG. 3 is a flowchart of the flow rate correction device according to the present invention. First, (1)
The calculation coefficient K of the calculation result shown in the equation is stored in the calculation processing device. step1: Wait for an interrupt of the interrupt pulse 1 of the odd pulse train. step 2: When the interrupt pulse 1 is input, the operation coefficient K is compared with "1". step3: If K <1, add the K value below the decimal point to the counter N. step4: If K ≧ 1 , K-1 = K0 is calculated and K0 below the decimal point is added to the counter N, and step5: a corrected flow pulse is output.

Step 6: Wait for an even pulse 2 interrupt. step7; Compare the added value of the counter N with 1 and if N <N
If it is 1 , the K value after the decimal point is added to the added value of the counter. Step 8: If N ≧ 1 , output a corrected flow pulse. Step 9: N-1 = N0 is calculated, and the K value of N0 is added to the counter N. As described above, the flow rate pulse is set as a double pulse, and flow rate correction is performed for each pulse.

In the above description, the flow rate pulse is doubled and the operation coefficient K is in the range of 2>K> 0.2 . However, when a doubling circuit for multiplying the flow rate pulse by n is used, n>K> n / 1
It is also possible to set a range of 0 to n of the input flow pulse.
It is possible to obtain a corrected flow rate pulse twice as fast.

[0014]

As is clear from the above description, according to the present invention, after shaping the flow pulse, the rising and falling edges of the flow pulse are used to form a double pulse, and output as an odd pulse train and an even pulse train. When input, the operation coefficient K of K <2 previously calculated and stored is compared with 1 to output a corrected flow rate pulse in real time, and the value after the decimal point is added to the counter. And outputs a corrected flow pulse in real time, so that a flow correction with a quick response according to the process variable is performed.

[Brief description of the drawings]

FIG. 1 is a flow rate pulse shaping device of a flow rate correction device according to the present invention.

FIG. 2 is a pulse waveform of a flow rate pulse and an interruption pulse of the circuit part of FIG.

FIG. 3 is a flowchart of a flow rate correction device according to the present invention.

[Explanation of symbols]

1: Flow rate pulse input terminal, 2, 4: Mono multi (M
M), 3 ... inverter, 5 ... OR circuit, 6 ... frequency divider circuit (CTC).

Claims (2)

(57) [Claims] 1. A double pulse circuit for outputting a flow pulse as a double pulse, pulse processing means for outputting a pulse train of the double pulse as an odd-numbered pulse and an even-numbered pulse train in order, and a pulse output from the pulse processing means. Correction means for correcting the flow rate for each output pulse of the multiplied pulse, wherein the correction means multiplies a pulse constant of the flow rate pulse, a correction coefficient for the pulse constant by a multiplication coefficient 1 / m, and multiplies the result. An arithmetic processing means for normalizing the coefficient K to a positive value smaller than 2 and storing the same; an odd pulse comparing means for comparing the arithmetic coefficient K with "1" each time the odd pulse is interrupted; A counter for outputting a corrected flow rate pulse when the comparison value of the means is larger than "1" and adding a surplus value smaller than "1"; and an added value of the counter each time the even-numbered pulse is interrupted. The flow rate correction device comprises: an even pulse comparison means for subtracting "1" from the added value when the value is greater than "1" and outputting a corrected flow rate pulse. 2. The flow correction device according to claim 1, wherein a frequency of the doubled pulse input to the pulse processing means is divided, and a division value of the division is multiplied by the operation coefficient K.