The transmission is a mechanism used to change the speed and torque from the engine. It can change the output shaft and input shaft ratio by fixed or split gear, also known as the gearbox. The transmission consists of a variable speed drive and an operating mechanism, and some have a power take-off mechanism. Most of the transmission mechanisms are driven by ordinary gears, and some are driven by planetary gears. Ordinary gear transmission shifting mechanisms generally use a slip gear and a synchronizer. According to the general domestic positioning of the car, the medium-sized car has a wheelbase of between 2.7 meters and 2.9 meters, and the displacement is from 1.8 to 2.5 L, such as Mazda 6, Accord, Mondeo, Sonata, Audi A4, Passat, Toyota Camry. Many models are among the midsize sedan camps.

The model in this design is GAC Toyota Camry, Camry is a model of GAC Toyota. Over the past 35 years, Camry has continued to lead, winning the trust of 20 million owners worldwide, and becoming the king of the world's best cars in the real sense.

The main tasks of the transmission are as follows: 1. Change the transmission ratio, expand the range of variation of the drive wheel and the speed to adapt to the frequently changing form conditions, and at the same time make the engine work under favorable conditions; 2.Under the premise that the engine rotation direction is unchanged, the car can be driven backwards; 3. Use the neutral gear to interrupt the power transmission, so that the engine can start, idle, and facilitate transmission shifting or power output.

The mechanical transmission uses a gear set, and the number of teeth of each gear set is fixed, so the gear ratio of each gear is a fixed value (also called ‘level’). For example, the first gear ratio is 3.85, the second gear is 2.55, and then the fifth gear is 0.75. These numbers are multiplied by the main reduction ratio, which is the total gear ratio. There are only 5 values in total (there are 5 levels), so we called it a stepped transmission.

It has been asserted that the shortcomings of cumbersome driving operations have hindered the pace of rapid development of automobiles. Therefore, most people expected that the mechanical transmission will to be ‘over’. However, from the perspective of market demand and application, mechanical transmissions will not leave prematurely.

2. 研究的基本内容与方案

1 Basic Content

1.Structural selection (structure form analysis and solution selection) of Camry's automotive mechanical transmission.

2.Design and calculation of Camry's automotive mechanical transmission (determination of main parameters of the transmission).

(1) Determination of main reduction ratio and block transmission ratio

(2) Calculating and checking gear parameters