Danfoss EHPS User guide
MAKING MODERN LIVING POSSIBLE
Technical Information
EHPS Steering Valve
PVE Actuation Module
OSPCX CN Steering Unit
powersolutions.danfoss.com
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Revision history Table of revisions
Date Changed Rev
May 2015 Minor update EB
August 2014 EHPS type 2 section updated EA
July 2014 Converted to Danfoss layout DA
October 2009 Steering column deleted CA
May 2009 Note added BC
2 520L0521 • Rev EB • May 2015
Technical Information
EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Contents
A wide range of Steering Components
For hydrostatic steering systems Danfoss offers:................................................................................................................. 5
For electrohydraulic steering systems Danfoss offers:....................................................................................................... 6
Characteristic features for steering units:................................................................................................................................6
Characteristic features for electrohydraulic steering systems with OSPE and EHPS:.............................................. 6
Conversion factors........................................................................................................................................................................... 6
Survey of literature with technical data on Danfoss Steering Components...............................................................6
General
Electrohydraulic steering...............................................................................................................................................................7
Steering valve EHPS and electrical actuation module PVE for EHPS
Versions................................................................................................................................................................................................8
EHPS type 0, hydrostatic steering system:.........................................................................................................................8
EHPS type 1, Hydrostatic and Electrohydraulic Steering System:............................................................................. 9
EHPS type 2, hydrostatic and electrohydraulic steering system:............................................................................ 10
Functional options overview................................................................................................................................................11
EHPS type 0, 1 or 2 with flanged on priority valve OLS 320:.....................................................................................12
Function............................................................................................................................................................................................ 13
EHPS valve...................................................................................................................................................................................13
Neutral position................................................................................................................................................................... 14
Steering left...........................................................................................................................................................................15
PVES and PVED-CLS, electrical actuation.........................................................................................................................16
Closed loop control..................................................................................................................................................................17
Principle....................................................................................................................................................................................... 17
Inductive transducer, LVDT...................................................................................................................................................17
Integrated pulse width modulation...................................................................................................................................17
Technical data
EHPS....................................................................................................................................................................................................18
PVES.................................................................................................................................................................................................... 19
PVED-CLS...........................................................................................................................................................................................19
Hysteresis, PVES and PVED-CLS................................................................................................................................................ 19
PVES and PVED-CLS.......................................................................................................................................................................20
Installation PVED-CLS................................................................................................................................................................... 21
Variants
Variants of EHPS..............................................................................................................................................................................22
Dimensioning
Dimensioning steering system with EHPS steering valve...............................................................................................24
Technical characteristics
Directional spool - oil flow characteristic for spool 40/5................................................................................................. 26
Directional spool - cylinder flow characteristic for all directional spools..................................................................27
Pilot pressure relief valve: (P - T, Qp) characteristic...........................................................................................................27
Pressure drop P-EF for Danfoss EHPS valve..........................................................................................................................28
Pressure drop P-EF for OLS integrated in EHPS............................................................................................................. 28
Pressure drop P-EF for OLS 320 static priority valve flanged on EHPS..................................................................28
Dimensions
EHPS type 0, stand alone.............................................................................................................................................................29
EHPS type 1, stand alone.............................................................................................................................................................31
EHPS type 1, with PVG..................................................................................................................................................................33
EHPS type 1, with OLS 320..........................................................................................................................................................35
Hydraulic systems
EHPS type 0, stand alone and OSPCX CN steering unit....................................................................................................37
EHPS type 1, stand alone, OSPCX CN steering unit and PVRES joystick.....................................................................37
EHPS type 1 with PVG 32, OSPCX CN pilot steering unit and PVRES joystick...........................................................38
System safety
Emergency steering...................................................................................................................................................................... 39
520L0521 • Rev EB • May 2015 3
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Contents
EHPS type 1 and type 2, prioritizing input signal...............................................................................................................40
Fault monitoring.......................................................................................................................................................................40
Passive fault monitoring........................................................................................................................................................ 41
Safety considerations..............................................................................................................................................................41
Safety considerations..............................................................................................................................................................42
On-road operation..............................................................................................................................................................42
Order specification
Order specification for EHPS and PVE.....................................................................................................................................43
Steering unit OSPCX CN
Version............................................................................................................................................................................................... 44
Closed center............................................................................................................................................................................. 44
Code numbers and weights
Order specification
Specification table for non catalogue numbers of Danfoss OSPCX CN steering units.........................................46
Technical data
Common data..................................................................................................................................................................................47
Manual steering pressure............................................................................................................................................................47
Displacement, flow and pressure.............................................................................................................................................47
Dimensions
Dimensions OSPCX CN.................................................................................................................................................................48
4 520L0521 • Rev EB • May 2015
Technical Information
EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
A wide range of Steering Components
Danfoss is one of the largest producers in the world of steering components for hydrostatic steering
systems on off-road vehicles. Danfoss offers steering solutions both at component and system levels. Our
product range makes it possible to cover applications of all types - ranging from ordinary 2-wheel
steering (also known as Ackermann steering) to articulated steering, automatic steering (e.g. by sensor)
and remote controlled steering via satellite. We can offer more than 1,800 different steering units and 250
different priority valves categorized in types, variants and sizes.
