对于工况卡车而言，如何在不牺牲关键牵引力和拖吊效率的前提下优化车辆的空载行驶驾乘舒适度，是一项长期的挑战。自2002 年以来，底盘技术供应商天纳克(Tenneco) 已经陆续推出了多款连续可变半主动悬架系统(CVSA)。不久，这家供应商还将推出一款名为 DRiV 的更简洁、更平价的半主动减振系统，主要定位皮卡和SUV 细分市场。

天纳克的 CVSAe 系统采用了一款外接电子阀，可根据道路输入和车辆对路面状况的反馈，实时调节减振器的压缩。系统的无限阻尼曲线（在最小/最大范围内）由计算机算法产生，可操控电子阀，根据车辆传感器传回的车轮和车身数据做出反应。与CVSAe 系统相比，CVSA2系统的成本较高，采用了2 个电液阀，从而实现了压缩和回弹的独立控制，可以扩大校准范围并提高驾驶员的舒适度和操控体验。

对比之下，目前正在研发中的DRiV 数字悬挂系统则直接将传感器和软件控制集成在系统内部，采用了更加简洁的集成式模块化设计。DRiV系统预计将在 2020 年上市。天纳克表示，DRiV 系统无需任何外部阀门或电子控制单元，因此非常容易集成至现有的悬挂系统中，几乎无需对目前的机械或电子系统进行太多改装。DRiV系统可通过驱动接口配置，分别提供8 种阻尼设置（驾驶员可通过信息娱乐系统的屏幕或驱动模式选择器进行设置），而且还内置了一款简化“网关”模块，可为系统提供网络安全保护，并支持车辆现有控制器局域网(CAN) 总线的通信。

专为极端环境设计

今年 6 月举行的媒体发布会上，天纳克副总裁、首席技术官Ben Patel 声称，DRiV是一款独一无二的产品。他指出，DRiV系统的设计简洁，能够快速适应不同的路面条件，“非常适合希望通过易于集成的平价悬挂解决方案，优化车辆驾乘性能的汽车制造商。”

在密歇根州 Pontiac 市附近的 WaterfordHills Raceway 试车场中，《汽车工程》跟随一辆雪佛兰Silverado，在试车场内专门设置的各种路面和弯道完成了一系列低速驾驶测试。测试证明，DRiV阻尼器能够优化车辆的驾乘和操控体验，并显著降低车辆的抖动、弹跳和制动下潜。毫无疑问，无论是空载或载重400 磅（181公斤）的情况下，装配 DRiV 系统卡车的驾乘体验和性能，都明显优于其他条件几乎完全相同的载货卡车。

我们采访了天纳克OE业务、汽车动力学和产品设计首席工程师Daniel Keil，并询问了 DRiV 系统的应用是否需要在车身或底盘增加传感器。“PCBA，也就是阻尼器内部的印刷电路板集成了传感器、加速度计等一系列智能电子外设。” Keil 回答，“我们可以直接使用车辆现有的传感器数据。此外，我们还可以从车辆获得转向、刹车、拖吊/载货及越野模式 CAN 信息数据。”

这些阻尼器及其内部PCBA 能否抵御灰尘、雨水、风雪、污泥的干扰？这些都是货运卡车经常遇到的严苛工作环境。“保护 PCBA、接口及相关元件免受腐蚀一直是产品上市面临的主要挑战之一。”Keil承认，“为了实现这个目标，我们已经做了大量工作。密封非常重要，我们将按照客户的要求对钢材料减震管增加防腐蚀涂层。”

客车定制

Keil补充说，DRiV技术也可用于乘用车辆，保证车上人员在常见及极端工作条件下的驾乘体验，并同时保留干脆、利落的操控性能。

天纳克首席工程师 Dan Keil 表示，天纳克将根据不同厂商的要求，针对具体车型对DRiV 数字悬挂系统进行校准。“根据我们的算法机制，系统仅会在有需要时调用控件。因此，如果你是在高速公路上平稳地行驶，阻尼器绝大部分时间均不会工作。然而，一旦有东西在你面前跳出来，而且你也立刻更换车道，系统则将进入控制模式，提供更多的阻尼。”

系统将在增加半主动控制前，校准被动阀门，接着“查看传感器数据，并决定车辆具体在什么时候需要多少阻尼。”

在车辆整合方面，为了使用DRiV 系统，OEM需要将通信系统集成至车辆网关（即天纳克和厂商系统之间的接口）。接着，“校准将由我们和厂商共同负责，”Keil 说，“如果 DRiV 系统的安装尺寸与传统减震设备相仿，那么系统的安装完全不会影响悬挂的其他部分。”

DRiV系统并不会限制车辆的装载或拖吊能力。“系统本身的目标就是协助卡车更好地完成日常工作，”Keil 补充说，而且还必须能够符合OEM所设定的限制要求。此外，由于系统的控制力更强，车辆需要启用悬挂系统的频率将更低，这也可以在一定程度上优化车辆的耐久性。

