https://cdn.motor1.com/images/mgl/8ANOOM/s3/corvette-rev-match-paddle.jpg美国东部时间2024 年 2 月 1 日下午1:25

作者：克里斯·帕金斯

几十年来，敏锐的手动变速箱驾驶员致力于掌握转速匹配的艺术，在降档期间使用油门“点”来同步发动机和变速箱之间的速度。然而，早在 2009 年，日产就推出了一项使该过程自动化的技术。现在，在美国销售的 几乎所有手动变速箱汽车都配备了转速匹配技术。

为了解释这项技术的工作原理，首先我们将介绍一些手动变速箱的基础知识。当汽车挂档并行驶时，发动机和变速器输入轴以相同的速度旋转，一切正常。踩下离合器踏板，发动机和变速箱脱开，两者都可以以不同的速度自由旋转。  

在升档时，当驾驶员松开离合器踏板，重新连接发动机和变速箱时，发动机转速会降低以匹配变速箱的转速。由于发动机转速在换档之间自然下降，当驾驶员松开油门时，这个过程快速而平稳。https://cdn.motor1.com/images/mgl/QemE03/s1/2009-nissan-370z.jpg

https://cdn.motor1.com/images/mgl/jl6yv7/s1/nissan-370z-engine-and-transmission.jpg

降档则是另一回事。 

高速接合较低齿轮，轴/离合器盘速度升高。当驾驶员松开离合器踏板时，发动机转速必须增加以匹配变速器的更高速度。如果离合器接合时两个速度不匹配，则可能会通过传动系统发出冲击，导致汽车颠簸。这不是一种愉快的体验，而且可能会在制动和转弯时的关键时刻破坏汽车的平衡。 

踩下离合器踏板时，油门会快速“响”一下，然后重新接合离合器，使发动机和变速箱速度相匹配，从而使降档过程变得平稳。一旦你有了感觉，做起来并不难。 

刹车时执行“blip”则完全是另一回事，因为大多数驾驶员只有两只脚。因此，出现了“脚跟-脚趾”技术，即驾驶员用右脚的一部分踩油门，同时踩下制动踏板。  

（“跟-趾”可能有点用词不当，具体取决于汽车的踏板设置。驾驶员通常会使用右脚内侧进行制动，并将右侧踩到油门踏板上。） 

这不是一个容易掌握的技术。急刹车有助于将踏板定位到适当的杠杆位置，以轻击油门踏板——这是你不太可能做的事情，例如，在高速公路出口匝道后停车制动。 

有时，刹车踏板和油门踏板距离太远，无法轻松同时工作。此外，当你处于赛道上的重制动区，在弯道前通过多个档位降档时，完美的脚跟-脚趾可能需要很多处理。  

这一过程的自动化使驾驶员的生活变得更加轻松，同时还带来了良好的跟趾降档的好处。虽然日产是第一家在公路车 370Z 上提供该系统的公司，但它的首次使用是在几年前的赛车运动中。 

法拉利在 1989 年的 640 一级方程式赛车中首次采用了“半自动”顺序变速箱，本质上是带有自动换档功能的手动变速箱。但直到 1992 年，线控油门才出现在 F1 中，实现了降档时自动发出油门信号。但在像法拉利这样的早期序列中，车手仍然必须在降档时进行转速匹配。（有些连续驾驶还要求驾驶员使用离合器，就像传统手动中一样。） https://cdn.motor1.com/images/mgl/P3g61L/s1/ct4-v-blackwing-shifter.jpg

凯迪拉克 CT5-V Blackwing 的换档杆。请注意左下角的“Rev Match”按钮。 

2009 年《汽车与驾驶员》杂志上一篇有关 370Z 的“SynchroRev Match”系统的文章对汽车制造商花了这么长时间才提出这项技术表示惊讶。Z 推出后不久，其他汽车制造商也开发了自己的版本。通用汽车的系统随 C7 Corvette 一起推出，现在CT4-V Blackwing和CT5-V Blackwing都配备了该系统。Motor1采访了肖恩·霍夫曼 (Sean Hoffman)，他是通用汽车公司的一名离合器控制校准员，曾在 Blackwings 上工作过。 

正如霍夫曼所解释的那样，通用汽车的系统依赖于曲轴位置传感器、齿轮位置传感器、离合器位置传感器和输出轴速度传感器。然后，发动机的 ECU 获取该信息并将其转换为发动机的扭矩请求。ECU 计算目标发动机转速，然后确定油门打开的程度和时间。

“我们总是根据变速箱输出速度和您要使用的档位来计算精确的转速，”霍夫曼说。“我们知道传动比是多少。只需将两者相乘即可得出目标发动机速度，因此计算是准确的（或者软件允许的小数位数），但显然，系统无法完美地做到这一点。” https://cdn.motor1.com/images/mgl/JO3zkM/s1/2023-cadillac-ct5-v-blackwing-motor1.com-star-awards.jpg