For hydrostatic steering systems Danfoss offers:
Mini steering units with displacements from 32 to 100 cm3/rev [1.95 to 6.10 in3/rev], flow up to 20
•
l/min [5.28 US gal/min], steering pressure up to 140 bar [2030 psi].
Steering units with displacements from 40 to 1200 cm3/rev [2.44 to 73.2 in3/rev], flow up to 100 l/min
•
[26.4 US gaL/min, steering pressure up to 240 bar [3481 psi].
Priority valves for rated flows at 40, 80, 120, 160 and 320 l/min [10.6, 21.1, 31.7, 42.3 and 84.5 US gal/
•
min], pressure up to 350 bar [5076 psi].
Pilot operated flow-amplifiers with amplification factors of 4, 5, 8, 10 or 20 for rated oil flows of 240
•
and 400 l/min [63.4 and 105.7 US gal/min], steering pressure up to 210 bar [3045 psi].
Pilot operated steering valve with steering flow up to 100 l/min [26.4 US gal/min], steering pressure
•
up to 250 bar [3625 psi] and with integrated priority valve for pump flow up to 120 l/min [31.7 US gal/
min].
520L0521 • Rev EB • May 2015 5
Technical Information
EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
A wide range of Steering Components
For electrohydraulic steering systems Danfoss offers:
Pilot operated steering valves (pilot operated by hydrostatic steering unit or by electrical signal) with
•
steering flows up to 100 l/min [26.4 US gal/min], steering pressure up to 250 bar [3625 psi].
Steering units with integrated electrical operated steering valve with steering flow up to 50 l/min
•
[13.2 US gal/min], steering pressure up to 210 bar [3045 psi].
Characteristic features for steering units:
Low steering torque: From 0.5 N•m to 3 N•m in normal steering situations
•
Low noise level
•
Low pressure drop
•
Many types available: Open center Non-reaction, Open center Reaction, Power Beyond, Closed center
•
Non-reaction, Load Sensing, Load Sensing Reaction
One or more built-in valve functions: relief valve, shock valves, suction valves, non-return valve in P-
•
line and in LS-line
Optional port connections (according to ISO, SAE or DIN standards)
•
Characteristic features for electrohydraulic steering systems with OSPE and EHPS:
Possibility of GPS, row sensor, variable steering ratio and joystick steering
•
The possibility of manual steering even on very heavy vehicles
•
EHPS: High steering pressure requiring smaller cylinders and flow
•
EHPS: Low pilot pressure and flow giving extremely low noise in the cabin
•
EHPS: Can be combined with Danfoss PVG 32 proportional valve
•
Conversion factors
1 N•m = [8.851 lbf•in] 1 l = [0.264 US gal]
1 N = [0.2248 lbf] 1 bar = [14.5 psi]
1 mm = [0.0394 in] °F = [1.8°C + 32]
1 cm3 = [0.061 in3]
Survey of literature with technical data on Danfoss Steering Components
Detailed data on all Danfoss steering components and accessories can be found in our steering
component catalogues, which is divided in to the following individual sub catalogues:
General information Steering components
Technical data on mini steering units OSPM
Technical data on open center, and closed center steering units OSPB, OSPC, and OSPD
Technical data on load sensing steering units, priority valves and flow
amplifiers
Technical data on hydraulic and electrohydraulic pilot operated steering
valves, electrical actuation modules and appropriate steering units.
Technical data on combined steering unit/electrohydraulic steering valves
and steering wheel sensors
Technical data on load sensing steering unit with amplification OSPU
For technical information on individual variants, please contact the Danfoss Sales Organization.
