负荷敏感控制LS和与负载无关的LUDV液压多路换向阀

Linde LSC 同步控制系统与负流量以及正流量控制系统的比较

 1. Main Control Philosophy

主要设计理念：

Load Sensing: all consumers are linked by a joint load sensing line. Generated by external loads, the highest LS pressure signal is selected, which is fed to the pump's controller. The controller keeps the pump pressure at [highest LS-signal plus delta p LS].

All controls operate load-independent, i.e. changing loads do not have to be compensated by the operator. In case of excessive power demand, all consumer speeds are reduced proportionally and simultaneously to match the available maximum power. Exceptions (priority functions) are feasible.

负荷传感：林德LSC、力士乐LUDV、小松CLSS系统。选出的执行元件的工作压力，并将其反馈到泵控制器 ，调节泵的排量，使主阀口两端压差保持的设定值。

各执行动作与载荷无关。换句话说，驾驶员不需要频繁调节手柄以适应执行元件载荷变化。如果执行元件需求流量超出泵能提供的流量，流入各执行元件的流量按主阀开口量大小进行分配。可以很方便地实现流量优先功能。

Negative Flow Control: a permanent purge flow through an orifice behind all consumers is kept constant by monitoring the corresponding pressure drop across the orifice, which is signalled to the pump controller.

负流量控制：主泵输出流量除了供给各个用户外，多余的流量经过一个固定阻尼孔，由此在阻尼孔两端产生的压差反馈给泵控制器，泵控制器根据该压差大小来调节泵的排量

Any combined movements or changing loads will require the operator to trim speeds by joystick adjustment.

缺点：复合动作时，各执行元件相互影响；载荷变化时，执行元件动作亦受影响。需驾驶员再行调节。

Positive Flow Control: similar to NFC technology with a constant purge flow, however, without measuring orifice. By cascading all control pressures through a complex grid of counterbalance valves, the system constantly selects the highest individual control pressure prevailing and passes it to the pump controller. Pump displacement is adjusted by relating any control pressure to defined displacement angles.

正流量控制：逻辑阀筛选出执行元件中的先导控制压力，并将其反馈给泵的变量控制机构，实现泵排量调节（参考A8VO）中的液压行程限制控制方式——正常情况下先导压力决定泵的排量，一旦功率超出事先设定的功率，功率限制器起作用）。