JPS6139521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air pulse signal/air pressure signal converter that converts an air pulse signal into an air pressure signal. More specifically, the present invention converts air pulse signals corresponding to pressure, flow rate, temperature, etc. output from a pressure meter, flow meter, thermometer, etc. using a vibratory transducer into a unified signal (for example, 0.2
This relates to an air pulse signal/air pressure signal converter that converts into an air pressure signal of ~1.0Kg/cm ² ).

(Prior Art) For example, a flow meter that outputs an air pulse signal corresponding to a flow rate signal is known as shown in Japanese Patent Application Laid-Open No. 119354/1983. This flowmeter outputs the movement of a diaphragm displaced by the Karman vortex as an air pulse signal using a nozzle flapper mechanism. An amplifier, such as a relay, converts it into a pneumatic signal and transmits it.

(Problem to be Solved by the Invention) However, the air pulse signal is limited to 0.2 to 1.0 Kg/cm ² by the aperture (corresponding to resistance) and the capacity tank.
For those that convert into air pressure signals, the fluid resistance value of the throttle is unstable because it is affected by the viscosity of the compressed air and the fluid temperature, and the fluid resistance value is unstable due to the influence of dust contained in the compressed air. The operation is stable over a long period of time because of the economic changes due to
Another problem was that the air pulse signal could not be converted into an air pressure signal with high accuracy.

The present invention was made in view of these problems, and its purpose is to realize an air pulse signal/air pressure signal conversion device that operates stably over a long period of time and has high accuracy. be.

(Means for Solving the Problems) To achieve such an object, the present invention provides a pulse/air pressure converter having a control end and converting an air pulse signal into an air pressure signal, and a preset reference value. and a value corresponding to the output pressure of the pulse/air pressure converter, and a reference air pulse signal generator that outputs an air pulse signal of a reference frequency. The output air pulse signal of the reference air pulse signal generator is intermittently applied to the input side, and the output of the deviation amplifier at this time is applied to the control end of the pulse/air pressure converter to change its input/output characteristics. It is characterized by the following.

(Operation) Each of the above technical means functions as follows.

Under normal conditions, an input air pulse signal is converted into an air pressure signal via a pulse/air pressure converter and output. Here, a reference air pulse signal from a reference air pulse signal generator is intermittently applied to the input side of the pulse/air pressure converter, and the air pressure signal from the pulse/air pressure converter at this time is extracted via a deviation amplifier. . The output of this deviation amplifier is
It shows the change over time in the conversion error from the initial state in the pulse/pneumatic converter. The output of the deviation amplifier is given to the control end of the pulse/pneumatic converter, which allows the pulse/pneumatic converter to change its input/output characteristics to eliminate conversion errors and maintain high accuracy over long periods of time. I try to do that.

(Examples) Hereinafter, the present invention will be described in detail together with examples.

FIG. 1 is a block diagram of a device according to an embodiment of the present invention. In the figure, reference numeral 1 indicates the input terminals to which the air pulse input signal P _i is applied. S ₁ and S ₂ are changeover switches that switch in synchronization with each other, 2 is a pulse/pneumatic converter, and input terminal 2 is to which the signal selected by changeover switch S ₁ is applied.
1, an output terminal 22, and a control terminal 23.

FIG. 2 is a configuration diagram showing an example of the pulse/air pressure converter 2. As shown in FIG. Here, three pure fluid elements
It is composed of Fd ₁ , Fd ₂ and Fd ₃ , and
The first pure fluid element Fd ₁ receives an air pulse signal P _i corresponding to the process amount, and shapes the waveform of this pulse signal. The second pure fluid element Fd ₂ constitutes a one-shot multi-mechanism together with a resistor γ ₁ consisting of an aperture mechanism etc. and a capacitance C ₁ consisting of a tank etc., and from the first pure fluid element Fd ₁ Convert the signal into a pulse signal with a constant width τ. The third pure fluid element Fd ₃ has a function as an amplifier that amplifies the pulse signal of constant width τ from the second pure fluid element Fd ₂ , and this output signal is generated by the resistance γ ₂ , the capacitance C ₂ and the bleed resistance γ The voltage is applied to a smoothing mechanism consisting of ₃ . Each constant of this smoothing mechanism is determined by the control end 2
It can be changed depending on the signal applied to 3.

