Table of Contents
Advertisement
Maximum operating
pressure
Minimum operating
pressure
Internal pilot oil supply
Pre-load valve
Product description | SYDFED-2X, SYDFED-3X, SYHDFED-1X
5.3.5
Operating pressure limits
Forcefully ejected parts and hydraulic fluid jet!
Risk of severe injury! The electrical pressure control does not assume a pressure
relief function.
▶ Make certain that the maximum operating pressure is not exceeded.
▶ If a pre-load valve is installed, you can use its pressure relief function. If no
pre-load valve is installed, provide a pressure relief valve, the pressure setting
of which is 10 % (recommended) higher than the operating pressure, in the
pressure line. Operating the system without this valve can lead to malfunction.
The maximum operating pressure specified in the data sheet must not be
exceeded.
At a pressure of ≥ 250 bar the following restrictions must be observed for
SYDFED (not for SYHDFED):
• The pressure transducer must be located downstream of a pulsation damper or
the high-pressure hose.
• When a standard pilot valve spool is used (version "A"), the pressure controller
P-gain may have to be reduced. This has an influence on the accuracy and
dynamics of the closed pressure control loop.
The minimum operating pressure depends on the pilot oil supply and is explained
in more detail in the following chapter.
5.3.6
Internal/external pilot oil
If the operating pressures of the application are always >20 bar, the version with
internal pilot oil supply should be selected, because no cavitation due to too small
command values can occur with this version.
Operation is also possible at pressures higher than approximately 12 bar, but
dynamics is restricted within the range below 20 bar.
This minimum (pilot) pressure level ensures that the pump can respond to the
electrical swivel signal at any time. When the consumer line is blocked, the
smallest achievable steady-state swivel angle is the zero stroke angle.
For applications, in which lower operating pressures occur or are to be controlled,
a pre-load valve (SYDZ for SYDFED) can be used. For this solution, the minimum
pressure is ≥1 bar
The advantage of the pre-load valve is that the pilot oil pressure of the pump
cannot fall below the value preset on the pre-load valve and that pressures
≤12 bar on the output side can be continuously controlled.
Being equipped with a pre-load valve the pump cannot permanently swivel back
over zero, irrespective of electrical actuating signals or any control errors. The
smallest achievable swivel angle during steady-state operation therefore is the zero
stroke. This is not valid for applications, in which, for example, a suspended load
can cause operating pressures ≥12 bar. In such cases the pump can also be used
in motor operation (for lowering the load). A check valve integrated in the pre-load
valve permits, within certain limits, a reversal of the direction of oil flow.
WARNING
RE 30017-B, Edition 11.2021, Bosch Rexroth AG
27/96
Advertisement
Table of Contents
