CA2838390A1 - Pressure adjustment apparatus - Google Patents
Pressure adjustment apparatus Download PDFInfo
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- CA2838390A1 CA2838390A1 CA2838390A CA2838390A CA2838390A1 CA 2838390 A1 CA2838390 A1 CA 2838390A1 CA 2838390 A CA2838390 A CA 2838390A CA 2838390 A CA2838390 A CA 2838390A CA 2838390 A1 CA2838390 A1 CA 2838390A1
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- Prior art keywords
- pressure
- chamber
- processor
- temperature
- temperature sensing
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Classifications
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D16/00—Control of fluid pressure
- G05D16/20—Control of fluid pressure characterised by the use of electric means
- G05D16/2006—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means
- G05D16/2013—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means using throttling means as controlling means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
- G01L27/002—Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
- G01L27/002—Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
- G01L27/005—Apparatus for calibrating pressure sensors
Abstract
The present disclosure relates to a pressure adjustment apparatus. The apparatus comprises: a temperature sensing chamber, a temperature control apparatus, a rough pressure adjusting mechanism, a processor, a touch screen, an analog-to-digital converter, a pressure sensor and a pressure-making chamber. The pressure sensor senses the pressure within the pressure-making chamber and outputs an electric signal which is computed by the processor to obtain a current pressure value after being converted by the analog-to-digital converter. The processor compares a set pressure value inputted by a user though the touch screen with the current pressure value detected in real time to obtain an error value. By using a double closed-loop PI control algorithm, the processor first controls the rough pressure adjusting mechanism of the inner loop to rapidly perform rough adjustment, and then controls the temperature control apparatus of the outer loop to change the chamber volume of the temperature sensing chamber by controlling temperature, and thus to achieve the function of precise pressure adjustment. The pressure adjustment control system in the present disclosure has high precision, simple structure, low cost, and wide application.
Description
PRESSURE ADJUSTMENT APPARATUS
TECHNICAL FIELD
The present disclosure relates to the field of industrial control, and in particular to a pressure adjustment apparatus using a double closed-loop PI control method to control a conventional rough pressure adjusting mechanism and the change of the chamber volume of a pressure-withstanding container of a material with a high thermal expansion coefficient to work in cooperation, so as to achieve precise adjustment of pressure.
BACKGROUND
Pressure measurement plays an important role in the industrial process control. The performance of a pressure calibrating apparatus decides the calibration precision, efficiency and cost of a pressure instrument. Fully automatic pressure calibrators are replacing conventional piston pressure gauges gradually, and are widely applied in the field of electrical power, petroleum, petrochemical engineering, metallurgy, pharmacy or the like for it has many advantages such as high precision, wide application area, easy operation, functional integration, small size and so on.
Fully automatic pressure calibrators can be classified into gas pressure calibrators and liquid pressure calibrators depending on different instruments to be calibrated. The gas pressure calibrator takes non-corrosive gas as working medium, and is usually used to calibrate pressure instruments with relatively small measure range. Normal gas pressure calibrators control the gas input quantity and the gas output quantity of the pressure-making chamber by using the ON/OFF of an electromagnetic valve to thus achieve the purpose of adjusting pressure, as shown in Fig. 1C. The liquid pressure calibrator takes non-conductive liquid such as transformer oil, sebacate, deionized water and so on as working medium, and is usually used to calibrate pressure instruments with relatively large measure range. Normal liquid pressure calibrators change the volume of the working medium in the cylinder by using an electric motor or gas to push the piston to move in the cylinder, thus achieving the purpose of adjusting pressure, as shown in Fig. 1A and Fig. 1B.
Currently, the pressure-making precision of a fully automatic pressure calibrator is mainly subject to the performance of the pressure sensor and the actuating mechanism.
The performance of the actuating mechanism is determined by the fabrication precision, the consistency of elements and the cost of fabrication and purchase of the actuating mechanism.
In a conventional gas pressure system, the response time of the electromagnetic valve is usually in the range of 10-30 ms, or in the range of 5-10 ms for better ones.
Moreover, its price is very high, and the consistency cannot be assured. The amount of gas flow during the smallest switching interval of the electromagnetic valve usually decides the precision of the pressure adjustment. Reducing the amount of gas flow during the smallest switching interval by reducing the pressure difference between the two sides of the electromagnetic valve would usually increase the complexity of the system and improve the cost. Though reducing the path diameter of the electromagnetic valve can reduce the amount of gas flow during the smallest switching interval, it increases the adjustment time at the same time. Increasing the volume of the pressure-making chamber would increase the vibration of the gas due to the bulk-cavity effect and would thus increase the adjustment time. In a conventional liquid pressure system, for a pressure-making system by the electric motor pushing the piston, the fabrication precision of the transmission screw would influence the shift of the piston in a unit step of the electric motor, and thus influence the resolution of the pressure adjustment. High precision screws are usually very expensive, and not easy to be fabricated. The electric motor adapted thereto also needs to be a stepper motor or a servo motor with high precision, stable torque, and low heating, which further . .
improves the cost of the system. For a pressure-making system with gas pushing liquid, the same difficulties as the gas pressure system exist.
