KR20230041222A - Differential Pressure Transmitter and the Method of Measuring Differential Pressure - Google Patents

Abstract

The present invention relates to a differential pressure transmission apparatus and a method for measuring differential pressure. More specifically, the present invention relates to a differential pressure transmission apparatus and a method for measuring a differential pressure, which are able to precisely measure a pressure of a fluid by measuring a temperature and pressure of the fluid at an inlet and an outlet of the fluid at a remote place, desirably 5 meters away or farther, and correcting the pressure based on the temperature measured at the inlet and the outlet, compensate the differential pressure obtained by calculating the difference in pressure of the fluid between the inlet and the outlet based on the temperature in the differential pressure transmission apparatus, use a slope analog-digital conversion method to calculate a sensor value by measuring a discharge time through the charging and discharging of condenser and resistance, allow the high-precision differential pressure measurement and transmission even in an environment with a low current, minimize the total current consumption used for a master sensor and a slave sensor to be equal to or lower than 3 mA, allow the supply of power and the transmission of a signal through two lines of electric wires in a complex structure such as a vessel, and reduce the used volume of electric wires and the placement cost.

Description

Differential Pressure Transmitter and the Method of Measuring Differential Pressure

The present invention relates to a differential pressure transmission device and a differential pressure measuring method, and more particularly, to measure the temperature and pressure of a fluid at a long distance, preferably at an inlet and an outlet of a fluid separated by 5 m or more, and then measured at the inlet and outlet. Precisely measure fluid pressure by correcting pressure based on temperature, compensate for differential pressure calculated by calculating the difference in fluid pressure at the inlet and outlet based on the temperature inside the differential pressure transmitter, and charge the resistor and condenser By using the slope analog-digital conversion method that calculates the sensor value by measuring the discharge time through over-discharge, high-precision differential pressure measurement and transmission is possible even in a low-current environment, so the total current consumption used in the master sensor and slave sensor is 3mA It relates to a differential pressure transmission device and a differential pressure measurement method that can reduce the amount of wire used and installation cost by minimizing the following to transmit signals while supplying power through a two-wire wire in a complex structure such as a ship.

As environmental regulations for ships to reduce fine dust and greenhouse gases due to climate warming are being strengthened not only by the International Maritime Organization (IMO) but also by national and regional units, the LDCL system has been developed to improve the performance of diesel engines for ships. (Load-Dependent Cylinder Liner jacket cooling water system) was introduced, which prevents cold corrosion of the inner wall of the cylinder of the engine, and achieves low SOx, low NOx emission, and fuel reduction.

The LDCL system controls the temperature control valve installed in the engine according to the temperature change at the outlet of the cylinder liner. When it is low, it is provided so that the coolant can be circulated to the cylinder liner. The LDCL system monitors the differential pressure at the inlet and outlet of the cooling water to control the temperature of the jacket cooling water across the cylinder liner of the diesel engine, and controls the temperature by converting the cooling water pressure into a flow rate. At this time, a differential pressure transmitter (PDT) may be used to measure and control the differential pressure at the inlet and outlet of the cooling water.

In the above system, the cooling water inlet and outlet are spaced apart from each other, and a pressure difference between the inlet and the outlet must be precisely measured for precise temperature control of the cooling water. However, since the pressure sensor provided at the inlet and outlet to measure the pressure of the cooling water uses a semiconductor device, the measured pressure varies depending on the temperature and is affected by temperature measurement error. As a result, an error in measuring the differential pressure between the cooling water inlet and the outlet increases, and as a result, an error in flow measurement occurs, resulting in cold corrosion and a decrease in reliability of the facility.

In addition, the conventional differential pressure transmitter has a problem of consuming a lot of power when converting the flow rate and pressure into an electrical signal and transmitting the signal to a remote controller, etc., and in a complex structure such as a ship, long and complicated wiring is required for long-distance signal transmission. there was

Therefore, in the industry, by performing pressure compensation according to temperature to reduce the error of the differential pressure transmitter having a pressure sensor spaced at a distance and performing precise measurement, the reliability of the facility is improved, low-power operation is possible, and it is possible to operate in a complex structure such as a ship. There is a demand for a differential pressure transmission device and a low-power, precise measurement method that can reduce installation costs by reducing the amount of wires for signal transmission.

US Registered Patent Publication No. US7341593 (2008.03.11.)

The present invention has been made to solve the above problems,

An object of the present invention is to measure the pressure of the fluid at the inlet or outlet of the fluid, a master measuring unit for sensing the temperature and pressure of the fluid at the inlet or outlet, a master input unit for converting the measured analog signal into digital, and the measured pressure value A master sensor having a controller that corrects the temperature according to the temperature, a slave measuring unit provided away from the master sensor and sensing the temperature and pressure of the fluid at the outlet or inlet of the fluid, and a slave input that converts the sensed analog signal into digital. The master input unit includes a power module for applying a constant current to the master measurement unit, and a slope analog-digital converting an analog signal transmitted from the master measurement unit into a digital signal to calculate a measured value. It is to provide a differential pressure transmission device that measures the pressure and temperature of a fluid at a distance from each other, including a transducer, and compensates the differential pressure according to the temperature.

Another object of the present invention is that the slope analog-to-digital converter includes a reference voltage capacitor for generating a reference voltage required for conversion, a discharge structure for inputting a discharge voltage through charging and discharging, and discharge from the reference voltage capacitor and the discharge structure. It includes a comparator that compares voltages and outputs a comparison signal, and a capture resist that measures a clock from the comparator. It is to provide a differential pressure transmission device capable of this.

Another object of the present invention, the master measuring unit includes a first pressure sensor for measuring the pressure of the fluid at the inlet or outlet and a first temperature sensor for measuring the temperature, the discharge structure is a reference resistance, pressure sensor resistance value , including a temperature sensor resistance value and a charging capacitor, wherein the reference resistance, the pressure sensor resistance value, and the temperature sensor resistance value are alternately connected to the charging capacitor so that the charging capacitor is alternately charged and discharged in the pressure sensor and the temperature sensor It is to provide a differential pressure transmission device capable of directly reading a measured resistance value.

Another object of the present invention is that the master input unit further includes a transmitter temperature sensor for measuring the temperature inside the differential pressure transmitter, and the control unit determines the differential pressure between the master sensor and the slave sensor according to the temperature inside the differential pressure transmitter. It is an object of the present invention to provide a differential pressure transmitter capable of correcting the temperature of the differential pressure by correcting it.

Another object of the present invention is that the control unit controls the discharge structure to read the pressure sensor resistance value and the temperature sensor resistance value from the first pressure sensor and the first temperature sensor of the master measuring unit, or from the transmitter temperature sensor. It is to provide a differential pressure transmission device capable of measuring high-precision differential pressure by controlling the resistance value of a temperature sensor to be read.

Another object of the present invention is to provide a differential pressure transmission device capable of deriving a corrected pressure value without a complicated calculation process by allowing the control unit to linearly approximate pre-input temperature-pressure correction data to calculate a corrected pressure value. will be.

Another object of the present invention is to provide a slave input unit, a power supply module for applying a constant current to the slave measurement unit, and a slope analog-to-digital converter for converting an analog signal transmitted from the slave measurement unit into a digital signal and calculating a measured value. The slave measurement unit includes a second pressure sensor for measuring the pressure of the fluid at the outlet or the inlet and a second temperature sensor for measuring the temperature, and the slope analog-to-digital converter is a standard for generating a reference voltage required for conversion. A voltage capacitor, a discharge structure for inputting a discharge voltage through charging and discharging, a comparator for outputting a comparison signal by comparing the reference voltage from the reference voltage capacitor and the discharge voltage from the discharge structure, and measuring a clock from the comparator A capture resist, wherein the discharge structure includes a reference resistance, a pressure sensor resistance value, a temperature sensor resistance value, and a charging capacitor, wherein the reference resistance, pressure sensor resistance value, and temperature sensor resistance value are alternately connected to the charging capacitor The charging capacitor is alternately charged and discharged, and the sensed resistance value of the pressure sensor and the resistance value of the temperature sensor are converted into the temperature and pressure measured by the slave measuring unit, and the second temperature sensor measures the temperature measured by the second temperature sensor. An object of the present invention is to provide a differential pressure transmission device capable of precisely correcting the pressure of a spaced outlet fluid according to temperature by correcting the pressure of a pressure sensor.

