(1) Computer Control
Compared with an analog servo system, digital electro-hydraulic servo system has
higher control precision, stronger anti-interference ability, wider and more flexible
functions. Taking the coordinated loading system for structural fatigue test of
American space shuttle as an example, there are 374 electro-hydraulic servo loading
actuators, 209 servo loops, and more than 5000 sensors in the system. An Xcrox
530 computer and inferior computer of each channel controls the loading program
to load each channel in coordination according to various load spectra (simulating
40 load conditions). It has the functions of working mode selection, real-time data
processing and monitoring, and protection. The 100-channel hydraulic loading
system controlled by computer was successfully developed by China Aviation
Industry Department in 1988.
(2) Computer-Aided Testing and Fault Diagnosis
The test automation of the electro-hydraulic servo valve debugging system of
MOOG Company has been greatly improved after the computer was used. The flow
characteristics, pressure characteristics, zero leakage characteristics, and pressure–
flow characteristics of the valve are tested automatically. The characteristic curves
and data (such as flow gain, pressure gain, linearity, symmetry, resolution, hysteresis and dynamic response) are given. Online monitoring of the operation of
hydraulic system is realized. For example, the cavitation diagnosis of hydraulic
pumps has been carried out at home and abroad. The pressure fluctuation spectra of
hydraulic pumps and the vibration power spectra of shell have been analyzed by
computer. According to the low-frequency component of pressure spectrum, the
occurrence of cavitation is judged, and the relationship between the frequency
component of vibration power spectrum, vibration energy of each frequency, and
cavitation is studied.
(3) Computer-Aided Design and Analysis
In recent years, China has introduced or developed a relatively complete hydraulic
CAD software system, simulation analysis and design software from abroad, which
can be applied to hydraulic components and system design calculation, dynamic
simulation, identification, and performance optimization of hydraulic systems.
(4) Digital Control Hydraulic Components
Digital hydraulic control components (such as pulse width modulated solenoid
valves) can receive computer information directly (if necessary, add amplifiers) to
achieve action. It simplifies the interface, but has low-frequency response, and is
used in occasions where control requirements are not high. The digital control flow
valve and pressure valve developed by the author in Tokyo Meter can directly set
and measure the flow and pressure through the button on the valve body and the
embedded chip. In addition, “stepping motor–reducer–screw/nut sleeve–hydraulic
slide valve” combination, whose input is pulse sequence and output is linear
74
9 High-Temperature and High-Speed Gas Turbine Pump …
Compared with an analog servo system, digital electro-hydraulic servo system has
higher control precision, stronger anti-interference ability, wider and more flexible
functions. Taking the coordinated loading system for structural fatigue test of
American space shuttle as an example, there are 374 electro-hydraulic servo loading
actuators, 209 servo loops, and more than 5000 sensors in the system. An Xcrox
530 computer and inferior computer of each channel controls the loading program
to load each channel in coordination according to various load spectra (simulating
40 load conditions). It has the functions of working mode selection, real-time data
processing and monitoring, and protection. The 100-channel hydraulic loading
system controlled by computer was successfully developed by China Aviation
Industry Department in 1988.
(2) Computer-Aided Testing and Fault Diagnosis
The test automation of the electro-hydraulic servo valve debugging system of
MOOG Company has been greatly improved after the computer was used. The flow
characteristics, pressure characteristics, zero leakage characteristics, and pressure–
flow characteristics of the valve are tested automatically. The characteristic curves
and data (such as flow gain, pressure gain, linearity, symmetry, resolution, hysteresis and dynamic response) are given. Online monitoring of the operation of
hydraulic system is realized. For example, the cavitation diagnosis of hydraulic
pumps has been carried out at home and abroad. The pressure fluctuation spectra of
hydraulic pumps and the vibration power spectra of shell have been analyzed by
computer. According to the low-frequency component of pressure spectrum, the
occurrence of cavitation is judged, and the relationship between the frequency
component of vibration power spectrum, vibration energy of each frequency, and
cavitation is studied.
(3) Computer-Aided Design and Analysis
In recent years, China has introduced or developed a relatively complete hydraulic
CAD software system, simulation analysis and design software from abroad, which
can be applied to hydraulic components and system design calculation, dynamic
simulation, identification, and performance optimization of hydraulic systems.
(4) Digital Control Hydraulic Components
Digital hydraulic control components (such as pulse width modulated solenoid
valves) can receive computer information directly (if necessary, add amplifiers) to
achieve action. It simplifies the interface, but has low-frequency response, and is
used in occasions where control requirements are not high. The digital control flow
valve and pressure valve developed by the author in Tokyo Meter can directly set
and measure the flow and pressure through the button on the valve body and the
embedded chip. In addition, “stepping motor–reducer–screw/nut sleeve–hydraulic
slide valve” combination, whose input is pulse sequence and output is linear
74
9 High-Temperature and High-Speed Gas Turbine Pump …