SUMMARY OF THE DISCLOSURE
In view of the above, the technical problems to be solved by the present disclosure is to overcome the disadvantages of the prior art, and provide a control system in which precise pressure adjustment is performed with the deformation of a pressure-withstanding container of a material with high thermal expansion coefficients such as aluminum, copper, iron, and so on in cooperation with a conventional rough pressure adjusting mechanism (e.g., a liquid pressure cylinder or a gas actuating electromagnetic valve ). A double closed-loop PI control method is used, so as to reduce the performance requirement on a conventional adjusting mechanism, simplify the system structure, reduce the influence of the element cost and consistency of the system, and improve the precision of the pressure-making to some extent.
In order to achieve the above object, one aspect of the present disclosure provides a pressure adjustment apparatus, comprising: an actuating mechanism (1) comprising a temperature sensing chamber (3), a temperature control apparatus (4), a rough pressure adjusting mechanism (5) and a pressure-making chamber (10), the pressure-making chamber (10) being connected to the chamber of the temperature sensing chamber (3) to make the pressure within the chambers equal; and a control mechanism (2) comprising a processor (6), a touch screen (7), an analog-to-digital converter (8) and a pressure sensor (9), wherein the pressure sensor (9) senses the pressure within the pressure-making chamber (10) and outputs an electric signal which is computed by the processor (6) to obtain a realtime pressure value after being collected by the analog-to-digital converter (8), and the processor (6) compares a set pressure value inputted by a user though the touch screen (7) with the current pressure value to obtain an error value, and performs a double closed-loop control on the actuating mechanism (1) to adjust the pressure within the pressure-making chamber (10) by comparing the error value with a set error threshold.
In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the double closed-loop control further comprises:
when the error value is outside the set error threshold range, the processor (6) initiating an inner loop to control the rough pressure adjusting mechanism (5) to perform rough pressure adjustment rapidly; when the error value is within the set error threshold range, the processor (6) initiating an outer loop to control the temperature control apparatus (4) to change the temperature of the temperature sensing chamber (3) and thus to change the chamber volume of the temperature sensing chamber (3).
In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the temperature sensing chamber is a pressure-withstanding container made of aluminum, copper or iron with a high thermal expansion coefficient.
In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the temperature control apparatus is composed of a power resistor, a Pt thermocouple, a heat dissipater and a power supply In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the analog-to-digital converter (8) is a y -A typed analog-to-digital converter (8).
Compared with the prior art, the present disclosure has the following advantages due to the adoption of the above features.
(1) In the present disclosure, an inner-loop conventional pressure adjusting mechanism and an outer-loop temperature control apparatus are used to cooperate with each other. A stable pressure adjustment with high precision is achieved by changing the . .
temperature and thus the volume of the temperature sensing chamber. The present disclosure can be applied to both the gas pressure system and the liquid pressure system.
(2) The present disclosure adopts a double closed-loop PI control method to make the rough pressure adjusting mechanism and the temperature control apparatus cooperate with each other so as to reach a stable set pressure rapidly. That is, when the error value is outside the set error threshold range, the rough pressure adjusting mechanism is initiated to rapidly adjust the pressure; when the error value is within the set error threshold range, the temperature control apparatus is initiated to adjust the pressure precisely. In both inner and outer PI components, when the error value is outside respective set error threshold ranges, the adjustment mechanism adjusts the pressure with the highest adjustment speed; and once the error value falls into the set error threshold range, a parameter self-regulating PI
control method is used to adjust the pressure. In order to improve the performance of the closed-loop control system, shorten the response time, and make the pressure-making system to reach the stable set pressure as soon as possible, in both inner and outer loops, the coefficients of respective components of the PI
controller are regulated appropriately according to the error value. Compared with the ordinary PI control method, it shortens the response time dramatically and improves the capability of disturbance resistance.
(3) The structure according to the present disclosure is simple, and the operation of the temperature control apparatus and the temperature sensing chamber is simple.
The conventional pressure adjustment mechanism adapted thereto needs relatively low fabrication precision and consistency. The cost is also reduced, and there is a promising potential market.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1A is a schematic diagram of a liquid pressure adjusting mechanism with an electric motor pushing a piston.
TECHNICAL FIELD
The present disclosure relates to the field of industrial control, and in particular to a pressure adjustment apparatus using a double closed-loop PI control method to control a conventional rough pressure adjusting mechanism and the change of the chamber volume of a pressure-withstanding container of a material with a high thermal expansion coefficient to work in cooperation, so as to achieve precise adjustment of pressure.
BACKGROUND
Pressure measurement plays an important role in the industrial process control. The performance of a pressure calibrating apparatus decides the calibration precision, efficiency and cost of a pressure instrument. Fully automatic pressure calibrators are replacing conventional piston pressure gauges gradually, and are widely applied in the field of electrical power, petroleum, petrochemical engineering, metallurgy, pharmacy or the like for it has many advantages such as high precision, wide application area, easy operation, functional integration, small size and so on.
