| Truck cranes are more and more used in engineering construction due to their advantages such as flexible transport and strong environmental adaptability,and their work requirements are also getting higher and higher.China ’s current annual output of truck cranes is nearly 40,000 units,and China is one of the world’s largest producers of truck cranes.But in the production of parts and components of truck crane,especially high-quality products still rely on imports.Multi-way directional control valve is the core component to control the movements of lifting,telescopic and luffing of truck crane.Its performance directly affects the working performance of truck crane.Domestic hydraulic components urgently need to be upgraded.The multi-way directional valve generates steady flow force when controlling the actuator through oil,which affects the movement of the spool and the operation of the multi-way directional valve.It seriously affect the working performance of the truck crane.Therefore,it is important to reduce the steady flow force for the design of multi-way directional valves.Generally,throttle grooves of different structures are opened on the circumferential steps of the main spool of the multi-way valve.Because the U-shaped groove has two-stage throttle characteristics,significant throttle effect,reasonable flow rate,good processing technology,and low cost,it is widely used in the spool design of multi-way directional valve.At the same time,in order to meet the multi-stage flow control of different working conditions,combined throttle grooves with U-shaped grooves as the basic structure are also increasingly used.Therefore,based on the analysis of the working characteristics of the crane multi-way valve,this paper proposes to optimize the combined U-shaped groove parameters to reduce the steady flow force.The main work of the paper includes the following:(1)The principle analysis and theoretical calculation of truck crane multi-way valve.The hydraulic system and working principle of the multi-way valve of the truck crane are discussed,and the principle and characteristics of the LUDV system are analyzed.The reasonable boundary conditions are determined for the subsequent simulation analysis of the multi-way valve of the truck crane.Equivalent throttling area of combined U-shaped throttling groove is analyzed and the steady flow force theoretical is calculated.(2)Modeling and simulation and steady flow force analysis of multi-way valve of truck crane.Establish a three-dimensional model of the crane’s multi-way valve,import FLUENT calculation software,and analyze the flow field simulation of the multi-way valve model with different spool positions by different ports,analyze the pressure and speed changes at different spool positions,and the trend of steady flow force with the movement of the valve stem.(3)Establish a single factor analysis model,and use FLUENT software to analyze the influence of the deep groove width parameters of single U-shaped groove and double U-shaped groove on the steady state flow force under different working conditions,and provide a basis for the subsequent optimization of steady flow force at P-B.(4)Steady flow force optimization and improvement.Based on the analysis of the steady flow force of the original structure,the combined U-shaped parameters were changed to simulate the improved parameters.The results showed that the improved structural parameters reduced the steady flow force peak by 11.9% compared to the original parameters. |