过冲或下冲（例如 50 到 100 RPM）是可以接受的。司机可能感觉不到这一点。目标转速也会不断变化。 

“显然，当你换档时，你会踩下离合器，车辆可能会稍微减速，或者你可能会刹车，”霍夫曼说。“因此，随着车速的变化，变速器输出速度也会发生变化，您总是需要计算新的目标转速。” 

虽然油门是达到发动机目标转速的主要装置，但 ECU 也可以控制燃油和火花。霍夫曼说，有时，一旦接近目标速度，系统可能会减少燃油，以防止出现大幅超调。 

在 Blackwings 中，自动转速匹配系统也适用于升档，有助于平稳过程，减少离合器随着时间的推移而磨损。通常，在自动转速匹配打开的情况下升档时，只要踩下离合器踏板，发动机就会减少燃油，这也有利于排放和燃油经济性。 

该系统从不考虑车轮速度，因此如果您改变 Blackwing 的后轮胎尺寸（从而改变齿轮中的车轮速度），转速匹配仍然可以正常工作。虽然可能性不大，但如果客户更换更轻或更重的飞轮，改变发动机加速和减速的速率，可能会影响系统。您可能会看到更多的下冲或过冲，因为系统仅设计用于与出厂时的发动机配合使用。您也可能会遇到离合器严重磨损的问题，但此时，您还会遇到其他问题。  https://cdn.motor1.com/images/mgl/9my1MG/s1/porsche-auto-blip-button.jpg

显然，仍然有肉质的部分在整个方程式中占主导地位。他们是移动变速杆并按下离合器的人，因此系统必须考虑离合器踏板的位置和行驶速度等因素，以使每次换档尽可能顺利。  

这里发生的事情与自动变速器的转速匹配过程没有太大不同。但霍夫曼指出，汽车将有自己的 ECU 与发动机的 ECU 通信，从而使过程更简单。  

还有一种适用于许多汽车的售后解决方案，称为 AUTO-BLiP。该公司的负责人阿尔·维加拉 (Al Vergara) 煞费苦心地说，该设备本身并不进行转速匹配。相反，它会插入汽车的 OBDII 端口，并在依次踩下制动踏板和离合器后产生油门提示音。Vergara 解释说，它使用简单的刹车灯开关、油门位置传感器和离合器联锁信号来产生油门信号。盒子上的旋钮允许驾驶员控制油门的长度以及踩下离合器后的延迟时间。 

它显然不像 OEM 内部那样复杂，但价格为 395 美元，是一种为旧车辆添加类似功能的经济实惠的方式，尽管旧车辆具有线控油门。该系统最常用于赛道赛车。 

有一种观点认为，这样的系统将驾驶员排除在外，而手动变速箱汽车的全部目的就是增加参与度。但就我个人而言，每当我测试具有此功能的汽车时，我都会经常打开和关闭它。有时尝试转速匹配是不切实际的，或者只是烦人。其他时候，我想多做一点工作，陶醉于完成完美的跟趾降档的满足感……如果我能做到的话。  

更多工程深入研究https://cdn.motor1.com/images/mgl/AkgJBP/s3/tesla-cybertruck-48-volt-architecture.jpg

Tesla Cybertruck 的 48 伏架构

https://cdn.motor1.com/images/mgl/AkgEyO/s3/nissan-xtronic-cvt.jpg为什么我们讨厌 CVT

Here's How Auto Rev-Match Works

A GM engineer explains how a car can heel-toe better than you. 

Feb 1, 2024 at 1:25pm ET

By: Chris Perkins

For decades, keen manual-transmission drivers worked to master the art of rev matching, using a “blip” of throttle to synchronize the speed between engine and transmission during a downshift. Back in 2009, however, Nissan introduced a technology to automate the process. Now rev-match tech is included with almost every manual-transmission car sold in the US. 

To explain how this technology works, first we’ll cover some manual-transmission basics. When a car is in gear and moving, the engine and transmission input shaft rotate at the same speed, and everything is all good. Push in the clutch pedal, the engine and transmission decouple, and both are free to rotate at different speeds.  

In an upshift, when a driver lets out the clutch pedal, recoupling the engine and transmission, engine speed decreases to match that of the transmission. Since engine speed naturally falls between gear shifts, as the driver has let off the throttle, this process is quick and smooth.

Downshifting is a different matter. 

Engage a lower gear at speed and the shaft/clutch disc speed rises. When the driver lets out the clutch pedal, engine speed must increase to match the higher speed of the transmission. If the two speeds are mismatched as the clutch engages, it can send a shock through the driveline, resulting in the car jolting. It’s not a pleasant experience, and one that can upset the balance of a car at critical moments during braking and cornering. 

A quick “blip” of the throttle while the clutch pedal is depressed matches engine and transmission speed before re-engaging the clutch, smoothing out the process of a downshift. It’s not too difficult to do, once you get a feel for it. 

Executing a blip while braking is an entirely different matter because, well, most drivers only have two feet. Hence the “heel-toe” technique, where the driver blips the throttle with part of their right foot, while holding down the brake pedal.  