OSPB, OSPC, OSPF, OSPD, OSPL,
OSPBX, OSPLX, OVPL, OLS and OSQ
EHPS, EHPS w. OLS 320, PVE for EHPS
and OSPCX
OSPE and SASA
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Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
General
Electrohydraulic steering
On loaders, large forklift trucks, dumpers, heavy tractors, combine harvesters, maize harvesters and other
similar machines there is often need for electrically actuated steering either in the form of a joystick, or
fully automatic.
For this purpose Danfoss has developed a pilot operated steering valve type EHPS (Electro Hydraulic
Power Steering).
A basic system (type 0) consists of a pilot steering unit as the signal source and an EHPS valve block which
controls oil flow to the steering cylinders proportional to the pilot flow.
The system can be extended to include an electrical actuator so that, as an alternative, it becomes
possible to steer with a joystick (EHPS type 1).
Alternatively the actuator can be an electrical programmable module (PVED-CLS) to give much more
different steering features such like, variable steering ratio, speed dependent steering ratio, steering
wheel drift compensation, active jerk force compensation and soft end stop. This system is called EHPS
type 2.
Electrohydraulic steering system
520L0521 • Rev EB • May 2015 7
Steering
cylinger
150-567.10
OSP
Q
Q
EHPS valve
CL CR EHPS type 0
L
R
Ps
Ts
TLSPEF
P301 028
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
Versions
EHPS type 0, hydrostatic steering system:
EHPS Type 0 is a hydraulic steering system only with the EHPS valve acting as a pilot operated directional
valve. The steering unit type OSPCX CN acts as a pilot unit delivering oil at a low pressure and low flow.
The steering unit needs less displacement compared with an ordinary hydrostatic steering system. The
displacement can be optimized for emergency steering.
8 520L0521 • Rev EB • May 2015
Steering
cylinger
Joystick
150-566.10
OSP
PVE
Q
Q
EHPS valve
PVES CL CR EHPS type 1
L
R
Ps
Ts
TLSPEF
P301 026
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
EHPS type 1, Hydrostatic and Electrohydraulic Steering System:
This system consists of an EHPS valve (type 0) equipped with an electrical module (PVES) for activating
the EHPS valve. There are 2 possibilities of steering: either hydraulic with the steering wheel (OSPCX CN)
or electrically using a signal from, for example, a joystick or a mini steering wheel. Input from the steering
wheel (OSPCX CN) will always have highest priority.
520L0521 • Rev EB • May 2015 9
Steering
cylinger
Joystick
Steering Wheel Sensor
Vehicle Speed Position Seorn
150-565.12
OSP
CAN bus
Q
Q
PVED CLS
EHPS valve
SASA
PVED CLS CL CR EHPS type 2
L
R
Ps
Ts
TLSPEF
P301 027
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
EHPS type 2, hydrostatic and electrohydraulic steering system:
PVED-CL must not be promoted any longer. PVED-CL will be replaced by PVED-CLS by the end of 2014.
Please contact Danfoss Sales Organization for further details.
This system consists of an EHPS valve (type 0) equipped with an electrical programmable module (PVEDCLS) for activating the EHPS valve. There are many possibilities of steering:
With the steering wheel either pure hydraulic by help of the OSPCX CN steering unit or electrohydraulic
by help of the SASA steering wheel sensor placed between column and steering unit.
The EPHS can be controlled electrically also by using signals from, for example, GPS controller, row
censor, joystick or mini steering wheel.
Input from the steering wheel will always have highest priority.
With PVED-CLS the following steering features in electro hydraulic steer mode are possible:
Variable steering ratio
•
Speed dependent steering ratio
•
Steering wheel drift compensation
•
Active jerk force compensation
•
Soft end stop
•
10 520L0521 • Rev EB • May 2015
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
Functional options overview
Section will be updated with PVED-CLS.
520L0521 • Rev EB • May 2015 11
P301 025
EF
EF
L
R
Ps
Ts
LS
LS
P
P
OLS 320
T
CL CR
EHPS
type 0
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
EHPS type 0, 1 or 2 with flanged on priority valve OLS 320:
EHPS sterring valve has build in priority valve, but for max. pump flow 120 l/min [31.7 US gal/min]. In
systems with EHPS and pump flow between 120 l/min [31.7 US gal/min] and 320 l/min [84.5 US gal/min] a
combination of EHPS and OLS 320 gives a good compact solution to reduce hosing and installation cost
compared with stand alone components.
