grinding surface is easy to flow out of the valve sleeve hole. After decomposition
and inspection of several sets of samples, no abrasive sand was found inside the
valve sleeve, which shows that this method is reliable and effective.
A variety of methods (such as demagnetization, vibration, bubble scrubbing,
ultrasonic scrubbing, washing, and high-pressure air blowing) are used comprehensively to remove the redundant parts repeatedly when assembling. When
assembling, the spool, bushing, piston, valve sleeve hole, and cylinder hole are
inspected by a special person with a microscope. Inspectors also need to review and
try their best to ensure that the assembled parts are free of redundancy.
The steering gear is assembled on the super clean worktable, and the production
site is kept regular, clean, and civilized. The steering gear is testing installed first.
Avoid the problem of screw coating falling off in formal assembly. After testing
installation, the electricity and ventilation running-in test of the steering gear under
different frequencies and atmospheric pressures is carried out. Then decomposition,
cleaning reviews the appearance of components, and then formal assembly. It is
conducive to eliminating the possible residue or the excess produced in the trial run.
10.4.3 Fit Clearance Control
The fit clearance between valve sleeve and valve core is an important characteristic
parameter in gas steering engine. Increasing the mating clearance will increase the
leakage of working medium, reduce the output torque, and increase the reaction
time, and the smaller the mating clearance, the more inflexible the movement of the
valve core will be, even stuck.
There are many factors affecting the fit clearance, so corresponding control
methods should be adopted.
The working medium for ground test of gas steering engine is compressed air at
room temperature, and the working medium for pilot fire or flight test is gas.
Although the gas is filtered, a large amount of carbon particles will be entrained into
the matching place, which makes the matching clearance relatively smaller and is
unfavorable to the movement of the valve core.
The heat capacity of the body assembly is much larger than that of the valve
core; and the valve sleeve, shell, and body are heated through the ventilation
channel, while the valve core is almost surrounded by gas; the radial expansion of
the valve sleeve is restricted by the shell and the body, but the valve core has no
such restriction. Because of these conditions, under the action of gas, the radial
expansion of the valve sleeve hole is less than the radial expansion of the valve core
in a certain period of time. This also makes the fit clearance smaller. This is the
reason why the gas steering gear with small clearance works normally in ground
test and will break down under the action of gas.
The design specifies the mating clearance between the valve sleeve and the
spool. Later, according to a large number of ignition test data, the clearance was
adjusted during assembly. It is difficult to accurately measure the dimension of
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10 Application of Aerodynamic Technology in Attitude Control …
and inspection of several sets of samples, no abrasive sand was found inside the
valve sleeve, which shows that this method is reliable and effective.
A variety of methods (such as demagnetization, vibration, bubble scrubbing,
ultrasonic scrubbing, washing, and high-pressure air blowing) are used comprehensively to remove the redundant parts repeatedly when assembling. When
assembling, the spool, bushing, piston, valve sleeve hole, and cylinder hole are
inspected by a special person with a microscope. Inspectors also need to review and
try their best to ensure that the assembled parts are free of redundancy.
The steering gear is assembled on the super clean worktable, and the production
site is kept regular, clean, and civilized. The steering gear is testing installed first.
Avoid the problem of screw coating falling off in formal assembly. After testing
installation, the electricity and ventilation running-in test of the steering gear under
different frequencies and atmospheric pressures is carried out. Then decomposition,
cleaning reviews the appearance of components, and then formal assembly. It is
conducive to eliminating the possible residue or the excess produced in the trial run.
10.4.3 Fit Clearance Control
The fit clearance between valve sleeve and valve core is an important characteristic
parameter in gas steering engine. Increasing the mating clearance will increase the
leakage of working medium, reduce the output torque, and increase the reaction
time, and the smaller the mating clearance, the more inflexible the movement of the
valve core will be, even stuck.
There are many factors affecting the fit clearance, so corresponding control
methods should be adopted.
The working medium for ground test of gas steering engine is compressed air at
room temperature, and the working medium for pilot fire or flight test is gas.
Although the gas is filtered, a large amount of carbon particles will be entrained into
the matching place, which makes the matching clearance relatively smaller and is
unfavorable to the movement of the valve core.
The heat capacity of the body assembly is much larger than that of the valve
core; and the valve sleeve, shell, and body are heated through the ventilation
channel, while the valve core is almost surrounded by gas; the radial expansion of
the valve sleeve is restricted by the shell and the body, but the valve core has no
such restriction. Because of these conditions, under the action of gas, the radial
expansion of the valve sleeve hole is less than the radial expansion of the valve core
in a certain period of time. This also makes the fit clearance smaller. This is the
reason why the gas steering gear with small clearance works normally in ground
test and will break down under the action of gas.
The design specifies the mating clearance between the valve sleeve and the
spool. Later, according to a large number of ignition test data, the clearance was
adjusted during assembly. It is difficult to accurately measure the dimension of
190
10 Application of Aerodynamic Technology in Attitude Control …