Fully automatic pressure calibrators can be classified into gas pressure calibrators and liquid pressure calibrators depending on different instruments to be calibrated. The gas pressure calibrator takes non-corrosive gas as working medium, and is usually used to calibrate pressure instruments with relatively small measure range. Normal gas pressure calibrators control the gas input quantity and the gas output quantity of the pressure-making chamber by using the ON/OFF of an electromagnetic valve to thus achieve the purpose of adjusting pressure, as shown in Fig. 1C. The liquid pressure calibrator takes non-conductive liquid such as transformer oil, sebacate, deionized water and so on as working medium, and is usually used to calibrate pressure instruments with relatively large measure range. Normal liquid pressure calibrators change the volume of the working medium in the cylinder by using an electric motor or gas to push the piston to move in the cylinder, thus achieving the purpose of adjusting pressure, as shown in Fig. 1A and Fig. 1B.
Currently, the pressure-making precision of a fully automatic pressure calibrator is mainly subject to the performance of the pressure sensor and the actuating mechanism.
The performance of the actuating mechanism is determined by the fabrication precision, the consistency of elements and the cost of fabrication and purchase of the actuating mechanism.
In a conventional gas pressure system, the response time of the electromagnetic valve is usually in the range of 10-30 ms, or in the range of 5-10 ms for better ones.
Moreover, its price is very high, and the consistency cannot be assured. The amount of gas flow during the smallest switching interval of the electromagnetic valve usually decides the precision of the pressure adjustment. Reducing the amount of gas flow during the smallest switching interval by reducing the pressure difference between the two sides of the electromagnetic valve would usually increase the complexity of the system and improve the cost. Though reducing the path diameter of the electromagnetic valve can reduce the amount of gas flow during the smallest switching interval, it increases the adjustment time at the same time. Increasing the volume of the pressure-making chamber would increase the vibration of the gas due to the bulk-cavity effect and would thus increase the adjustment time. In a conventional liquid pressure system, for a pressure-making system by the electric motor pushing the piston, the fabrication precision of the transmission screw would influence the shift of the piston in a unit step of the electric motor, and thus influence the resolution of the pressure adjustment. High precision screws are usually very expensive, and not easy to be fabricated. The electric motor adapted thereto also needs to be a stepper motor or a servo motor with high precision, stable torque, and low heating, which further . .
improves the cost of the system. For a pressure-making system with gas pushing liquid, the same difficulties as the gas pressure system exist.
SUMMARY OF THE DISCLOSURE
In view of the above, the technical problems to be solved by the present disclosure is to overcome the disadvantages of the prior art, and provide a control system in which precise pressure adjustment is performed with the deformation of a pressure-withstanding container of a material with high thermal expansion coefficients such as aluminum, copper, iron, and so on in cooperation with a conventional rough pressure adjusting mechanism (e.g., a liquid pressure cylinder or a gas actuating electromagnetic valve ). A double closed-loop PI control method is used, so as to reduce the performance requirement on a conventional adjusting mechanism, simplify the system structure, reduce the influence of the element cost and consistency of the system, and improve the precision of the pressure-making to some extent.
In order to achieve the above object, one aspect of the present disclosure provides a pressure adjustment apparatus, comprising: an actuating mechanism (1) comprising a temperature sensing chamber (3), a temperature control apparatus (4), a rough pressure adjusting mechanism (5) and a pressure-making chamber (10), the pressure-making chamber (10) being connected to the chamber of the temperature sensing chamber (3) to make the pressure within the chambers equal; and a control mechanism (2) comprising a processor (6), a touch screen (7), an analog-to-digital converter (8) and a pressure sensor (9), wherein the pressure sensor (9) senses the pressure within the pressure-making chamber (10) and outputs an electric signal which is computed by the processor (6) to obtain a realtime pressure value after being collected by the analog-to-digital converter (8), and the processor (6) compares a set pressure value inputted by a user though the touch screen (7) with the current pressure value to obtain an error value, and performs a double closed-loop control on the actuating mechanism (1) to adjust the pressure within the pressure-making chamber (10) by comparing the error value with a set error threshold.
In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the double closed-loop control further comprises:
when the error value is outside the set error threshold range, the processor (6) initiating an inner loop to control the rough pressure adjusting mechanism (5) to perform rough pressure adjustment rapidly; when the error value is within the set error threshold range, the processor (6) initiating an outer loop to control the temperature control apparatus (4) to change the temperature of the temperature sensing chamber (3) and thus to change the chamber volume of the temperature sensing chamber (3).
In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the temperature sensing chamber is a pressure-withstanding container made of aluminum, copper or iron with a high thermal expansion coefficient.
In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the temperature control apparatus is composed of a power resistor, a Pt thermocouple, a heat dissipater and a power supply In accordance with the pressure adjustment apparatus in a preferable embodiment of the present disclosure, the analog-to-digital converter (8) is a y -A typed analog-to-digital converter (8).
Compared with the prior art, the present disclosure has the following advantages due to the adoption of the above features.
