Control system for valve reliability test and control method thereof

Abstract

The invention discloses a control system for a valve reliability test and a control method thereof, the control system comprises a test design subsystem, a self-checking subsystem and an automatic test subsystem, the test design subsystem is used for inputting a test target, a test piece design parameter and a test profile requirement, setting a temperature rise rate, a temperature drop rate and a pressure rate, and through FMEA analysis and comparison optimization, the automatic test subsystem is used for carrying out self-checking on the test piece design parameter and the test profile requirement; obtaining an identification and reliability combined test profile combination, and calculating a test period; the self-inspection subsystem is used for executing acquisition self-inspection, electrical self-inspection and test piece joint debugging operation, and automatically completing confirmation of the connection state of the control system and the test device and fault prompt; and the automatic test subsystem executes active valve control logic operation and check valve control logic operation based on the input of the test design subsystem so as to realize automatic operation of reliability tests of different types of valves. According to the invention, the unified control system is adapted to different types of test devices, so that the test cost is reduced, and the equipment configuration is simplified.

Description

Technical Field

[0001] The invention relates to the technical field of reliability testing of electromechanical equipment, and in particular to a control system and a control method thereof for valve reliability testing. Background Art

[0002] Valve reliability testing is a key step to ensure that the valve can operate safely and stably under various working conditions. It is crucial to ensure the safety and efficiency of the entire working system. There are many testing standards and specifications internationally, such as API and ISO standards, which stipulate the technical requirements and corresponding testing methods for different types of valves.

[0003] Testing methods include static testing (such as pressure testing and air tightness testing) and dynamic testing (simulating multiple opening and closing actions under actual operating conditions), as well as environmental adaptability testing (changing environmental factors such as temperature and humidity). These tests are usually conducted in a well-controlled laboratory environment and collect a large amount of data. Data analysis software is used to help identify problems and make improvements. With technological advances, new technologies such as non-contact measurement technology and smart sensors have also been introduced into valve testing, making the testing process more efficient and accurate.

[0004] However, there is a lack of joint test design in the process of reliability testing of multiple valves. The current tests are mainly carried out in stages and items according to the verification objectives. This approach leads to problems such as a large number of test pieces, little single test data, and insufficient overall reliability evaluation. At the same time, the existing valve reliability test control system is usually only targeted at specific test devices and lacks adaptability to different devices, which means that each test device requires a dedicated control system, resulting in high test costs. In addition, when a control system needs to adapt to multiple test devices, it is also necessary to solve the problems of safety monitoring and automatic testing of multiple types of test valves.

[0005] To this end, this application specifically proposes a control system and a control method for valve reliability testing that can perform comprehensive, automated, intelligent control and data analysis. It can also be adapted to different test devices to solve the above-mentioned technical problems and has important technical value and application prospects. Summary of the invention

[0006] The main purpose of the present invention is to provide a control system and a control method for valve reliability testing. By adapting different types of test equipment to a unified control system, the test cost is reduced and the equipment configuration is simplified, so as to solve the technical problems in the existing valve reliability test proposed in the background technology, such as lack of joint test design, large number of test pieces, insufficient single data, and inconsistent data between systems.

[0007] The present invention adopts the following technical solutions to solve the above technical problems:

[0008] A control system for valve reliability test, based on system hardware implementation, includes a test design subsystem, a self-checking subsystem and an automatic test subsystem, wherein:

[0009] The test design subsystem is used to input the test objectives, test piece design parameters and test profile requirements, set the heating and cooling and pressure rates, obtain the identification and reliability joint test profile combination through FMEA analysis and comparative optimization, and calculate the test cycle;

[0010] A self-test subsystem is used to perform acquisition self-test, electrical self-test and test piece joint debugging operations, and automatically complete the confirmation of the connection status between the control system and the test device and the fault prompt based on the system hardware;

[0011] The automatic test subsystem is used to execute the active valve control logic operation and the check valve control logic operation based on the input of the test design subsystem to realize the automatic operation of the reliability test of different types of valves.

[0012] Preferably, the system hardware is composed of a power module, control hardware and acquisition hardware, and the corresponding valves of the corresponding devices are connected according to the loop diagram and device names indicated by the test design subsystem to match multiple test devices.

[0013] Preferably, the power module includes a 0-1000V thyristor DC power module, a 0-500V electric transformer and auxiliary connectors, which are used to supply power to electrical equipment;

[0014] The control hardware includes a test valve controller and a test valve controller, which are used to control the switch and operation of various valves;

[0015] The acquisition hardware includes a temperature collector, a pressure collector, a vibration collector, a current sensor, a voltage sensor, a strain collector and an acoustic emission collector, which are used to collect the test valve and system status during the valve reliability test at a high frequency under a preset acquisition frequency state.

[0016] Preferably, four temperature sensors and four pressure sensors are respectively deployed before and after the test valve, eight temperature sensors are equidistantly deployed on the outside of the valve body along the vertical line of the center of gravity, three single-axis vibration sensors are deployed at the center of gravity of the valve, and one of the valve power cables is selected to deploy a current sensor and a voltage sensor, and connected to the corresponding controller.

