JPH051785Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a vortex flowmeter with a built-in totalizer,
In particular, the present invention relates to a vortex flowmeter that obtains a pulse output by converting a vortex signal into a pulse number and switching between unscaled pulses and scaled pulses.

<Prior Art> A vortex flow meter converts the flow rate flowing through a pipe into a vortex signal, and this vortex signal is output as a unified current signal of 4 to 20 mA, or a pulse signal, for example. When outputting as a pulse signal, when outputting as a scaled pulse,
There are times when it is output as an unscaled pulse.

In general, vortex flowmeters measure various objects such as gases and liquids, and in the case of gas, the standard volumetric flow rate is used to express the flow rate value, and in the case of steam, the standard rate of weight flow rate is used to express the flow rate value. Therefore, in these cases, temperature/pressure correction is required to convert to the standard state due to changes in temperature, pressure, or specific weight. However, when temperature, pressure, or specific weight can be considered to be approximately constant, or when simple instrumentation is used where variations do not pose a problem, temperature, pressure, and specific weight are treated as constants.

When the temperature, pressure, or specific weight can be considered to be approximately constant, a correction calculation is performed in the circuit that multiplies the pulse of the vortex signal by a predetermined scaling constant, for example, 1
It is output as a scaled pulse that has been corrected so that the pulse is in neat units such as 1 liter or 0.1 liter. This has the advantage of making it easier to understand when displayed on the built-in totalizer.
Ru.

On the other hand, if the temperature, pressure, or specific weight cannot be considered constant, a pulse of the vortex signal will be output to the correction calculator and correction will be made there. It is more convenient to output the pulse as it is to the correction calculator, and for this purpose unscaled pulses are used.

FIG. 4 shows the configuration of a conventional vortex flowmeter converter that can switch between scaled pulses and unscaled pulses.

The converter 10 is composed of a main body section 11 and an integrating section 12. The main body 11 includes a detector (not shown).
The vortex flow rate signal is input to the terminal 13, and the vortex signal/
The pulse conversion circuit 14 converts it into a number of pulses. The converted pulse number is input to the pulse output circuit 16 via the switch 15 and output via the terminal 17.

On the other hand, the pulse output converted by the eddy signal/pulse conversion circuit 14 is input to the integrating unit 12 via terminals 18 and 19 to a scaling circuit 20 . The pulses scaled by the scaling circuit 20 are input to the integrator 21, where they are integrated and sent to the terminal 2.
It is output to the switch 15 via 2 and 23. The switch 15 switches either the unscaled pulse that is the output of the eddy signal/pulse conversion circuit 14 or the scaled pulse that is the output of the scaling circuit 20 and inputs it to the pulse output circuit 16.
Therefore, either the scaled pulse or the unscaled pulse is connected to the terminal 17 by the switch 15.
can be obtained by switching.

When the main body part 11 incorporates the integrating section 12 having a scaling function, the configuration shown in FIG. 4 makes it easy to attach and detach only the integrating section 12. In this case, a switch 15 or a switching jumper for obtaining a scaled pulse or an unscaled pulse at the terminal 17 is housed in the main body 11.

<Problems to be solved by the invention> However, in the conventional vortex flowmeter with such a configuration, when the totalizer is not used, the main body 11
A switch or the like must always be provided to switch between scaled pulse and unscaled pulse, which is inconvenient to handle and also causes high costs.

<Means for Solving the Problems> In order to solve the above problems, this invention has a conversion means for converting the eddy flow rate signal into pulses, and a destination connected to the output end of this conversion means through at least a resistor. a main body having a pulse output circuit that outputs pulses of The switch means is connected to both ends of the pulse output circuit, and is configured to select and supply either the previous pulse or the scaled pulse to the previous pulse output circuit.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention. Note that parts having the same functions as those in FIG. 4 are designated by the same reference numerals, and their explanations will be omitted as appropriate.