(“Heel-toe” can be something of a misnomer, depending on the pedal setup of the car. Oftentimes, a driver uses the inside of their right foot for the brakes and rolls the right side onto the throttle pedal.) 

It’s not an easy technique to master. Braking hard helps position the pedals for the right amount of leverage to blip the throttle pedal – something you’re not likely to be doing, say, braking from a stop after a highway offramp. 

Sometimes, the brake and gas pedals are spaced too far apart to easily work both simultaneously. Moreover, a perfect heel-toe can be a lot to manage when, say, you’re in a heavy braking zone on track, downshifting through multiple gears before a corner.  

Automating this process makes life a lot easier for the driver, while also bringing the benefits of a good heel-toe downshift. And while Nissan was the first to offer the system in a road car, the 370Z, its first use was in motorsport years earlier. 

Ferrari first employed a “semi-automatic” sequential gearbox with the 640 Formula 1 car of 1989, essentially a manual transmission with automated shifting. But it wasn’t until 1992 that throttle-by-wire came to F1, enabling automated throttle blips for downshifts. But in early sequentials like the Ferrari’s, drivers still had to rev match on downshifts. (Some sequentials also required drivers to use the clutch, as in a conventional manual.) 

The shifter of the Cadillac CT5-V Blackwing. Note the "Rev Match" button at the bottom left corner. 

A 2009 Car and Driver article about the 370Z’s “SynchroRev Match” system expresses surprise that it took so long for an automaker to come up with this technology. Not long after the Z, other automakers developed their own versions. GM’s system arrived with the C7 Corvette, and now, both the CT4-V Blackwing and CT5-V Blackwing have it. Motor1 spoke with Sean Hoffman, a clutch control calibrator at GM, who worked on the Blackwings. 

As Hoffman explains, GM’s system relies on crankshaft-position sensors, gear-position sensors, clutch-position sensors, and output shaft-speed sensors. The engine’s ECU then takes this information and turns it into a torque request to the engine. The ECU calculates a targeted engine speed and then determines how much and for how long to open the throttle.

“We're always calculating an exact number of RPM, and it's based on the transmission output speed and the gear that you’re going into,” Hoffman says. “We know what the gear ratio is. Just multiplying the two together gives you your target engine speed, so the calculation is exact — or to as many decimal places as the software allows — but obviously, the system can’t do it perfectly.” 

An overshoot or an undershoot of, say, 50 to 100 RPM is acceptable. A driver likely can’t feel that. The target RPM constantly changes, too. 

“[O]bviously when you shift, you depress the clutch, and the vehicle is likely to decelerate somewhat, or you might be braking,” Hoffman says. “And so, as the vehicle speed changes, that transmission output speed changes and you're always calculating a new target RPM.” 

While the throttle is the primary device for getting to the target engine speed, the ECU has control over fuel and spark as well. Hoffman says that sometimes, the system might cut fuel once it gets close to the targeted speed to prevent a large overshoot. 

In the Blackwings, the auto rev-match system also works on upshifts, helping smooth the process, reducing clutch wear over time. Typically, on an upshift with auto rev-match turned on, the engine will cut fuel as soon as you put in the clutch pedal, also a boon to emissions and fuel economy. 

The system never looks at wheel speed, so if you change rear tire sizes in your Blackwing – thus changing wheel speed in gear – rev matching will still work fine. While perhaps unlikely, if a customer swaps in a lighter or heavier flywheel, changing the rate at which the engine builds and loses speed, that could affect the system. You might see more undershoots or overshoots, as the system is only designed to work with the engine as it comes from the factory. You may also encounter issues with a severely worn clutch, too, but at that point, you’ve got other problems.  

Obviously, there’s still the fleshy bit lording over the whole equation. They’re the ones moving the shift lever and pressing the clutch, so the system must account for things like the position of the clutch pedal and the rate of travel to make every shift as smooth as possible.  

What’s happening here isn’t too different from the process of rev-matching with an automatic transmission. But Hoffman points out that an auto will have its own ECU talking to the engine’s ECU, making the process simpler.  

There’s also an aftermarket solution of sorts that works for many cars called AUTO-BLiP. Al Vergara, who runs the company, is at pains to say that the device doesn’t do rev matching, as such. Instead, it plugs into a car’s OBDII port and generates a throttle blip after the brake pedal and clutch are pressed in sequence. Vergara explains that it uses simple brake-light switch, throttle-position sensor, and clutch interlock signals to generate a throttle blip. Knobs on the box allow drivers to control the length of the throttle blip, and the delay between after the clutch is depressed. 

It’s obviously not as sophisticated as what an OEM can do in-house, but at $395, it’s an affordable way to add similar functionality to older vehicles, albeit one that has by-wire throttle. The system is most commonly used on track-day cars. 

There’s an argument to be made that systems like this take the driver out of the equation, and the whole point of a manual-transmission car is to increase engagement. But personally, whenever I’m testing a car that has this functionality, I switch it on and off often. There are times where trying to rev-match is impractical, or just annoying. Other times, I want to work a bit more, reveling in the satisfaction of nailing a perfect heel-toe downshift... if I can manage it.