[0017] Preferably, the test design subsystem obtains the identification and reliability joint test profile combination through FMEA analysis and comparative optimization, and the specific operation steps of calculating the test cycle include:

[0018] S1. The test cycle and test energy consumption are obtained through orthogonal combination, and the best test profile combination is provided. At this time, the test objectives are MTBF, confidence level, number of test samples X, and X≤3, and the design temperature T, design pressure P, and type of the test piece are preset;

[0019] S2. The identification test profile is given by a piecewise function (t 1 , p 1 , n 1 )、(t 2 , p 2 , n 2 ),…,(t c , p c , n c ), where t=(t 1 , t 2 ,…,t c ) is temperature, p=(p 1 , p 2 ,…,p c ) is pressure, n=(n 1 , n 2 ,…,n c ) is the number of actions;

[0020] S3. Conduct reliability analysis: Conduct structural FMEA analysis on the test piece, combine the database or other manual information, manually input the probability value of each failure mode, classify and screen by failure cause, arrange according to the sum of the probability values ​​of the corresponding failure modes, obtain the failure causes that affect the reliability of the test piece, obtain the failure causes that affect the reliability of the test piece, and manually select and confirm the correlation between temperature and pressure on the failure cause according to each failure cause. If there is a correlation, select the corresponding pressure and temperature combination. When selecting the range, identify the (t 1 , p 1 , n 1 )、(t 2 , p 2 , n 2 ),…,(t c , p c , n c ) in the (t, p) combination, and then distribute them in proportion according to the failure probability corresponding to the failure cause. At this time, when distributing in proportion, the distribution ratio y 1 :y 2 :y 3 :…:y j , there exists condition y 1 +y 2 +y 3 +…+y j =1;

[0021] S4. Select a statistical method according to the MTBF and confidence level in the test objectives, specify the number of operations required to be performed according to the assumed life distribution form through the acceptance criteria, and since this method is mature, represent the calculation result as b(MTBF, confidence level, f(x)), where f(x) represents the number of operations;

[0022] S5. Calculate the number of operations required for each valve under the verified reliability index:

[0023]

[0024] If x n < MTBF, then x n = MTBF, and the acceptance limit remains unchanged, then the number of operations required for reliability testing under each failure cause is obtained (t 1 , p 1 , y 1 *x n ), …, (t j , p j , y j *x n );

[0025] S6. Profile optimization: Based on the qualification test profile, compare the values of the number of operations at the same t and p in sequence to obtain a new profile combination. The specific comparison principles include:

[0026] If y j *x n < n j , then the number of this profile combination remains unchanged;

[0027] If y j *x n > n j , then the number of this profile combination becomes (t j , p j , y j *x n ), and a new set of profile combinations is obtained: (t 1 , p 1 , n i ), (t 2 , p 2 , n q ), …, (t c , p c , n m );

[0028] S7. Arrange the new profile combinations in ascending order of t, and calculate the overall test time according to the heating / cooling and pressure rates;

[0029] The processed information is stored in the database according to the preset mapping relationship, and the test device name matching the test piece is popped up according to the input test piece type to execute the corresponding test process.

[0030] Preferably, the specific operation steps of the self-test subsystem performing electrical self-test include:

[0031] a1. Check whether the overload protection value for the test valve is set in advance in the system. If yes, energize the test valve with one-way power to the insulation self-test value;

[0032] a2. If the power voltage of the tested valve is 380V, the insulation self-test value is 1000V DC. If the power voltage of the tested valve is 220V, the insulation self-test value is 500V.

[0033] a4. If the insulation test value is greater than 10MΩ, conduct a self-check of the circuit and energize the tested valve for 1 second. If there is current in the tested valve, the connection is normal;

[0034] If there is any problem during the electrical self-test of the self-test subsystem, it will be fed back for manual inspection.

[0035] Preferably, the specific operation steps of the self-test subsystem to perform collection self-test include: by checking the final path self-test measurement data of the electrical self-test, if the current, vibration, voltage, and current data have a data segment greater than 50% of the measured data when power is not on, the data is considered normal, otherwise it is fed back for manual processing.

[0036] Preferably, the specific operation steps of the self-test subsystem performing the test piece joint debugging operation include:

[0037] b1. Perform steering test: according to the feedback value of the position signal of the tested valve, jog in the reverse direction. If there is no signal from the valve position indicator during the steering test, notify the operator to manually adjust the valve to the open position;

[0038] b2. If the valve position signal disappears or the valve opening becomes smaller after jogging, the valve steering is normal, otherwise notify manual adjustment of the valve control power phase;

[0039] b3. Carry out inspection tests on the action performance and sealing performance. The process of the action performance inspection test includes: automatically giving the valve signal, controlling the valve to perform three opening and closing actions, and collecting the corresponding signal as the initial signal; the process of the sealing performance inspection test includes: using a booster pump to perform a pressure test on the test valve in the closed state. The pressure is obtained from the valve design parameters in the test design subsystem. The pressure test time is 15 minutes, and the pressure before and after the valve is collected; if the pressure change before and after the valve is less than 0.1MPa, it is considered that there is no problem with the seal, otherwise it is prompted for manual processing.

[0040] Preferably, the automatic test subsystem executes the active valve control logic operation including:

[0041] L1. The user sets the action interval of each valve;

[0042] L2. Select the initial valve A to participate in the automatic cycle test;

[0043] L3. Execute the control process: open valve A for automatic circulation until valve A completes one cycle;

[0044] L4. If there is another valve that has chosen to participate in the automatic cycle test when the action interval time expires, open the valve for automatic cycle until the valve completes one cycle action, and then repeat the cycle until all valves complete the cycle action;

[0045] L5. Data storage: Data is stored at a rate of not less than 1000Hz. The storage file name is marked with the current test type, test valve serial number, test time, current test number, working conditions before and after the test valve, and fault code in the fault state. Each valve action is stored separately as a file;

[0046] L6. Storage file processing: According to the change of pressure before and after the test valve, determine the time point when the pressure before and after the test valve is balanced, and divide the file into two working condition data files before and after the valve is opened based on this time point.