(1) In the present disclosure, an inner-loop conventional pressure adjusting mechanism and an outer-loop temperature control apparatus are used to cooperate with each other. A stable pressure adjustment with high precision is achieved by changing the . .
temperature and thus the volume of the temperature sensing chamber. The present disclosure can be applied to both the gas pressure system and the liquid pressure system.
(2) The present disclosure adopts a double closed-loop PI control method to make the rough pressure adjusting mechanism and the temperature control apparatus cooperate with each other so as to reach a stable set pressure rapidly. That is, when the error value is outside the set error threshold range, the rough pressure adjusting mechanism is initiated to rapidly adjust the pressure; when the error value is within the set error threshold range, the temperature control apparatus is initiated to adjust the pressure precisely. In both inner and outer PI components, when the error value is outside respective set error threshold ranges, the adjustment mechanism adjusts the pressure with the highest adjustment speed; and once the error value falls into the set error threshold range, a parameter self-regulating PI
control method is used to adjust the pressure. In order to improve the performance of the closed-loop control system, shorten the response time, and make the pressure-making system to reach the stable set pressure as soon as possible, in both inner and outer loops, the coefficients of respective components of the PI
controller are regulated appropriately according to the error value. Compared with the ordinary PI control method, it shortens the response time dramatically and improves the capability of disturbance resistance.
(3) The structure according to the present disclosure is simple, and the operation of the temperature control apparatus and the temperature sensing chamber is simple.
The conventional pressure adjustment mechanism adapted thereto needs relatively low fabrication precision and consistency. The cost is also reduced, and there is a promising potential market.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1A is a schematic diagram of a liquid pressure adjusting mechanism with an electric motor pushing a piston.
. .
Fig. 1B is a schematic diagram of a liquid pressure adjusting mechanism with gas pushing a piston.
Fig. 1C is a diagram of a gas pressure adjusting mechanism with an electromagnetic valve controlling the gas input quantity and the gas output quantity.
Fig. 2 is a structural block diagram of a pressure adjustment apparatus provided in an embodiment of the present disclosure.
Fig. 3 is a schematic diagram of a temperature sensing chamber and a temperature control apparatus of the present disclosure.
Fig. 4 is a flowchart of the processor implementation in the present disclosure.
Fig. 5 is a structural diagram the parameter self-regulating PI control.
DETAILED DESCRIPTION
In the following, the technical solutions of the present disclosure will be further described in detail in connection with drawings and embodiments.
As shown in Fig. 2, embodiments of the present disclosure provide a pressure adjustment apparatus which performs precise pressure adjustment with temperature control. The apparatus comprises an actuating mechanism 1 and a control mechanism 2. The actuating mechanism 1 comprises a temperature sensing chamber 3, a temperature control apparatus 4, a rough pressure adjusting mechanism 5 and a pressure-making chamber 10, the pressure-making chamber 10 being connected to the chamber of the temperature sensing chamber 3 to make the pressure within the chambers equal. The control mechanism 2 comprises a processor 6, a touch screen 7, an analog-to-digital converter 8 and a pressure sensor 9. The control mechanism composed of the pressure sensor 9, the analog to digital converter 8, and the processor 6 is also referred to as a control circuit. With the double closed-loop PI
control method, the control mechanism can control the rough pressure adjusting mechanism 5 and the change in the chamber volume of the temperature sensing chamber 3 controlled by the temperature apparatus 4 to make them cooperate with each other to achieve a stable and fast pressure adjustment.
As shown in Fig. 3, the temperature sensing chamber of the present disclosure can adopt a common pressure-withstanding container made of aluminum, copper or iron with a high thermal expansion coefficient. The temperature control apparatus is simple in principle, and can usually be composed of a power resistor, a Pt thermocouple, a heat dissipater and a power supply. The processor controls the temperature of the temperature sensing chamber and then changes the chamber volume thereof through the temperature control apparatus. When the pressure needs to be raised, the voltage modulation duty cycle on the power resistor of the temperature control apparatus is reduced to reduce the temperature of the power resistor. The surface area of the heat dissipater can be chosen to be larger, and if necessary, a heat dissipating fan can be additionally provided to reduce the temperature of the temperature sensing chamber accordingly. Then the chamber volume of the temperature sensing chamber decreases when the temperature decreases. When the pressure needs to be reduced, the voltage modulation duty cycle on the power resistor of the temperature control apparatus is raised to increase the temperature of the power resistor. If a heat dissipating fan is additionally provided, it should be turned off to make the temperature of the temperature sensing chamber increase accordingly. Then the chamber volume of the temperature sensing chamber increases when the temperature increases.
Since the temperature sensing chamber is connected to the pressure-making chamber, there is an equal pressure within their chambers. The chamber volume of the temperature sensing chamber should be suitable for the total volume of the entire pressure-making circuit. If it is too small, the pressure adjusting range would be small. If it is too large, it cannot function for precise pressure adjustment. At the same time, the pressure adjusting resolution of the rough pressure adjusting mechanism also needs to be considered.
Fig. 1B is a schematic diagram of a liquid pressure adjusting mechanism with gas pushing a piston.
