Hydraulic transmission is an ideal transmission device for construction machinery. The progress and development of construction machinery depends on hydraulic technology. At present, construction machinery is the largest market in the hydraulic industry. More than half of hydraulic parts are used in construction machinery. Construction machinery places high requirements on hydraulic technology. The development of hydraulic technology is mainly to meet the needs of construction machinery. The level of hydraulic technology is mainly reflected in For construction machinery, for example, the large-scale, small-scale and high-pressure hydraulic parts, the maximum working pressure has reached 70MPa. Both construction machinery and hydraulic technology promote mutual development.
Therefore, it is necessary to deeply analyze the characteristics of hydraulic transmission and its existing problems, the requirements of construction machinery for hydraulic transmission, in order to further improve and improve the performance of hydraulic transmission.
Hydraulic transmission transmits energy through the pipeline connection, just like the biological blood vessel, only the pipeline can deliver the energy to the place where it is needed. It brings great flexibility and convenience to the design and layout. The hydraulic transmission is easy to realize various forms of movement, which is very suitable for the construction machinery that requires power and multiple working devices to achieve the requirements of complex movements.
The power density transmitted by the hydraulic transmission is large (the power transmitted per unit volume or unit weight), the structure is compact, and the weight is light, which is suitable for the requirements of strong and heavy construction machinery and heavy horsepower.
Hydraulic transmission has excellent transmission performance, stable transmission, easy to prevent overload, simple speed regulation, stepless speed change performance, simple maintenance, long service life, etc., can well meet the transmission performance requirements of construction machinery.
Hydraulic transmission has good control performance, hydraulic pressure is the interface between machinery and electronics, electro-hydraulic control is the key technology of the integration of machine and telecommunications.
However, there are unsatisfactory deficiencies in hydraulic transmission, some have been improved, and there are still problems to be solved that require further brainstorming. The following problems need to be solved during the use of construction machinery.
1. Energy saving requirements: adapt to the load changes to provide the hydraulic power (flow and pressure) required by the load, minimize the flow and pressure loss, and change the throttle speed control to volume speed control, especially to provide the load according to the load needs. Traffic.
Requires that the hydraulic system can absorb the energy of the working device in reverse, and has the energy storage function of energy regeneration and utilization.
2. Speed control requirements: hope that when the control valve is used to control the speed, it will not be affected by the load pressure change and the oil pump flow rate change, and can be adjusted according to the man's operation instructions.
3. Compound action manipulation requirements: single pump for multiple actuators: when multiple actuators act at the same time, it is required that they do not interfere with each other, and each actuator can be manipulated to supply oil at the required flow rate. Distribute the flow reasonably and realize the ideal compound action.
4. The matching problem between the hydraulic pump (single pump or multiple pumps) and the prime mover: it can make full use of the power of the prime mover and keep working at the maximum power point of the engine, while preventing the engine from stalling: in order to save energy, the hydraulic pump and engine are required to work At the most economical point.
5. The pressure loss problem of single pump for multiple actuators: when a single pump is for several actuators, according to the Pascal principle, the system pressure is determined by the pressure required to overcome the maximum load, so the oil circuit with lower supply load must exist Whether pressure loss can solve this problem by using something like a transformer in the circuit is being explored.