Another object of the present invention is performed by a master sensor provided at an inlet or outlet of a fluid, and compensates for a pressure value measured by a first pressure sensor of the master sensor according to a temperature measured by a first temperature sensor, thereby compensating for the master sensor. The master sensing step of calculating the corrected pressure value at the side, is performed in the slave sensor provided at the outlet or inlet of the fluid, and the pressure value measured by the second pressure sensor of the slave sensor is compensated according to the temperature measured by the second temperature sensor. and a slave sensing step of calculating a corrected pressure value on the slave sensor side, wherein the master sensing step is performed through a slope analog-to-digital converter in the master sensor, and alternately charges and discharges the charging capacitor. When the capacitor is discharged, the charging capacitor is alternately connected with the reference resistance, the pressure sensor resistance value read from the 1st pressure sensor, and the temperature sensor resistance value read from the 1st temperature sensor, and the reference voltage and discharge from the reference voltage capacitor in the comparator A master measurement step of measuring a clock generated by comparing voltages, calculating resistance values of the first pressure sensor and the first temperature sensor provided in the master sensor according to the clock measured in the master measurement step, and calculating the resistance values from the resistance values. Including the master calculation step of converting the first pressure and the first temperature and the master compensation step of correcting the first pressure according to the first temperature, the total current consumption used is minimized to 3mA or less, so that it is a two-wire wire in complex structures such as ships. It is to provide a differential pressure measurement method that allows a signal to be transmitted while supplying power through the.

Another object of the present invention is that the master measuring step is the step of primarily charging the charging capacitor in the slope analog-to-digital converter, discharging the charging capacitor by connecting it to a reference resistance in the slope analog-to-digital converter, Step of measuring the clock generated by comparing the discharge voltage with the reference voltage from the reference voltage capacitor, secondarily charging the charging capacitor, connecting the charging capacitor to the pressure sensor resistance value read from the first pressure sensor while discharging, measuring the clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator, tertiarily charging the charging capacitor, and reading the charging capacitor from the first temperature sensor It is to provide a differential pressure measurement method capable of accurately measuring differential pressure, including the step of measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging in connection with the temperature sensor resistance value.

Another object of the present invention is performed in the master sensor, and further includes a transmitter sensing step of measuring the internal temperature of the differential pressure transmitter, and a differential pressure display step of correcting the differential pressure according to the temperature measured in the transmitter sensing step. In the transmitter sensing step, the charging capacitor provided in the slope analog-to-digital converter in the master sensor is alternately charged and discharged. When the charging capacitor is discharged, the charging capacitor is used as a reference resistance and the temperature sensor resistance read from the transmitter temperature sensor. Transmitter measurement step of measuring the clock generated by comparing the reference voltage and the discharge voltage from the reference voltage capacitor in the comparator by connecting alternately to the value, calculating the resistance value of the transmitter temperature sensor according to the clock measured in the transmitter measurement step, A transmitter calculation step of converting the internal temperature of the differential pressure transmitter from the resistance value, wherein the transmitter measurement step includes primarily charging a charging capacitor in a slope analog-to-digital converter, and converting the charging capacitor to a slope analog-to-digital converter. Measuring the clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging by connecting to the reference resistance in the converter, secondarily charging the charging capacitor, and transmitting the charging capacitor to the transmitter The step of measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging in connection with the resistance value of the temperature sensor read from the temperature sensor, and differential pressure transmitter according to the internal temperature of the differential pressure transmitter. It is to provide a differential pressure measurement method capable of more precise measurement by compensating for the pressure.

Another object of the present invention is to further include a resting step in which the master sensor and the slave sensor are maintained in a power-free state by the control unit, and the master sensing step, the slave sensing step, the transmitter sensing step, the differential pressure displaying step, and the resting step. It is to provide a differential pressure measurement method capable of regular differential pressure measurement and transmission by controlling the steps to be repeatedly performed at intervals of 0.7 seconds.

The present invention is implemented by an embodiment having the following configuration in order to achieve the above object.

According to one embodiment of the present invention, the present invention measures the pressure of the fluid at the inlet or outlet of the fluid, and the master measurement unit for sensing the temperature and pressure of the fluid at the inlet or outlet, converting the measured analog signal to digital A master sensor having a master input unit and a control unit that corrects the measured pressure value according to temperature, a slave measuring unit provided away from the master sensor and sensing the temperature and pressure of the fluid at the outlet or inlet of the fluid, and the sensed analog signal A value measured by converting an analog signal transmitted from the master measurement unit into a digital signal and a power module for applying a constant current to the master measurement unit. It is characterized in that it comprises a slope analog-to-digital converter that calculates.

According to another embodiment of the present invention, the slope analog-to-digital converter includes a reference voltage capacitor for generating a reference voltage required for conversion, a discharge structure for inputting a discharge voltage through charging and discharging, and the reference voltage capacitor and the discharge structure. a comparator that compares the discharge voltage from the voltage and outputs a comparison signal, and a capture resist that measures the clock from the comparator, and the control unit converts the measured clock into temperature and pressure and corrects the measured pressure according to the temperature. characterized by

According to another embodiment of the present invention, the master measuring unit includes a first pressure sensor for measuring the pressure of the fluid at the inlet or outlet and a first temperature sensor for measuring the temperature, the discharge structure is a reference resistance, pressure It includes a sensor resistance value, a temperature sensor resistance value, and a charging capacitor, wherein the reference resistance, the pressure sensor resistance value, and the temperature sensor resistance value are alternately connected to the charging capacitor so that the charging capacitor is alternately charged and discharged. do.

According to another embodiment of the present invention, the master input unit further includes a transmitter temperature sensor for measuring the temperature inside the differential pressure transmitter, and the control unit measures the differential pressure between the master sensor and the slave sensor inside the differential pressure transmitter. It is characterized in that it is corrected according to temperature.

According to another embodiment of the present invention, the control unit controls the discharge structure to read the pressure sensor resistance value and the temperature sensor resistance value from the first pressure sensor and the first temperature sensor of the master measurement unit, or the transmitter It is characterized in that the control is performed to read the temperature sensor resistance value from the temperature sensor.

According to another embodiment of the present invention, the control unit calculates the corrected pressure value by performing a linear approximation of the pre-input temperature-pressure correction data.

According to another embodiment of the present invention, the slave input unit may include a power module for applying a constant current to the slave measurement unit, and a slope analog-for converting an analog signal transmitted from the slave measurement unit into a digital signal to calculate a measured value. A digital converter, wherein the slave measuring unit includes a second pressure sensor for measuring the pressure of a fluid at an outlet or an inlet and a second temperature sensor for measuring a temperature, and the slope analog-to-digital converter converts a reference voltage required for conversion. A reference voltage capacitor to generate, a discharge structure to input discharge voltage through charging and discharging, a comparator to output a comparison signal by comparing the reference voltage from the reference voltage capacitor and the discharge voltage from the discharge structure, and a clock from the comparator Including a capture resist for measuring, wherein the discharge structure includes a reference resistance, a pressure sensor resistance value, a temperature sensor resistance value, and a charging capacitor, wherein the reference resistance, pressure sensor resistance value, and temperature sensor resistance value alternately charge the capacitor connected to, the charging capacitor is alternately charged and discharged, and the sensed pressure sensor resistance value and temperature sensor resistance value are converted into the temperature and pressure measured by the slave measuring unit and converted to the temperature measured by the second temperature sensor. It is characterized in that the pressure of the second pressure sensor is corrected according to.