The converter 24 is composed of a main body part 25 and an integrating part 26. The output end of the vortex signal/pulse conversion circuit 14 and the input end of the pulse output circuit 16 of the main body section 25 are connected via a resistor 27, and both ends thereof are connected to terminals 18 and 23, respectively. The output section _Q1 of the vortex signal/pulse conversion circuit 14 is composed of an integrated circuit element, and the input section Q1 of the pulse output circuit 16
Q ₂ each consists of a transistor.

The input terminal of the scaling circuit 20 of the integrating section 26 is connected to the terminal 19, and the output terminal thereof is connected to the switch 28.
is connected to the terminal 22 via the totalizer 21.
connected to the input end of the Scaling circuit 2
The input part Q ₃ of 0 is constituted by a transistor, and its output part Q ₄ is constituted by an integrated circuit element.

Next, the operation of the converter of the vortex flowmeter configured as above will be explained.

The vortex signal/pulse conversion circuit 14 outputs an unscaled pulse in which the vortex signal applied from the detector to the terminal 13 is simply converted into a pulse number. This signal is scaled by a scaling circuit 20 and converted into a scaled pulse, which is integrated and displayed by an integrator 21.

On the other hand, an unscaled pulse is obtained via the pulse output circuit 16 at the terminal 17 as an output pulse of the eddy signal/pulse conversion circuit 14 when the switch 28 is off. In this case, the resistor 27 is simply connected to the vortex signal/pulse conversion circuit 14 and the pulse output circuit 16.
It only has the function of connecting.

When the switch 28 is turned on, the logic levels at both ends of the resistor 27 can be in the following four states, assuming that "H" is a high level state and "L" is a low level state.

State of terminal 18 State of terminal 23 (a) H H (b) H L (c) L H (d) L L Among these, in the case of states (a) and (d), terminal 1
Since both the 8 and 23 sides are at the "H" level and the "L" level, the potentials at both ends of the resistor 27 are equal. Therefore,
No current flows through the resistor 27, which is substantially equivalent to an open state.

In the case of (b), from the terminal 18 side to the terminal 23
A current flows through the resistor 27 on the side. The output parts Q ₁ and Q ₄ need the ability to control the input parts Q ₂ and Q ₃ so that the logic level (b) does not change even if current flows through the resistor 27.

For this purpose, the output part Q ₁ must first supply enough current to flow through the resistor 27 and the scaling circuit 2
It is necessary to use an IC that can operate the input section Q ₃ of 0 and has a capacitance that can sufficiently absorb the current flowing through the resistor 27 for the output section Q ₄ .

Such an IC can be realized by having a current supply capacity of, for example, 400 μA or more when the output is at a high level, and an IC that has a current absorption capacity of, for example, 400 μA or more when the output is at a low level. CMOS-ICs are commonly available.

Next, the larger the resistance value of the resistor 27 is, the less current is required to flow, but if the current is too small, it will not be possible to turn on the input section Q ₂ during unscaled pulse output. Furthermore, if the resistance value of the resistor R1 is too large, the input section _Q3 cannot be turned on.

Furthermore, the current i _b required to turn on the input parts Q ₂ and Q ₃ is determined by the relationship i _b ≧I _c /h _fe , where h _fe is the current amplification factor of each transistor and I _c is the collector current. determined by

If the values of the resistor 27 and the resistor R1 are selected in consideration of the above points, the state (b) can be maintained even when current flows through the resistor 27.

The state (c) is exactly the opposite of the state (b), but if the values of the resistor 27 and the resistor R1 are selected as described above, the state (c) will not change.

A specific numerical example would be as follows. Using the above IC, the resistance value of resistor 27 is R _A = 62KΩ, R _B = 62KΩ, R _C = 130KΩ, R _D =
27KΩ, R _E = 300KΩ, R _F = 300KΩ, R1 = 1MΩ
etc.

