Design Of A New Type Of Vehicle Hydraulic Retarder And Research Of Internal Flow Field

Hydraulic retarder,which is one of the core components of commercial vehicles,is widely used in heavy commercial vehicles.The complex structure and manufacture technology,as well as high cost technology,limit the application of existing hydraulic retarder.Based on simplifying the structure of the hydraulic retarder and improving the manufacturability of the product,a new type of hydraulic retarder is proposed based on the working principle of the fluid transporting machinery.Based on the CFD theory,the flow field inside the new hydraulic retarder is simulated by fluent software,and the experiment bench is designed to validate it.According to the simulation and experimental results,the optimal design direction of the hydraulic retarder is determined and the control system of the new hydraulic retarder is preliminarily designed.By simplifying the structure to reduce manufacturing costs,this dissertation promotes the application the hydraulic retarder in the light commercial vehicles to extend the service life of medium and light commercial vehicle service brakes.This dissertation focuses on the new structure of the hydraulic retarder forward design,simulation and bench tests.It can be divided into the following aspects:(1)The braking principle and control mode of the existing hydraulic retarder are thoroughly researched.Based on a comparative analysis of the general hydraulic transmission machinery and hydraulic conveying machinery characteristics,this dissertation is inspired by hydraulic couplers and torque converters.A new type of hydraulic retarder mechanical structure is designed using the low efficiency of the vortex pump,according to the fluid conveying machinery vortex pump basic structure.(2)Based on the related literature of engine auxiliary brake,the vehicle matching of the hydraulic retarder with the combination of engine auxiliary brake and hydraulic retarder under long downhill condition is analyzed using the relevant parameters of the target vehicle.The trend of braking force demand of hydraulic retarder about vehicle speed is obtained and the geometrical parameters of the hydraulic retarder are designed by one-dimensional flow theory.(3)Pro E 3D software is used to extract and reasonably adjust the internal flow channels of the new type hydraulic retarder with different blade shapes.The internal flow channels are divided and meshed by ICEM CFD software,and finally imported into Fluent fluid simulation software for internal flow field numerical simulation.The braking performance difference between different blade shapes of the new hydraulic retarder is obtained,and the optimization direction of the mechanical structure of the hydraulic retarder is determined.(4)The control system of the new hydraulic retarder is preliminarily designed and the experiment bench is constructed to validate the retarder's braking performance.The test results are analyzed and compared with the results of numerical simulation,and the reference of further optimization of the new hydraulic retarder is provided.In addition,the new hydraulic retarder prototype with different circulation circle diameters is compared to provide a reference for the follow-up product serialization design.