Views: 209 Author: Site Editor Publish Time: 2020-12-01 Origin: Site
The hydraulic transmission system is an integral part of hydraulic machinery, and the design of the hydrostatic drive systems should be carried out simultaneously with the overall design of the main engine. When starting to design, we must proceed from the actual situation, combine various transmission forms, and give full play to the advantages of hydraulic power transmission system. We should strive to design a hydraulic transmission system with simple structure, reliable work, low cost, high efficiency, simple operation and convenient maintenance.
There is no strict sequence for the design steps of the hydraulic system, and the steps are often interleaved with each other. Generally speaking, after clarifying the design requirements, proceed roughly as follows.
1) Determine the form of hydraulic actuator;
2) Analyze working conditions and determine the main parameters of the system;
3) Develop a basic plan and draw up a schematic diagram of the hydraulic mechanical transmission;
4) Select hydraulic components;
5) Performance checking calculation of hydraulic system;
6) Draw work diagrams and prepare technical documents.
There is no strict sequence for the design steps of the hydraulic power transmission system, and the steps are often interleaved with each other. Generally speaking, after determining the design requirements, follow the steps below to design the hydraulic system.
1) Determine the form of hydraulic actuator;
2) Analyze working conditions and determine the main parameters of the system;
3) Develop a basic plan and draw up a schematic diagram of the hydraulic system;
4) Select hydraulic components;
5) Performance check of hydraulic system;
6) Draw work diagrams and prepare technical documents;
7) Requirements for dustproof, explosion-proof, cold-proof, noise, safety and reliability;
7) Requirements for efficiency and cost.
After the hydraulic actuator is determined, the control of its movement direction and movement speed is the core issue of drafting the hydraulic circuit.
The direction control is realized by reversing valve or logic control unit. For general automatic transmission hydraulic system with small and medium flow, most of the required actions are achieved through the organic combination of reversing valves. High-pressure and large-flow hydraulic systems mostly use a logical combination of cartridge valves and pilot control valves.
The speed can be controlled by changing the input or output flow of the hydraulic actuator or using the volume change of the sealed space. The corresponding adjustment methods include throttling speed regulation, volumetric speed regulation and the combination of the two, that is, volumetric throttling speed regulation.
Throttle speed regulation generally uses a quantitative pump to supply oil, and a flow control valve is used to change the flow of input or output hydraulic actuators to adjust the speed. The structure of this speed regulation method is simple. Because this kind of system must use a flash valve, it has low efficiency and large heat generation, and it is mostly used in occasions with low power.
Volume speed regulation is to achieve the purpose of speed regulation by changing the displacement of the hydraulic pump or hydraulic motor. Its advantage is that there is no overflow loss and throttling loss. But an auxiliary pump is needed to dissipate heat and supplement leakage. This speed regulation method is suitable for hydraulic systems with high power and high movement speed.
Volume throttling speed regulation generally uses a variable pump to supply oil. The flow control valve is used to adjust the flow of input or output hydraulic actuators, and the oil supply and demand can be adapted. This kind of speed control loop has higher efficiency and better speed stability, but its structure is more complicated.
Throttling speed control generally adopts an open cycle form, and volume speed control mostly adopts a closed cycle form.
