Among the auto parts, there are many types of steering gears according to the different transmission pairs used by the steering gears. Common ones include recirculating spherical spherical worm gear, worm crank pin type, and rack and pinion type. It is widely used on the front axle of various automobiles.
?????The structure of the steering gear determines its efficiency characteristics and the requirements for the change characteristics of the diagonal transmission ratio. The choice of the steering gear of that efficiency characteristic should be determined by the use of the vehicle and related to the steering system scheme. Cars and passenger cars that often drive on good roads can use high-efficiency and highly reversible steering gear.
The characteristics of the steering gear are high efficiency, reliable work, and stability. The spiral grooves on the worm and nut are hardened after grinding and are therefore wear-resistant and have a long life. The adjustment of the meshing clearance between the rack fan and the rack is easy. Compared with other types of steering gears, its structure is complex, and it requires higher machining accuracy of main parts. The change characteristics of the angular transmission ratio of the worm crank pin type steering gear and the change of the meshing clearance characteristics are limited, and cannot fully satisfy the designer's intention. The rack and pinion steering gear has a simple structure, so it is easy to manufacture, has a low cost, and has high forward and reverse efficiencies. In order to prevent and mitigate the reverse impact from being transmitted to the steering wheel, a larger transmission ratio or a shock absorber equipped with a vibration absorbing device must be selected.
Structure and working principle of recirculating ball type steering gear: generally has two-stage transmission pair. The first stage is the screw and nut transmission pair, and the second stage is the rack and pinion transmission pair. The journal of the steering screw is supported on two tapered roller bearings. Bearing tightness can be adjusted with adjusting shims. The lower surface of the steering nut is machined so that the rack meshes with the tooth sector in the tooth sector shaft. When the steering screw is rotated through the steering wheel, the steering nut does not rotate, but can only move axially and drive the gear fan shaft to rotate. In order to reduce the friction between the steering screw and the steering nut, small steel balls are installed between them to achieve rolling friction. The spiral grooves of the two can cooperate to form a spiral tubular channel with an approximately circular cross-sectional profile. Outside the steering nut, there are a pair of through holes in which two ends of the two pipes are inserted into the nut. The catheter is filled with steel balls. The two tubes and the spiral tubular channel in the nut are combined into two independent closed steel ball flow channels. The work of the diverter is that the two rows of steel balls only circulate in their closed flow channels without falling out. The rack on the steering nut is inclined, so the teeth meshing with it should be a thickened tooth fan whose tooth thickness on the index circle changes linearly along the tooth fan axis. Because the positive transmission efficiency of the circulating ball steering gear is very high, the operation is light and the service life is long.