According to another embodiment of the present invention, it is performed in a master sensor provided at the inlet or outlet of the fluid, and the pressure value measured by the first pressure sensor of the master sensor is compensated according to the temperature measured by the first temperature sensor. The master sensing step of calculating the calibrated pressure value on the master sensor side is performed in the slave sensor provided at the outlet or inlet of the fluid, and the pressure value measured by the second pressure sensor of the slave sensor is the temperature measured by the second temperature sensor and a slave sensing step of calculating a corrected pressure value at the slave sensor side by compensating according to the pressure value, and the master sensing step is performed through a slope analog-to-digital converter in the master sensor, and alternately charges and discharges the charging capacitor. , When the charging capacitor is discharged, the charging capacitor is alternately connected with the reference resistance, the pressure sensor resistance value read from the first pressure sensor, and the temperature sensor resistance value read from the first temperature sensor. A master measurement step of measuring a clock generated by comparing voltage and discharge voltage, calculating resistance values of a first pressure sensor and a first temperature sensor provided in the master sensor according to the clock measured in the master measurement step, and calculating the resistance It is characterized in that it includes a master calculation step of converting the first pressure and the first temperature from the value, and a master compensation step of correcting the first pressure according to the first temperature.

According to another embodiment of the present invention, the master measuring step is the step of primarily charging the charging capacitor in the slope analog-to-digital converter, discharging the charging capacitor by connecting it to the reference resistance in the slope analog-to-digital converter. , measuring the clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator, secondarily charging the charging capacitor, the pressure sensor resistance reading the charging capacitor from the first pressure sensor measuring the clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging in connection with the value, tertiarily charging the charging capacitor, and using the charging capacitor as a first temperature sensor. and measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging in connection with the temperature sensor resistance value read from the comparator.

According to another embodiment of the present invention, the transmitter sensing step is performed in the master sensor and measures the internal temperature of the differential pressure transmitter, and the differential pressure display step of correcting the differential pressure according to the temperature measured in the transmitter sensing step. Further, the transmitter sensing step alternately charges and discharges the charging capacitor provided in the slope analog-to-digital converter in the master sensor. When the charging capacitor is discharged, the charging capacitor is read from the reference resistance and the transmitter temperature sensor. Transmitter measurement step of measuring the clock generated by comparing the discharge voltage with the reference voltage from the reference voltage capacitor in the comparator by connecting alternately with the temperature sensor resistance value, the resistance value of the transmitter temperature sensor according to the clock measured in the transmitter measurement step and a transmitter calculation step of calculating and converting the internal temperature of the differential pressure transmitter from the resistance value, wherein the transmitter measurement step comprises: primarily charging a charging capacitor in a slope analog-to-digital converter; Measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging by connecting to a reference resistor in the analog-to-digital converter, secondarily charging the charging capacitor, the charging step It is characterized in that it comprises the step of measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the capacitor by connecting it to the temperature sensor resistance value read from the transmitter temperature sensor.

According to another embodiment of the present invention, a rest step in which the master sensor and the slave sensor are maintained in a state in which power is not used by the control unit is further included, and the master sensing step, the slave sensing step, the transmitter sensing step, and the differential pressure display It is characterized in that the step and the pause step are controlled to be repeatedly performed with a cycle of 0.7 seconds.

The present invention can obtain the following effects by combining and using the above embodiments and configurations to be described below.

The present invention measures the pressure of the fluid at the inlet or outlet of the fluid, and the master measurement unit for sensing the temperature and pressure of the fluid at the inlet or outlet, the master input unit for converting the measured analog signal to digital, and the measured pressure value A master sensor having a controller that corrects according to temperature, a slave measuring unit provided away from the master sensor and sensing the temperature and pressure of the fluid at the outlet or inlet of the fluid, and a slave input unit that converts the sensed analog signal into digital. The master input unit includes a power supply module for applying a constant current to the master measurement unit, and a slope analog-to-digital converter for converting an analog signal transmitted from the master measurement unit into a digital signal to calculate a measured value. The differential pressure can be compensated according to the temperature by measuring the pressure and temperature of the fluid at a distance from each other, including

In the present invention, the slope analog-to-digital converter includes a reference voltage capacitor for generating a reference voltage required for conversion, a discharge structure for inputting a discharge voltage through charging and discharging, and comparing the discharge voltage from the reference voltage capacitor and the discharge structure. and a capture resist that measures a clock from the comparator and a comparator that outputs a comparison signal, and the control unit converts the measured clock into temperature and pressure and corrects the measured pressure according to the temperature to drive with low power. have

In the present invention, the master measurement unit includes a first pressure sensor for measuring the pressure of the fluid at the inlet or outlet and a first temperature sensor for measuring the temperature, and the discharge structure includes a reference resistance, a pressure sensor resistance value, and a temperature sensor resistance. value and a charging capacitor, wherein the reference resistance, the pressure sensor resistance value, and the temperature sensor resistance value are alternately connected to the charging capacitor so that the charging capacitor is alternately charged and discharged to the resistance value measured by the pressure sensor and the temperature sensor. can be read directly.

In the present invention, the master input unit further includes a transmitter temperature sensor for measuring the temperature inside the differential pressure transmitter, and the control unit corrects the differential pressure between the master sensor and the slave sensor according to the temperature inside the differential pressure transmitter to obtain differential pressure Accurate temperature correction is possible.

In the present invention, the control unit controls the discharge structure to read the pressure sensor resistance value and the temperature sensor resistance value from the first pressure sensor and the first temperature sensor of the master measuring unit, or the temperature sensor resistance value from the transmitter temperature sensor. It is accompanied by the effect that high-precision differential pressure measurement is possible by controlling to read.

The present invention gives the effect of providing a differential pressure transmitter capable of deriving a corrected pressure value without a complicated calculation process by allowing the control unit to linearly approximate pre-input temperature-pressure correction data to calculate a corrected pressure value.

In the present invention, the slave input unit includes a power module for applying a constant current to the slave measurement unit, and a slope analog-to-digital converter for converting an analog signal transmitted from the slave measurement unit into a digital signal and calculating a measured value, wherein the The slave measuring unit includes a second pressure sensor for measuring the pressure of the fluid at the outlet or inlet and a second temperature sensor for measuring the temperature, and the slope analog-to-digital converter includes a reference voltage capacitor for generating a reference voltage required for conversion, charging A discharge structure for inputting a discharge voltage through over-discharge, a comparator for outputting a comparison signal by comparing the reference voltage from the reference voltage capacitor and the discharge voltage from the discharge structure, and a capture resist for measuring a clock from the comparator. However, the discharge structure includes a reference resistance, a pressure sensor resistance value, a temperature sensor resistance value, and a charging capacitor, wherein the reference resistance, pressure sensor resistance value, and temperature sensor resistance value are alternately connected to the charging capacitor so that the charging capacitor The pressure sensor resistance value and the temperature sensor resistance value that are alternately charged and discharged and sensed are converted into the temperature and pressure measured by the slave measuring unit, and the pressure of the second pressure sensor is determined according to the temperature measured by the second temperature sensor. It is possible to provide a differential pressure transmitter capable of precisely correcting the fluid pressure at the outlet outlet separated by temperature.

The present invention is performed in a master sensor provided at the inlet or outlet of the fluid, and the pressure value measured by the first pressure sensor of the master sensor is compensated according to the temperature measured by the first temperature sensor to compensate for the corrected pressure at the master sensor side. The master sensing step of calculating the value is performed by the slave sensor provided at the outlet or inlet of the fluid, and the pressure value measured by the second pressure sensor of the slave sensor is compensated according to the temperature measured by the second temperature sensor, It includes a slave sensing step of calculating a corrected pressure value, and the master sensing step is performed through a slope analog-to-digital converter in the master sensor, and alternately charges and discharges a charging capacitor, while the charging capacitor is discharged. By connecting the charging capacitor alternately with the reference resistance, the pressure sensor resistance value read from the first pressure sensor, and the temperature sensor resistance value read from the first temperature sensor, the comparator compares the reference voltage from the reference voltage capacitor and the discharge voltage. A master measurement step of measuring the generated clock, calculating resistance values of the first pressure sensor and the first temperature sensor provided in the master sensor according to the clock measured in the master measurement step, and calculating the first pressure and the first pressure from the resistance values. By minimizing the total current consumption to 3mA or less, including a master calculation step that converts 1 temperature and a master compensation step that corrects the first pressure according to the first temperature, power is supplied through a 2-wire wire in a complex structure such as a ship. While supplying, it allows the signal to be transmitted.