In this state, terminal 18 is at high level H, terminal 2
3 is low level L, the current i ₂₇ flowing through the resistor 27 is about i ₂₇ = 90 μA, and the current flowing through the resistor R1
i ₁ is approximately i ₁ = 5 μA. Therefore, the output part Q ₁
The supply current of (i ₂₇ + i ₁ ) is approximately 95 μA, and the input section Q ₃ is definitely turned on at i ₁ . Further, at this time, the current i ₂ flowing into the resistor R _B becomes i ₂ =0 μA, and the input section Q ₂ is definitely turned off.

Next, when the terminal 18 is at low level L and the terminal 23 is at high level H, the current i ₂₇ flowing through the resistor 27
is approximately −i ₂₇ =0 μA, and the current i ₁ flowing through the resistor R1 is approximately −i ₁ =0 μA. Therefore, the absorption current of the output part _Q1 becomes _-i27 , _i1 is 0, and the input part _Q3 is definitely turned off. Further, at this time, the current supplied to the output section Q ₄ is (-i ₂₇ +i ₂ ), and i ₂ is approximately 90 μA. Therefore, input section _Q2 is definitely turned on.

Therefore, the logic level state of the pulse output of the eddy signal/pulse conversion circuit 14 and the scaling circuit 2
Since there is no mutual interference with the logic level state of the output of 0, the scaled pulse is transmitted to the pulse output circuit 16 via the scaling circuit 20 and switch 28 without any problem.

FIG. 2 shows another embodiment of the invention. Main body part 2
The output terminal of the vortex signal/pulse conversion circuit 14 of No. 9 and the input terminal of the pulse output circuit 16 are connected by a series circuit of a resistor 27 and a diode 30. In this case, there is no need to consider the current flowing through the resistor 27 in the state (c).

FIG. 3 is a block diagram showing still another embodiment of the present invention. The output section Q ₅ of the vortex signal/pulse conversion circuit 32 of the main body section 31 is configured with a transistor, the input section Q ₆ of the pulse output circuit 33 is configured with an integrated circuit, and the input section Q ₇ of the scaling circuit 35 of the integration section 34 is configured. is made up of an integrated circuit, and its output section _Q8 is made up of a transistor.

When the output parts Q ₅ and Q ₈ are composed of transistors,
For example, if the power supply voltage of the transistor in the output section _Q5 is +
V ₅ , collector resistance is R ₅ , resistance value of resistor 27 is R ₂
Then, the potential of the terminal 18 becomes +V ₅ when the terminal 23 is at the "H" level, but becomes R ₂ /(R ₂ +R ₅ ) when the terminal 23 is at the "L" level. A similar thing occurs at terminal 23. However, the voltage of the transistor at the output part Q ₈ is +V ₈ (=+V ₅ ), and its collector resistance is R ₈ (=R ₅ ).

<Effects of the invention> As explained above in detail with the embodiments, according to the invention, switching between scaled pulses and unscaled pulses can be performed simply by adding at least one resistor to the main body of the converter. Since this can now be done on the integration section side, it is sufficient to prepare one type of main body regardless of whether or not it incorporates an integration section, thereby ensuring cost reduction and ease of handling.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing a second embodiment showing the main parts of the invention, and Fig. 3 is a block diagram showing a third embodiment of the invention. 4 are block diagrams showing the structure of a converter of a conventional vortex flowmeter. 10, 24... converter, 11, 25, 29, 3
1...Main unit, 12, 26, 34...Integrator part, 1
4, 32... Vortex signal/pulse conversion circuit, 16, 3
3... Pulse output circuit, 20, 35... Scaling circuit, 21... Totalizer.

Claims (1)

[Scope of utility model registration request] A main body comprising a converting means for converting a vortex flow rate signal into a pulse, a pulse output circuit connected to an output end of the converting means via at least a resistor and outputting the pulse, a scaling circuit, a switch means, and an integrator. a series circuit of the scaling circuit and switching means is connected to both ends of at least the resistor, and the switching means selects either the pulse or the scaled pulse to the pulse output circuit. A vortex flow meter characterized by supplying