[0047] Preferably, the automatic test subsystem executes the check valve control logic operation to select different test positions individually or combine multiple test positions to carry out the test under different check valve automatic working conditions, and the check valve automatic working conditions include cold and hot conditions and high and low pressure back pressure conditions:

[0048] (1) Under the hot state and low back pressure conditions, the specific operation steps of the automatic test subsystem to perform the check valve control logic operation include:

[0049] c1. Status confirmation: confirm the pressure and temperature of the regulator, confirm the temperature after the test valve, confirm the status of the test valve, and confirm the status of each accompanying test valve in the test valve circuit;

[0050] c2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0051] c3. Preset the number of cycles and automatically control the steam inlet valve and the exhaust solenoid valve in front of the valve to perform automatic cycle test;

[0052] c4. At different times of the test, determine the pressure and temperature before and after the valve and at the regulator position to ensure the stable operation of the program. When an over-limit occurs, the system takes corresponding actions, alarms through the interface, and sends the fault code to the data acquisition system;

[0053] c5. All interlocking signals, interlocking upper and lower limits, and delay values;

[0054] c6. Store all data at 1000Hz, for playback of waveform images at any time, free configuration of playback signals, and export of data to Excel;

[0055] (2) Under the hot state and high back pressure conditions, the specific operation steps of the automatic test subsystem to perform the check valve control logic operation include:

[0056] d1. Status confirmation: confirm the pressure and temperature of the regulator, confirm the temperature after the test valve, confirm the status of the test valve, and confirm the status of each accompanying test valve in the test valve circuit;

[0057] d2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0058] d3. Preset the number of cycles and automatically control the steam inlet valve, the exhaust solenoid valve before the valve, and the exhaust valve after the valve to perform automatic cycle test;

[0059] d4. At different times of the test, determine the pressure and temperature before and after the valve and at the regulator position to ensure the stable operation of the program. When an over-limit occurs, the system takes corresponding actions, alarms through the interface, and sends the fault code to the data acquisition system;

[0060] d5. All interlocking signals, interlocking upper and lower limits, and delay values;

[0061] d6. Store all data at 1000Hz, for playback of waveform images at any time, free configuration of playback signals, and export of data to Excel;

[0062] (3) Under cold conditions and high back pressure, the specific operation steps for the automatic test subsystem to perform the check valve control logic operation include:

[0063] e1. Status confirmation: confirm the nitrogen source pressure, the test valve status, and the status of each accompanying test valve in the test valve circuit;

[0064] e2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0065] e3. Preset the number of cycles and automatically control the nitrogen inlet valve and the exhaust solenoid valve in front of the valve to perform automatic cycle test;

[0066] e4. At different times of the test, determine the pressure before and after the valve to ensure the stable operation of the program. When the limit is exceeded, the system will take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system;

[0067] e5. All interlocking signals, interlocking upper and lower limits, and delay values.

[0068] (4) Under cold conditions and low back pressure, the specific operation steps for the automatic test subsystem to perform the check valve control logic operation include:

[0069] f1. Status confirmation: confirm the nitrogen source pressure, the test valve status, and the status of each accompanying test valve in the test valve circuit;

[0070] f2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0071] f3. Preset the number of cycles and automatically control the nitrogen inlet valve, the exhaust solenoid valve before the valve and the exhaust valve after the valve to perform automatic cycle test;

[0072] f4. At different times of the test, determine the pressure before and after the valve to ensure the stable operation of the program. When the limit is exceeded, the system will take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system;

[0073] f5. All interlocking signals, interlocking upper and lower limits, and delay values.

[0074] A control method for executing any of the above control systems for valve reliability testing comprises the following specific operating steps:

[0075] (1) Use system hardware to access the valve to be tested and connect multiple sets of test devices;

[0076] (2) Based on the test objectives, test piece design parameters, and test profile requirements input into the test design subsystem, set the heating and cooling rates and pressure rates;

[0077] (3) Use the self-test subsystem to complete the confirmation of the connection status between the control system and the test device and the fault prompt;

[0078] (4) Preset the number of test cycles and use the automatic test subsystem to automatically perform test operations on different types of valves based on the input of the test design subsystem.

[0079] It can be seen from the above technical solution that the present invention provides a control system and a control method for valve reliability testing. Compared with the prior art, the present invention has the following advantages:

[0080] 1. The present invention can adapt to various types of test devices through a unified control system, thereby reducing the test cost and avoiding the need to design a control system separately for each test device.

[0081] 2. The present invention adopts automatic control and data acquisition functions to realize automatic testing of various types of valves, improve test efficiency, reduce manual intervention, and also collect multiple physical quantity data in real time to ensure the comprehensiveness and consistency of the data. It also realizes global optimization by automatically recommending the optimal test plan, facilitates comprehensive evaluation of valve reliability, and ensures safety during the test and stability of the system through safety monitoring and multi-level self-test subsystems, reducing test interruptions caused by equipment failures.

[0082] 3. Through orthogonal experimental design and automated operation, the system can automatically generate the optimal experimental profile according to the experimental objectives and parameters, which simplifies the experimental design process, improves the intelligent level of the experiment, and is efficient and convenient.

[0083] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become easy to understand through the following description. Of course, it is not necessary to achieve all of the advantages described above simultaneously for any product implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0085] Figure 1 It is a schematic diagram of the overall system framework of the present invention;

[0086] Figure 2 It is a schematic diagram of the overall architecture of the database of the present invention;

[0087] Figure 3 A logic diagram for executing the electrical self-test function of the present invention;

[0088] Figure 4 A schematic diagram of the execution logic of the acquisition self-checking function of the present invention;

[0089] Figure 5 It is a schematic diagram of the test piece joint debugging logic of the present invention;

[0090] Figure 6 It is a logic diagram of the action performance test of the present invention;

[0091] Figure 7 It is a logical diagram for executing the automatic cycle valve test interlocking function of the present invention;

[0092] Figure 8 It is a schematic diagram of the single action control logic of the check valve under the hot low back pressure condition of the present invention;

[0093] Fig. 9 It is a schematic diagram of the single action control logic of the check valve under hot low and high pressure conditions of the present invention;

[0094] Fig.10 It is a schematic diagram of the single action control logic of the check valve under the cold high back pressure condition of the present invention;

[0095] Fig.11 It is a schematic diagram of the single action control logic of the check valve under the cold low back pressure condition of the present invention;

[0096] Fig.12 It is a schematic diagram of the overall flow of the control method of the present invention. DETAILED DESCRIPTION

[0097] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0098] In the embodiment, see Figures 1 to 12 .