In the present invention, the master measuring step is the step of primarily charging the charging capacitor in the slope analog-to-digital converter, discharging the charging capacitor by connecting it to a reference resistance in the slope analog-to-digital converter, and measuring the discharge voltage and Measuring a clock generated by comparing the reference voltage from the reference voltage capacitor, secondarily charging the charging capacitor, discharging the charging capacitor by connecting it to the pressure sensor resistance value read from the first pressure sensor, The step of measuring the clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator, the step of thirdly charging the charging capacitor, and the temperature sensor resistance value reading the charging capacitor from the first temperature sensor. While discharging in connection with the comparator, it has an effect of enabling precise differential pressure measurement, including the step of measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor.

The present invention, carried out by the master sensor, further includes a transmitter sensing step of measuring the internal temperature of the differential pressure transmitter, and a differential pressure display step of correcting the differential pressure according to the temperature measured in the transmitter sensing step, wherein the transmitter The sensing step alternately charges and discharges the charging capacitor provided in the slope analog-to-digital converter in the master sensor. Transmitter measurement step of measuring the clock generated by comparing the discharge voltage with the reference voltage from the reference voltage capacitor by connecting the comparator, calculating the resistance value of the transmitter temperature sensor according to the clock measured in the transmitter measurement step, and calculating the resistance value from the resistance value A transmitter calculation step of converting the internal temperature of the differential pressure transmitter, wherein the transmitter measurement step is a step of primarily charging the charging capacitor in the slope analog-to-digital converter, and the reference resistance in the slope analog-to-digital converter. While discharging by connecting to, measuring the clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator, secondarily charging the charging capacitor, reading the charging capacitor from the transmitter temperature sensor Compensating the differential pressure according to the internal temperature of the differential pressure transmitter This has the effect of enabling more precise measurements.

The present invention further includes an idle step in which the master sensor and the slave sensor are maintained in a state in which power is not used by the control unit, and the master sensing step, the slave sensing step, the transmitter sensing step, the differential pressure display step, and the idle step are 0.7 seconds. Regular differential pressure measurement and transmission is possible by controlling to be repeatedly performed with a period of .

1 is a block diagram of a differential pressure transmission device according to a preferred embodiment of the present invention
2 is a view showing that the master sensor 100 and the slave sensor 200 are provided at the inlet 81 and the outlet 82 of the fluid according to a preferred embodiment of the present invention.
3 is a diagram showing a slope analog-to-digital converter (ADC, 121) according to an embodiment of the present invention
4 is a charge for measuring resistance values of a first pressure and a first temperature measured by a first pressure sensor and a first temperature sensor in a slope analog-to-digital converter (ADC, 121) according to a preferred embodiment of the present invention. A diagram showing measuring the number of clocks through charging and discharging of a capacitor
5 is a graph showing the resistance value of the internal temperature of the differential pressure transmitter measured by the transmitter temperature sensor in the slope analog-to-digital converter (ADC, 121) according to a preferred embodiment of the present invention through charging and discharging of the charging capacitor. A diagram showing measuring the number of clocks
6 is a diagram illustrating power consumed in an active mode and a sleep mode according to an embodiment of the present invention;
7 is a flowchart of a differential pressure measuring method (S) according to an embodiment of the present invention
8 is a flowchart of a differential pressure measuring method (S) according to a preferred embodiment of the present invention
9 is a view showing the current consumption according to each step of the differential pressure measuring method (S) according to an embodiment of the present invention

Hereinafter, a surgical instrument according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that like elements in the drawings are indicated by like numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted. Unless there is a special definition, all terms in this specification are the same as the general meaning of the term understood by a person skilled in the art to which the present invention belongs, and if it conflicts with the meaning of the term used in this specification, the present invention Follow the definitions used in the specification.

Throughout the specification, when a part is said to "include" a certain element, this means that it does not exclude other elements unless otherwise stated, and may further include other elements, and the specification Terms such as “~unit” described herein mean a unit that processes at least one function or operation. In addition, when it is said that certain components are "connected", this is not limited to being in direct contact with each other and fastening, but includes fastening through other components, and even if they are not fastened, a predetermined force or energy can be transmitted. It can mean that it is arranged so that Terms such as "first ~" and "second ~" may be used to indicate the same or substantially the same configuration in a different order, and may be used to indicate the same or substantially the same configuration as "first" or "second". can be interpreted as composition. Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings.

1 is a block diagram of a differential pressure transmitter 1 according to a preferred embodiment of the present invention. The differential pressure transmission device 1 measures the temperature and pressure of the fluid at the inlet and outlet of the fluid at a distance, preferably 5 m or more, and then corrects the pressure based on the temperature measured at the inlet and outlet to obtain the Precisely measure the pressure, compensate for the differential pressure calculated by calculating the pressure difference between the fluid at the inlet and outlet based on the temperature inside the differential pressure transmitter, and measure the discharge time through the charging and discharging of the resistor and condenser to measure the sensor value. By using a slope analog-digital conversion method that calculates , high-precision differential pressure measurement and transmission is possible even in a low current environment, minimizing the total current consumption used in the master sensor and slave sensor to less than 3mA, so that in complex structures such as ships, 2 It is possible to reduce the amount of wire used and installation cost by allowing signals to be transmitted while power is supplied through the wire. The differential pressure transmitter 1 includes a master sensor 100 and a slave sensor 200 . As shown in FIG. 2 , the master sensor 100 and the slave sensor 200 are provided at the inlet and outlet of the fluid to measure the temperature and pressure of the fluid. In a preferred embodiment of the present invention shown in FIG. 2, the master sensor 100 is provided on the side of the inlet 81 through which coolant flows in the engine 80 such as the LDCL system, and is spaced a predetermined distance from the inlet 81 and the slave sensor 200 may be provided on the side of the outlet 82 through which cooling water flows out. In this way, when the inlet and the outlet are separated, preferably by 5 m or more, the temperature of the cooling water at the inlet 81 and the outlet 82 is different from each other, and the pressure sensor for measuring the pressure of the cooling water using a semiconductor device depends on the temperature. Since the measured pressure is different, an error occurs in the differential pressure measurement. Therefore, the master sensor 100 and the slave sensor 200 according to the present invention are connected to each other to transmit the measured temperature and pressure as electrical signals while minimizing the error of the measured pressure according to the temperature.

The master sensor 100 measures the pressure of the fluid at the inlet or outlet of the fluid, and the master measuring unit 110 senses the temperature and pressure of the fluid at the inlet or outlet, converts the measured analog signal into digital, and converts the measured analog signal to a temperature. A master input unit 120 that compensates for the pressure sensed according to the temperature, a control unit 130 that corrects the measured pressure value according to temperature, and a master that outputs an electrical or visual signal and allows an external user to operate the differential pressure transmitter. An output unit 140 may be included.

The master measuring unit 110 is provided to sense the temperature and pressure of the fluid at the inlet or outlet, and may be preferably provided at the inlet side of the fluid. The master measuring unit 110 may include a first pressure sensor 111 and a first temperature sensor 112 to measure the pressure and temperature of the fluid passing through the inlet. The first pressure sensor 111 may be a Wheatstone bridge type pressure sensor. Since the first pressure sensor 111 is provided as a wheatstone bridge type pressure sensor, a semiconductor device is used, and the first temperature sensor 112 for measuring the temperature at the inlet to compensate for the measurement pressure error according to the temperature is may be provided.

