The relationship between flow and pressure should satisfy its theoretical limit curve. The mathematical model of the curve is automatically established and revised by the computer for the performance requirements of different models. The water source of the washing pump is provided by the upper tank at work. The inlet water of the washing pump is automatically triggered in the positioning and clamping process of the pump to shorten the auxiliary time. The pump power supply DC 030V can be adjusted to meet the needs of different types of washing pumps. According to the characteristic that the flow rate and pressure of the variable displacement pump change with the pressure loss of the output line, a multi-path throttle valve is set at the outlet end of the wash pump to regulate the flow and pressure, and the automatic switching is realized by computer control, thereby avoiding the adoption of Electro-hydraulic servo control valve has the disadvantages of high cost and difficulty in stable control of ultra-small flow.
Interface circuit design features such as the external signal opto-isolated by the conditioning circuit, signal conversion and amplification to send multi-function PC card, complete A / D conversion, digital I / O and timing, interrupt control and other functions. The IPC obtains external signals through queries, timed interruptions, etc. to perform real-time display and recording of test data and control of the test flow. The test results are saved in the file and output with sound signals at the same time. The operator can classify the washing pump accordingly. deal with.
The A/D conversion rate is 25s. After the end of the conversion, an interrupt signal is sent to the IPC through the 8253 on the multifunction card. The sampling speed can be as high as 30kHz. The sampling frequency can be adjusted by setting the 8253 timer. Practice has shown that as long as the correct interrupt number is set (be careful not to interrupt the resource with the IPC) and prioritize the handling of interrupt signals in the dynamic link library design, a very high sampling rate can also be obtained in the Windows environment.
The flow rate of the wash pump in the collection and processing of the ultra-small flow sensing signal is 0180L/h, and the ultra low flow sensor of the series of 0200L/h from Italy ULF (ultralowflow) series is used. The impeller material in this sensor adopts special organic The composite material ensures working life and chemical resistance. Each blade is equipped with a permanent magnet. When the impeller rotates under the impact of water, a fixed Hall effect sensor receives the rotation signal of the impeller through a permanent magnet. It is converted into square wave output.
When the flow rate is stable, the rotation speed of the impeller is directly proportional to the flow rate. The output signal is calibrated to 7200 pulses/L. The steady flow time and the corresponding PID algorithm are determined according to the actual test object during debugging. Since the pulse frequency corresponding to 1L/h (liter/hour) is 7200/3600=2Hz, the sampling time is T(s), and the number of sampling pulses in T time is N, then F=N/T, corresponding to the flow rate It is Q=N/(2T). It can be seen that the sampling speed is inversely proportional to the sampling accuracy. Taking into account the accuracy of the sensing signal itself, if taking T=06s, the sampling accuracy is 1L/12h.
Washing Pump Quality Analysis System (1) Function Module of the System The software system of the testing platform consists of four modules: file management, real-time control, parameter setting and data processing. Among them, the file module completes the establishment, opening, saving, format conversion and printing functions of the database file; the real-time control module completes the real-time data collection and processing; the module can measure the flow of different parameters of the statistical area, the mathematical models of different products and test points. The value is set; the data processing module can perform a flexible combination of query, statistical analysis (including histograms, distribution maps, control charts) and quantitative studies of substandard product quality problems.
(2) Data structure of the system In order to meet the needs of real-time data recording and quality analysis, two major databases have been established. The structure adopts a random format, and the data files cannot be changed, which ensures the objectivity of the data. In terms of function, a database is used to store various real-time data of products during testing, and the other is a database that stores the product's characteristic parameters, test dates, and test results. In the use of the two databases constitute a whole, data records using a one-to-many mapping.
Conclusion In view of the fact that the performance data of the car wash pump is difficult to detect and difficult to save, an automatic detection and analysis system for the wash pump quality was developed. The system integrates real-time detection, database management, and quality statistical analysis into one, achieving ultra-small in fast cycle production. High-precision flow detection requirements, including pressure readings accurate to three decimal places, range 004MPa; flow readings after one decimal place, range 0200L / h; voltage readings after two decimal places, range 030V; current decimal place two, range 010A The 5-way computer detection time is less than 52 seconds, and the new search by the national search workstation shows that this achievement has filled the domestic blank in this field.
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