[0099] refer to Figure 1 The control system for valve reliability test proposed in the embodiment of the present invention is composed of a test design subsystem, a hardware part and a software part, wherein:

[0100] (1) Test design subsystem: It can input the test objectives, test piece design parameters and test profile requirements, set the heating and cooling rates, and pressure rates, obtain the combination of identification and reliability joint test profiles through FMEA analysis and comparative optimization, and calculate the test cycle

[0101] (2) The hardware includes three parts: power module, control hardware and acquisition hardware. By connecting the corresponding valves of the corresponding devices according to the loop diagram and device name indicated by the test design subsystem, the function of matching multiple test devices with one control system can be realized;

[0102] Power module: including 0-1000V thyristor DC power module, 0-500V electric transformer and auxiliary connectors, responsible for supplying power to all electrical equipment;

[0103] Control hardware: including 12 groups of test valve controllers and 3 groups of tested valve controllers, controlling the switch and operation of various valves;

[0104] Collection hardware: including 24 temperature collectors, 9 pressure collectors, 9 vibration collectors, 3 current sensors, 3 voltage sensors, 12 strain collectors and 24 acoustic emission collectors, which are used to collect the test valve and system status during the test at high frequency. The collection frequency can be set in the software.

[0105] (3) The software part includes two parts: the self-test subsystem and the automatic test subsystem;

[0106] Self-test subsystem: including acquisition self-test, electrical self-test and joint debugging of test pieces, automatically completing the confirmation of the connection status between the control system and the test device and providing fault prompts;

[0107] Automatic test subsystem: Based on the input of the test design subsystem, the active valve control logic and the check valve control logic are used to realize the automatic operation of the test of different types of valves.

[0108] In a specific embodiment, the test design subsystem can input the test objectives, test piece design parameters and identification test profile requirements, set the heating and cooling and pressure rates, optimize the test profile through the reliability analysis module, obtain the test cycle and test energy consumption through orthogonal combination, and provide the best test profile combination. The test objectives are MTBF, confidence level, number of test prototypes X, and X≤3; the test piece design temperature T, design pressure P, and test piece type are preset; the identification test profile is given according to the piecewise function (t 1 , p 1 , n 1 )、(t 2 , p 2 , n 2 ),…,(t c , p c , n c ), where t=(t 1 , t 2 ,…,t c ) is temperature, p=(p 1 , p 2 ,…,p c ) is pressure, n=(n 1 , n 2 ,…,n c ) is the number of actions.

[0109] First, conduct a reliability analysis. Perform a structural FMEA analysis on the test piece. Combine database or other manual information, and manually input the occurrence probability values of each failure mode. Then, classify and screen by failure cause, and arrange them according to the sum of the occurrence probability values of the corresponding failure modes by failure cause to obtain the failure causes affecting the reliability of the test piece. According to each failure cause, manually select and confirm the relevance of temperature and pressure to the failure cause. If there is a correlation, select the corresponding combination of pressure and temperature. The selection range is the (t 1 , p 1 , n 1 ), (t 2 , p 2 , n 2 ), …, (t c , p c , n c ) in the (t, p) combinations given by the qualification profile. Then, proportionally allocate the failure probabilities corresponding to the failure causes according to the ratio. For example, y 1 : y 2 : y 3 : …: y j , with the condition y 1 + y 2 + y 3 + … + y j = 1.

[0110] After that, according to the MTBF and confidence level in the test objectives, select a statistical method and specify the acceptance criteria. Here, the number of actions required can be calculated by referring to the national standard or according to the assumed life distribution form.

[0111] Here is a detailed explanation: First, assume the life distribution form of the equipment. The life distribution of electromechanical equipment can be divided into Weibull distribution or exponential distribution. If it is set that the valve life distribution conforms to the exponential distribution, then according to the requirements of GJB899, select a statistical method to calculate the number of actions required. If the valve life distribution follows other distribution forms, refer to the calculation method of GJB899 to calculate the number of actions required.

[0112] This method is mature and is represented by b(MTBF, confidence level, f(x)), where f(x) represents the number of actions. Therefore, the number of actions required for each valve:

[0113]

[0114] If x n < MTBF, then x n = MTBF, and the acceptance limit remains unchanged. Then, the number of actions required for reliability inspection under each failure cause is obtained as (t 1 , p 1 , y 1 * xn ),…,(t j , p j ,y j *x n ).

[0115] Finally, profile optimization is started. Based on the identification test profile, the number of actions under the same t and p is compared in turn, and the distribution ratio y is used to optimize the profile. j , if y j *x n <n j , then the number of profile combinations remains unchanged. If y j *x n >n j , then the number of combinations of this section becomes (t j , p j ,y j *x n ), so we get a new set of (t 1 , p 1 , n i )、(t 2 , p 2 , n q ),…,(t c , p c , n m ) section combination.

[0116] Arrange this combination according to the size of t, and calculate the overall test time according to the heating and cooling and pressure rates, and we have:

[0117] T time =T change +T test +T prepare

[0118] Where T time is the overall test time, T change is the cumulative time of variable working conditions, T test is the accumulated time of valve action, T prepare It is the preparation time required for the valve test. The default value is the average of the previous preparation test time and can be modified manually.

