24/104 About this product
Bosch Rexroth AG
, A4... with HS5E pilot control valve/Series 3x, RE 92076-01-B/10.2017
sensor (
4
) determines the position of the swashplate, with a pressure measuring
sensor acquiring the actual pressure value. Both of the actual values are fed to the
control electronics and linked with one another via the software. The torque actual
value is formed from the product of the actual pressure value, the actual swivel angle
value, and the displacement. By means of a minimum value former, the controller
software ensures that the controller that corresponds to the operating point is
always active.
In the static state, i.e. the swivel angle command value is equal to the actual swivel
angle value; the torque command value is equal to the torque actual value; or the
pressure command value is equal to the actual pressure value, the valve’s control
spool is in the central position.
If the higher-level controllers request an increase in the swivel angle, for example
(which corresponds to an increase in the flow), the system must keep deflecting the
valve spool from the central position until the swivel angle has reached the required
value.
The sectional view shows the A4VS… variable pump with HS5E control; the internal
control electronics actuates the proportional valve (
1
).
Information about HS5E control:
With a de-energized proportional valve and a clockwise-turning pump, as well as
control pressure present, the pump swivels in the following cases:
– Standard version A4VSO to swivel angle α = 0% (
V
g min
)
– Standard version A4VSG to swivel angle α = –100%
5.3 Parallel and cascade control of the HS5E control system
The pump controller has two different control structures. It is possible to switch
between them using pump controller control word “P-0-2950, pump controller
control word” bit 15. Setting bit 15 = 0 uses the parallel structure; with bit 15 = 1,
you use the cascade structure. Using both structures, it is possible to control the
pressure and the swivel angle. Depending on the machine's system characteristics,
both of the structures offer different advantages.
When switching over from the parallel structure to the cascade structure, the
cascade control is always initialized in swivel angle control mode. If switching over
to pressure control were necessary, the switching logic would then carry it out. On
switching back to the parallel structure, you do not need to take into account any
special initialization.
The pump controller differentiates between an open circuit and a closed one. You
make this selection using parameter “P-0-2989, configuration of pump controller”.
The closed circuit makes possible four-quadrant operation; for this, you need two
pressure sensors on the pump.
In the possible operating modes, up to two controllers are continuously active:
•
Swivel angle controller
•
Pressure controller
These controllers alternate automatically and on a stepless basis by means of the
switching logic.
The controller takes over whose actual value has best approximated the command
value.
Basic operating modes