Fig. 1C is a diagram of a gas pressure adjusting mechanism with an electromagnetic valve controlling the gas input quantity and the gas output quantity.
Fig. 2 is a structural block diagram of a pressure adjustment apparatus provided in an embodiment of the present disclosure.
Fig. 3 is a schematic diagram of a temperature sensing chamber and a temperature control apparatus of the present disclosure.
Fig. 4 is a flowchart of the processor implementation in the present disclosure.
Fig. 5 is a structural diagram the parameter self-regulating PI control.
DETAILED DESCRIPTION
In the following, the technical solutions of the present disclosure will be further described in detail in connection with drawings and embodiments.
As shown in Fig. 2, embodiments of the present disclosure provide a pressure adjustment apparatus which performs precise pressure adjustment with temperature control. The apparatus comprises an actuating mechanism 1 and a control mechanism 2. The actuating mechanism 1 comprises a temperature sensing chamber 3, a temperature control apparatus 4, a rough pressure adjusting mechanism 5 and a pressure-making chamber 10, the pressure-making chamber 10 being connected to the chamber of the temperature sensing chamber 3 to make the pressure within the chambers equal. The control mechanism 2 comprises a processor 6, a touch screen 7, an analog-to-digital converter 8 and a pressure sensor 9. The control mechanism composed of the pressure sensor 9, the analog to digital converter 8, and the processor 6 is also referred to as a control circuit. With the double closed-loop PI
control method, the control mechanism can control the rough pressure adjusting mechanism 5 and the change in the chamber volume of the temperature sensing chamber 3 controlled by the temperature apparatus 4 to make them cooperate with each other to achieve a stable and fast pressure adjustment.
As shown in Fig. 3, the temperature sensing chamber of the present disclosure can adopt a common pressure-withstanding container made of aluminum, copper or iron with a high thermal expansion coefficient. The temperature control apparatus is simple in principle, and can usually be composed of a power resistor, a Pt thermocouple, a heat dissipater and a power supply. The processor controls the temperature of the temperature sensing chamber and then changes the chamber volume thereof through the temperature control apparatus. When the pressure needs to be raised, the voltage modulation duty cycle on the power resistor of the temperature control apparatus is reduced to reduce the temperature of the power resistor. The surface area of the heat dissipater can be chosen to be larger, and if necessary, a heat dissipating fan can be additionally provided to reduce the temperature of the temperature sensing chamber accordingly. Then the chamber volume of the temperature sensing chamber decreases when the temperature decreases. When the pressure needs to be reduced, the voltage modulation duty cycle on the power resistor of the temperature control apparatus is raised to increase the temperature of the power resistor. If a heat dissipating fan is additionally provided, it should be turned off to make the temperature of the temperature sensing chamber increase accordingly. Then the chamber volume of the temperature sensing chamber increases when the temperature increases.
Since the temperature sensing chamber is connected to the pressure-making chamber, there is an equal pressure within their chambers. The chamber volume of the temperature sensing chamber should be suitable for the total volume of the entire pressure-making circuit. If it is too small, the pressure adjusting range would be small. If it is too large, it cannot function for precise pressure adjustment. At the same time, the pressure adjusting resolution of the rough pressure adjusting mechanism also needs to be considered.
. .
As shown in Fig. 4, the processor 6 in the present disclosure receives a set pressure value set by a user through the touch screen 7. The pressure sensor 9 senses the pressure value within the pressure-making chamber 10. The pressure value is collected by the analog-to-digital converter 8 and then computed by the processor 6 to obtain the current pressure value. The processor 6 compares the set pressure value with the current pressure value to obtain an error value. When the error value is outside the set error threshold range, the processor 6 initiates the rough pressure adjusting mechanism 5 of the inner loop through a parameter self-regulating PI
control method to adjust the pressure rapidly while the temperature control apparatus 4 of the outer loop does not work. When the error value is within the set error threshold range, the processor 6 initiates the temperature control apparatus 4 of the outer loop to perform precise pressure adjustment through a parameter self-regulating PI
control method while the rough pressure adjusting mechanism 5 of the inner loop does not work. The above closed-loop control method is performed cyclically until the stable set pressure is achieved.
As shown in Fig. 5, in the embodiments of the present disclosure, the processor 6 controls the pressure through a double closed-loop parameter self-regulating PI control method. The processor adjusts the proportion coefficient Kp and the integration coefficient Ki of the PI component according to the error value through the PI
control algorithm. The output of Kp control is proportional to the input error value and is used for fast response. The output of Ki control is proportional to the integral of the error value, and is used to eliminate the static error. That is, when the absolute error value is relatively large (in the present embodiment, larger than 20% of the input value of the inner or outer loop), Kp takes a relatively large value (in the present embodiment, 30), Ki takes 0, and at this point the rough pressure adjusting mechanism 5 or the temperature sensing chamber 3 adjusts the pressure rapidly or increases or decreases temperature rapidly to make the absolute error value decrease as soon as possible.
