KR19980040914A - Pressure / Flow Integrated Sensor - Google Patents

Abstract

A pressure sensor having a structure in which a strain resistor is installed at a lower part of a diaphragm and connected to a bridge circuit includes a flow sensing rod installed at an upper part of the diaphragm and embedded in a fluid flow in a pipe.

Therefore, since the integrated structure is not attached to the respective sensor devices, an expensive flow sensor function is added to the pressure sensor structure, thereby achieving a low cost effect.

Description

Pressure / Flow Integrated Sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure / flow integrated sensor, and more particularly, to a pressure / flow integrated sensor which is a complex sensor having a simple configuration by integrating a pressure sensor and a flow sensor used in various pumps or water supply devices.

A pressure sensor (or pressure gauge) refers to a sensor that measures the pressure of a liquid, and because of the rm structure, there are liquid pressure gauges, deadweight standard pressure gauges, electric pressure gauges, and semiconductor pressure gauges. Among the elastic pressure gauges, bourdon tube sensors are generally used. And bellows type sensors and diaphragm type sensors.

As an example, a conventional diaphragm type pressure sensor has a structure in which a strain resistor 20 is installed on a metal diaphragm 10 to be immersed in a fluid 30 as shown in FIGS. 1 and 2. 1 is a cross-sectional view showing the structure of a conventional pressure sensor, Figure 2 is a circuit diagram adopted in the conventional pressure sensor. In the diaphragm 10 pressure sensor, as shown in FIG. 2, when the diaphragm 10 is bent due to pressure, the stress applied to the strain resistor 20 changes, and the stress change value is changed to a resistance value. The change value resistance value is converted into a voltage as the bridge amplifier 100 so that the change in pressure can be known.

On the other hand, the flow meter (flow meter) is a measure of the flow of liquid or gas, also known as a flow sensor, by placing the diaphragm in the fluid in the pipeline increases the speed of the fluid passing through the portion (υ ₁ → υ ₂ ) In order to decrease (P ₁ → P ₂ ), an aperture sensor, that is, Bernoulli's theorem, which measures the pressure difference before and after the aperture and obtains the flow rate, is used. An area flow meter that changes the area to obtain a constant flow rate, a volumetric flow meter that measures the number of fluids passing through the volume of a single volume, and counts how many times it is measured. And mass flow meters using a property of proportional to.

In the conventional diaphragm flow sensor, as shown in FIG. 3, the flowmeter using an orifice which measures the head of both orifices in a pipe and finds out the flow volume is most. 3 is an explanatory diagram showing the principle of a conventional orifice flow meter.

In this figure, reference numerals P1 and P2 denote orifices and 200 denotes pipelines. In the conduit 200, an orifice P1 having a large cross-sectional area and an orifice P2 having a small cross-sectional area are provided, and the flow rate is measured by calculating the pressure difference thereof.

That is, the relational expression of the flow rate Q = C√Δ P holds. Where C is an integer and ΔP is the pressure difference between the orifice P1 and the orifice P2.

In addition to the orifice flowmeter, the Kalman flowmeter is a method of installing a non-streamlined insert that obstructs the flow of fluid in the pipeline and measuring the vortex (Kalman vortex) by generating a downstream thereof. In other words, when the ratio of the interval between the vortex heat and the distance of the vortex is 0.281, the vortex heat is stably generated to detect the flow velocity at the vortex generation frequency. The relational expression is shown below.

Where f is the vortex frequency, d is the width of the column in the flow, v is the flow rate, and St is the Strouhal number.

Recently, there is an electromagnetic flowmeter which measures the generated voltage according to the flow rate by Faraday's law by using an electromagnetic field, and an ultrasonic flowmeter which is measured by using the Doppler effect.

As shown in Fig. 4, the electromagnetic flow meter (electromagnetic folwmeter) has an inner diameter placed between the electrodes so that the conductive fluid flows at an average speed υ. The magnetic field (magnetic flux density B) is applied at right angles to the flow. According to the 3 Law of, electromotive force of E = CυBd (C: integer) is generated between the electrodes facing the tube wall.

Assuming that the flow rate is Q, a relationship of Q = (π / 4C) (d / B) E is established. There are two types of electromagnetic flowmeters, AC type and DC type, but industrially, AC type is widely used, and is used for measuring the flow rate of industrial water, pulp liquid, blood, molten metal, water supply and drainage, or hydraulic power pipe. In Fig. 4, reference numeral 40 denotes a magnet and 50 denotes a pipe.

When the ultrasonic flowmeter launches ultrasonic waves of several MHz in parallel or inclined to the flow, the time that the sound waves reach the receiver spaced from the oscillator is emitted in the direction in which the ultrasonic waves flow or in the opposite direction. different. By measuring these time differences or phase differences, the flow velocity is obtained and the flow rate is obtained here. Ultrasonic flowmeters have the advantage of quickly and accurately measuring in-stream, atmospheric, ocean, and stream flows without disrupting the flow.

However, depending on the device to be applied, there may be a case where the pressure sensor and the flow sensor are simultaneously provided to achieve the desired purpose. The conventional two sensors are required to be separate parts due to the configuration of each, causing a rise in manufacturing cost.

Accordingly, an object of the present invention is to provide a complex sensor having a simple configuration by integrating a pressure sensor and a flow sensor used in various pumps or water supply devices.

