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Pressure and flow control system SYDFE1 series 2X, 3X
| Product description
Bosch Rexroth AG, Edition 10.2021, RE 30011-B
5.4
SPECIAL OPERATING MODES
This chapter describes certain applications. In these cases, the basic operating
modes (see chapter on page 5.3 on page 19) are active.
For starting up SYDFE1 systems, no hydraulic circuit needs to be provided for the
classical start-up at zero pressure.
When small command values for pressure and swivel angle are provided, starting
up under almost no-load conditions is possible.
In the case of systems with internal supply and without pre-load valve, hydraulic
circulation circuits must be dimensioned so that a minimum pressure of 8...12 bar
is obtained, because the pump requires this pressure level to be able to respond
to electrical control signals.
Operating mode of the pump, in which an operating point is steadily closed-loop-
controlled with a corresponding command value over a longer period of time.
Observe the notes on permitted pressures in chapter 5.5.1 ”Internal/external pilot
Operating mode of the pump that refers to the smallest achievable swivel angle
and to which the pump usually changes over when no closed-loop control is active.
The withdrawal of the enable signal, missing supply voltage or an error message
(exception: J1 set, see page 63) cause the pump to automatically swivel in to
zero stroke operation (actuating system with
internal supply
). Whereas in the case
of actuating systems with
external supply
the pump swivels to the mechanical
positive stop “-100%“ (consumer line closed) irrespective of the command value
received.
The feedforward of “0 bar” via the pressure command value branch is not
permitted for actuating systems with external supply. In the case of systems with
internal supply this is problematic only in the case of a step-change from a high
pressure to 0, because undershoots may occur.
5.4.1 Regenerative operation
Regenerative operation is a special operating mode of the SYDFE1 control system,
since in this case the SYDFE1 control system is operated as both, generator and
motor.
We can distinguish between continuous regenerative operation and brief
regenerative operation. In the first case, by this we understand coupling of the
variable displacement pump with a fixed displacement pump. Here, the two pump
displacements are fed together to a common consumer.
This operating mode can be utilized in conjunction with a fixed displacement pump
in order to increase the displacement. To achieve “zero” displacement, the closed-
loop-controlled pump must “take over” the entire flow from the fixed displacement
pump and therefore swivels to the negative swivel angle range (motor operation).
It must be noted here that both pump sizes must be matched to each other so that
the controlled pump (in regenerative operation) must swivel in to max. –70 %. The
fixed displacement pump should be mounted to a through-drive of the SYDFE1
control system.
The following pump variants are available for continuous regenerative operation:
0487: Continuous regenerative operation with external supply
0541: Continuous regenerative operation without external supply (for SYDFE1-3X
only)
Starting up at zero
pressure
Circulation operation
(by-pass filtration,
cooling)
Stand-by operation
Zero stroke operation
Continuous regenerative
operation
