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com Table E001-9/E

Solenoid directional valves: user’s guidelines

due stadi, pilotate, dimensioni ISO/Cetop 07 e 08
Atos solenoid valves have been designed and tested with innovative concepts to satisfy the advanced needs of modern machines: rapid or damped
switching, quiet operation, reduced power absorbed, versatility, reliability and safety of use.
This table gives engineers, in condensed form, a series of useful information for the choice and the use of modern solenoid valves.

1 DESCRIPTION OF FUNCTION

Solenoid directional valves are used for

changing flow direction in hydraulic systems.
Main features are:
1.1 New integrated design between hydrau-
lic and electrical parts with more com-
pact construction and better efficiencies.
. 1.6 1.8 1.1 1.3

1.2 Wet solenoids for maximum reliability,

also available in flame-proof, intrinsically
safe and stainless steel execution.
1.3 All seals are static and all the moving
.
. . . .
parts are protected and lubricated by
the fluid.

.
1.4 Smoother switching with effective regu-
lation thanks to optional switching con-
trol devices.
1.5 Plastic encapsulated coils easily inter-
changeable and UL certified. A B
1.6 Electric or electronic connectors, depen-
ding on the application and on electric 1.4 1.2 1.5 1.7
control board interface.
1.7 Cored oil passages with low pressure
drops.
1.8 Interchangeable spools for various Fig. 1 Cross-section of direct operated solenoid valve
directional functions.

2 SOLENOID IDENTITY P
According to European Convention solenoid
“A” is close to “A” port and solenoid “B” is A B
close to “B” port of the direct operated valves.
T
When pilot operated, the solenoids are identi-
fied according to following practice: solenoid
“A” is at port A end of pilot valve and solenoid
Solenoid “A” Solenoid “B”
“B” at port B end, independent of main stage Fig. 2 Solenoid identification
valve port location or spool type.

3 SPOOLS CHARACTERISTICS Type Scheme Intermediate passages

Standard interchangeable spools are availa-

ble in a wide range of configurations, as indi- 0
cated in table 3.
Specific spools to reduce water hammer- 1
shocks during switching: variants 1/1, 4/8
and 5/1. Their special shape reduces water
hammer-shocks during switching. Use of 2
these spools is not recommended with maxi-
mum flow greater than 80% of the nominal 3
values, because of higher pressure drops
generated in the valve.
Response times and control of switching 4
time: direct operated solenoid valves.
The solenoid valve response times can be
controlled by the use of specific devices 5
(option L); associated with the spools */1
and */8 it is possible to control smooth 58
acceleration/deceleration of the connected
actuator. The L* devices allow an effective
control of the solenoid valve switching time, 6
slowing down the spool speed without redu-
cing the solenoid force.
They are available in different configurations. 7
For correct use a slight backpressure (2 bar)
on solenoid valve T port is recommended.
Valve response time is also influenced by 8
operating conditions (oil characteristics and
temperature), elasticity of the hydraulic cir- 0/2
cuit and by use of electronic connectors.
Response time and control of switching
time: pilot operated solenoid valves. 1/2
The response time of the piloted valves can
be adjusted by means of the options /H
(meter-out control) or /H9 (meter-in control). 2/2
This options provide the installation between
the main stage and the pilot valve of a modu- 16
lar throttle valve, type HQ-*/U specific for fine
pilot flow control.
Associated with */1 and */8 spools, smooth 17
acceleration/deceleration can be controlled
on loads. Table 3 Basic spools, schemes and intermediate passages between central and external positions.
The spools are not available for all the directional valves. For their availability see
the relevant valve table.
E001
*P spools for direct operated solenoid val- Table 3.2 Spools to reduce water hammer shocks associated with switching
ves to reduce leakage.
They are normally used on pilot valve for Type Scheme Intermediate passages
pressure and directional control valves, for
cartridge valves and systems with specific 0/1
requirements.
Use of these spools is not recommended 1/1
with maximum flow greater than 70% of the
nominal values, because of the higher pres-
3/1
sure drops generated in the valve.
Following types available: 1P, 3P, 1/2 P, 8P
4/8
(for ISO size 06 valves).