Figure 2 is a cross-sectional view showing the structure of a conventional pressure sensor

2 is a circuit diagram adopted in a conventional pressure sensor

3 is an explanatory diagram showing the principle of a conventional orifice flow meter;

Figure 5 schematically shows the structure of the pressure / flow rate integrated sensor of the present invention,

(A) is a longitudinal sectional view,

(B) is a cross-sectional view.

6 is an explanatory view showing the operation of the pressure / flow integrated sensor of the present invention,

(A) shows a modification of the diaphragm under pressure action,

(B) shows an example in which the diaphragm is deformed due to pressure and flow rate.

7 is a circuit diagram of a pressure / flow integrated sensor of the present invention;

* Description of the symbols for the main parts of the drawings *

10: diaphragm 20: strain resistor

30 fluid 40 magnet

50, 200: pipeline 70: flow detection rod

80: operation measuring instrument 100: bridge amplifier

P1, P2: Orifice

Pressure / flow integrated sensor of the present invention for achieving the above object is a pressure sensor of the structure formed by installing a strain resistor in the lower portion of the diaphragm and connected to the bridge circuit, it is installed on the upper portion of the diaphragm and the fluid flow in the pipe It is to include a flow sensing rod that is embedded.

In addition to this configuration, the strain resistor is provided as one component of the bridge circuit, and the strain resistor may be connected in series to form a bridge circuit and connected to an operational measuring instrument to perform a predetermined process. The calculator measures the resistance change of S ₁ + S ₂ = 2P ₁ to extract the pressure change component, and calculates the resistance change of S1-S2 = 2Q1 to extract the flow rate component.

The pressure / flow rate integrated sensor of the above configuration has an advantage that it can be realized at low cost by adding an expensive flow sensor function to the pressure sensor structure because the pressure / flow integrated sensor is integrated without attaching respective devices.

EXAMPLE

Hereinafter, the pressure / flow rate integrated sensor of the present invention will be described in detail with reference to FIGS. 5 to 7.

Parts similar to those of the conventional description will be described with the same reference numerals to avoid the complexity of the description.

Figure 5 schematically shows the structure of the pressure / flow integrated sensor of the present invention, (a) is a longitudinal cross-sectional view, (b) is a cross-sectional view, Figure 6 is an explanatory view showing the operation of the pressure / flow integrated sensor of the present invention. , (A) shows a modification of the diaphragm 10 during the pressure action, (B) shows an example in which the diaphragm 10 is deformed by the pressure and the flow rate. 7 is a circuit diagram of the pressure / flow integrated sensor of the present invention.

In FIG. 5, reference numeral 70 denotes a flow sensing rod installed in the conduit 200. The diaphragm 10 is installed at the lower end of the flow sensing rod 70, and a plurality of strain resistors 20 are attached to the bottom of the diaphragm 10.

Referring to FIG. 7, the strain resistor 20 is installed as one component of a bridge circuit, and the two strain resistors 20 are connected in series and connected to the operational measuring device 80 to perform a predetermined process. It is.

Referring to the operation of the present invention having such a configuration, as shown in Figure 6, since the flow rate sensing rod 70 is provided as a sensor for sensing the flow rate on the diaphragm 10, when there is no usual flow rate It receives only the pressure and operates as a general pressure sensor.

On the other hand, when ignoring the influence of pressure and considering only the flow velocity, a force proportional to the flow velocity is transmitted to the flow rate sensing rod 70, and a twisting phenomenon occurs in the diaphragm 10 due to the flow velocity, and the twist is shown in FIG. 6. As shown in (B), the direction is opposite and the force is the same with respect to the X axis (axis of the flow sensing rod).

In general, since the pressure and the flow rate exist on the flow path, the diaphragm 10 is combined with the deformation caused by the pressure (see FIG. 6A) and the deformation due to the flow rate to appear as shown in FIG.

These strains include strains proportional to pressure and strains proportional to flow velocity. That is, in the deformation of the diaphragm 10 due to pressure and flow rate, the amount of strain change attached to the diaphragm 10 is read, and the pressure and flow rate are measured.

At this time, since the pressure change component takes a constant input to the diaphragm 10 over the entire surface, the resistance change is set to P1, and the resistance cotton due to the flow rate has the same size but different direction Q1, and the resistance change of P1 + Q1 in S1. Occurs, and the resistance change of P1-Q1 occurs in S2.

The operational measuring unit 80 calculates the resistance change of S1-S2 = 2Q1 to extract the flow rate change component. To extract the pressure change, the resistance change of S ₁ + S ₂ = 2P ₁ is extracted. Each of these calculated extracts is amplified to measure and show the pressure and flow rate.

As described above, according to the pressure / flow rate integrated sensor of the present invention, since the device is integrated without attaching each device, an expensive flow sensor function can be added to the pressure sensor structure to realize a low cost.

Claims (4)

In the pressure sensor of the structure formed by installing a strain resistor in the lower part of the diaphragm and connected to the bridge circuit And a flow rate sensing rod mounted on the diaphragm and embedded in the fluid flow in the pipe. The method of claim 1, The strain resistor is provided as one component of the bridge circuit, pressure / flow rate integrated sensor. The method according to claim 1 or 2, The strain resistors are connected in series to form a bridge circuit, and connected to an operational measuring device to perform a predetermined process. The method of claim 3, wherein Wherein the operational meter, the pressure / flow rate integrated sensor, characterized in that for calculating the change in resistance S1-S2 = 2Q1 to extract the pressure change component.