Descriptions Of Operation - Aventics CONTROLAIR HC-2 Series Service Information

Description of Operation
®
For HC-2 Controlair
Note in the diagrammatic view that supply pressure is connected to
port (2) and this supply pressure is directed only to the pressure-
graduating portion. The delivery from the pressure graduating portion
encounters plugged port (8) (a pressure gage can be connected at
this port) and continues to become the supply air to each of the side
valves. The delivery from the side valves is directed to outlet ports
(1) or (3).
With the handle in neutral position, both outlet ports are exhausted to
atmosphere through their respective side valve.
Movement of the handle through the first 10 degrees of travel from
neutral operates one of the 3 way side valves to connect the gradu-
ated pressure from the graduating portion to the appropriate outlet
port (1) or (3).
Movement of the handle beyond 10 degrees either side of center po-
sition starts the cam to push down on the pressure control plunger
closing the exhaust valve and opening the upper supply valve that
allows air to flow through the selected side valve to an outlet port. As
the pressure builds up in the delivery line, it acts through the sensing
port orifice and deflects the control diaphragm downward, compress-
ing the control spring. When sufficient diaphragm deflection is ob-
tained to allow the upper supply valve in the pressure control portion
to close, the pressure in the delivery line is held to that value.
The value of the pressure delivered to the outlet port is proportional
to the pressure graduating portion plunger movement. This move-
ment in turn is controlled by the cam contour and is proportional to
the handle travel.
The HC-2 Controlair Valve will automatically compensate for air pres-
sures changes. These air pressure changes can be caused by line
leakage, temperature change or load feedback. If air pressure at the
outlet port increases over that called for by the handle position, the
diaphragm in the control portion will deflect downward opening the
lower exhaust valve and exhausting air until the original setting is ob-
tained. If the pressure drops below that called for by the handle posi-
tion, the decreased force on the diaphragm will allow the control
spring to force the diaphragm upward, opening the upper supply
valve to restore the set pressure.
The range of pressure is controlled by the strength of the diaphragm
spring. Various values are available as shown on the Identity Sched-
ule on page 7.
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