[0119] Specifically:

[0120]

[0121] Where i is the i-th section and n is the number of all sections;

[0122] T test =max(x 1 *T running , x 2 *Trunning , ..., x n *T running )

[0123] where x n is the number of times each valve needs to act, T running It is the time required for the valve to operate once.

[0124] Click Save Project, and the above information will be saved as follows: Figure 2 The preset mapping relationship shown is stored in the database, and then the test device name and test flow chart matching the test piece are popped up according to the input test piece type.

[0125] The preset mapping relationship includes: after the information is stored in the basic database, it is associated with a group of application data based on the primary mapping relationship, and is synchronously fed back to other multiple groups of application data. After analysis and processing, the associated application data is associated with the data stored in the database based on the secondary mapping relationship.

[0126] In a specific embodiment, the test valves of the control system hardware part are connected to the equipment on the test device, and each test valve is connected to the corresponding controller according to the control interface. Four temperature sensors and four pressure sensors are deployed in front and behind each test valve, and eight temperature sensors are deployed equidistantly along the vertical line of the center of gravity on the outside of the valve body. Three single-axis vibration sensors are deployed at the center of gravity of the valve. One valve power cable is selected to deploy a current sensor and a voltage sensor, and connected to the corresponding controller.

[0127] In a specific embodiment, the software runs a self-check subsystem, which performs an installation condition check:

[0128] like Figure 3 As shown, first perform an electrical self-test to check whether the overload protection value for the test valve is set in advance in the software. If yes, energize the test valve with one-way power to the insulation self-test value. If the power voltage of the test valve is 380V, the insulation self-test value is 1000V DC. If the power voltage of the test valve is 220V, the insulation self-test value is 500V. If the insulation test value is greater than 10MΩ, perform a path self-test and energize the test valve for 1s. If there is current in the test valve, it is connected normally. If there is any problem with the above self-test, feedback is sent for manual inspection.

[0129] like Figure 4 As shown, a self-test is then performed to collect and self-check the final path self-test measurement data of the electrical self-test. If the current, vibration, voltage, and current data have a data segment greater than 50% of the measured data when power is not on, the data is considered normal, otherwise it is fed back for manual processing.

[0130] like Figure 5As shown, the test piece is finally debugged jointly. First, the steering test is carried out. According to the feedback value of the test valve position signal, the valve is jogged in the reverse direction. For example, if the valve is in the open position, the valve is controlled to be closed, and vice versa. If there is no signal from the valve position indicator, the operator is notified to manually adjust the valve to the open position; if the valve position signal disappears or the valve opening becomes smaller after jogging, the valve steering is normal, otherwise the operator is notified to adjust the valve control power phase continuously.

[0131] After that, performance tests are carried out, including action performance and sealing performance tests, such as Figure 6 As shown, the software automatically gives the valve signal during the action performance, controls the valve to perform three opening and closing actions, and collects the corresponding signal as the initial signal. The software controls the booster pump to perform a pressure test on the closed valve. The pressure is obtained from the valve design parameters in the test design subsystem. The pressure test time is 15 minutes. The pressure before and after the valve is collected. If the pressure change before and after the valve is less than 0.1MPa, it is considered that there is no problem with the seal, otherwise it prompts manual processing.

[0132] In a specific embodiment, the automatic test subsystem executes the active valve control logic based on the automatic cycle test, and the specific steps include:

[0133] The user sets the action interval of each valve and selects the valves to participate in the automatic cycle test;

[0134] The control process is: open valve A for automatic circulation → valve A completes one cycle action → action interval time expires → open valve B for automatic circulation (if any) → valve B completes one cycle action → action interval time expires → open valve C for automatic circulation (if any);

[0135] Data storage: Data is stored at a rate of not less than 1000Hz. The storage file name must be marked with the current test type, test valve serial number, test time, current test number, working conditions before and after the test valve, and if a fault occurs, the fault code should also be reflected; each valve action is stored separately as a file;

[0136] Storage file processing: According to the changes in pressure before and after the test valve, accurately determine the time point when the pressure before and after the test valve is balanced, and divide the file into two working condition data files before and after the valve is opened based on this time point.

[0137] In a specific embodiment, during the automatic test subsystem executing the check valve automatic test process, different test positions can be selected separately, or multiple test positions can be combined to carry out the test. The automatic implementation of the check valve test condition is as follows: Figure 7 As shown, there are:

[0138] (1) Figure 8 As shown, under hot conditions, the back pressure is low pressure:

[0139] Status confirmation: confirm the pressure and temperature of the regulator; confirm the temperature behind the test valve; confirm the status of the test valve; confirm the status of each accompanying test valve in the test valve circuit;

[0140] Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0141] Automatically control the steam inlet valve and the exhaust solenoid valve before the valve to achieve the purpose of automatic cycle test;

[0142] At different times of the test, the pressure and temperature before and after the valve, the regulator and other positions are judged to ensure the stable operation of the program; when the limit is exceeded, the system needs to take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system;

[0143] All interlocking signals, interlocking upper and lower limits, delay values, and cycle times can be set;

[0144] Full data storage at 1000Hz rate, waveform screen at any time can be played back, playback signal can be freely configured, and data can be exported to Excel.

[0145] (2) Fig. 9 As shown, under hot conditions, the back pressure is high pressure:

[0146] Status confirmation: confirm the pressure and temperature of the regulator; confirm the temperature behind the test valve; confirm the status of the test valve; confirm the status of each accompanying test valve in the test valve circuit;

[0147] Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0148] Automatically control the steam inlet valve, the exhaust solenoid valve before the valve, and the exhaust valve after the valve to achieve the purpose of automatic cycle test;

[0149] At different times of the test, the pressure and temperature before and after the valve, the regulator and other positions are judged to ensure the stable operation of the program; when the limit is exceeded, the system needs to take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system;

[0150] All interlocking signals, interlocking upper and lower limits, delay values, and number of cycles can be set.