过去 10 到 15 年中，超过六百万部天纳克 CVSAe 系统已经成功登陆 10 家汽车厂商（主要为欧洲厂商）的超过40 款不同型号车型。目前，天纳克公司正在向北美SUV 市场扩张。虽然简化版DRiV 系统将主要针对全尺寸皮卡和SUV 细分市场，尤其是一些用于拖吊的车型。但2020 年后，该系统还将有机会登陆更多不同类型的道路车辆。然而，天纳克公司目前并未计划公布任何 DRiV 系统的客户名单。

One enduring challenge of work-truck engineering is how to make the vehicles ride and drive comfortably when unloaded without diminishing their vital hauling and towing capabilities. Since 2002, chassis-technology supplier Tenneco has offered ontinuously variable semi-active suspension (CVSA) systems. It will soon launch a simpler, less expensive semi-active damping system called DRiV (Digital Ride Valve). It is aimed initially at pickups and truck-based SUVs.

Tenneco’s CVSAe systems use an external electronic valve to adjust damper compression in real time to road inputs and the vehicle’s body reactions to them. Their infinite damping curves (within minimum/maximum limits) are created by a computer algorithm that drives the valve’s reactions to wheel and body motions provided by sensors on the vehicle. The costlier CVSA2 system uses two electro-hydraulic valves to control both compression and rebound independently for a larger tuning range and higher levels of comfort and control.

But the simpler DRiV digital suspension technology now under development for a 2020 launch has an integrated modular design with sensors and software controls nestled inside the damper itself. With no external valve or electronic control unit, Tenneco says DRiV is easy to integrate into the vehicle’s existing suspension with little re-engineering of mechanical or electrical systems. It offers eight discreet damping settings with or without a driver interface (it can be driver activated through an infotainment screen or drive mode selector) and uses a simplified “gateway” module that provides cyber security and communication with the vehicle’s existing controller area network (CAN) bus.

Designed for extreme environments

DriV is "unique in the market,” claimed Ben Patel, Tenneco Vice President and Chief Technology Officer Ben Patel in a June release. He noted that the damper’s simplified design and ability to quickly adapt to road surfaces and conditions "make it an excellent option for manufacturers looking for an easy-to-integrate solution for improved ride performance in any vehicle segment…at an affordable cost.”

As Automotive Engineering experienced in a series of low-speed test drives of Chevrolet Silverados over and through strategically placed surface events and chicanes at Waterford Hills Raceway near Pontiac, MI, the DRiV dampers improved both ride and handling while significantly reducing shake, bounce and brake dive. There was no question that the DRiV-equipped truck, both unloaded and with 400 lb. (181 kg) of ballast behind its rear axle, was dramatically better in feel and performance than the near-identically equipped stock truck.

We asked Daniel Keil, Chief Engineer of Tenneco's OE Business, Vehicle Dynamics and Product Engineering, whether the DRiV system needs sensors added to the vehicle’s body or chassis. “The PCBA, the printed circuit board inside the damper, has sensors, accelerometers and all the electronics intelligence integrated into it,” he said, “and we use data from sensors already on the vehicle. We also get steering, braking, tow/haul and off-road mode CAN message data from the vehicle.”

Are these dampers and their internal PCBAs sufficiently protected from the dirt, water, snow, slush, etc. that hard-working trucks will experience over time? “Having to protect the PCBA and the other interfaces from corrosion and all the elements has been one challenge in getting this to market,” Keil admitted. “We have done a lot of work to protect those things. Sealing is very important, and we will follow customer requirements on the anti-corrosion coating of the steel damper tubes.”

Tunable for passenger cars

Keil added that the DRiV technology also can be used in passenger cars to provide smooth ride under normal conditions but transition to crisp, athletic handling on demand.

“It will be calibrated to each individual vehicle with the OEM based on how they want its DNA," he said. "The strategy we use in our algorithms is to call for control only when it’s needed. So if you're cruising on a smooth freeway, the dampers will be in soft mode most of the time. But if something jumps out in front of you and you do a lane-change, they will go into a controlled mode with more damping."

Engineers will tune the passive valving before adding the semi-active control, then "the system looks at the sensor data and decides how much you need and when you need it.”

Regarding vehicle integration, OEMs will have to integrate communications to the gateway [the interface between Tenneco's and the OEM's system] and harnesses to the DRiV system will have to be completed. Then, "the calibration will be a joint effort between us and them," Keil said. "If fits in the same space where a normal shock does, so the rest of the suspension does not have to be touched.”

He adds that DRiV technology does not limit a vehicle’s cargo or towing capabilities. “The intention is that it can do anything the truck can do,” he stated. “It has to be able to encompass the limits set for the vehicle by the OEM. And it will reduce the durability loads on the vehicle because it will have better control and hit the suspension stops less often.”

More than six million Tenneco CVSAe systems have been featured in 40 different models from 10 (mostly premium European) brands over the last 15 years. The company is now expanding availability to the North American SUV market. And while the simpler DRiV system will be initially aimed at full-frame pickups and SUVs, especially those used for towing, beginning in 2020, there may be opportunities for it down the road in a wide variety of vehicles. The company is not ready to name any customers for DRiV or to provide any cost information for it, however.

Author: Gary Witzenburg
Source: SAE Automotive Engineering Magazine