User Manual

Bosch Rexroth AG
Open and Closed Loop Speed Control SPC RE 95300/12.07
11/16
Figure 8: Typical configuration for the SPCD closed loop speed control
Variant SPCD
The electronic closed loop speed control (Speed Control,
SPCD) is an easily configurable software application for
the closed loop control of hydraulic drives in concrete mixer
vehicles. The hydraulic drive here consists of a pump and a hy-
draulic motor. It is used to turn the drum of the concrete mixer
vehicle. The SPCD closed loop speed control is used to keep
the hydraulic drive speed constant, independent of the speeds
of the diesel engine and the pump.
The SPCD electronic closed loop speed control is designed to
control a variable pump in a closed hydraulic circuit.
The following hydraulic concept is used:
• An A4VTG, A4VG or A10VG variable pump with electropro-
portional control EP together with an A2FM, A2FE, A4FM,
A10FM or MCR fixed motor
The following diesel engine design is used:
• Diesel engine with or without CAN bus interface
The closed loop speed control does not use the CAN bus.
Neither the set speed nor the actual speed of the diesel
engine is necessary for closed loop speed control. The
closed loop control is dependent on the set speed and
actual speed of the hydraulic motor.
Functional Description
In order to keep the output speed of hydraulic drives constant
and independent of the diesel engine speed and the pump
speed, the swivel angle of the hydraulic variable pump is ad-
justed by electroproportional control.
Closed loop speed control
The set speed of the drum is set by means of two pushbut-
tons (right/left) in the vehicle. The actual speed of the drum is
measured by a speed sensor in the hydraulic motor. When the
actual speed changes, the pump control and, thus, the swivel
angle of the pump are regulated in such a way that the flow
stays constant. As a result, the output speed of a hydraulic
motor connected to the pump is held constant at the set speed
value. This keeps the drum rotating at a constant speed inde-
pendent of the diesel engine speed and pump speed.
This is achieved by regulating the swivel angle of the hydraulic
variable pump in the closed circuit by electroproportional con-
trol. The pump control varies according to the time ramp that
has been set for the working behavior.
The closed loop speed control can be switched on or off dur-
ing commissioning.
If closed loop speed control has been switched off during com-
missioning, the pump is controlled in proportion to the setpoint
specification and the speed of the diesel engine. All swivel
angles are then possible in the range 0 to 100%.
Power supply
Ignition
switch
Controller RC2-2/20
with SPCD software
BODAS service
PC software
Diagnostics
socket
CAN bus
interface
Safety
switch
Speed sensor
Engine Variable pump
A4VTG...EP
or optionally:
A4VG...EP or
A10VG...EP
RS232
Fixed motor
A2FM
or optionally:
A2FE or
A4FM or
A10FM or
MCR
Right pushbutton
Funnel function
Fill level sensor
Left pushbutton
Error lamp