When the absolute error value is medium (in the present embodiment, larger than 10%
and smaller than 20% of the input value of the inner or outer loop), Kp takes a medium value (in the present embodiment, 25), Ki takes a relatively small value (in the present embodiment, 0.0005), and at this point the rough pressure adjusting mechanism 5 or temperature sensing chamber 3 reduces the speed of adjusting the pressure or increasing or decreasing temperature to avoid over-adjusting. When the absolute error value decreases further (in the present embodiment, larger than 5% and smaller than 10% of the input value of the inner or outer loop), Kp takes a relatively small value (in the present embodiment, 5), Ki takes a medium value (in the present embodiment, 0.02), and at this point, the rough pressure adjusting mechanism 5 or the temperature of the temperature sensing chamber 3 is adjusted slowly. When the absolute error value reaches the smallest (in the present embodiment, smaller than 5% of the input value of the inner loop), Kp takes a medium value (in the present embodiment, 20), Ki takes the maximum value (in the present embodiment, 0.02), and at this point, mainly the temperature of the temperature sensing chamber 3 is adjusted finely to achieve the function of precise pressure adjustment. The above process makes both the inner and outer loops respond rapidly so that the closed-loop system can reach the stable set pressure faster. The method responds faster than the conventional PI control method.
The pressure sensor 9 can adopt commonly used silicon piezoresistive pressure sensors or silicon resonant pressure sensors, depending on the requirement of precision and performance.
Considering that the electric signal output by the pressure sensor 9 usually is a weak signal in the level of uA or mV, and the pressure signal within the pressure-making chamber 10 cannot change rapidly within a short time, it is proposed to use a high resolution, high signal-to-noise ratio, high integration I-A typed analog-to-digital converter 8, for example, AD7714.
The processor 6 can be implemented by commonly used digital signal processors, ARM or the like, for example, TMS320F28335 or the like.
As shown in Fig. 4, the processor 6 in the present disclosure receives a set pressure value set by a user through the touch screen 7. The pressure sensor 9 senses the pressure value within the pressure-making chamber 10. The pressure value is collected by the analog-to-digital converter 8 and then computed by the processor 6 to obtain the current pressure value. The processor 6 compares the set pressure value with the current pressure value to obtain an error value. When the error value is outside the set error threshold range, the processor 6 initiates the rough pressure adjusting mechanism 5 of the inner loop through a parameter self-regulating PI
control method to adjust the pressure rapidly while the temperature control apparatus 4 of the outer loop does not work. When the error value is within the set error threshold range, the processor 6 initiates the temperature control apparatus 4 of the outer loop to perform precise pressure adjustment through a parameter self-regulating PI
control method while the rough pressure adjusting mechanism 5 of the inner loop does not work. The above closed-loop control method is performed cyclically until the stable set pressure is achieved.
As shown in Fig. 5, in the embodiments of the present disclosure, the processor 6 controls the pressure through a double closed-loop parameter self-regulating PI control method. The processor adjusts the proportion coefficient Kp and the integration coefficient Ki of the PI component according to the error value through the PI
control algorithm. The output of Kp control is proportional to the input error value and is used for fast response. The output of Ki control is proportional to the integral of the error value, and is used to eliminate the static error. That is, when the absolute error value is relatively large (in the present embodiment, larger than 20% of the input value of the inner or outer loop), Kp takes a relatively large value (in the present embodiment, 30), Ki takes 0, and at this point the rough pressure adjusting mechanism 5 or the temperature sensing chamber 3 adjusts the pressure rapidly or increases or decreases temperature rapidly to make the absolute error value decrease as soon as possible.
When the absolute error value is medium (in the present embodiment, larger than 10%
and smaller than 20% of the input value of the inner or outer loop), Kp takes a medium value (in the present embodiment, 25), Ki takes a relatively small value (in the present embodiment, 0.0005), and at this point the rough pressure adjusting mechanism 5 or temperature sensing chamber 3 reduces the speed of adjusting the pressure or increasing or decreasing temperature to avoid over-adjusting. When the absolute error value decreases further (in the present embodiment, larger than 5% and smaller than 10% of the input value of the inner or outer loop), Kp takes a relatively small value (in the present embodiment, 5), Ki takes a medium value (in the present embodiment, 0.02), and at this point, the rough pressure adjusting mechanism 5 or the temperature of the temperature sensing chamber 3 is adjusted slowly. When the absolute error value reaches the smallest (in the present embodiment, smaller than 5% of the input value of the inner loop), Kp takes a medium value (in the present embodiment, 20), Ki takes the maximum value (in the present embodiment, 0.02), and at this point, mainly the temperature of the temperature sensing chamber 3 is adjusted finely to achieve the function of precise pressure adjustment. The above process makes both the inner and outer loops respond rapidly so that the closed-loop system can reach the stable set pressure faster. The method responds faster than the conventional PI control method.
The pressure sensor 9 can adopt commonly used silicon piezoresistive pressure sensors or silicon resonant pressure sensors, depending on the requirement of precision and performance.
Considering that the electric signal output by the pressure sensor 9 usually is a weak signal in the level of uA or mV, and the pressure signal within the pressure-making chamber 10 cannot change rapidly within a short time, it is proposed to use a high resolution, high signal-to-noise ratio, high integration I-A typed analog-to-digital converter 8, for example, AD7714.
