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B. Functional structure
The deflation device mainly comprising deflation valve spool, deflation valve spring, valve ball, clearance
adjustment pad and retaining ring is installed in the safety valve spool. Oil pressure fluctuates as the piston
moves back and forth during operation. When the piston is pushed in, the deflation valve spool is jacked by
spring; when the piston is pushed out, gas will flow out of the oil chamber through the clearance of valve spool
due to instantaneous pressure increase in the diaphragm chamber after the valve ball is jacked. The deflation
valve spool will compress the valve spring and stop gas exhaust. The opening height of valve spool is adjusted
according to the washer thickness, and the flow is generally in direct proportion to the opening height. For
example, when the system pressure is high, the opening height of valve spool can be appropriately reduced. For
low flow pumps, the opening height of valve spool may be controlled within 0.05~01mm. But for large flow
pumps, that shall be controlled within 0.2~0.5mm.
C. Adjustment
The opening pressure of deflation safety valve has been set as required when it leaves the factory, and if the
actual exhaust pressure is different from the rated exhaust pressure, it shall be adjusted according to the table
below.
Rated exhaust pressure of pump, P
dr
(MPa)
0.2
～
1.2
1.2
～
4.5
4.5
～
9.0 9
～
20.0
Opening pressure of hydraulic safety valve, P
k
(MPa)
P
dr
+0.3
1.3P
dr
1.2P
dr
1.15P
dr
Early opening or opening failure of the safety valve when the working pressure of pump is lower/higher than the
opening pressure given in the table is abnormal; if any, the compression force of safety valve spring shall be
adjusted or even the safety valve shall be disassembled for cleaning, so as to ensure the normal operation of
exhaust safety valve and maintain the stability of flow.
Attention: The deflation safety valve of the pump is used to ensure the safety of the oil cylinder of the pump,
especially for high flow pumps, and shall not be mounted on the process line.
2.3 Pump flow regulation
The adjusting handwheel is rotated to drive the adjusting screw for axial movement of the adjusting nut which is
engaged with it; as the pointer installed on the adjusting nut is connected with the guide and the E-type slide
shaft is connected with the guide through the bearing, the E-type slide shaft will axially move as the adjusting
handwheel rotates, and the eccentricity of the eccentric gear will change under the action of the slide shaft chute,;
namely, the turning radius of the eccentric gear will change for the purpose of changing the reciprocating