[0151] (3) Fig.10 As shown, under cold conditions, the back pressure is low pressure:

[0152] Status confirmation: confirm the nitrogen source pressure; confirm the test valve status; confirm the status of each accompanying test valve in the test valve circuit;

[0153] Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0154] Automatically control the nitrogen inlet valve and the exhaust solenoid valve in front of the valve to achieve the purpose of automatic cycle test;

[0155] At different times of the test, the pressure before and after the valve is determined to ensure the stable operation of the program; when an over-limit occurs, the system needs to take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system;

[0156] All interlocking signals, interlocking upper and lower limits, delay values, and number of cycles can be set.

[0157] (4) Fig.11 As shown, under cold conditions, the back pressure is low pressure:

[0158] Status confirmation: confirm the nitrogen source pressure; confirm the test valve status; confirm the status of each accompanying test valve in the test valve circuit;

[0159] Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data;

[0160] Automatically control the nitrogen inlet valve, the exhaust solenoid valve before the valve, and the exhaust valve after the valve to achieve the purpose of automatic cycle test;

[0161] At different times of the test, the pressure before and after the valve is determined to ensure the stable operation of the program; when an over-limit occurs, the system needs to take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system;

[0162] All interlocking signals (interlocking signals include: temperature, pressure, allowed action time, current, voltage), interlocking upper and lower limits, delay value, and number of cycles can be set.

[0163] On the other hand, the present invention further discloses a control method for executing any control system for valve reliability test in the above embodiments, comprising the following specific operation steps:

[0164] (1) Use system hardware to access the valve to be tested and connect multiple sets of test devices;

[0165] (2) Based on the test objectives, test piece design parameters, and test profile requirements input into the test design subsystem, set the heating and cooling rates and pressure rates;

[0166] (3) Use the self-test subsystem to complete the confirmation of the connection status between the control system and the test device and the fault prompt;

[0167] (4) Preset the number of test cycles and use the automatic test subsystem to automatically perform test operations on different types of valves based on the input of the test design subsystem.

[0168] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0169] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0170] In another embodiment provided in the present application, a computer program product including instructions is also provided. When the computer is run on the computer, the computer is loaded with any control system for valve reliability testing in the above embodiments and executes its control method.

[0171] It is understandable that the system provided by the embodiment of the present invention corresponds to the method provided by the embodiment of the present invention, and the explanation, examples and beneficial effects of the relevant contents can refer to the corresponding parts in the above method.

[0172] The embodiment of the present application also provides an electronic device, including a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus.

[0173] Memory, used to store computer programs;

[0174] The processor is used to implement any of the above control systems for valve reliability testing and execute its control method when executing the program stored in the memory.

[0175] The communication bus mentioned in the above electronic device can be a peripheral component interconnect standard bus or an extended industrial standard architecture bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc.

[0176] The communication interface is used for communication between the above electronic device and other devices.

[0177] The memory may include a random access memory, or may include a non-volatile memory, such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0178] The above-mentioned processor can be a general-purpose processor, including a central processing unit, a network processor, etc.; it can also be a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component.

[0179] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integration. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium, or a semiconductor medium (e.g., a solid-state hard disk Solid State Disk), etc.

[0180] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0181] In addition, it should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0182] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A control system for valve reliability testing, characterized in that: Based on the system hardware implementation, it includes test design subsystem, self-check subsystem and automatic test subsystem, among which: The test design subsystem is used to input the test objectives, test piece design parameters and test profile requirements, set the heating and cooling and pressure rates, obtain, identify and reliability joint test profile combinations through analysis and comparison optimization, and calculate the test cycle; A self-test subsystem is used to perform acquisition self-test, electrical self-test and test piece joint debugging operations, and automatically complete the confirmation of the connection status between the control system and the test device and the fault prompt based on the system hardware; The automatic test subsystem is used to execute the active valve control logic operation and the check valve control logic operation based on the input of the test design subsystem to realize the automatic operation of the reliability test of different types of valves.

2. The control system for valve reliability test according to claim 1, characterized in that: The system hardware consists of a power module, control hardware and acquisition hardware, and is connected to corresponding valves of corresponding devices according to the loop diagram and device names indicated by the test design subsystem to match multiple test devices.

3. The control system for valve reliability test according to claim 2, characterized in that: The power supply module includes a 0-1000V thyristor DC power supply module, a 0-500V electric transformer and auxiliary connectors, which are used to supply power to electrical equipment; The control hardware includes a test valve controller and a test valve controller, which are used to control the switch and operation of various valves; The acquisition hardware includes a temperature collector, a pressure collector, a vibration collector, a current sensor, a voltage sensor, a strain collector and an acoustic emission collector, which are used to collect the test valve and system status during the valve reliability test at a high frequency under a preset acquisition frequency state.

4. The control system for valve reliability test according to claim 3, characterized in that: Four temperature sensors and four pressure sensors are deployed in front and behind the test valve respectively, eight temperature sensors are deployed equidistantly along the vertical line of the center of gravity on the outside of the valve body, three single-axis vibration sensors are deployed at the center of gravity of the valve, and one of the valve power cables is selected to deploy a current sensor and a voltage sensor, and connected to the corresponding controller.

