Background technology

Automobile steering system has experienced from simple Purely mechanical steering swivel system, hydraulic power-assist steering system and has developed into electric liquid servo steering system and the electric boosting steering system that is just starting widespread use at present, compare with conventional hydraulic servo steering system, EPS can be independent of engine operation, can save oil consumption and get over 5%-8%, having the advantages such as result exquisiteness, energy-conserving and environment-protective, safety and comfort, is the developing direction of automobile assisted power steering system.C-EPS and P-EPS all adopt turbine and worm decelerator at present, in order to reduce worm gear pair transmission noise, existing worm gear adopts cast or the thicker nylon of injection moulding one circle outside metal wheel hub mostly, the tooth portion of worm gear is all nylon, solved the transmission noise problem of worm gear pair, but the load-carrying capacity of worm gear, torque resistant ability and strength at repeated alternation problem are difficult to solve, particularly heavier vehicle easily causes broken teeth, and for proof strength, the tooth root of worm gear will ensure thicker nylon to metal insert cylindrical, the nylon material of same volume is high doubly more a lot of than the cost of Steel material.The worm gear that directly adopts metallic material to manufacture, noise problem is difficult to solve.