The master input unit 120 may be provided to convert a measured analog signal into a digital signal. Also, the master input unit 120 may be provided to apply a constant current to the master measurement unit 110 . The master input unit 120 may include a slope analog-to-digital converter (slope ADC, 121), a transmitter temperature sensor 122, and a power module 123.

3 is a diagram illustrating a slope analog-to-digital converter (ADC) 121 according to an embodiment of the present invention. Referring to FIGS. 2 and 3 , the slope analog-to-digital converter 121 outputs a first temperature and a first pressure in an analog format measured from the master measurement unit 110 and/or a transmitter temperature sensor 122 to be described later. The measured internal temperature of the differential pressure transmitter can be converted into a digital signal. At this time, the slope analog-to-digital converter 121 according to an embodiment of the present invention measures the discharge time through charging of the capacitor and discharging by the resistance, and calculates the measured values, that is, the temperature and pressure. can be a converter. The slope analog-to-digital converter 121 receives and compares an input signal having a constant voltage level and a ramp signal, and determines a time or time point at which the voltage level of the input signal and the voltage level of the ramp signal are equal. It is an ADC that converts to a digital signal (or digital code). The slope analog-to-digital converter 121 may include a discharge structure 1211, a comparator 1212, a capture resist 1213, a timer resist 1214, and a reference voltage capacitor 1215. In low-power operation, an ultra-low-power MCU (eg, STM32L071, etc.) may be used for the slope analog-to-digital converter 121 .

The discharge structure 1211 may be provided to sense a resistance value in a comparator 1212 and a capture resist 1213 to be described later by inputting a discharge voltage through charging and discharging. The discharge structure 1211 is charged and discharged according to a series of processes under the control of the controller 130 or an MCU (not shown) in the slope analog-to-digital converter 121 in the MCU in the slope analog-to-digital converter 121. Allows direct reading of temperature sensor and pressure sensor values.

As shown in FIG. 3 , the discharge structure 1211 may include a reference resistance R _ref , a temperature sensor resistance value R _T , a pressure sensor resistance value R _P , and a charging capacitor C _M . The charging capacitor (C _M ) is provided so that it can be charged with a reference voltage through Pz. The reference resistance (R _ref ), the temperature sensor resistance value (R _T ), and the pressure sensor resistance value (R _P ) are provided to be connected to the charging capacitor (C _M ) in a circuit, and the reference resistance (R _ref ), the temperature The sensor resistance value (R _T ) and the pressure sensor resistance value (R _P ) are alternately connected so that the charging capacitor (C _M ) can be discharged. The charging and discharging process of the charge capacitor (C _M ) will be described later.

The reference resistance (R _ref ) is provided inside the slope analog-to-digital converter 121, the reference resistance (R _ref ) may be a predetermined value, and is connected to the MCU in the slope analog-to-digital converter 121 through Py As a result, the charging capacitor (C _M ) can be discharged. As the charging capacitor C _M is alternately charged and discharged, the discharge voltage input from the discharge structure 1211 to the comparator 1212 may have a waveform as shown in FIG. 4 .

The pressure sensor resistance value (R _P ) and the temperature sensor resistance value (R _T ) may be provided to read the resistance values of the pressure sensor and the temperature sensor, respectively, and may be substantially electrical signals transmitted from the pressure sensor and the temperature sensor. . Since the temperature and pressure measured by the first pressure sensor 111, the first temperature sensor 112, or the transmitter temperature sensor 122 of the master measuring unit 110 have variable values, the pressure sensor resistance value (R _P ) and the temperature sensor resistance value (R _T ) can be displayed as a variable resistance. The pressure sensor resistance value (R _P ) and the temperature sensor resistance value (R _T ) are connected to the MCU in the slope analog-to-digital converter 121 through Pw and Px, respectively, so that the charging capacitor ( _CM ) can be discharged. .

The comparator 1212 compares a reference voltage from a reference voltage capacitor 1215 to be described later with a discharge voltage from the discharge structure 1211 and outputs a comparison signal. The comparator 1212 outputs a comparison signal (eg, a signal indicating a value of High or 1) at the point in time when the reference voltage and the discharge voltage are compared. The comparison signal output from the comparator is a clock signal and may be input to the capture resist 1213 to be described later. Therefore, as can be seen in FIGS. 4 and 5, the charging capacitor is discharged in connection with the reference resistance (R _ref ), the pressure sensor resistance value (R _P ), and the temperature sensor resistance value (R _T ), so that the discharge voltage is converted into a comparator ( 1212), the comparator 1212 compares the discharge voltage with the reference voltage and outputs a clock as a comparison signal.

The capture resist 1213 is provided to measure the number of clocks output from the comparator 1212 . The value of the counter register may increase at a constant clock rate according to the clock Cout output from the comparator 1212 .

The timer register 1214 performs counting according to the internal clock number of the system. When the reference voltage capacitor ( _CM ) is discharged, many clocks may be generated depending on the pressure sensor resistance value ( _RP ) and the temperature sensor resistance value (RT _T ), so the timer resist 1214 of the present invention is a 32-bit counter/timer resist It is preferable to be provided with. The number of clocks may be calculated as an oscillator value used in an MCU (not shown).

The reference voltage capacitor 1215 is a configuration provided to supply a constant voltage to the ADC, and can generate a reference voltage required for conversion operation of the ADC 121. The reference voltage V _ref generated through the reference voltage generator (not shown) may be stored in the reference voltage capacitor Cref. The reference voltage (V _ref ) stored in the reference voltage capacitor (C _ref ) is input to the comparator and compared with the discharge voltage. Since the reference voltage Vr _ef is provided to the ADC 121 through the reference voltage capacitor C _ref , operation stability may be improved compared to a case in which the reference voltage generator is directly connected to the ADC 121 . The reference voltage (V _ref ) may be provided to the comparator through another method not illustrated.

The transmitter temperature sensor 122 is provided to measure the internal temperature of the differential pressure transmitter, and preferably can measure the internal temperature of the transmitter. In order to precisely compensate for the differential pressure, the measured temperature may be transmitted as an electrical signal to the temperature sensor resistance value of the slope analog-to-digital converter (ADC) 121 as described above.

The power module 123 is provided to apply a constant current to the master measuring unit 110, and to continuously have a constant current (eg, constant current of 0.9 mA) in order to operate the differential pressure transmitter according to the present invention with low power. Authorization) is preferably provided. Even when the internal resistance of the pressure sensor varies depending on the manufacturer and environment such as temperature, the voltage output to apply the constant current may be variable.

The control unit 130 is provided to correct the measured pressure value according to the temperature, and can control the electrical signal output through the master output unit 140 and the display format. The controller 130 calculates the discharge time based on the measured number of clocks, corrects the pressure according to the temperature, calculates the differential pressure between the master sensor 100 and the slave sensor 200, and calculates the pressure according to the temperature. After correction, the result may be transmitted or displayed through the master output unit 140 . In addition, the controller 130 may be provided so that the user can adjust the differential pressure measurement period, and can be controlled by software in an MCU (not shown). As can be seen in FIG. 6, the step of measuring the temperature and pressure in the master sensor 100 and the slave sensor 200, correcting the pressure according to the temperature, and displaying and transmitting the differential pressure is called an active mode, and the measurement And if the differential pressure transmitter enters the rest state after displaying the sleep mode, in a preferred embodiment of the present invention, the time used in the active mode is 0.6 seconds, the standby time in the sleep mode is 0.1 seconds, and the differential pressure It can be seen that the shorter the measurement period, the lower the power consumed by the differential pressure transmitter including the slope analog-to-digital converter.

The control unit 130 may calculate a corrected pressure value by performing a linear approximation of the pre-input temperature-pressure corrected data. In this case, the correction pressure value may be calculated by approximating a linear function having a slope of a change in correction data according to a change in measured pressure within a pressure range of temperature-pressure data including the measured pressure.

In one embodiment of the present invention, temperature-pressure data as shown in Table 1 below may be pre-input into the control unit 130, and a linear approximation corrected pressure value may be calculated as follows.

