雪佛兰迈锐宝转向系统设计开题报告

1. 研究目的与意义（文献综述）

in the process of driving, we need to change the direction of the car according to the driver's idea, which is called car steering.steering system is used to change the direction of the car and keep the car straight.it is composed of steering gear and steering transmission.the vehicle with power steering is also equipped with a power system.this design is the chevrolet malibu steering system.it can be found from the parameter configuration table of chevrolet 2020 malibuxl that eps electric power steering system is used in the steering system of chevrolet malibu.based on the traditional mechanical steering system, the electric power steering system adds sensor device, electronic control device and power steering mechanism, which can control the electric motor to generate power to realize the steering and completely get rid of the way of oil pressure power.in 1954, general motors first applied hydraulic power steering system to automobiles. after a series of technical innovation, the electronic hydraulic power steering system appeared in the early 1980s.in 1988, suzuki automobile company of japan first equipped electric power steering system on its small car cervo.globally, the car eps carrying rate has exceeded 50%. in china, the use of hps in passenger cars is about 63%, and the use of eps is about 35%. however, the eps carrying rate of our own brand cars is only about 20%, which has great potential for future development.in recent years, the production and sales of domestic independent brand eps are growing rapidly. according to the data, in 2015, the sales volume of independent brand eps products was about 2.293 million, an increase of 30.5% year on year, and the market share reached 19%, 1.3 percentage points higher than that of the previous year.with the improvement of intelligent and electronic electrification of passenger cars and the rapid growth of sales of new energy vehicles, there will be more room for china's automotive eps market.this course design will ignore electronic components, mainly design the mechanical part of the steering system, complete the selection of steering system components, motion verification and structural design of each steering component.

component selection is mainly about the selection of steering gear.the function of the steering gear is to reduce the steering torque and increase steering angle from the steering wheel, and then output them to the steering rod mechanism, so as to make the car turn, so the steering gear is essentially a decelerating transmission device.there are many types of steering gear, such as gear tooth bar type, circulating ball type, spherical worm roller type, worm crank pin type and so on.rack and pinion steering gear is widely used in middle and small cars, buses and freight cars with front axle load less than 1.2t.the spherical worm wheel steering gear has been widely used in light and medium-sized vehicles, for example: the current axle load is no more than 2.5t, no power steering and no more than 4t with power steering can choose this structure.circulating ball steering gear is a widely used structure, which is widely used in high-end cars, light buses and freight cars.circulating steering gear is developed on the basis of screw nut steering gear.its structural feature is that the third element-steel ball is added to the screw-nut driving pair, so that the sliding friction can be replaced by rolling friction to the maximum extent.although it has a short history, it has been widely used. the steering gear of the malibusteering system is designed with the circulating ball steering gearthis time. there are also two types of circular ball steering gear, the common circular ball-toothed fan type, and the other, the circular ball-tool pin type. they each have two transmission pairs: the screw, the steel ball and the nut drive pair, and the rack on the nut and the gear fan drive pair on the rocker shaft; the latter are the screw, the steel ball and nut drive pair, and the pin seat on the nut and the cone pin or ball pin drive pair on the rocker shaft.the clearance adjustment method of both structures is to use the adjusting bolt to move the rocker shaft for adjustment.the transmission efficiency of the circulating ball steering gear is high, the work is stable and reliable. the screw groove on the screw and nut is carburized, quenched and grinded, with good wear resistance and long service life.it is easy to adjust the meshing clearance between the gear sector and the rack, and the matching arrangement between this structure and the power steering hydraulic device is also very convenient.

besides the steering gear, it is the design of steering transmission mechanism.the steering transmission mechanism is a steering rod and arm system which is used to transfer force and movement from the steering rocker arm to the left and right steeringwheels. its task is to change the swing of the steering rocker arm at the output end of the steering gear into the deflection of the left and right steering wheels around their steering master pins, and make them deflect to different track circles around the same instantaneous steering center, so as to realize the wheel rolling steering without sliding.in order to make the relationship between the left and right steering wheel angle meet the requirements of the vehicle steering kinematics. it should be ensured by the precise design of the steering trapezoid mechanism in the steering transmission mechanism.there are two types of steering trapezoid mechanism: integral type and sectional type. the integral design is used for steering wheel with dependent suspension.the segmented design is used for the steering wheel with independent suspension. mcpherson type independent suspension is adopted as the front drive wheel of chevrolet malibu, so it is necessary to design and calculate the steering trapezoid mechanism with subsection.finally, it is necessary to select the material and check the strength of the arm, rod and ball pin in the steering transmission mechanism.

2. 研究的基本内容与方案

basic content:1. an overview of the development of the internal and external steering system.2.complete the selection and check of steering gear.3.complete the design of steering trapezoid.4. complete material selection and strength check of arm, rod and ball pin of transmission mechanism.

target:1.understand the new eps power steering system in recent years.2.fully learn the structure and working principle of four kinds of mechanical steering gear. the advantages of the circulating ball steering gear are compared and the steering gear angle transmission ratio, steering gear center distance and crank radius are selected.3.chevrolet malibu adopts mcpherson independent suspension, so it adopts and designs sectional steering trapezoid.4.it mainly includes the strength calculation of the steering rocker arm, the strength calculation of the steering longitudinal rod and the tie rod, and the wear resistance check of the ball pin.

3. 研究计划与安排

1-2（7 学期第18-19周） 确定毕业设计选题、完善毕业设计任务书(相关参数)、校内外资料收集

3（8 学期第1周） 方案构思、文献检索、完成开题报告

4～5（8学期第2-3周） 外文翻译、资料再收集

6～8（8学期第4-6周） 设计计算、草图绘制（3.19开题答辩）

4. 参考文献（12篇以上）

[1]马竹樵,张虓,罗秋华,费叶琦.循环球式动力转向器的数模构建与仿真分析[j].内燃机与配件,2018(23):55-56.

[2]彭俊翔.关于汽车的转向系统探讨[j].内燃机与配件,2019(03):71-72.

[3]张春兰,赵佳成.电助力汽车转向系统结构及新式直拉杆设计[j].南方农机,2019,50(18):16-17.