9.1.1.1 Development Status of Airborne Electro-Hydraulic Control
Technology
Up to now, the level of electro-hydraulic control technology can be roughly
reflected by the following details:
Many electro-hydraulic control valves are equipped with electronic devices,
so-called “on-borne” electronic devices. This combined installation method, which
directly installs the driver and signal regulating circuit on the valve body, has the
advantage of reducing the number of connections between the valve and the central
control system. Because according to the traditional layout, the valve is always
adjacent to the actuator and the central control device is often located in the electric
control platform far from the actuator. Many long cables and electrical connectors
are needed to connect the two systems, and they are the least reliable part of the
electro-hydraulic control system. The combination installation of embedded chips
improves the reliability significantly by simplifying and omitting cable connections
and connectors. A single electro-hydraulic device can have many functions, thus
saving many devices and simplifying the system and operation. The only thing to
do is to send the right signals to them. For example, it can control speed, position,
acceleration, force or pressure as long as the corresponding sensors, feedback
devices, and control logic/processing devices are provided for the servo valve.
In addition to improving reliability, the on-borne electronic circuits of valves and
pumps can also form a coexistence mode of distributed control and centralized
control. For industrial applications, the preferred equipment configuration is a
programmable logic controller (PLC), which can send instructions to several valves
and pumps. A variety of on-borne functional components, especially those suitable
for open-loop control, have emerged as the times require. Some components can
provide adjustable switching-on and disconnection of slope change, i.e., flexible
transformation, so that acceleration and deceleration can be controlled, thereby
mitigating the system impact caused by on–off valve control. These devices are
generally integrated and can be adjusted online. When used in motion control with a
high requirement, an industrial motion control device is usually used to realize
simultaneous control of acceleration, speed, and position. This device can be either
a controller for independent application or a plug-in for the extended bus of PLC.
Because of the implementation of serial communication bus standard, a large
number of electro-hydraulic devices such as valves, pumps, and solenoids can be
controlled by only one pair of wires.
9.1.1.2 Development Trend
(1) Development and restrictive factors of ultrahigh pressure
Hydraulic technology is famous for its high output force and power density.
The key is to use high pressure. It is a trend to continue to develop toward
ultrahigh pressure. However, the increase in working pressure of hydraulic
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
53
Technology
Up to now, the level of electro-hydraulic control technology can be roughly
reflected by the following details:
Many electro-hydraulic control valves are equipped with electronic devices,
so-called “on-borne” electronic devices. This combined installation method, which
directly installs the driver and signal regulating circuit on the valve body, has the
advantage of reducing the number of connections between the valve and the central
control system. Because according to the traditional layout, the valve is always
adjacent to the actuator and the central control device is often located in the electric
control platform far from the actuator. Many long cables and electrical connectors
are needed to connect the two systems, and they are the least reliable part of the
electro-hydraulic control system. The combination installation of embedded chips
improves the reliability significantly by simplifying and omitting cable connections
and connectors. A single electro-hydraulic device can have many functions, thus
saving many devices and simplifying the system and operation. The only thing to
do is to send the right signals to them. For example, it can control speed, position,
acceleration, force or pressure as long as the corresponding sensors, feedback
devices, and control logic/processing devices are provided for the servo valve.
In addition to improving reliability, the on-borne electronic circuits of valves and
pumps can also form a coexistence mode of distributed control and centralized
control. For industrial applications, the preferred equipment configuration is a
programmable logic controller (PLC), which can send instructions to several valves
and pumps. A variety of on-borne functional components, especially those suitable
for open-loop control, have emerged as the times require. Some components can
provide adjustable switching-on and disconnection of slope change, i.e., flexible
transformation, so that acceleration and deceleration can be controlled, thereby
mitigating the system impact caused by on–off valve control. These devices are
generally integrated and can be adjusted online. When used in motion control with a
high requirement, an industrial motion control device is usually used to realize
simultaneous control of acceleration, speed, and position. This device can be either
a controller for independent application or a plug-in for the extended bus of PLC.
Because of the implementation of serial communication bus standard, a large
number of electro-hydraulic devices such as valves, pumps, and solenoids can be
controlled by only one pair of wires.
9.1.1.2 Development Trend
(1) Development and restrictive factors of ultrahigh pressure
Hydraulic technology is famous for its high output force and power density.
The key is to use high pressure. It is a trend to continue to develop toward
ultrahigh pressure. However, the increase in working pressure of hydraulic
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
53