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P301 018
1
2
4
5
6
7
3
8
9
2
2
10
11
11
Technical Information
EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
Function
EHPS valve
The EHPS includes the following main components:
1.
Electrical actuation module
2. Housing
3. Directional spool
4. Shock and suction valve
5. Pilot pressure reduction valve for steering unit
6. Pilot pressure valve for electrical actuating module also called metering valve
7. Priority valve
8. Cover
9. Emergency steering valve
10. Pilot pressure relief valve
11. Shuttle valves
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P301 020
Technical Information
EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
Neutral position
1. Electrical actuation module
3. Directional spool
4a. Shock valvea
4b. Suction valves
5. Pilot pressure reduction valve for steering unit
6. Metering valve
7a. Priority valve spool
7b. Priority valve spring
9. Emergency steering valve
10. Pilot pressure relief valve
11. Check valve for emergency steering
12. Check valve in LS line
13. Shuttle valves
When the engine is turned off, the priority valve spool (7a) is pushed to the right by the spring (7b).
The passage to the EF port is blocked and the passage to CF to the directional spool (3) is open.
When the engine is on and the steering unit OSPCX CN is in neutral position, the CF pressure will rise to
match the spring force in the integrated priority valve, and the spool (7a) will move to the left and the oil
will pass from the pump across the priority valve (7a + 7b) and out through the EF port.
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P301 021
Technical Information EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
The priority valve is a “dynamic” type, meaning that a flow passes from CF through the Dynamic orifice
(integrated in spool 7a) and into the LS line through the check valve (12) to the directional spool (3). In
neutral position this dynamic oil flow passes on to the tank.
When the steering unit is in neutral position and no signal is generated to PVES, the directional spool will
be in its center position. This means that knocks and impacts from the cylinder are not transmitted to the
steering unit.
Steering left
When steering, the steering unit will get oil supplied from the pilot pressure reduction valve (5).
The pressure for the steering unit is reduced to approximate 30 bar.
When steering left, oil will be passing on to the L-port of the EHPS and it will fill the left side chamber of
the directional spool (3), which makes the spool move to the right.
1. Electrical actuation module
3. Directional spool
4a. Shock valvea
4b. Suction valves
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Technical Information
EHPS Steering Valve PVE Actuation Module OSPCX CN Steering Unit
Steering valve EHPS and electrical actuation module PVE for EHPS
5. Pilot pressure reduction valve for steering unit
6. Metering valve
7a. Priority valve spool
7b. Priority valve spring
9. Emergency steering valve
10. Pilot pressure relief valve
11. Check valve for emergency steering
12. Check valve in LS line
13. Shuttle valves
When moving the directional spool (3), the LS signal will be connected to the steering pressure CL. The
pressure will then increase in the spring chamber of the priority valve and the priority valve spool (7a) will
be pushed towards the right side. Consequently, oil will flow through CF from the priority valve to the
directional spool (3).
Oil will now push the steering cylinder rod out and it will cause steering to the left side.
Return oil from the opposite cylinder site will stream into the CR port through the directional spool (3)
and into the right end of the metering valve (6). The metering valve spool is moved to the left and the
main stream from CR can pass through the metering valve into the tank.
The metering valve needs 12 bar to move. This return pressure is used for feeding an electrical actuation
module PVES in a EHPS type 1 system.
When the metering valve is open, it also leads pilot oil from the steering unit to the tank.
When the steering cylinder has reached end stop, no oil will pass through the CR port, and the control
pressure for the metering valve (6) will be reduced. The metering valve will now move to the right, and
the valve is closing the tank connection and the pilot oil flow will be blocked. This way you will feel the
end stop in the steering wheel.
When turning right, the movement of the directional spool (3) will be opposite. All other functions are
equal as when steering left. When steering with an electrical signal the directional spool (3) will be
controlled by hydraulic signal from the PVES which is converting electrical signal to hydraulic signal to
the directional spool (3), so that the movement of the directional spool (3) will be proportional to the
electrical signal to the PVES. The shuttle valves (13) will lead oil from PVES (1) to directional spool (3).
PVES and PVED-CLS, electrical actuation
The philosophy of Danfoss electrohydraulic actuation, type PVE, is integration of electronics, sensors and
actuators into a single unit that interfaces directly to the EHPS steering valve body.
16 520L0521 • Rev EB • May 2015
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