液压抓斗的原理图

一、节约能源，系统温升小

Maximum of Energy-saving, Less temperature rise

传统电动液压抓斗抓取货物时，一旦闷死或油缸到位，定量泵高压溢流，油温急剧上升。导致油液黏度大幅下降，加速密封及油管的老化，出现保压保不住等不稳定现象，抓取的货物也会脱落。The conventional electro-hydraulic grab is equipped with constant pump. When material gives  excessive resistance or bucket fully closes during the grabbing process, the constant pump overflows at a high pressure, which causes a number of negative effects such as sudden temperature rise, oil viscosity decrease, inability to maintain pressure, and then results in material’s falling off the bucket. In the long term, this will also do great harm to sealing and oil pipe.

改用变量泵后，抓取货物出现闷死现象时，油泵切换为压力补偿功能。液压抓斗压力逐渐增大的同时减小排量，维持在高压小流量状态保压。由于油液溢流部分很少，系统发热降到。为企业直接减少了能源成本。初步估算，比传统定量泵系统节能达40-60%。同时抓斗处于高压力工作状态，保证抓斗在移位过程中即使液压锁失灵抓斗也不会自动打开。However, the introduction of variable pump has solved this problem. When facing the same situation, the pump will switch to pressure compensation status. It means when the pressure goes up the oil flow capacity will decrease in order to maintain the pressure steadily. Since there is little overflow, the system temperature would be kept at the lowest level. This directly reduces the energy consumption and cost. Roughly estimated, it will save up to 40-60% energy compared to conventional design. In the meanwhile, it guarantees that even when the hydraulic lock seizes up during move the grab will not open automatically.

二、液压抓斗工作效率高，提高抓取能力

Higher work efficiency, better grabbing performance

一旦工作压力降低，泵感应到压差增大，会自动增大斜盘角度增大排量，抓斗又处于工作状态。系统响应时间约0.2-0.6s，不需人为干预。液压抓斗由于系统发热很小，可以长时间连续工作，提高了工作效率。可连续24小时不停工作，而定量泵系统发热大，因此无法24小时连续不停工作，如连续工作则会使液压系统长期处于高温情况下工作，会造成液压系统故障而影响抓斗的使用寿命。When the pressure decreases, variable pump will detect this change and automatically increase the angle to augment flow capacity, which causes the grab back to normal working condition. This process will take 0.2 – 0.6 seconds, no need of intervention. In addition, the very low system temperature also contributes to the continual operation up to 24 hours of the machine, which drmaticaly enhance the efficiency. On the contrary, due to the above said reason, such as high system temperature, the constant pump can’t work around the clock.

变量泵系统设定的压力，可大于同等功率下定量泵系统压力，液压抓斗直接提高了抓取力。Variable pump’s setting pressure could be higher than that of constant pump, so the grab equipped with variable pump has a better grabbing performance.

三、电机启动电流小，对电器元件有保护作用

Low startup current, better protection of electrical elements

电机起动时液压泵理论上没有流量输出，电机基本属于空载起动。起动电流很小，对电器元件起到保护作用。定量泵由于其排量恒定，电机启动时属于带载起动，电机启动电流大，易烧毁电器元件。电机的启动电流通常是工作电流的4~6倍，电机正反转控制抓斗开闭的系统都是在带载情况下启动，其启动电流通常是正常工作电流的6倍以上，由于其频繁正反转，因此相当于电力系统长期处于高负荷状态，对供电系统产生大于其额定功率的负荷。同时电机频繁正反转对电机本身也产生巨大冲击，容易造成铸铁电机罩壳破碎。In theory, there is hardly any current output on variable pump when startup, and for which the electric motor is basically in no-load startup. The low startup current creates better protection of electrical elements; while, the constant pump belongs to startup-under-load, requiring high startup current and easy to damage electrical elements. The startup current of the constant pump is usually 4 to 6 times of the normal operating current, while the normal and reverse transfer system’s startup current reaches up to 6 times of the normal operating current. As a result of frequent normal and reverse transfers, the power supply system is under a constant high load capacity status, which exceeds its rated capacity. At the same time, the frequent n&r transfer generate huge force to the electric motor itself and tends to break the motor’s cast-iron frame.

四、 液压抓斗液压系统启动压力冲击小，不容易爆管

Less pressure impact, less risk of pipe explosion

液压阀开启有响应时间，定量泵系统启动时，瞬间压力冲击特别大，油管容易爆裂。变量泵启动时只有3MPA左右的待命压力，消除了爆管的隐患。同时由于定量泵控系统电机频繁正反转也会产生巨大的液压冲击，造成液压系统爆管等故障，影响抓斗的正常使用。As there is certain response time for hydraulic valve startup, constant pump has to bear the momentary extremely high pressure impact with a high risk of oil pipe explosion. For variable pump, it only needs to stand 3MPA or so, which greatly remove the said risk. In addition, the frequent normal and reverse transfers in constant pump system usually produce huge hydraulic force, which will quite probably result in pipe explosion.)

五、系统刚性高，速度稳定性好

Good rigidity, stable speed

由于我司生产的液压抓斗阀组带压力补偿功能，流量跟外负载无关，速度不随负载波动。工作时不会因为抓取力增大而影响工作速度。定量泵控系统由于抓斗在工作过程中会造成温升过高，因此液压油在高温情况下会黏度会变得比较低，液压系统内泄露相对比较大，因此会产生抓取无力现象。The valve group is provided with the function of pressure compensation, which keeps the speed stable, not influenced by external load. Besides, the operation speed will not be affected by the fluctuation of material weight. As to constant pump system, under the high system temperature, the oil will become less thick and easy to leak; consequently, the grabbing performance becomes poor.)

六、液压抓斗维护方便，维修简单

Convenient maintenance, easy repair

液压元件采用模块化设计，出现故障时不必更换整套元器件，只需更换个别零件，大大缩短维修时间，降低维修成本。抓斗的轴瓦也采用了免维护轴瓦，维护更加方便。

Hydraulic components take modular design. Therefore, instead of changing the complete set of components and parts, now can only replace the broken components, which dramatically cut down the repair time and cost. The bearing shell is maintenance free.

七、液压抓斗工作时噪音小，工作平稳

Low noise throughout operation, stable operation

我司生产的电动液压抓斗在调试以及实际使用过程中，其产生的噪音远远小于电机正反转泵控系统所产生的噪音，通常我司抓斗的工作噪音比电机正反转泵控系统所产生的噪音低20分贝左右，抓斗的震动也比较小，因此工作比较平稳。

            Our electro-hydraulic grab generates around 20 dB less noise during commissioning and operation than constant pump system. And less vibration ensures its stable operation.

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