Graduation Design of Shandong Jiaotong University (Thesis)
order
The application of automatic transmission has become a trend of automobile development, and the number of automobiles equipped with automatic transmission has also increased rapidly in recent years. Compared with the traditional manual transmission, the automatic transmission has complex structure and various types. But the automatic car is simple, economical and safe to operate. However, due to the combination of mechanical technology, hydraulic technology and electronic technology, the maintenance is more challenging.
Because the automatic transmission has good automatic adjustment and adaptability, the vehicle starts more smoothly and accelerates more evenly. Good damping performance reduces the dynamic load and torsional vibration of the transmission system, prolongs the service life of the transmission system, and makes passengers feel more comfortable when riding and safer when driving. The average speed of vehicles is also improved. Although automatic transmission has excellent performance compared with manual transmission in many aspects, its low efficiency is also a problem that automatic transmission can not be ignored. Therefore, it is urgent to understand the structure and working principle of automatic transmission and the function and working principle of various components of automatic transmission. At the same time, its fault diagnosis and maintenance should also be followed up synchronously to ensure the normal use and development of automatic transmission vehicles.
When the automatic transmission encounters a fault, because its structure is more compact and complicated than the traditional manual transmission, it is more troublesome and time-consuming to maintain. Generally, there are few faults, because its performance is superior, its structure is more reasonable and its design is more perfect. For the smooth maintenance, it is very important to be familiar with the structure and working principle of each part. Only after repeated practice, the skilled maintenance process can better complete the maintenance work and calmly deal with the transmission failure. In this paper, the structure and working principle of Toyota A34 1E automatic transmission are studied and analyzed, and the fault diagnosis and maintenance are discussed. The simple working principle of A34 1E automatic transmission is that the power is output by the engine and transmitted to the automatic transmission through the hydraulic torque converter. Through the planetary gear mechanism of automatic transmission, the driver operates the joystick to shift different gears to achieve the purpose of speed change.
Fault diagnosis is to test and analyze the automatic transmission with various fault diagnosis methods, and sometimes use corresponding instruments to diagnose the mechanical system, hydraulic control system and electronic control system of the automatic transmission according to certain methods and steps to determine the specific parts and parts where the fault occurs.
1
Jiangge: The structure, working principle and maintenance of Toyota A34 1E automatic transmission.
1 Overview of automatic transmission
1. 1 development of automatic transmission
The growth process of automobile automatic transmission is relatively slow. The growth stage of hydraulic torque converter is from 1939 to 1950. In this growth stage, the speed change is completed by the planetary gear mechanism, and the hydraulic transmission part of the hydraulic torque converter does not use the hydraulic coupler. Even if this structure is simple and the cost is not high, the hydraulic transmission part is only used as a coupling and cannot realize the function of changing torque. The change of transmission torque depends on the planetary gear mechanism. In 1950s, Ford Motor Company successfully developed and manufactured a 3-speed automatic transmission with hydraulic torque variation, which made the application of hydraulic automatic torque converter in automobiles enter a mature stage.
Due to the increasingly strict requirements for high speed ratio, fuel economy and noise control, the range of teeth number and speed ratio of hydraulic transmission planetary gear mechanism tends to increase. 1977, Toyota of Japan developed a four-speed automatic transmission, and after 1977, it successfully developed an overdrive automatic transmission. This kind of transmission with overdrive not only improves the torque ratio and transmission part, but also shifts gears smoothly. Because it adopts the design concept of three-dimensional hydraulic torque converter and multi-gear planetary gear mechanism. The most widely used planetary gear transmission in automatic transmission is Simpson planetary gear transmission, which was invented by an engineer named Simpson of Ford Company in the United States.
1983, Nissan successfully developed the planetary gear mechanism of 4-speed hydraulic automatic transmission. Its obvious advantage is compact mechanism, which lays the foundation for multi-speed hydraulic automatic transmission. 1989, the 5-speed hydraulic automatic transmission developed by Nissan Motor Company was successfully put into use. These two transmissions are designed by adding a set of planetary transmission gear mechanisms on the basis of the original 3-speed and 4-speed hydraulic transmissions.