Returning to Fig. 1, 3 is a pressure & power amplifier that amplifies the power of air pressure, and inputs the signal from the pulse/air pressure converter ₂ applied via the changeover switch S2, and amplifies the power by, for example, 0.2. ~1.0Kg/ ^cm2
outputs a pneumatic pressure signal P _p . As this pressure and power amplifier, a known mechanism such as a pilot relay or a nozzle flapper and pilot relay can be used.

4 is a deviation amplifier which inputs the pneumatic signal P _p applied via the changeover switch S ₂ and controls the pulse/pneumatic converter 2 by outputting a signal P corresponding to the deviation between this signal and a preset reference signal. terminal 2
3.

FIG. 3 is a configuration diagram showing an example of this deviation amplifier 4. As shown in FIG. Here, a bellows 41 to which an air pressure signal P _p is applied, a spring 42 that generates a force corresponding to a reference value, a flapper 43 and a flapper 43 that are displaced in accordance with the difference between the bellows 41 and the reference spring 42
Nozzle 4, which together constitutes a nozzle flapper mechanism.
4, the pneumatic pressure signal P corresponds to the deviation between the force corresponding to the pneumatic pressure signal P _p and the reference force corresponding to the reference pressure set in advance in the reference spring 42.
is output as the back pressure of the nozzle 44.

In Fig. 1, 5 is a reference air pulse signal generator (hereinafter simply referred to as a reference oscillator) that outputs an air pulse signal having a reference frequency, and the output pulse signal is transmitted through a changeover switch _S1 . It is applied to the input end of the pulse/pneumatic converter 2.

FIG. 4 is a configuration diagram showing an example of this reference oscillator 5. Here, a thin strip-shaped diaphragm 51 to which a certain tension is applied, a drive nozzle 52 for vibrating this diaphragm 51 at its natural frequency, and a drive nozzle 52 that faces this diaphragm 51 and is connected to the vibration of the diaphragm 51. The detection nozzle 53 outputs a corresponding air pulse signal.

Then, an air pulse signal P _s of a constant frequency corresponding to the tension applied to the diaphragm 51 is obtained from the detection nozzle 53. By adjusting the tension applied to the diaphragm 51, the frequency can be made variable.

The changeover switches S ₁ and S ₂ have terminals a and b to which an air signal is applied, and are intermittently driven from contact a to contact b side in synchronization with each other, for example, using a known diaphragm. A switch or a spool (piston) switch is used. Further, the driving means for these changeover switches can be realized by a combination of a pneumatic timer and a diaphragm type switch.

The operation of the apparatus configured in this way will be explained next. First, when the changeover switches S ₁ and S ₂ are connected to the terminal a side, the air pulse signal P _i applied to the input terminal 1 is passed through the changeover switch S ₁ to the pulse/air pressure converter 2. The applied signal, which is converted into a pneumatic signal here, is applied to the pressure & power amplifier 3, where it is amplified and becomes the output pneumatic pressure P _p . By the way, if this state continues for a long time,
In the pulse/pneumatic converter 2, for example, the resistance γ
The input/output related gain (input/output characteristics) changes due to changes in ₁ to _γ3 , contamination of the pipe, etc., resulting in conversion errors. That is, the resistance value of fluid resistance changes depending on the viscosity and specific weight of the fluid. Furthermore, the viscosity and specific weight are affected by temperature, and the presence of fine dust and oil in the instrumentation air causes the characteristics to change over time. In the device of the present invention, the changeover switches S ₁ and S ₂ are intermittently connected to the terminal b side to perform a calibration operation and eliminate this conversion error. That is, when the changeover switches S ₁ and S ₂ are connected to the terminal b side, a pulse signal P _s of a constant frequency serving as a reference is applied from the reference oscillator 5 to the pulse/air pressure converter 2, and this output pressure is applied to the pressure & power amplifier. 3. Applied to the bellows 41 of the deviation amplifier 4 via the changeover switch _S2 . In the deviation amplifier 4, the pulse/pneumatic converter 2,
If there is no conversion error in the pressure & power amplifier 3, the spring 42 is adjusted in advance so that the forces between the reference spring 42 and the bellows 41 are balanced. If there is a conversion error, the corresponding deviation signal P is applied to the control terminal 23 of the pulse/pneumatic converter 2, and the conversion is performed so that the force of the bellows 41 is balanced with the force of the reference spring 42. Pulse/pneumatic converter 2 to eliminate errors
For example, the resistors γ ₂ and γ ₃ or the capacitor C ₂ are adjusted to change the input/output characteristics. Through such a calibration operation, conversion errors and drifts of the pulse/pneumatic converter 2 and the pressure & power amplifier 3 are removed. After the calibration operation is completed, switches S ₁ and S ₂ are connected to the terminal a side.