Press.
Temp. 0 One 2 3 4 5 6 7 8 9 10 0 0.012 1.126 2.085 3.003 3.964 4.934 5.885 6.843 7.814 8.762 9.854 10 0.013 1.134 2.103 3.031 3.992 4.952 5.901 6.864 7.837 8.784 9.877 20 0.015 1.142 2.123 3.063 4.019 4.977 5.927 6.885 7.861 8.803 9.900 30 0.018 1.150 2.144 3.097 4.045 4.991 5.943 6.901 7.883 8.828 9.923 ... ... ... ... ... ... ... ... ... ... ... ... 300 0.108 1.233 2.214 3.149 4.189 5.129 6.002 7.154 8.135 9.153 10.185

Pressure measurement range: 0 ~ 10 bar

Pressure reading: 1.5 bar

Temperature reading: 25.5 ℃

In the previously entered temperature-pressure data, since 25.5 ° C is close to the 30 ° C section, the 30 ° C section line is applied. When the linear approximation equation is obtained, y = 0.994x + 0.156 is derived, and when the measured pressure value 1.5 is applied to x, the corrected pressure value is derived as 1.647 bar.

In a preferred embodiment of the present invention, an accurate corrected pressure value can be obtained by setting the interval of the temperature section of the temperature-pressure correction data to 1°C.

In addition, upon reflection of the compensated pressure value according to an embodiment of the present invention, the pressure compensation equation may be Pa'=((25°C-Ta)*0.3)Pa+Pa. Here, Pa' may be a correction pressure value after compensation, Ta may be a measured temperature, and Pa may be a measured pressure.

The master output unit 140 transmits and displays the precisely measured differential pressure as an electrical signal, and may be driven by the control unit 130. The master output unit 140 includes a digital-to-analog converter (DAC, 141) that converts a digital signal into an analog signal, a display module 142 that externally displays the converted analog differential pressure, and a user operating the differential pressure transmitter. It may include a manipulation module 143 capable of input so as to be able to do so.

Referring again to FIGS. 1 to 3, the slave sensor 200 of the present invention is described. The slave sensor 200 measures the pressure of the fluid at the outlet or inlet of the fluid, and measures the temperature and temperature of the fluid at the outlet or inlet. It may include a slave measurement unit 210 that senses pressure and a slave input unit 220 that converts a measured analog signal into a digital signal.

The slave measuring unit 210 is provided to sense the temperature and pressure of the fluid at the outlet or the inlet, and may be provided at the outlet side of the fluid spaced apart from the inlet by a predetermined distance. The slave measurement unit 210 may include a pressure sensor and a temperature sensor similar to the above-described master measurement unit 110, and may include a second pressure sensor 211 and a second pressure sensor 211 to measure the pressure and temperature of the fluid passing through the outlet. A second temperature sensor 212 may be included. The second pressure sensor 211 may be a Wheatstone bridge type pressure sensor.

The slave input unit 220 may be provided to convert a measured analog signal into a digital signal. As in the case of the master input unit 120 described above, the slave input unit 220 may be provided to apply a constant current to the slave measurement unit 210 . The slave input unit 220 may include a control module 221, a slope analog-to-digital converter (slope ADC, 222), and a power module 123.

The control module 221 controls the slave input unit 220 and the slave measuring unit 210, and the discharge time calculation and temperature compensation process of the slave sensor 200 are performed by the control module 221 or An electrical signal may be transmitted by the control module 221 to be performed by the controller 130 of the master sensor 100 . The control module 221 may be an MCU included in the slave input unit 220 .

The slope analog-to-digital converter (slope ADC, 222) may be substantially the same as the slope analog-to-digital converter (slope ADC, 121) provided in the master sensor. Accordingly, the slope analog-to-digital converter (slope ADC, 222) may be a single slope analog-to-digital converter that calculates the measured values, that is, temperature and pressure, by measuring the discharge time through charging of the capacitor and discharging by the resistor, The resistance values from the second pressure sensor 211 and the second temperature sensor 212 are converted into digital signals so that the resistance values of the second pressure and the second temperature measured by the slave measuring unit 210 are directly corrected. can do. The detailed configuration of the slope analog-to-digital converter (slope ADC, 222) will be described by replacing it with the slope analog-to-digital converter (slope ADC, 121) provided in the master sensor.

Hereinafter, a differential pressure measuring method (S) according to an embodiment of the present invention will be described with reference to FIGS. 4 to 9 . The differential pressure measuring method (S) according to the present invention measures the temperature and pressure of the fluid at the inlet and outlet of the fluid at a distance, preferably 5 m or more, and then corrects the pressure based on the temperature measured at the inlet and outlet By doing so, the pressure of the fluid is precisely measured, the differential pressure is compensated by calculating the difference in pressure between the fluid at the inlet and outlet based on the temperature inside the differential pressure transmitter, and the discharge time is measured through the charging and discharging of the resistor and capacitor. By using the slope analog-digital conversion method that calculates the sensor value by using the slope analog-digital conversion method to enable high-precision differential pressure measurement and transmission even in a low current environment, the total current consumption used by the master sensor and slave sensor is minimized to less than 3mA, so that complex It is possible to reduce the amount of wire used and the cost of installation by allowing the structure to transmit signals while supplying power through a two-wire wire. The differential pressure measuring method (S) includes a master sensing step (S1), a slave sensing step (S2), a transmitter sensing step (S3), a differential pressure display step (S4), a pause step (S5) and a control step (S6). can do. In a preferred embodiment of the present invention, the master sensing step (S1), the slave sensing step (S2), and the transmitter sensing step (S3) are sequentially performed, but the master sensing step (S1), the slave sensing step (S2), and the transmitter sensing step (S2) The sensing step (S3) may be performed in a reversed order.

The master sensing step (S1) is performed by a master sensor provided at the inlet or outlet of the fluid, and the pressure value measured by the first pressure sensor of the master sensor is compensated according to the temperature measured by the first temperature sensor to compensate the master sensor. The step of calculating the corrected pressure value on the side includes a master measurement step (S11), a master calculation step (S12) and a master compensation step (S13).

In the master measuring step (S11), the charging capacitor ( _CM ) is alternately charged and discharged, and when the charging capacitor is discharged, the charging capacitor is reference resistance (R _ref ) and the pressure sensor resistance value read from the first pressure sensor (R _P ), alternately connected to the temperature sensor resistance value (R _T ) read from the first temperature sensor, and measuring the clock generated by comparing the discharge voltage with the reference voltage from the reference voltage capacitor in the comparator, It can be performed through the slope analog-to-digital converter 121 in the master sensor. Therefore, the master measuring step (S11) converts the first pressure and the first temperature in analog format measured from the first pressure sensor 111 and the first temperature sensor 112 of the master sensor 100 into digital format. . In particular, the first pressure sensor is a Wheatstone bridge type, and since the measured value changes depending on the temperature using a semiconductor device, an error occurs in the differential pressure, so the pressure sensor resistance value (R _P ) corresponding to the first pressure and the first temperature and the temperature sensor resistance value (R _T ) must be converted into digital form and calculated.

The master measuring step (S11), as shown in FIGS. 4 and 9, is a step of primarily charging the charging capacitor in the slope analog-to-digital converter (S111), and the charging capacitor as a reference in the slope analog-to-digital converter. While discharging by connecting to a resistor, measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor (S112), secondarily charging the charging capacitor (S113), and the charging Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the capacitor by connecting it to the resistance value of the pressure sensor read from the first pressure sensor (S114), Thirdly charging (S115) and discharging the charging capacitor by connecting it to the temperature sensor resistance value read from the first temperature sensor, and comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator to a clock generated. It may include measuring (S116).

That is, by the control of the slope analog-to-digital converter 121 or the MCU (not shown) inside the ADC 121, the charging capacitor (C _M ) is primarily charged up to V _cc with a reference voltage through Pz (S111 ). When the primary charge is completed, while the charging capacitor (C _M ) is primary discharged through the reference resistor (R _ref ), the comparator 1212 generates a comparison signal until the discharge voltage is reduced to 25% of Vcc and captures The register 1213 and the timer register 1214 measure the number of pulses or clocks (S112). Through this, the number of clocks corresponding to the resistance value of the reference resistor R _ref can be obtained.

