User Manual

Bosch Rexroth AG
Open and Closed Loop Speed Control SPC RE 95300/12.07
13/16
When the button used to select the direction of rotation is
pressed once more, the drum starts to move again. The drive
uses the stored speed and direction of rotation. This takes
place with an adjustable time ramp. The time ramp for the
memory function is set at the same time as the time ramp for
the stop function.
If the other button is pressed, the stored speed and direction
of rotation are erased. This also happens if both buttons are
pressed together. The drum drive must then be started as
described under "working behavior".
• Funnel function
The funnel function is used to control delivery from the mixer,
for example into the funnel of a concrete pump. A switch in
the vehicle is used to switch it on and off. The function must
be activated during commissioning.
When the funnel function is switched on and the "left" button
is pressed, the function starts up and the drum starts moving
counter-clockwise. Only counter-clockwise rotation is used
for delivery. The speed is preset and stored with the button.
The concrete then flows from the drum on the vehicle into
the funnel.
A sensor monitors the fill level in the funnel. When the funnel
is full, the fill level sensor opens (i.e. the input voltage at the
controller is 0 V) and the drum is stopped according to the
preset time ramp.
While the fill level sensor is open, only the clockwise
direction of rotation can be used. This is used to maintain
the mixing function while the funnel function is stopped. The
speed can then be increased using the right button and
reduced with the left one. The speed of clockwise rotation is
not stored at this time.
When the funnel is empty, the fill level sensor closes (the
input voltage at the controller is 24 V) and the following
applies:
– If the drum is at a downtime, it time ramps up again,
moving counter-clockwise, in order to continue
discharging. The drive uses the stored speed.
– If the drum is moving clockwise, it must be stopped before
delivery can continue in the counter-clockwise direction.
The stop ramp for the funnel function is set separately from
the time ramps for mixing operation.
While the funnel function is active, the error lamp remains on
all the time. It acts as a status lamp in this case.
Safety functions
Various options are available for monitoring working behavior:
• Start condition
The start condition is used to prevent the drive from starting
unintentionally.
After switching on the controller (ignition on), the starting
condition must be satisfied in order for the drive to be
started. The starting condition is met if no buttons are
pressed.
• Monitoring the actual speed
The actual speed of the drum is measured in the hydraulic
motor. The speed sensor is monitored for wire breaks and
short circuit
In case of an error, the maximum swivel angle for each
adjustment is limited to ±20 % and closed loop speed
control is switched off.
• Monitoring the inputs and outputs
The lines for setpoint inputs and outputs and the proportional
solenoid outputs are monitored for wire breaks and short
circuits.
In case of an error or if the safety switch is actuated, the
drive is turned off immediately.
An error lamp also flashes if there is an error.
Important features
• Two buttons (right/left) are used for the setpoint specifica-
tion.
• The setpoints for speed and direction of rotation can be
stored using the memory function.
• The funnel function can control delivery from the mixer drum
into the funnel of a concrete pump.
• A sensor in the hydraulic motor (integrated or external)
measures the actual speed of the drive.
• Accurate closed loop speed control is possible even at low
speeds.
• The working behavior of the drive is monitored by safety
functions such as the starting condition and the actual speed
monitor.
• The inputs and outputs of the controller (e.g. pushbuttons)
are monitored (for cable breaks and short circuit). In case of
an error or if the safety switch is actuated, the drive is turned
off immediately.
• All errors that occur are stored in the controller and can
also be read out later in plain text using the BODAS service
diagnostic tools.