User Manual

2/16 Bosch Rexroth AG
Open and Closed Loop Speed Control SPC RE 95300/12.07
Note
Variant C is described on page 7.
Variant D is described on page 11.
Variant SPCA
The electronic open loop speed control (Speed Control,
SPCA) is an easily configurable software application for
controlling hydraulic drives. These drives usually consist of a
hydraulic pump and one or more hydraulic motors. The open
loop speed control serves to keep the output speed constant,
independent of the speeds of the diesel engine and the pump.
The SPCA electronic speed control is designed to control a
variable pump in an open or closed hydraulic circuit.
The following hydraulic concept is used in an open hydraulic
circuit:
• A variable pump A11VO, A7VO or KVA with electropropor-
tional control EP together with one or more fixed motors
A2FM, A2FE, A4FM, A10FM or MCR
In a closed hydraulic circuit, the following hydraulic concept is
used:
• A variable pump A4VG or A10VG with electroproportional
control EP together with one or more fixed motors A2FM,
A2FE, A4FM, A10FM or MCR
Two different designs of diesel engine can be used:
• In the case of diesel engines without a CAN bus interface,
the actual speed of the diesel engine is sent to the speed
control by a speed sensor on the starter gear ring.
• In diesel engines with a CAN bus interface, the speed
control receives the actual speed of the diesel engine via the
CAN bus.
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.
Open circuit speed control
A joystick supplies the target output speed. An external speed
sensor or the CAN bus acquires the actual speed of the diesel
engine. If the actual speed of the diesel engine exceeds a set
minimum speed (start of control), open loop speed control
begins. If the diesel engine speed increases further, the electric
control current (PWM signal) to the pump is reduced. This
reduction is inversely proportional to the increase of the diesel
engine speed. Thus, in spite of increasing diesel engine speed,
the pump flow and, as a result, the hydraulic motor speed, re-
main constant. The SPCA open loop speed control thus keeps
the output speed at the value specified by the target output
speed independent of the diesel engine speed.
When the open loop speed control is not active, the pump
control uses adjustable time ramps to achieve linear adjust-
ment according to the desired setpoint. The time ramps are set
for the joystick deflection (without the intervention of the open
loop speed control).
SPCA open loop speed control can be used for variable
pumps in both open and closed hydraulic circuits.
When a pump is used in an open circuit, only one direction of
rotation can be used for the drive (either forwards or back-
wards).
The open loop speed control can be switched on or off with a
switch in the vehicle.
Ordering Code
Ordering information
The AS/SPC application software
may only be operated with the
controller RC2-2/21 (variant A)
or RC2-2/20 (variants C and D)
and other additional components.
When ordering, link the hardware
and software type codes with a
"+":
Example: RC2-2/21+AS/
SPCA20
Type
01
Application software
AS/
Software
02
Open and closed loop speed control
SPC
Variants
03
Open loop speed control with speed pick-up in the diesel engine
A
Closed loop speed control with speed pick-up in the hydraulic motor
C
Closed loop speed control for concrete mixer vehicles
D
Version
04
Variants C and D
10
Variant A
20
AS/ SPC
01 02 03 04