FIG. 5 is a block diagram of another embodiment of the present invention. In this embodiment device, two pulse/pneumatic pressure converters 2A and 2B are provided, and during the calibration operation of one converter, the output pressure is obtained through the other converter, and the output pressure is obtained through the other converter. During the calibration operation, the output pressure is obtained through one of the converters. In other words, the changeover switch
When S ₁₁ , S ₁₂ , S ₂₁ , S ₂₂ , and S ₃ are connected to the contact a side, the input air pulse signal P _i is connected to the first pulse/air pressure converter 2A and the pressure & power amplifier 3. The output pressure P _{p is obtained through the output pressure P p} . On the other hand, the reference pulse signal P _s from the reference oscillator 5 is applied to the second pulse/air pressure converter 2B, and its output pressure is applied to the control terminal 2 of the converter 2B via the deviation amplifier 4.
3 is applied. With this, this converter 2B
change the input/output characteristics of When each changeover switch is connected to the contact b side, the input air pulse signal P _i is transmitted to the second pulse/air pressure converter 2.
B, the output pressure becomes P _p via the pressure & power amplifier 3. On the other hand, the pulse signal P _s from the reference oscillator 5
is applied to the first converter 2A, and its output pressure is applied to the control terminal 23 of the converter 2A via the deviation amplifier 4.
is applied to This changes the input/output characteristics of this converter 2A.

In addition, in this embodiment, the changeover switch
An intermediate junction C is provided at S ₂₁ and S ₂₂ , but this waits for the output pressure of the pulse/pneumatic converters 2A and 2B to stabilize so that the output pressure P _p does not change suddenly when switching the switch. This is for switching between
Not necessarily necessary.

Furthermore, in each of the embodiments described above, the configurations of the pulse/pneumatic converter 2, the deviation amplifier 4, and the reference oscillator 5 may be other configurations than those illustrated.

(Effects of the Invention) As described above, according to the present invention, it is possible to realize an air pulse signal/air pressure signal conversion device that operates stably over a long period of time and has high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention.
Fig. 2 is a block diagram showing an example of a pulse/air pressure converter used in the device shown in Fig. 1, Fig. 3 is a block diagram showing an example of a deviation amplifier used in the device shown in Fig. 1, and Fig. 4 is a block diagram showing an example of a deviation amplifier used in the device shown in Fig. 1. 1 is a block diagram showing an example of a reference oscillator used in the device, and FIG. 5 is a block diagram showing another embodiment of the present invention. 1...Input terminal, 2...Pulse/air pressure converter, 3...Pressure & power amplifier, 4...Difference amplifier, 5...Reference oscillator, _S1 , _S2 ...Switching switch.

Claims (1)

[Claims] 1. A pulse/pneumatic converter having a control end and converting an air pulse signal into a pneumatic signal, and a preset reference value and a value corresponding to the output pressure of the pulse/pneumatic converter. a deviation amplifier for detecting a deviation; and a reference air pulse signal generator for outputting an air pulse signal of a reference frequency; An air pulse signal/air pressure signal conversion device characterized in that a pulse signal is applied, and the output of the deviation amplifier at this time is applied to a control end of the pulse/air pressure converter to change its input/output characteristics. 2. Two pulse/air pressure converters are provided, and the output air pulse signal of the reference air pulse signal generator is applied alternately to the input side of these two converters, and the output air pulse signal of the reference air pulse signal generator is applied to the input side of these two converters, and the 2
An air pulse signal/air pressure signal conversion device according to claim 1, wherein the input/output characteristics of the pulse/air pressure converters are alternately changed. 3. Claims in which the reference air pulse signal generator is constituted by a thin strip plate under tension, a driving means for vibrating the thin strip plate at its natural frequency, and a nozzle flapper mechanism using the thin strip plate as a flapper. The air pulse signal/air pressure signal conversion device according to item 1 or 2.