1. Avoid recirculation of hot air during the application process
The filler near the radiator is often called "sponge". But it cannot replace any sponge. The demand for ultra-small excavators is mainly to avoid the recirculation of hot air, so corrosion resistance, temperature resistance and air permeability are definitely insufficient. That is, when the temperature of the cold air sucked in from the front of the radiator rises and enters the rear of the radiator (engine compartment), it cannot return to the front of the radiator. When the high-temperature gas returns to the radiator, the heat dissipation of the system is reduced, the oil and water temperature rises, and the engine cannot work normally and may be damaged in advance. Therefore, when operating a hydraulic excavator, it is impossible to ignore the observation and correction of the "sponge" near the radiator, and a part of it needs to be replaced in time.
2. Heat dissipation area
In the working process of the ultra-small excavator, the ventilation area of the radiator core is easily blocked by air movement and various reasons. If there is a protective net, it is necessary to deal with obstacles on time. If there is no protective net, the external pollutants of the radiator must be cleaned according to environmental changes and construction conditions. Otherwise, if the air flow channel is blocked, the ventilation area and heat dissipation should be reduced. that power. More importantly, avoid internal pollution of the radiator. It is not necessary to strictly abide by the provisions of the random technical document, regularly replace and clean the antifreeze, and participate in sewage drainage instead of the antifreeze. If the blockage constitutes the internal liquid flow path, it is difficult to see as long as the radiator is replaced, and the other is difficult to clean and eliminate. Positive and negative flow control of super mini excavator
The forward flow control system for ultra-small excavators is a technology of Rexroth in the 1980s. Its main feature is that the pilot pressure of the joystick not only controls the reversing valve, but also adjusts the displacement of the oil pump. When the actuator is not working, the oil pump has no pilot pressure, the swash plate angle is small, and the oil pump only outputs a small amount of standby flow. By operating the pilot handle, a pressure proportional to the deflection of the handle is established in the hydraulic pilot circuit to control the displacement of the reversing valve spool and the displacement of the pump.
The flow rate of the ultra-small excavator oil pump and the working speed of the actuator are proportional to the pilot pressure control pressure.
The negative flow control system of the ultra-small excavator is also the technology of Rexroth in the 1980s. Its main feature is to adjust the displacement of the main oil pump according to the amount of oil returned by the main control valve, that is, the corresponding control pressure before the main control valve. Throttle throttle valve. The displacement of the main oil pump is inversely proportional to the control pressure. Some people in the industry may not be familiar with the positive hydraulic system of an ultra-small excavator. Its main feature is that the displacement of the main pump is proportional to the signal pressure output by the pilot operating handle. The main controller judges the flow demand and change trend of the actuator according to the pilot pressure signal and its change trend, and adjusts the displacement of the main pump accordingly, so that the flow supply of the system can dynamically follow the flow demand of the actuator. ND implementation system. Real-time traffic matching meets "requirements" and "requirements". The system has relatively small medium flow loss in a relatively negative flow system, high reliability in a relatively load-sensitive system, and good overall energy saving effect. The efficiency of this series of machines is about 8% higher than other models, and the energy consumption is reduced by about 10%. The negative flow control system of the subminiature excavator means that the output of the hydraulic pump is controlled by the control valve (reversing valve). The oil is divided into two parts: one part enters the hydraulic cylinder or hydraulic motor, which is the effective flow, and the other part passes through the valve position. Returning the gas tank is a waste of traffic. In order to control the flow of this part of the waste liquid and keep it within the possible small range, a hole is added to the oil return passage of the control valve. The pressure difference is generated by the hole, and the pressure is directed to the pump before the throttle valve. The exit. The volume adjustment mechanism controls the displacement of the pump. The greater the flow through the orifice port, the greater the pilot pressure before the orifice port and the smaller the pump displacement. The control pressure (pilot pressure) of the variable pump mechanism is inversely proportional to the pump displacement, so it is called negative flow control. This type of control reduces flow loss.