The processor 6 can be implemented by commonly used digital signal processors, ARM or the like, for example, TMS320F28335 or the like.
=
The set pressure input by a user can be implemented by a touch screen or a simple button or digital tube.
The principle of the present disclosure is as follows. A conventional rough pressure adjusting mechanism and the change in the chamber volume of a pressure-withstanding chamber of materials with high thermal expansion coefficients are used to cooperate with each other to achieve a high speed and stable pressure-making function by a double closed-loop PI control method. In the aspect of the actuating mechanism, the requirement on the performance of the conventional rough pressure adjusting mechanism is reduced since it is only used for rough pressure adjustment.
When the error value is within the set error value range, the temperature control apparatus is initiated to work in order to change the temperature of the temperature sensing chamber and then to change the chamber volume of the temperature sensing chamber, whereby the purpose of precise pressure adjustment is achieved. In the aspect of software, a double closed-loop PI control method is used in which the current pressure value read realtime by the pressure sensor is compared with the user set value to obtain an error value. According to the amplitude of the error value, the parameters of PI components are self-regulated, reducing the adjustment time drastically. The rough pressure adjusting mechanism of the inner loop is controlled first to rapidly adjust the pressure to fall within the set error threshold range.
Then the adjustment of the inner loop is stopped, and the temperature control apparatus of the outer loop is controlled to rapidly and stably perform precise pressure adjustment.
The above specific implementation provides a further detailed description of the object, the technical solutions and the technical benefits of the present disclosure.
It should be understood that the above description is only specific embodiments of the present disclosure and is not intended to limit the protection scope of the present disclosure.
Any modification, equivalent replacement, enhancement or the like within the principle of the present disclosure should all be contained within the protection scope of the present disclosure.
The set pressure input by a user can be implemented by a touch screen or a simple button or digital tube.
The principle of the present disclosure is as follows. A conventional rough pressure adjusting mechanism and the change in the chamber volume of a pressure-withstanding chamber of materials with high thermal expansion coefficients are used to cooperate with each other to achieve a high speed and stable pressure-making function by a double closed-loop PI control method. In the aspect of the actuating mechanism, the requirement on the performance of the conventional rough pressure adjusting mechanism is reduced since it is only used for rough pressure adjustment.
When the error value is within the set error value range, the temperature control apparatus is initiated to work in order to change the temperature of the temperature sensing chamber and then to change the chamber volume of the temperature sensing chamber, whereby the purpose of precise pressure adjustment is achieved. In the aspect of software, a double closed-loop PI control method is used in which the current pressure value read realtime by the pressure sensor is compared with the user set value to obtain an error value. According to the amplitude of the error value, the parameters of PI components are self-regulated, reducing the adjustment time drastically. The rough pressure adjusting mechanism of the inner loop is controlled first to rapidly adjust the pressure to fall within the set error threshold range.
Then the adjustment of the inner loop is stopped, and the temperature control apparatus of the outer loop is controlled to rapidly and stably perform precise pressure adjustment.
The above specific implementation provides a further detailed description of the object, the technical solutions and the technical benefits of the present disclosure.
It should be understood that the above description is only specific embodiments of the present disclosure and is not intended to limit the protection scope of the present disclosure.
Any modification, equivalent replacement, enhancement or the like within the principle of the present disclosure should all be contained within the protection scope of the present disclosure.
Claims (5)
1. A pressure adjustment apparatus, characterized by comprising:
an actuating mechanism (1) comprising a temperature sensing chamber (3), a temperature control apparatus (4), a rough pressure adjusting mechanism (5) and a pressure-making chamber (10), the pressure-making chamber (10) being connected to the chamber of the temperature sensing chamber (3) to make the pressure within the chambers equal;
a control mechanism (2) comprising a processor (6), a touch screen (7), an analog-to-digital converter (8) and a pressure sensor (9), wherein the pressure sensor (9) senses the pressure within the pressure-making chamber (10) and outputs an electric signal which is computed by the processor (6) to obtain a realtime pressure value after being collected by the analog-to-digital converter (8), and the processor (6) compares a set pressure value inputted by a user though the touch screen (7) with the current pressure value to obtain an error value, and performs a double closed-loop control on the actuating mechanism (1) to adjust the pressure within the pressure-making chamber (10) by comparing the error value with a set error threshold.
an actuating mechanism (1) comprising a temperature sensing chamber (3), a temperature control apparatus (4), a rough pressure adjusting mechanism (5) and a pressure-making chamber (10), the pressure-making chamber (10) being connected to the chamber of the temperature sensing chamber (3) to make the pressure within the chambers equal;
a control mechanism (2) comprising a processor (6), a touch screen (7), an analog-to-digital converter (8) and a pressure sensor (9), wherein the pressure sensor (9) senses the pressure within the pressure-making chamber (10) and outputs an electric signal which is computed by the processor (6) to obtain a realtime pressure value after being collected by the analog-to-digital converter (8), and the processor (6) compares a set pressure value inputted by a user though the touch screen (7) with the current pressure value to obtain an error value, and performs a double closed-loop control on the actuating mechanism (1) to adjust the pressure within the pressure-making chamber (10) by comparing the error value with a set error threshold.
