are used in refrigeration systems, and the pressure is
controlled by the on-off of contacts. There are mainly high pressures controllers
, low pressure controllers
, high and low pressure controllers, differential pressure controllers
and oil pressure protection pressure
controllers. The action principle of the pressure controller is basically the same, which is detected by the
pressure detection mechanism and controlled by the actuator.
The bellows are compressed to produce
expansion deformation, which drives the swing rod to move. Then the swing rod
moves the contacts to open and break so as to control the pressure.
Two parameters, DIFF and RANGE, are often
seen in pressure controllers. RANGE is the range of pressure, and DIFF is the
pressure difference, which refers to the switching difference. In the other
word, it is the dead zone, which is a switching area.
Each pressure switch has this parameter,
and the switching difference of the controller can be adjusted or not according
to different requirements. Adjustable setting point is called adjustable
setting point; otherwise it is not adjustable setting point.
For example, the
fixed working pressure difference of Jy616 pressure controller is 0.5-1
kgf/cm2, which fixes the pressure difference in a certain range.
High-Pressure Pressure Controllers and Low-Pressure
(1) Action principle: High-pressure pressure controllers and low-pressure pressure controller
have the same function principle.
When the pressure in the bellows rises and its value is higher than the setting
value of the main adjusting spring, the bellows extend or shorten (the external
compression type of bellows is shortened, the internal compression type is
elongated), push the swing rod, move the contacts, cut off the power supply to
play a high-voltage protection role. If the power supply is cut off when the
pressure is too low, it will play a low-voltage protection role. Taking the high-pressure pressure controller as an
example, the range of control pressure is introduced. When the pressure is P1,
the contacts are open, and when the pressure is P, the contacts are broken. The
working pressure difference ranges from P to P1.
When the pressure is high, the contact
breaks, and when the pressure drops to point P1, the contact opens. When the
pressure rises to point P, the contact breaks off again. The action of the low-pressure pressure controller is the
(2) Work pressure difference: Work pressure
difference refers to the working pressure interval between on and off contacts.
If the disconnection pressure of the high-voltage controller is set at 14kg and
the working pressure difference is set at 2kg, the controller will be
disconnected when the pressure exceeds 14kg, and the controller will be
connected when the pressure is lower than 12kg. Reducing the working pressure
difference can improve the control accuracy. But don't adjust it too small,
otherwise it will move frequently. Controller contact action should be
flexible, to instantly on and off, otherwise spark discharge will occur,
(3) Structure and adjustment: When the
pressure of the input bellows increases, the bellows bottom plate moves (the
movement is determined by the difference between the pressure and the spring
force), driving the swing rod and controlling the contact action. When it is
necessary to adjust the pressure control range, rotate the pressure adjustment
screw counterclockwise/clockwise, and adjust the pressure set by oneself with