should also be provided by the manufacturer to the user. Once these ideas and
requirements are universally recognized and responded to by manufacturers and
implemented, the mathematical model of hydraulic components will become as
common as assembly drawings. This is also a great contribution to simulation
or simulation technology.
9.1.1.3 Material—An Important Contributing Factor to the Evolution
of Electro-Hydraulic Technology
The emergence and application of new materials further promote the evolutionary
changes of electro-hydraulic technology. As far as the steel materials used most in the
hydraulic system are concerned, if they have higher strength without increasing the
cost and reducing the machinability, the hydraulic machinery will be more powerful
and reliable. The use of ceramic materials in hydraulic systems has been tried and
achieved some success. The improvement of the properties of magnetic materials
(magnets) is more effective in promoting the development of electro-hydraulic
technology. If the magnetic saturation current of the magnetic material can be
increased, the coil or solenoid with the same turn number can produce greater
electromagnetic force. As the electrical–mechanical interface of the electro-hydraulic
valve, solenoid generates greater force, which means that the direct valve with a
larger flow can be manufactured at almost no additional cost. High-performance
magnets have high saturation current and high flux density, allowing a large current
to be overdriven, resulting in greater electromagnetic force. This force can be
effectively used to accelerate the spool valve, resulting in greater dynamic bandwidth
or higher frequency response. When the solenoid which can give greater force is used
as the electrical–mechanical interface of the electro-hydraulic valve, the pilot stage
will not be used. This creates conditions for the development of large flow, fast
action, and low-cost electro-hydraulic valves.
9.1.1.4 Electrorheological Technology
Electrorheological fluids (ER fluids) are suspended fluids that can flow freely in a
free state. Once it is under the action of electric field, it will solidify rapidly and
show viscous, cementitious, or hard properties according to the intensity of electric
field. This characteristic makes it ideal for valves, dampers, and power transmission
devices of hydraulic and mechanical systems. ER fluid responds very quickly to
electrical signals, and can change the state of liquid–solid or solid–liquid in less
than 1 ms. The solidification degree is proportional to the field strength. This makes
it suitable for direct control by fast electronic devices, such as microcomputers. This
is its most important advantage. The possibility of ER fluid technology application
is mainly based on its two characteristics: low input power and high response speed.
Although the working voltage is as high as several thousand volts, the current
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
57
requirements are universally recognized and responded to by manufacturers and
implemented, the mathematical model of hydraulic components will become as
common as assembly drawings. This is also a great contribution to simulation
or simulation technology.
9.1.1.3 Material—An Important Contributing Factor to the Evolution
of Electro-Hydraulic Technology
The emergence and application of new materials further promote the evolutionary
changes of electro-hydraulic technology. As far as the steel materials used most in the
hydraulic system are concerned, if they have higher strength without increasing the
cost and reducing the machinability, the hydraulic machinery will be more powerful
and reliable. The use of ceramic materials in hydraulic systems has been tried and
achieved some success. The improvement of the properties of magnetic materials
(magnets) is more effective in promoting the development of electro-hydraulic
technology. If the magnetic saturation current of the magnetic material can be
increased, the coil or solenoid with the same turn number can produce greater
electromagnetic force. As the electrical–mechanical interface of the electro-hydraulic
valve, solenoid generates greater force, which means that the direct valve with a
larger flow can be manufactured at almost no additional cost. High-performance
magnets have high saturation current and high flux density, allowing a large current
to be overdriven, resulting in greater electromagnetic force. This force can be
effectively used to accelerate the spool valve, resulting in greater dynamic bandwidth
or higher frequency response. When the solenoid which can give greater force is used
as the electrical–mechanical interface of the electro-hydraulic valve, the pilot stage
will not be used. This creates conditions for the development of large flow, fast
action, and low-cost electro-hydraulic valves.
9.1.1.4 Electrorheological Technology
Electrorheological fluids (ER fluids) are suspended fluids that can flow freely in a
free state. Once it is under the action of electric field, it will solidify rapidly and
show viscous, cementitious, or hard properties according to the intensity of electric
field. This characteristic makes it ideal for valves, dampers, and power transmission
devices of hydraulic and mechanical systems. ER fluid responds very quickly to
electrical signals, and can change the state of liquid–solid or solid–liquid in less
than 1 ms. The solidification degree is proportional to the field strength. This makes
it suitable for direct control by fast electronic devices, such as microcomputers. This
is its most important advantage. The possibility of ER fluid technology application
is mainly based on its two characteristics: low input power and high response speed.
Although the working voltage is as high as several thousand volts, the current
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
57