5. The control system for valve reliability test according to claim 1, characterized in that: The test design subsystem obtains, identifies and combines reliability test profiles through analysis and comparison optimization, and the specific operation steps of calculating the test cycle include: S1. The test cycle and test energy consumption are obtained through orthogonal combination, and the best test profile combination is provided. At this time, the test objectives are MTBF, confidence level, number of test samples X, and X≤3, and the design temperature T, design pressure P, and type of the test piece are preset; S2. The identification test profile is given by the piecewise function (t1, p1, n1), (t2, p2, n2), ..., (t c ,p c ,n c ), where t = (t1, t2, ..., t5) is the temperature, p = (p1, p2, ..., p c ) is the pressure, n=(n1,n2,…,n c ) is the number of actions; S3. Conduct reliability analysis to obtain the causes of failures that affect the reliability of the test piece. According to each cause of failure, manually select and confirm the correlation between temperature and pressure and the cause of failure. If there is a correlation, select the corresponding combination of pressure and temperature. When selecting the range, identify the (t1, p1, n1), (t2, p2, n2), ..., (t c ,p c ,n c ) and then distribute them in equal proportion according to the failure probability corresponding to the failure cause according to the ratio; S4. According to the MTBF and confidence level in the test objectives, select the statistical method, specify the acceptance criteria, calculate the number of actions required according to the assumed life distribution form, and mature the method. Use b(MTBF, confidence level, f(x)) to represent the calculation result, where f(x) represents the number of actions; S5. Calculate the number of times each valve needs to be operated under the reliability index: If x n <MTBF, then x n = MTBF, and the acceptance limit remains unchanged, then the required number of actions for reliability tests under each failure cause (t1, p1, y1 * x n ), …, (t j , p j , y j * x n ) are obtained; S6. Profile optimization: Based on the identification test profile, the values ​​of the number of actions under the same t and p are compared in sequence to obtain a new profile combination; S7. Arrange the new section combinations according to the size of t, and calculate the overall test time according to the heating and cooling and pressure rates.

6. The control system for valve reliability test according to claim 5, characterized in that: The specific analysis steps of the reliability analysis in step S3 include: Conduct structural FMEA analysis on the test piece, combine database information, and manually input the probability of occurrence of each failure mode; The failure causes are classified and screened, and the failure modes corresponding to the failure causes are arranged according to the sum of the probability values ​​of occurrence, so as to obtain the failure causes that affect the reliability of the test piece.

7. The control system for valve reliability test according to claim 5, characterized in that: When performing equal proportion distribution in step S3, the distribution ratio is y1:y2:y3:...:y j , there exists the condition y1+y2+y3+…+y j =1.

8. The control system for valve reliability test according to claim 5, characterized in that: In step S6, the specific comparison principle for comparing the values ​​of the number of actions under the same t and p to obtain a new profile combination includes: If y j *x n <n j , then the number of profile combinations remains unchanged; If y j *x n >n j , then the number of combinations of this section becomes (t j ,p j ,y j *x n ), and obtain a new set of profile combinations: (t1, p1, n i )、(t2,p2,n q ),...,(t c ,p c ,n m ).

9. The control system for valve reliability test according to claim 5, characterized in that: After the test design subsystem completes the corresponding operation, it also includes: storing the processed information in a database according to a preset mapping relationship, and popping up a test device name matching the test piece according to the input test piece type to execute the corresponding test process.

10. The control system for valve reliability test according to claim 9, characterized in that: The preset mapping relationship includes: after the information is stored in the basic database, it is associated with a group of application data based on the primary mapping relationship, and is synchronously fed back to other multiple groups of application data. After the associated application data is analyzed and processed, it is associated with the data stored in the database based on the secondary mapping relationship.

11. The control system for valve reliability test according to claim 9, characterized in that: The database includes model data and usage data, wherein: The model data includes a life model and an RBD reliability model, and the model data is processed based on an FTA fault tree analysis method and an FMMEA mechanism and effect analysis method; Usage data includes design data, maintenance data, operation data and test data.

12. The control system for valve reliability test according to claim 1, characterized in that: The specific operation steps of the self-test subsystem for performing electrical self-test include: a1. Check whether the overload protection value for the test valve is set in advance in the system. If yes, energize the test valve with one-way power to the insulation self-test value; a2. If the power voltage of the tested valve is 380V, the insulation self-test value is 1000V DC. If the power voltage of the tested valve is 220V, the insulation self-test value is 500V. a4. If the insulation test value is greater than 10MΩ, a self-check is performed and the valve under test is energized for 1 second. If there is current in the valve under test, the connection is normal.

13. The control system for valve reliability test according to claim 12, characterized in that: If there is any problem during the electrical self-test of the self-test subsystem, it will be fed back for manual inspection.

14. The control system for valve reliability test according to claim 1, characterized in that: The specific operation steps of the self-test subsystem to perform the collection self-test include: by checking the final path self-test measurement data of the electrical self-test, if the current, vibration, voltage, and current data have a data segment greater than 50% of the measured data when power is not on, the data is considered normal, otherwise it is fed back for manual processing.

15. The control system for valve reliability test according to claim 1, characterized in that: The specific operation steps of the self-test subsystem performing the test piece joint debugging operation include: b1. Perform steering test: according to the feedback value of the position signal of the tested valve, jog in the reverse direction; b2. If the valve position signal disappears or the valve opening becomes smaller after jogging, the valve steering is normal, otherwise notify manual adjustment of the valve control power phase; b3. Carry out inspection tests on the action performance and sealing performance.

16. The control system for valve reliability test according to claim 15, characterized in that: If there is no signal from the valve position indicator during the steering inspection in step b1, a person is notified to manually adjust the valve to the open position.

17. The control system for valve reliability test according to claim 15, characterized in that: The process of performing the action performance inspection test in step b3 includes: automatically giving a valve signal, controlling the valve to perform three opening and closing actions, and collecting the corresponding signal as the initial signal.