4 COIL CHARACTERISTICS
Table 3.3 Specific spools for special uses or in regenerative circuits
Solenoid valves are available both with DC and
AC coils. Three main solenoids for use with fol- Type Scheme Intermediate passages
lowing supply for DH* valves:
• OI solenoid for AC and DC supply (only 09
replacing coil);
• OU and OO solenoid for DC supply only; 90
The solenoid OO can be used also with AC
supply: in this case it must be coupled with 19
the connector SP-669 having the rectifier
bridge. 91
Coils are fully encapsulated; they are easily
replaceable without aid of tools in DHI and 39
DHU valves. AC and DC solenoids are avai-
lable for DKE* valves. The DC solenoids can 93
be also fed with AC supply, by using SP-669
connector. The coils with different nominal 49
voltages can be interchanged on the same
solenoid type. 94

5 ELECTRICAL CONNECTORS TO
ISO 4400 (DIN 43650)
The cable entry on electrical plugs can be fit-
ted at 90° intervals by reassembling the con-
tact holder relative to the plug housing. maximum flow on the valve.
The cable entry is Pg. 11 suitable for cable Ø Dilatation and contraction of flexible hoses
6-10 mm. subjected to variations of system pressure
Following types are available: can generate high instantaneous flow rates. 24 VDC
Standard connectors, IP65 protection degree The version indicated in fig. 6 can be directly
(SP-666); inserted into P port of the valve but also in
Connectors with built in LED (SP-667); other valve ports.
Connectors with built in rectifier bridge (SP- Where throttle valve may be required they can
669) to supply DC coils by alternating cur- be supplied with following codes:
rent AC. SP-PLUG H-** (for DH* valves)
In addition to the above DIN connectors, SP-PLUG K-** (for DKE* valves)
other type of electrical interfaces are availa- ** the double asterisk identifies the dimension PNP
ble on request: in tenths of a millimeter. TRANSISTOR
- Lead Wire connection Example: SP-PLUG H-05 = 0,5 mm diameter
- Deutsch connector DT-04-2P (IP67)
E-SE
- AMP Junior Timer connector (IP67) Limits on two-way and three-way operation
for direct operated solenoid valves. COIL
When used as two-way and three-way valves
6 ELECTRONIC CONNECTORS with P, A or B ports blocked or not subject to
Operational principle flow, or with flow much lower than flow on
E-SE for direct current power supply on DC other ports, maximum catalogue performance
coils with reduction of power consump- cannot be assured.
tion and increase of performance;
E-SD to eliminate electric disturbances when Minimum pilot pressure for pilot operated
solenoids are deenergized; solenoid valves.
Fig. 4 E-SE electrical connection
E-SR to pilot the solenoid valves with a low A minimum pressure value must be guaranteed
power signal (20 mA max); for piloting the valve. This value is 8 bar (or 10
bar in the case of valves with hydraulic cente-
E-SE main characteristics ring). In case of circuits with lower pilot pressu- Table 5
They allow a modulation of the power supply re on P port, the option /R should be used. Recommended torque for the fixing screws
voltage and thus an effective control of the
solenoid force to obtain increased perfor- Operation combined with hydraulic cylin- Valve type Fixing screws Torque
class 12.9
mance and reduction of power consumption. ders with high section ratios.
The use of electronic E-SE connector allows Operational limits may occur with cylinders DH* M5 8 Nm
a considerable increase in solenoid valve with section ratios (piston/rod) greater than
performance. 1.25. In these cases multiplications or demulti- DKE* M6 15 Nm
plications of flow and pressure may disturb
the correct operation of the solenoid valve. DP**-2 M10 and M6 70 Nm and 15 Nm

DP**-3 M12 125 Nm

7 OPERATING NOTES 8 SPECIAL VERSION SOLENOID VALVES
DP**-6 M20 600 Nm
Tightening of the fixing screws to the subplates • for explosion-proof environments
and of the plastic coil ring-nut. • for intrinsically safe operation
It is particularly important to check that the • stainless steel execution for marine or
tightening of the fixing screws respects the aggressive environments
torque limits indicated in table 5. • for operation beyond the allowed tempera-
Hi g h e r v a l u e s m a y c a u se a n o m a lo u s ture limits.
deformations of the body and prevent sliding
of the spool. 12.9 class fixing screws are
recommended. The plastic coil ring-nuts will
be fixed on the solenoid with a torque 3Nm:
this deforms properly the seals and protects
against external particles and water.
Operation in circuits with flow exceeding
the nominal valve flow
In circuits with flow rates greater than the
nominal values and in circuits with accumula-
tors, where the instantaneous flow can exceed
nominal values, is recommended a throttle Fig. 6 Throttle valve which can be inserted in
valve on P port of solenoid valve to limit the port P (or A and B) of the solenoid
valve to limit the flow.

03/07