167086
4/3-way proportional valve
A
B
P
T
Y1
Y2
Y1
Y2
4
1
T
14
Design
13
A
2
P
5
3
B
12
11
10
9
8 7
6
The 4/3-way proportional valve is mounted on a function plate with four quick
coupling connectors. The four electrical connections are equipped with safety jackplugs. The component is fitted to the grid system of the slotted assembly board by
means of the two blue levers (mounting variant “A”).
The valve consists of: Piston (1), housing (2), spring (3), earthing contact (4),
electrical connections of solenoid (5),
emergency manual override (6), sliding bearing (7),
compensating bore (8), solenoid coil (9), plunge (10),
spring disc (11), control notch (12), stem (13),
pressure tube (14)
© Festo Didactic GmbH & Co. KG, 04/2003
Subject to change
1/4
167086
4/3-way proportional valve
Function
2/4
The proportional valve is suitable for both the directional control of flow rates and
their magnitude and is directly actuated by means of DC solenoid coils.
Characteristic of this valve is the continuous adjustability of the piston.
The valve is shown in the mid-position in the sectional view. All ports are mutually
closed. The valve assumes the mid-position via the two compression springs, if
neither of the two solenoids are energised (spring force). If voltage is applied to the
solenoid coil (energised) Y2 (9), the plunger (10) pushes the piston (1) against the
spring opposite. This connects port P to port A and port B simultaneously to port T. If
the solenoid coil Y1 is energised, the piston is pushed in the opposite direction. Port
P is then connected to port B and port A simultaneously to port T.
The difference between a proportional valve and a switching valve is in the type of
adjustability of the piston. Whereas the switching valve only has two statuses, i.e.
energised and de-energised, whereby the piston is either completely extended or
not at all, the proportional valve can approach any number of intermediate
positions.
This infinite adjustability is assumed by the proportional solenoid. A force is created
if the solenoid is energised, which acts on the plunger. The magnitude of the force is
dependent on the magnitude of current flowing through the solenoid coil. The
plunger with the stem pushes the valve piston against the opposite compression
spring until an equilibrium of forces is established between the force of the plunger
and the compression spring. The displacement length of the valve piston is
proportional to the magnetic flux applied.
From the mid-position, the piston initially needs to traverse an overlap. During this,
the ports still remain closed. The control notch (12) of the piston then starts to open
against the ridge of the housing. Two groups of control notches always open at any
time (P->A and B->T or P->B and A->T). The cross-sectional area of the gap opens up
increasingly. The degree at which the area and as such the flow change depends on
the shape and number of control notches. A V-shaped notch results in a progressive
flow pattern, whereas a rectangular notch produces a linear flow pattern.
An emergency manual override (6) also facilitates actuation without electrical
energy.
Subject to change
© Festo Didactic GmbH & Co. KG, 04/2003
167086
4/3-way proportional valve
4
∆p =
l/min
6 MPa
3
4 MPa
Flow rate q
2.5
2
2 MPa
1.5
1
1 MPa
0.5
0
1000
mA
500
0
Current I
Magnet B
500
mA
1000
Current I
Magnet A
Flow rate signal characteristic curve
6
MPa
Pressure pA, pB
4
2
0
240
mA
120
0
Current I
Magnet B
120
mA
240
Current I
Magnet A
Pressure signal characteristic curve
© Festo Didactic GmbH & Co. KG, 04/2003
Subject to change
3/4
167086
4/3-way proportional valve
Note
The valve ports are identified by letters.
A, B Working ports
P
Supply port
T
Return-line port (tank connection)
The electrical connections are protected against overvoltage. The switching status is
indicated by an LED.
The emergency manual override must not be actuated by means of a sharp-edged
objects (e.g. screwdriver) so that its smooth operation and leak-proofness are
maintained. A stiff manual override may result in malfunction of the solenoid valve.
Technical data
4/4
Hydraulic
Medium
Mineral oil, recommended viscosity 22 cSt (mm²/s)
Operating pressure p
60 bar (6 Mpa)
Max. permissible pressure pmax
120 bar (12 Mpa)
Valve construction
Directly actuated spool valve
Port pattern, hydraulic
ISO/DIN 4401 Size 02
Nominal flow rate
qN 1.2 l/min when pN = 0.5 MPa/control edge
Leakage loss
qL <0.01 l/min at 6 Mpa
Maximum degree of
contamination
Class 19/17/14 to ISO ( Class 8 to NAS )
Oil temperature, maximum
75 °C
Actuation
Proportional solenoid, pressure-tight, pushing
Voltage
24 V DC
Nominal current
800 mA
Resolution
<1 mA
Switching time – signal jump 0 –
100 %
40 ms
Repetition accuracy
<1 %
Connections, electrical
Via 4 mm safety connector plug
Connections, hydraulic
Via 4 coupling sockets
Subject to change
© Festo Didactic GmbH & Co. KG, 04/2003