After the primary discharge is completed, the charging capacitor (C _M ) is secondarily charged with the reference voltage through Pz (S113). When the secondary charge is completed, discharge proceeds through the pressure sensor resistance value (R _P ), and the comparator compares the reference voltage from the reference voltage capacitor (C _ref ) and the discharge voltage from the discharge structure (1211) to capture the resist. The number of clocks (C _out ) corresponding to the resistance value (R _P ) of the pressure sensor is obtained by measuring the number of clocks through (S114).

In this way, after charging the charging capacitor (C _M ) tertiarily with the reference voltage (S115), the tertiary discharge is performed through the temperature sensor resistance value (R _T ), and the temperature sensor resistance value (R _T ) A corresponding number of clocks can be obtained (S116). In this way, the clock number for the resistance value corresponding to the first pressure and the first temperature is obtained through the alternating charging and discharging of the charging capacitor (CM ₎ .

In the master calculation step (S12), the resistance values (R _P , R _T ) of the first pressure sensor and the first temperature sensor provided in the master sensor are calculated according to the number of clocks measured in the master measurement step, and the resistance values are calculated. This is a process of converting the first pressure and the first temperature from

The master compensation step (S13) is a process of correcting the first pressure according to the first temperature, a process of correcting the first pressure according to the first temperature measured as described above, and may be performed by the control unit 130. there is. As described above, the master compensation step (S13) may be performed to calculate a corrected pressure value by performing a linear approximation of the pre-input temperature-pressure correction data.

7 and 8 again, the slave sensing step (S2) is performed by the slave sensor 200 provided at the outlet or inlet of the fluid, and the second pressure measured by the second pressure sensor of the slave sensor A step of compensating according to the second temperature measured by the second temperature sensor to calculate a corrected pressure value on the slave sensor side, including a slave measurement step (S21), a slave calculation step (S22) and a slave compensation step (S23). . Hereinafter, the slave measurement step (S21), the slave calculation step (S22), and the slave compensation step (S23) are the second pressure obtained from the second pressure sensor 211 and the second temperature sensor 212 of the slave sensor 200. Since it is substantially the same as the corresponding steps performed in the master sensing step (S1) through the second temperature and the description of the above-described master measuring step (S11), master calculation step (S12) and master compensation step (S13) let it change

The transmitter sensing step (S3) is a process of measuring the internal temperature of the differential pressure transmitter, and may be performed by the control of the control unit 130 in the master sensor. The transmitter sensing step (S3) may include a transmitter measuring step (S31) and a transmitter calculating step (S33).

In the transmitter measuring step (S31), the charging capacitor provided in the slope analog-to-digital converter in the master sensor is alternately charged and discharged. When the charging capacitor is discharged, the charging capacitor is the reference resistance and the temperature sensor resistance read from the transmitter temperature sensor. This is the process of measuring the clock generated by comparing the reference voltage and the discharge voltage from the reference voltage capacitor in the comparator by connecting alternately to the value. is performed to convert to

As shown in FIG. 5, the transmitter measuring step (S31) is a step of primarily charging the charging capacitor in the slope analog-to-digital converter (S311), connecting the charging capacitor to the reference resistance in the slope analog-to-digital converter While discharging, measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor (S312), secondarily charging the charging capacitor (S313), and setting the charging capacitor to the transmitter temperature and measuring a clock generated by comparing the discharge voltage in the comparator with the reference voltage from the reference voltage capacitor while discharging in connection with the resistance value of the temperature sensor read from the sensor (S314). That is, since the pressure is not separately measured in the transmitter measuring step (S31), it is performed without measuring the number of clocks for the pressure sensor resistance value (R _P ).

The transmitter calculation step (S33) is a process of calculating the resistance value of the transmitter temperature sensor according to the clock measured in the transmitter measurement step and converting the internal temperature of the differential pressure transmitter from the resistance value.

In the differential pressure display step (S4), the differential pressure is calculated by calculating the first pressure and the second pressure measured and corrected by the master sensor 100 and the slave sensor 200 to obtain the differential pressure, which is the internal temperature of the transmitter and/or the differential pressure transmitter. This is the process of obtaining the calibrated differential pressure by compensating according to , and then displaying it or transmitting it as an electrical signal. The differential pressure display step (S4) includes a differential pressure compensation step (S41) and a display step (S42).

The differential pressure compensation step (S41) may be performed by the control unit 130, and the differential pressure converted in the transmitter sensing step (S3) after obtaining the difference between the corrected pressure values of the master sensor 100 and the slave sensor 200 As a step of compensating the differential pressure according to the internal temperature of the transmission device, it may be performed in substantially the same manner as the pressure compensating process in the controller 130 described above. That is, a corrected differential pressure value may be calculated by performing a linear approximation of previously input temperature-pressure correction data, and in another embodiment of the present invention, differential pressure compensation may be performed according to a compensation formula.

The display step (S42) is a step of displaying or transmitting the corrected differential pressure to the outside, and the differential pressure converted to analog format by the digital-to-analog converter (DAC, 141) is displayed on the display module 142 or It can be transmitted as an electrical signal of 20mA current.

The pause step (S5) is a process in which the master sensor and the slave sensor are maintained in a state in which power is not used, and can be achieved by entering the MCU (not shown) of the master sensor and the slave sensor into a sleep mode by the control unit 130. can After the pause step (S5), the processes of the master sensing step (S1) to the differential pressure display step (S4) may be repeatedly performed according to the control. As shown in FIG. 6, in a preferred embodiment of the present invention, the process of master sensing step (S1) to differential pressure display step (S4) is performed at a time of 0.6 seconds, and the pause step (S5) is maintained for 0.1 second, so that the master The process of the sensing step (S1) to the pausing step (S5) may be repeatedly performed at a cycle of 0.7 seconds. However, the period of 0.7 seconds may be controlled by software manipulation.

The control step (S6) is a process of controlling each component of the differential pressure transmitter 1 or each step of the differential pressure measuring method (S) according to the present invention, preferably a master sensing step, a slave sensing step, The time required for each of the transmitter sensing step, differential pressure display step, and pause step can be adjusted. In particular, the time at which the slope analog-to-digital converters 121 and 222 of the master input unit 120 and the slave input unit 220 convert analog signals into digital signals can be adjusted, and the duration of the pause step (S5) can be adjusted. You can adjust the time required.

The above detailed description is illustrative of the present invention. In addition, the foregoing is intended to illustrate and describe preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, changes or modifications are possible within the scope of the concept of the invention disclosed in this specification, within the scope equivalent to the written disclosure and / or within the scope of skill or knowledge in the art. The written embodiment describes the best state for implementing the technical idea of the present invention, and various changes required in the specific application field and use of the present invention are also possible. Therefore, the above detailed description of the invention is not intended to limit the invention to the disclosed embodiments. Also, the appended claims should be construed to cover other embodiments as well.