2. The pressure adjustment apparatus according to claim 1, characterized in that the double closed-loop control further comprises:
when the error value is outside the set error threshold range, the processor (6) initiating an inner loop to control the rough pressure adjusting mechanism (6) to perform rough pressure adjustment rapidly;
when the error value is within the set error threshold range, the processor (6) initiating an outer loop to control the temperature control apparatus (4) to change the temperature of the temperature sensing chamber (3) and thus to change the chamber volume of the temperature sensing chamber (3).
when the error value is outside the set error threshold range, the processor (6) initiating an inner loop to control the rough pressure adjusting mechanism (6) to perform rough pressure adjustment rapidly;
when the error value is within the set error threshold range, the processor (6) initiating an outer loop to control the temperature control apparatus (4) to change the temperature of the temperature sensing chamber (3) and thus to change the chamber volume of the temperature sensing chamber (3).
3. The pressure adjustment apparatus according to claim 1, characterized in that the temperature sensing chamber is a pressure-withstanding container made of aluminum, copper or iron with a high thermal expansion coefficient.
4. The pressure adjustment apparatus according to any one of claims 1-3, characterized in that the temperature control apparatus is composed of a power resistor, a Pt thermocouple, a heat dissipater and a power supply.
5. The pressure adjustment apparatus according to any one of claims 1-4, characterized in that the analog-to-digital converter (8) is a .SIGMA.-.increment. typed analog-to-digital converter (8).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310000145.7 | 2013-01-04 | ||
| CN201310000145.7A CN103116370B (en) | 2013-01-04 | 2013-01-04 | Pressure regulating device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2838390A1 true CA2838390A1 (en) | 2014-07-04 |
Family
ID=48414779
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2838390A Abandoned CA2838390A1 (en) | 2013-01-04 | 2013-12-30 | Pressure adjustment apparatus |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN103116370B (en) |
| CA (1) | CA2838390A1 (en) |
| WO (1) | WO2014106437A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109596566A (en) * | 2018-10-29 | 2019-04-09 | 中国科学院合肥物质科学研究院 | A kind of gas detection absorption inside cavity temperature and pressure integrated control unit |
| CN110471469B (en) * | 2019-09-26 | 2021-03-16 | 湖南航天机电设备与特种材料研究所 | Self-adaptive temperature control method based on PI algorithm |
| CN111288296A (en) * | 2020-02-13 | 2020-06-16 | 蓝箭航天技术有限公司 | Control device and method of nitrogen replacement equipment |
| CN113220045B (en) * | 2021-05-10 | 2023-03-31 | 南京英锐创电子科技有限公司 | Air pressure control device and method |
| CN114483695A (en) * | 2022-01-30 | 2022-05-13 | 北京康斯特仪表科技股份有限公司 | Liquid pressure checking device |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6269034A (en) * | 1985-09-24 | 1987-03-30 | Hitachi Ltd | Temperature regulator |
| DE4103769C1 (en) * | 1991-02-08 | 1992-06-17 | Draegerwerk Ag, 2400 Luebeck, De | |
| CN2168275Y (en) * | 1992-12-30 | 1994-06-08 | 郭福玲 | Internal-pressure automatic regulating device for sealed container |
| US20050087238A1 (en) * | 2003-10-22 | 2005-04-28 | Wilson Robert E. | Compressed air control system refinements |
| JP4819581B2 (en) * | 2006-06-02 | 2011-11-24 | 富士フイルム株式会社 | Liquid storage device and image forming apparatus |
| CN201466727U (en) * | 2009-05-26 | 2010-05-12 | 长沙矿山研究院 | Deep sea pressure compensator |
| CN102103381B (en) * | 2009-12-16 | 2014-06-25 | 上海神开石油化工装备股份有限公司 | Electron pressure controller |
| CN201886370U (en) * | 2010-12-16 | 2011-06-29 | 河南省中分仪器有限公司 | Intelligent gas flow rate and pressure controller |
| CN102385397A (en) * | 2011-09-29 | 2012-03-21 | 北京振兴计量测试研究所 | High-precision pressure control system based on high-speed solenoid valve |
| CN102677024A (en) * | 2012-05-28 | 2012-09-19 | 上海华力微电子有限公司 | Cavity pressure adjustment method and cavity pressure adjustment device |
| CN103092222B (en) * | 2012-12-31 | 2016-01-27 | 孙晓君 | A kind of pressure precise adjustment device |
-
2013
- 2013-01-04 CN CN201310000145.7A patent/CN103116370B/en active Active
- 2013-12-23 WO PCT/CN2013/090206 patent/WO2014106437A1/en active Application Filing
- 2013-12-30 CA CA2838390A patent/CA2838390A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| CN103116370B (en) | 2015-06-03 |
| WO2014106437A1 (en) | 2014-07-10 |
| CN103116370A (en) | 2013-05-22 |
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