In recent years, with the improvement and perfection of the structural performance of various parts of automatic transmission, especially the integration of electronic technology and automatic control technology with traditional technology, the electronically controlled automatic transmission was born, which includes electronically controlled hydraulic mechanical transmission and electronically controlled gear mechanical transmission. Improve the fuel economy, power and safety of the car, and make the car more green and environmentally friendly. The optimal combination of transmission and engine is realized, which promotes the healthy development of automobile industry.
1.2 Type of automatic transmission
According to the different transmission ratio changes, automatic transmission can be divided into two categories: stepped automatic transmission and stepless automatic transmission.
Commonly used stepped automatic transmission can be generally divided into three categories: hydraulic automatic transmission (AT), electronically controlled mechanical automatic transmission (AMT) and dual clutch automatic transmission (DCT). Toyota A34 1E automatic transmission is actually an electronically controlled hydraulic automatic transmission. At present, the hydraulic automatic transmission used in automobiles is generally four-speed, five-speed or six-speed, but the gear of the hydraulic transmission can be three to eight. The more gears there are, the more complicated the structure will be and the higher the requirements for various technologies will be. The electronically controlled mechanical automatic transmission, like the traditional mechanical transmission, has high transmission efficiency and is generally assembled and used in small-displacement passenger cars and heavy commercial vehicles. The structure of dual-clutch automatic transmission is relatively complex and difficult to manufacture, but it has the advantage of high transmission efficiency of mechanical transmission and has great development space. No steps
2
Graduation Design of Shandong Jiaotong University (Thesis)
Automatic transmission has the advantages of simple structure, small volume, wide working speed ratio range and easy to form ideal matching with engine, which is the development trend of transmission in the future.
1.3 difference between automatic transmission and manual transmission
(1) The transmission lever is different.
The manual transmission lever is shown in figure 1. 1.
Fig. 1. 1 manual transmission lever diagram 1. 1 manual transmission lever
The joysticks of cars equipped with these two transmissions have different functions. The joystick of a manual transmission car is used to change the gear, which is realized by changing the position of the joystick. The gear position corresponds to the position of the joystick. The gears of a car equipped with a manual transmission are: first gear, direct gear, reverse gear, neutral gear and so on. The joystick of a car equipped with an automatic transmission is used to change the working mode. The working modes of an automobile equipped with an automatic transmission are: parking (P), reversing (R), neutral (N), automatic transmission (D), limited automatic transmission and other working modes. For an automatic car running normally, the joystick is placed on the automatic gear (D), and the car can automatically switch from high gear to low gear. The automatic transmission joystick is shown in figure 1.2.
Fig. 1.2 automatic transmission lever diagram 1.2 automatic transmission lever
three
Jiangge: The structure, working principle and maintenance of Toyota A34 1E automatic transmission.
Secondly, in terms of the number of pedals, a car equipped with manual gear has three pedals: accelerator pedal, brake pedal and clutch pedal. An automatic car has only two pedals: the accelerator pedal and the brake pedal, and there is no clutch pedal.
A car equipped with a manual transmission is also called a manual transmission car. An automatic transmission car is also called an automatic transmission car. In order to change the speed of a manual transmission car, it is necessary to change the meshing position and transmission ratio of gears in the transmission by shifting the gear lever, thus changing the wheel speed. Only when you press the clutch can you move the gear lever. Only when the driver is skilled, the manual car will be faster and more fuel-efficient than the automatic car when accelerating and overtaking. An automatic car can change gears automatically, and the driver only needs to step on the accelerator pedal. The automatic transmission will automatically shift according to the changes of pedal and vehicle speed.
(2) Compared with manual transmission, automatic transmission has the following advantages and disadvantages:
(1) can actively shift gears, with continuous torque change and continuous power when shifting gears; ② Good passability, simple starting, simple and smooth shifting and good comfort; ③ Low impact and dynamic load and long service life. Disadvantages:
① Complex structure, high manufacturing standard, great difficulty and high cost; ② Low transmission efficiency, high price and high fuel consumption; ③ The technical level of maintenance personnel is required to be higher.