18. The control system for valve reliability test according to claim 15, characterized in that: The process of performing the sealing performance inspection test in step b3 includes: Use a booster pump to perform a pressure test on the closed valve. The pressure is obtained from the valve design parameters in the test design subsystem. The pressure test time is 15 minutes, and the pressures before and after the valve are collected. If the pressure change before and after the valve is less than 0.1MPa, it is considered that there is no problem with the seal, otherwise it is prompted for manual processing.

19. The control system for valve reliability test according to claim 1, characterized in that: The automatic test subsystem performs the active valve control logic operation including: L1. The user sets the action interval of each valve; L2. Select the initial valve A to participate in the automatic cycle test; L3. Execute the control process: open valve A for automatic circulation until valve A completes one cycle; L4. If there is another valve that has chosen to participate in the automatic cycle test when the action interval time expires, open the valve for automatic cycle until the valve completes one cycle action, and then repeat the cycle until all valves complete the cycle action; L5. Data storage: Data is stored at a rate of not less than 1000Hz. The storage file name is marked with the current test type, test valve serial number, test time, current test number, working conditions before and after the test valve, and fault code in the fault state. Each valve action is stored separately as a file; L6. Storage file processing: According to the change of pressure before and after the test valve, determine the time point when the pressure before and after the test valve is balanced, and divide the file into two working condition data files before and after the valve is opened based on this time point.

20. The control system for valve reliability test according to claim 1, characterized in that: The automatic test subsystem executes the check valve control logic operation to select different test positions individually or combine multiple test positions to carry out tests under different check valve automatic working conditions. The check valve automatic working conditions include cold and hot conditions and high and low pressure back pressure conditions.

21. The control system for valve reliability test according to claim 20, characterized in that: Under the hot state and low back pressure conditions, the specific operation steps of the automatic test subsystem to perform the check valve control logic operation include: c1. Status confirmation: confirm the pressure and temperature of the regulator, confirm the temperature after the test valve, confirm the status of the test valve, and confirm the status of each accompanying test valve in the test valve circuit; c2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data; c3. Preset the number of cycles and automatically control the steam inlet valve and the exhaust solenoid valve in front of the valve to perform automatic cycle test; c4. At different times of the test, determine the pressure and temperature before and after the valve and at the regulator position to ensure the stable operation of the program. When an over-limit occurs, the system takes corresponding actions, alarms through the interface, and sends the fault code to the data acquisition system; c5. All interlocking signals, interlocking upper and lower limits, and delay values; c6. Store all data at a rate of 1000Hz, used to replay waveform images at any time, freely configure playback signals, and export data to Excel.

22. The control system for valve reliability test according to claim 20, characterized in that: Under the hot state and high back pressure conditions, the specific operation steps of the automatic test subsystem to perform the check valve control logic operation include: d1. Status confirmation: confirm the pressure and temperature of the regulator, confirm the temperature after the test valve, confirm the status of the test valve, and confirm the status of each accompanying test valve in the test valve circuit; d2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data; d3. Preset the number of cycles and automatically control the steam inlet valve, the exhaust solenoid valve before the valve, and the exhaust valve after the valve to perform automatic cycle test; d4. At different times of the test, determine the pressure and temperature before and after the valve and at the regulator position to ensure the stable operation of the program. When an over-limit occurs, the system takes corresponding actions, alarms through the interface, and sends the fault code to the data acquisition system; d5. All interlocking signals, interlocking upper and lower limits, and delay values; d6. Stores all data at a rate of 1000Hz, used to replay waveform images at any time, freely configure playback signals, and export data to Excel.

23. The control system for valve reliability test according to claim 20, characterized in that: Under the cold state and high back pressure conditions, the specific operation steps of the automatic test subsystem to perform the check valve control logic operation include: e1. Status confirmation: confirm the nitrogen source pressure, the test valve status, and the status of each accompanying test valve in the test valve circuit; e2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data; e3. Preset the number of cycles and automatically control the nitrogen inlet valve and the exhaust solenoid valve in front of the valve to perform automatic cycle test; e4. At different times of the test, determine the pressure before and after the valve to ensure the stable operation of the program. When the limit is exceeded, the system will take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system; e5. All interlocking signals, interlocking upper and lower limits, and delay values.

24. The control system for valve reliability test according to claim 20, characterized in that: Under the cold state and low back pressure conditions, the specific operation steps of the automatic test subsystem to perform the check valve control logic operation include: f1. Status confirmation: confirm the nitrogen source pressure, the test valve status, and the status of each accompanying test valve in the test valve circuit; f2. Valve opening preparation: send the valve opening instruction to the data acquisition system, and the data acquisition system starts to collect and store data; f3. Preset the number of cycles and automatically control the nitrogen inlet valve, the exhaust solenoid valve before the valve and the exhaust valve after the valve to perform automatic cycle test; f4. At different times of the test, determine the pressure before and after the valve to ensure the stable operation of the program. When the limit is exceeded, the system will take corresponding actions, alarm through the interface, and send the fault code to the data acquisition system; f5. All interlocking signals, interlocking upper and lower limits, and delay values.

25. A control method for executing the control system for valve reliability test according to any one of claims 1 to 24, characterized in that: The specific steps are as follows: (1) Use system hardware to access the valve to be tested and connect multiple sets of test devices; (2) Based on the test objectives, test piece design parameters, and test profile requirements input into the test design subsystem, set the heating and cooling rates and pressure rates; (3) Use the self-test subsystem to complete the confirmation of the connection status between the control system and the test device and the fault prompt; (4) Preset the number of test cycles and use the automatic test subsystem to automatically perform test operations on different types of valves based on the input of the test design subsystem.

Images