核心部件一：液力变矩器——“软连接”的动力传递

Core component one: Hydraulic torque converter - power transmission of "soft connection"

液力变矩器是AT自动变速箱最核心的部件之一，安装在发动机飞轮与变速箱输入轴之间。它的作用相当于手动变速箱中的离合器，但原理完全不同。

The hydraulic torque converter is one of the most essential components of the AT automatic transmission, installed between the engine flywheel and the transmission input shaft. Its function is equivalent to a clutch in a manual gearbox, but the principle is completely different.

液力变矩器内部充满了变速箱油，由泵轮、涡轮和导轮三个主要元件组成。发动机带动泵轮旋转，泵轮搅动油液冲击涡轮，涡轮再带动变速箱输入轴转动——动力就这样通过液体“软连接”传递出去。这种传递方式带来了一个巨大优势：车辆起步和停车时，发动机可以怠速运转而不会熄火，行驶中的换挡冲击也被油液吸收，平顺性远优于手动变速箱。

The hydraulic torque converter is filled with transmission oil inside, consisting of three main components: pump impeller, turbine, and guide wheel. The engine drives the pump wheel to rotate, which agitates the oil and impacts the turbine. The turbine then drives the transmission input shaft to rotate - power is transmitted through the liquid "soft connection". This transmission method brings a huge advantage: when the vehicle starts and stops, the engine can idle without stalling, and the shifting shock during driving is also absorbed by the oil, making the smoothness much better than manual transmissions.

液力变矩器还具备“增矩”功能——在车辆起步和急加速时，它能将发动机扭矩放大，帮助车辆更轻松地起步和超车。当车速达到一定数值后，变矩器内部的锁止离合器会锁止泵轮和涡轮，实现硬连接，提高传动效率、降低油耗。

The hydraulic torque converter also has a "torque increasing" function - when the vehicle starts and accelerates rapidly, it can amplify the engine torque, helping the vehicle start and overtake more easily. When the vehicle speed reaches a certain value, the lock up clutch inside the torque converter will lock the pump wheel and turbine, achieving a hard connection, improving transmission efficiency, and reducing fuel consumption.

核心部件二：行星齿轮机构——变速的“魔法齿轮”

Core component 2: Planetary gear mechanism - the "magic gear" for variable speed

如果说液力变矩器是自动变速箱的“离合器”，那么行星齿轮机构就是它的“变速器”。行星齿轮机构由太阳轮、行星架（带行星轮）和齿圈三部分组成。这三者中任意一个被固定、另一个作为动力输入、第三个作为动力输出，就能得到一个特定的传动比。通过改变固定、输入和输出的组合，一组行星齿轮就能实现多个不同的挡位。

If the hydraulic torque converter is the "clutch" of an automatic transmission, then the planetary gear mechanism is its "gearbox". The planetary gear mechanism consists of three parts: the sun gear, the planet carrier (with planet gears), and the ring gear. If any one of these three is fixed, the other serves as the power input, and the third serves as the power output, a specific transmission ratio can be obtained. By changing the combination of fixed, input, and output, a set of planetary gears can achieve multiple different gears.

在实际的自动变速箱中，通常会串联两组或三组行星齿轮机构，通过离合器和制动器的配合，实现4至10个前进挡。挡位越多，发动机就越能在高效区间运转，动力响应和燃油经济性也就越好。

In actual automatic transmissions, two or three sets of planetary gear mechanisms are usually connected in series, and 4 to 10 forward gears are achieved through the cooperation of clutches and brakes. The more gears there are, the more efficient the engine can operate, resulting in better power response and fuel economy.

核心部件三：换挡执行元件——精准控制的“操盘手”

Core component three: Shift actuator - precise control "operator"

有了变速机构，还需要一套执行系统来控制它。换挡执行元件主要包括离合器、制动器和单向离合器。离合器负责将行星齿轮的某个元件与动力输入轴连接或断开；制动器则负责将某个元件固定住；单向离合器只允许元件单向旋转。

With the transmission mechanism, an execution system is also needed to control it. The gear shifting actuators mainly include clutches, brakes, and one-way clutches. The clutch is responsible for connecting or disconnecting a component of the planetary gear from the power input shaft; The brake is responsible for fixing a certain component; The one-way clutch only allows components to rotate in one direction.

这些执行元件的动作由液压控制系统和电子控制系统共同指挥。液压控制系统通过阀体总成将变速箱油泵产生的油压分配给各个执行元件；电子控制系统则通过传感器采集车速、发动机转速、节气门开度、油温等信息，由变速箱控制单元（TCM）计算出最佳的换挡时机，通过电磁阀精确控制液压系统的动作。

The actions of these executing components are jointly commanded by the hydraulic control system and the electronic control system. The hydraulic control system distributes the oil pressure generated by the transmission oil pump to various actuator components through the valve body assembly; The electronic control system collects information such as vehicle speed, engine speed, throttle opening, and oil temperature through sensors, and calculates the optimal shifting timing through the transmission control unit (TCM). The hydraulic system is precisely controlled through solenoid valves.