工程机械正流量控制内部资料

Positive Control:
•
Improved development based on Negative Control,
•
Pump is no longer controlled by back pressure from NC orifice,
•
Pump is swiveled out by pressure sensors in pilot lines and electronic,
the pump
Bosch Rexroth Controls for Excavator
New Rexroth 2-Loop Positive Control 6M9-25
Positive Control
Open Center
GFB+A10FD
pI
(slew drive)
pilot
A1
pressure MC
movements
with the optimum combination of speed and power.
3. Defined speed control for Priority for option on request possible each consumer by individual flow adjustment
3. In case of undersaturation the consumer with the highest pressure stops moving.
Load Sensing System
4. Different consumer pressures are levelled by the compensators.
Requirements for Control of Excavator
• Good fine control of consumers • Simultaneous movements • Controllability • Low hydraulic losses • Efficient use of power • Compact design of components • Space saving and service friendly installation • Possibility of adding options • Fast movements
Flow Sharing System
1. The difference to LS systems are the compensators.
2. The delta p in LUDV is installed in the pump regulator not in the compensators.
The operator does not have to think about changing lever strokes, because the Rexroth LUDV-system instantly, silently and automatically send just the right
最新内部培训教材
2- loop Positive Control Block M9-25
Hydraulic Systems at Bosch Rexroth
Throttle-Control
Negative Control
Positive Control
LUDV
PS T A1
+ -
PST A1
PST
5. 1-loop System possible • only one variable displacement pump needed for all functions
LUDV Control Block M7 - Applications
New Rexroth 1-Loop Flow Sharing Block
It is used in crawler excavators smaller 20ton and wheeled excavators
Negative Control
1. It is a Open Centre system mainly used from Japanese and Korean companies.
Comparison of Excavator Control Principles
Three Different Systems
Flow Sharing Systems, LUDV • it can be realised a 1-loop system with a load independent control.
amount of oil to the actuators, at just the
right pressure to accommodate the change.
2. Constant fine control at
single and simultaneous The front end equipment works naturally
Three Different Systems
Positive control
1. This is also a Open Centre system, based on the NC systems. 2. There is a tendency of Japanese companies moving towards
Advantages of LUDV Systems in Excavators
4. Flexibility for Options • easy to adopt one or more optional consumers as all functions are parallel • Priority for Option on Request
New Generation Hydraulic valve
•
With this, independent and consumer adjusted flow controlled by the pump.
•
Energy savings as no losses in neutral, and no control losses at swiveling out
3. The signal of the cylinder with the highest load is send to all compensators.
4. In case of undersaturation they close and the remaining flow will be proportional reduced in each function. None of the consumer stops.
5. The individual flow to each cylinder is installed in the meter-in orifice of the main spool.
6. When the delta p of the compenator spring is saturated, the compensator closes and there are no losses to the tank.
for faster actuator speed without cavitation • Anti drift valves on Boom piston side and Arm rod side • Boom floating possible
Comparison of Design Comparison:
DRE
pilot pressure
A8VO
(travel and implement
hydraulics)
pI
MC
pI
MX-25
GFT+A10FD
(travel drive)
TH6
(pilot control units)
New Rexroth 2-Loop Positive ConBaidu Nhomakorabearol 7M9-25
this system. 3. The pilot pressure which moves the main spool is also used
to swivel out the pump 4. The advantage is an independent management of valve and
pump.
1-loop System in Flow Sharing for Wheel Excavator
有误
1-loop System in Flow Sharing for Crawler
Advantages of LUDV Systems in Excavators
1. Sensitive and load independent control of different consumers
1. Here each axis has an individual pressure compensator which is located before the meter-in orifice.
2. The highest consumer pressure is called to the pump which swivels out to the requested flow.
New 1 loop LUDV Block M7- 400
• 6 section monoblock • Spools on two levels for a very
compact design • Section flow up to 420 lpm
due to spool dia. 32 mm for Boom and Arm • Mainly focused on el. - hydraulic remote control • Easy to attach options, also with priority (MFV) • New arm- and boom regeneration system
+ -
一一介绍
PST A1
+ -
Open Center system
1. The pump flow in going to the tank when the main spool is in middle position.
2. With moving the main spool the flow gets throttled until the pressure raises to the consumer level and the cylinder moves.
LUDV: System with high flexibility for options,
individual flow adjustment for consumer, load independent, 1-loop System possible
Negative Control: In 2-loop a good technical and proven system
2. In neutral the pump always saturates the NC orifices. 3. When a main spool gets moves out of centre, the neutral closes
and the pressure at the NC orifice drops. This swivels out the pump.
3. This system was originally designed for constant pumps, but is used today with variable displacement pumps to run on a constant power curve.
Load Sensing System