Analysis of hydraulic system fault of 1 small concrete mixer

小型混凝土搅拌车在建设进程中的重要效果日益显示。大型自动上料拌和车一般从拌和站装上拌和好的混凝土，转运工地运用；而小型混凝土搅拌车一般是在工地邻近，具有自装卸、配料与自拌和功用，削减长距离运送且省工的特色。小型混凝土搅拌车的液压体系又分为闭式液压体系与开式液压体系。

The important effect of small concrete mixer truck in the construction process is increasingly shown. The large-scale automatic feeding mixer generally loads the mixed concrete from the mixing station and transports it to the construction site for use; The small concrete mixer is usually near the construction site, which has the functions of self loading and unloading, batching and self mixing, reducing long-distance transportation and saving labor. The hydraulic system of small concrete mixer is divided into closed hydraulic system and open hydraulic system.

一客户的批量小型混凝土搅拌车在运用进程中呈现以下几种毛病现象：（1）空载下，转罐转速可到达规划要求，而装满料今后很难起动，即便在发起机转速下转罐转速也很低；（2）液压油散马达的进油胶管呈现多台爆管毛病；（3）转罐马达的毛病率十分高，多台呈现马达内部卡死或轴端密封损坏向外串油。

A customer's batch of small concrete mixer truck in the process of using presents the following defects: (1) under no-load, the rotating speed of the drum can reach the planning requirements, but it is difficult to start when the material is full in the future, even under the speed of the initiator, the rotating speed of the drum is very low（ 2) The oil inlet hose of hydraulic oil dispersion motor has the problem of multiple tube explosion（ 3) The failure rate of the rotary drum motor is very high, many motors are stuck inside or the shaft end seal is damaged, and oil flows out.

从原理上来看，小型混凝土搅拌车液压体系为开式负载灵敏开芯回路，通过设备在发起机上的齿轮泵持续向换向阀供油，由先导操控阀作为总开关，通过操控电磁换向阀的翘板开关完结转罐马达的正转与回转。换向阀的回油分两路回油箱：一路通过节流阀回油箱，另一路驱动油散马达，为其他体系的回油进行散热。

In principle, the hydraulic system of the small concrete mixer is an open load sensitive open core circuit, which continuously supplies oil to the directional valve through the gear pump on the initiator. The pilot control valve is used as the main switch, and the forward rotation and rotation of the rotary motor are completed by controlling the rocker switch of the electromagnetic directional valve. The return oil of the reversing valve is divided into two ways: one is returned to the oil tank through the throttle valve, and the other is driven by the oil dispersion motor to dissipate heat for the return oil of other systems.

小型混凝土搅拌车液压体系的优化

Optimization of hydraulic system of small concrete mixer truck

通过毛病状况与原理比照剖析，以为换向阀的回油通过节流阀的阀口来操控油散马达的作业转速，且节流阀阀口是在出厂前依据发起机怠速调节油散马达转速的，一旦节流阀阀口固定，通油才能就会被约束在必定的范围内，但是换向阀的输出流量与发起机的转速成正比联系。

Through the analysis of the fault condition and principle, it is thought that the return oil of the directional valve controls the operating speed of the oil dispersion motor through the orifice of the throttle valve, and the throttle valve orifice regulates the speed of the oil dispersion motor according to the idle speed of the initiator before leaving the factory. Once the orifice of the throttle valve is fixed, the oil can be restricted in a certain range, But the output flow of the directional valve is directly proportional to the speed of the engine.

在发起机高速作业时，换向阀T口油液无法快速回到油箱，形成油散马达的进油管处压力过高，超越胶管接受的压力，所以爆管现象时有发作。因无法得到更具体的技术参数与材料，重载转速慢及马达毛病率高是否有直接相关，通过现场检查实车的体系现状及运用进程工况，从运用工况来剖析毛病原因。

During the high-speed operation of the initiator, the oil at the T port of the directional valve can not quickly return to the oil tank, resulting in the high pressure at the oil inlet pipe of the oil dispersion motor, which exceeds the pressure accepted by the rubber hose, so the tube burst occurs from time to time. Because we can not get more specific technical parameters and materials, whether there is a direct correlation between the slow speed of heavy load and the high fault rate of motor, through the on-site inspection of the system status and operation process of the real vehicle, we analyze the fault causes from the operation condition.

从现场的管路状况看到，吸油管过长过细，且齿轮泵的方位高于油箱吸油口的方位，经理论核算齿轮泵吸油管液压油流速到达4m/s，远超越规划标准。一起，齿轮泵自身的自吸才能差，在高转速时吸油管内发作负压，齿轮泵内部吸油缺乏加速磨损，容积功率快速下降，导致转罐在重载状况下转速下降显着。

According to the field pipeline conditions, the oil suction pipe is too long and too thin, and the orientation of the gear pump is higher than that of the oil suction port of the oil tank. Through theoretical calculation, the hydraulic oil flow rate of the oil suction pipe of the gear pump reaches 4m / s, far exceeding the planning standard. At the same time, the self-priming ability of the gear pump itself is poor, the negative pressure occurs in the oil suction pipe at high speed, the lack of oil suction in the gear pump accelerates the wear, and the volume power decreases rapidly, which leads to a significant decrease in the rotating speed of the drum under heavy load.