自动变速箱的换挡完全由变速箱控制模块(TCU:Transmission Control Unit)进行控制，其核心逻辑是在最佳的时机进行档位的切换，以保证车辆的动力性、换挡的平顺性和车辆的燃油经济性。

　　The shifting of automatic transmission is completely controlled by the Transmission Control Unit (TCU), whose core logic is to switch gears at the best time to ensure the vehicle's power performance, smooth shifting, and fuel economy.

　　TCU通过变速箱内部的传感器、整车控制模块(PCM：Powertrain Control management)的实时监测数据进行档位的切换，最主要的是根据车辆速度和油门踏板的深度（即驾驶员对动力的需求）进行及时的档位切换。

　　TCU switches gears in a timely manner based on the vehicle speed and the depth of the accelerator pedal (i.e. the driver's power demand) through real-time monitoring data from sensors inside the gearbox and the Powertrain Control Management (PCM) module.

　　换挡分为升档和降档，升档存在动力升档和滑行升档两种情况，降档也存在动力降档和滑行降档两种情况。下面将结合具体的换挡曲线对四种升降档情况进行讲解。

　　Shifting gears can be divided into upshifts and downshifts. Upshifts can occur in two ways: power upshifts and coasting upshifts, while downshifts can also occur in two ways: power downshifts and coasting downshifts. Below, we will explain the four types of upshifts and downshifts based on specific shifting curves.

　　对升降档进行讲解前，我们首先了解一下换挡线shifting schedule/shifting map。

　　Before explaining the upshift and downshift, let's first understand the shifting schedule/shifting map.

　　如下图所示换挡线是一个由横坐标为车速(Km/H)纵坐标为油门开度(%)的图。

　　The shift line shown in the following figure is a graph with the horizontal axis representing the vehicle speed (Km/H) and the vertical axis representing the throttle opening (%).

　　上图中：实线为升档换挡点的曲线，虚线为降档换挡点的曲线。升档换挡曲线会比降档换挡曲线的车速更高。

　　In the above figure, the solid line represents the curve of the upshift shifting point, and the dashed line represents the curve of the downshift shifting point. The upshift shift curve will result in a higher vehicle speed than the downshift shift curve.

　　1、动力升档

　　1. Power upshift

　　正常油门开车过程中，油门开度维持一个相对稳定的值，随着车速的提高变速箱由一个低档位升到一个高档位。

　　During normal throttle driving, the throttle opening maintains a relatively stable value, and as the vehicle speed increases, the gearbox shifts from a low gear to a high gear.

　　如下图所示:红色箭头的换挡过程，油门开度在15%左右，车速由60kph提升到90kph的过程中，车辆在80kph完成咯5档升6档的动力升档过程。

　　As shown in the figure below, during the shifting process indicated by the red arrow, with the throttle opening at around 15% and the vehicle speed increasing from 60kph to 90kph, the vehicle completes the power upshift from 5th to 6th gear at 80kph.

　　2、滑行升档

　　2. Coasting upshift

　　车辆在下坡过程中，油门开度很小或者无油门情况下，随着车速的升高，档位跟随者升高。这种比较简单，也很容易理解。还有一种是在超车或者急加速以后出现的滑行升档。

　　During the downhill process, if the throttle opening is very small or there is no throttle, the gear follower will increase as the vehicle speed increases. This is relatively simple and easy to understand. Another type is coasting upshifting that occurs after overtaking or rapid acceleration.

　　如下图所示:红色箭头的换挡过程，油门开度在80%左右，车速在90kph，松掉油门踏板以后，油门开度从80%向下掉，档位从绿色实线的左上方4档完成4档升5档。继续往下走穿过红色实线，完成5档升6档的过程。

　　As shown in the following figure: The shifting process of the red arrow, with the throttle opening at around 80% and the vehicle speed at 90kph, after releasing the throttle pedal, the throttle opening decreases from 80% downwards, and the gear shifts from 4th gear in the upper left corner of the green solid line to 5th gear. Continue walking down and cross the red solid line to complete the process of shifting from 5th gear to 6th gear.

　　3、动力降档

　　3. Power downshift

　　车辆进行急加速或者超车时为了提供更好的加速性能，变速箱会进行动力降档。

　　In order to provide better acceleration performance during rapid acceleration or overtaking, the gearbox will downshift its power.

　　如下图所示:红色剪头的换挡过程，车速在90kph，踩油门进行加速。油门开度从18%左右提升到60%左右，箭头穿越咯红色虚线，变速箱完成了从6档到5档的切换，实现了动力降档过程。

　　As shown in the figure below: The shifting process of the red scissor is accelerated by stepping on the accelerator at a speed of 90kph. The throttle opening has increased from around 18% to around 60%, and the arrow crosses the red dashed line. The gearbox has completed the transition from 6th gear to 5th gear, achieving the process of power downshifting.

　　4、滑行降档

　　4. Coasting downshifting

　　滑行降档是我们最容易理解的换挡形式，每一次开车都会遇到的一种换挡模式。

　　Sliding downshifting is the most easily understood form of shifting, and it is a shifting mode that we encounter every time we drive.

　　如下图所示:红色箭头的换挡，车速从90kph降档40kph，红色箭头穿越咯红色虚线和绿色虚线，完成咯6档降5档和5档降4档的两次滑行降档。

　　As shown in the following figure: shifting with a red arrow, downshifting from 90kph to 40kph, the red arrow crosses the red and green dashed lines, completing two coasting downshifts from 6th gear to 5th gear and from 5th gear to 4th gear.

　　自动变速箱换挡的4种模式已经全部讲解完，除此之外，不同的驾驶模式如经济、运动、雪地本质上是改变了这套换挡逻辑的“性格”。运动模式会让升挡更迟、降挡更积极；而经济模式则相反，一切以省油为先。

　　All four modes of automatic transmission shifting have been explained. In addition, different driving modes such as economy, sport, and snow essentially change the "personality" of this shifting logic. Sports mode will make upshifts later and downshifts more aggressive; The economic model, on the other hand, prioritizes fuel efficiency.

　　简单来说，自动挡的换挡逻辑就像一个聪明的助手，它根据你的“脚法”和车辆状态，自动为你选择最合适的挡位。

　　Simply put, the shifting logic of automatic transmission is like a smart assistant that automatically selects the most suitable gear for you based on your "footwork" and vehicle status.

　　浅见疏漏之处，恳请不吝赐教。

　　I apologize for any omissions and kindly ask for your guidance.

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