(1) Recirculation and conflux (Low loading)
1.
On starting arm-in operation, arm-in operating pilot secondary pressure is input to arm 1 spool,
arm 2 spool and low pressure sensor.
2.
The output voltage of low pressure sensor is input to mechatro controller and the mechatro
controller processes pilot signal and outputs command according to the input voltage to P1 and P2
proportional valves, P1 and P2 unload proportional valves and reverse proportional valve for arm-in
2 spool.
In case of combined operation, the pilot pressure other than arm-in operation is input to low
pressure sensor and the output voltage is input to mechatro controller. And the mechatro
controller processes pilot signal according to the combined operation and outputs command, which
is different from the arm-in independent operation, to P1 pump proportional valve, P1 unload
proportional valve and reverse proportional valve for arm-in 2 spool.
3.
Primary pressure of reverse proportional valve for arm-in 2 spool is arm-in pilot secondary pressure
and it switches arm 2 spool by proportional secondary pressure according to command. (Arm 2
spool controls recirculation rate and conflux rate.)
The other proportional valves output proportional secondary pressure according to command from
mechatro controller. These proportional valves change the delivery rate of P1, P2 pump, and
switch P1, P2 unload valve.
4.
The arm 1 spool is switched according to original oil pressure command, and P1, P2 pumps, P1,
P2 unload spools and arm 2 spool are switched according to the command output by mechatro
controller, and consequently the return oil from the arm cylinder rod side is recirculated in P1 and
P2 pumps delivery oil during arm operation.
(2) Recirculation cut
The voltage output by high pressure sensor on P2 side is input to mechatro controller, and when the
load is raised during arm operation the mechatro controller processes pilot signal processing according
to the pressure detected by high pressure sensor and outputs command to cut recirculation into
reverse proportional valve for arm-in 2 spool.
The reverse proportional valve for arm-in 2 spool outputs pilot secondary pressure according to the
command output by mechatro controller and switches arm 2 spool to recirculation cut position, and
consequently recirculation passage is blocked.
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21. MECHATRO CONTROLLER
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