1: Differential pressure measuring device
100: master sensor 110: master measurement unit
111: first pressure sensor 112: first temperature sensor
120: master input unit 121: slope analog-to-digital converter (ADC)
1211: discharge structure 1212: comparator
1213: capture resist 1214: timer resist
1215: reference voltage capacitor (C _ref )
C _M : charging capacitor R _ref : reference resistance
R _P : Resistance value of pressure sensor R _T : Resistance value of temperature sensor
122: transmitter temperature sensor 123: power module
130: control unit
140: master output unit 141: digital-to-analog converter (DAC)
142: display module 143: control module
S: Differential pressure measurement method
S1: master sensing step S11: master measuring step
S12: Master calculation step S13: Master compensation step
S2: Slave sensing step S21: Slave measuring step
S22: Slave calculation step S23: Slave compensation step
S3: Transmitter sensing step
S31: Transmitter measurement step S32: Transmitter calculation step
S4: differential pressure display step
S41: differential pressure compensation step S42: display step

Claims (13)

A master measurement unit that measures the pressure of the fluid at the inlet or outlet of the fluid, senses the temperature and pressure of the fluid at the inlet or outlet, a master input unit that converts the measured analog signal to digital, and corrects the measured pressure value according to the temperature A master sensor having a control unit to
A slave sensor provided apart from the master sensor and having a slave measuring unit for sensing the temperature and pressure of the fluid at the outlet or inlet of the fluid and a slave input unit for converting the sensed analog signal into digital,
The master input unit includes a power supply module for applying a constant current to the master measurement unit, and a slope analog-to-digital converter for converting an analog signal transmitted from the master measurement unit into a digital signal to calculate a measured value. . According to claim 1,
The slope analog-to-digital converter includes a reference voltage capacitor that generates a reference voltage required for conversion, a discharge structure that inputs a discharge voltage through charge and discharge, and a comparison signal by comparing the discharge voltage from the reference voltage capacitor and the discharge structure. A comparator for outputting and a capture resist for measuring a clock from the comparator,
The control unit converts the measured clock into temperature and pressure and corrects the measured pressure according to the temperature. The method of claim 2, wherein the master measuring unit comprises a first pressure sensor for measuring the pressure of the fluid at the inlet or outlet and a first temperature sensor for measuring the temperature,
The discharge structure includes a reference resistance, a pressure sensor resistance value, a temperature sensor resistance value, and a charging capacitor,
The differential pressure transmission device, characterized in that the reference resistance, the pressure sensor resistance value, and the temperature sensor resistance value are alternately connected to the charging capacitor so that the charging capacitor is alternately charged and discharged. The method of claim 3, wherein the master input unit further comprises a transmitter temperature sensor for measuring the temperature inside the differential pressure transmitter, and the controller corrects the differential pressure between the master sensor and the slave sensor according to the temperature inside the differential pressure transmitter Differential pressure transmission device, characterized in that. The method of claim 4, wherein the control unit controls the discharge structure to read a pressure sensor resistance value and a temperature sensor resistance value from the first pressure sensor and the first temperature sensor of the master measuring unit, or controls the temperature sensor from the transmitter temperature sensor. Differential pressure transmission device characterized in that the control to read the resistance value. 6. The differential pressure transmission device according to claim 5, wherein the control unit calculates the corrected pressure value by performing a linear approximation of the pre-input temperature-pressure correction data. The method according to any one of claims 1 to 6, wherein the slave input unit is a power module for applying a constant current to the slave measurement unit, converting an analog signal transmitted from the slave measurement unit into a digital signal to calculate a measured value Includes a slope analog-to-digital converter;
The slave measuring unit includes a second pressure sensor for measuring the pressure of the fluid at the outlet or the inlet and a second temperature sensor for measuring the temperature,
The slope analog-to-digital converter includes a reference voltage capacitor that generates a reference voltage required for conversion, a discharge structure that inputs a discharge voltage through charging and discharging, and compares the reference voltage from the reference voltage capacitor with the discharge voltage from the discharge structure. A comparator for outputting a comparison signal and a capture resist for measuring a clock from the comparator,
The discharge structure includes a reference resistance, a pressure sensor resistance value, a temperature sensor resistance value, and a charging capacitor,
The reference resistance, the pressure sensor resistance value, and the temperature sensor resistance value are alternately connected to a charging capacitor so that the charging capacitor is alternately charged and discharged.
The sensed pressure sensor resistance value and the temperature sensor resistance value are converted into the temperature and pressure measured by the slave measuring unit, and the pressure of the second pressure sensor is corrected according to the temperature measured by the second temperature sensor. pressure transmitter. It is performed in a master sensor provided at the inlet or outlet of the fluid, and the pressure value measured by the first pressure sensor of the master sensor is compensated according to the temperature measured by the first temperature sensor to calculate a corrected pressure value at the master sensor side master sensing stage,
Slave that is performed in the slave sensor provided at the outlet or inlet of the fluid and compensates the pressure value measured by the second pressure sensor of the slave sensor according to the temperature measured by the second temperature sensor to calculate the corrected pressure value on the slave sensor side Including the sensing step,
The master sensing step,
It is performed through the slope analog-to-digital converter in the master sensor, and the charging capacitor is alternately charged and discharged. When the charging capacitor is discharged, the charging capacitor is referred to as the reference resistance, the pressure sensor resistance value read from the first pressure sensor, and the first A master measurement step of measuring a clock generated by comparing the discharge voltage with the reference voltage from the reference voltage capacitor in a comparator by alternately connecting the resistance value of the temperature sensor read from the temperature sensor;
A master calculation step of calculating resistance values of a first pressure sensor and a first temperature sensor provided in the master sensor according to the clock measured in the master measurement step and converting a first pressure and a first temperature from the resistance values; and
A differential pressure measuring method comprising a master compensation step of correcting the first pressure according to the first temperature. The method of claim 8, wherein the master measurement step,
Primarily charging the charging capacitor in the slope analog-to-digital converter;
Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to a reference resistor in the slope analog-to-digital converter;
Secondarily charging the charging capacitor;
Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to the pressure sensor resistance value read from the first pressure sensor;
thirdly charging the charging capacitor; and
and measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to the temperature sensor resistance value read from the first temperature sensor. Differential pressure measurement method. The method of claim 8, wherein the slave sensing step comprises:
It is performed through a slope analog-to-digital converter, and the charging capacitor is alternately charged and discharged. When the charging capacitor is discharged, the charging capacitor is measured from the reference resistance, the pressure sensor resistance value read from the second pressure sensor, and the second temperature sensor. A slave measurement step of measuring a clock generated by comparing the discharge voltage with the reference voltage from the reference voltage capacitor in the comparator by alternately connecting the read temperature sensor resistance value;
A slave calculation step of calculating resistance values of a second pressure sensor and a second temperature sensor provided in the slave sensor according to the clock measured in the slave measurement step and converting a second pressure and a second temperature from the resistance values; and
A slave compensation step of correcting the second pressure according to the second temperature,
The slave measurement step,
Primarily charging the charging capacitor in the slope analog-to-digital converter;
Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to a reference resistor in the slope analog-to-digital converter;
Secondarily charging the charging capacitor;
Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to the resistance value of the pressure sensor read from the second pressure sensor;
thirdly charging the charging capacitor; and
and measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to the temperature sensor resistance value read from the second temperature sensor. Differential pressure measurement method. The method of claim 8, wherein the transmitter sensing step is performed in the master sensor and measures the internal temperature of the differential pressure transmitter;
Further comprising a differential pressure display step of correcting the differential pressure according to the temperature measured in the transmitter sensing step,
In the transmitter sensing step, the charging capacitor provided in the slope analog-to-digital converter in the master sensor is alternately charged and discharged. Transmitter measurement step of measuring the clock generated by connecting alternately and comparing the reference voltage and the discharge voltage from the reference voltage capacitor in the comparator;
A transmitter calculation step of calculating a resistance value of the transmitter temperature sensor according to the clock measured in the transmitter measurement step and converting the internal temperature of the differential pressure transmitter from the resistance value,
The transmitter measurement step,
Primarily charging the charging capacitor in the slope analog-to-digital converter;
Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to a reference resistor in the slope analog-to-digital converter;
Secondarily charging the charging capacitor;
Measuring a clock generated by comparing the discharge voltage and the reference voltage from the reference voltage capacitor in the comparator while discharging the charging capacitor by connecting it to the temperature sensor resistance value read from the transmitter temperature sensor. Differential pressure measurement method. The differential pressure measuring method according to any one of claims 8 to 11, further comprising a resting step in which the master sensor and the slave sensor are maintained in a state in which power is not used by the control unit. The differential pressure measuring method according to claim 12, wherein the master sensing step, the slave sensing step, the transmitter sensing step, the differential pressure displaying step, and the pause step are repeatedly performed at intervals of 0.7 seconds.

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