如今，OEM开始更多的将注意力关注车辆的动力传动系统上，并开始与一级供应商合作，以追求更高的效率、更低的重量、更优化的NVH特性以及更低的成本。目前 AAM（AmericanAxle & Manufacturing，中文译名：美国轮轴制造公司 或 美国车桥制造有限公司）正在展示一种全新Quantum技术，这种技术背后的设计理念正是打造更高效、更轻质、更“智能”的驱动桥系统。Quantum是AAM的系列驱动桥产品，据称可以为车辆实现30%到40%的质量减少，和20%的功率密度提升。近日，AAM副总裁兼CTO Phil Guys接受了《汽车工程》的采访，向大家介绍了有关Quantum技术的相关研发情况，摘选如下：

SAE：Quantum的概念从何而来？

Phil：Quantum技术是我们先进工程团队一次头脑风暴的成果。那时，我们刚刚完成了一项旨在实现更高能效的内部项目 – 工程团队采用了新的轴承、更轻的润滑系统以及超精加工的准双曲面齿轮。这是一次很常见的迭代，但我们认为其他一级供应商也能和我们做的一样好，从产品功能的角度来说，这次迭代不能让我们与其他厂商真正拉开差距。

我们知道客户想要重量更轻、效率更高、运行安静、可靠耐用且成本更低的解决方案，在这种背景下，我们再一次进行了严肃对话，讨论如何才能真正从驱动桥市场中脱颖而出。我们的先进工程团队开始将目光转移至汽车行业之外，包括航空航天、医疗器械等领域中任何涉及扭矩能量转移的设计。

6个月后，也就是2014年，他们拿出了一套方案，这也就是现在的Quantum技术。Quantum技术的桥设计采用了一套截然不同的齿轮支持结构，结合了适用于后驱动车型的梁式桥和独立后悬挂（IRS）设计以及一款全轮驱动（AWD）系统。当时我们认为这种概念过于激进，可能不会有客户感兴趣。

SAE：Quantum技术“激进”在哪儿？

Phil：嗯，这种解决方案与传统的桥设计有很大不同，我们的一些客户可能会有点怀疑，别人都没见过这种设计，因此我们肯定要尽可能地提供更多的验证、开发、效率、NVH和耐用性数据，打消大家的疑虑。此外，我们还打造了多款演示原型，以展示Quantum产品的安静运行能力。

我们打造了一款梁式桥，这是目前公司产品目录中最大的一款产品，也是Quantum技术的首个真正应用。我们认为，减重和提效应该是卡车市场优先考虑的重点，而我们的演示原型实现了30-35%的减重效果。目前，一款1500系列皮卡的标准梁式桥重量为82公斤（180磅），而Quantum解决方案的重量仅为57公斤（125磅），减重比例高达30%；2500系列皮卡的标准梁式桥重量为144公斤（317磅），Quantum解决方案的重量为98公斤（180磅），减重比例达30-40%。目前，我们还没有尝试量化Quantum可以在车辆减重方面发挥的作用，这可以留给客户自己去做。

无论何时，Quantum技术总能给不同应用带来减重方面的能力提升。与现有技术先比，采用Quantum技术的AWD车型可实现40%左右的减重。“我们已经减低了40%的寄生损失，并取得了大约1%的燃料经济性提升。”之前，我们已经完成了一次迭代，并对Quantum进行了更多优化。14个月前，我们又完成了对Quantum技术的第二次迭代，并开始向客户正式介绍这款产品。

SAE：Quantum技术的“秘密武器”是什么？

Phil：现在，我们还不会透露Quantum技术的内部结构，但可以说这款产品的核心在于采用了356号热处理铝材。我可以告诉你，虽然我们采用的金属环-小齿轮滚珠轴承来自航空航天领域，但成本却相当亲民！我们通过这种滚锥轴承实现了产品的差异化。Quantum系列产品的所有能效提升均来源于金属环-小齿轮轴承结构的支持，这些轴承并非双排设计，也无需事先加载，因此我们并没有使用垫片，而为了预先加载小齿轮轴承，通常垫片在车桥设计中的使用非常常见。这就是Quantum设计中最激进的地方。

SAE：外壳和轴承座的设计也有不同吗？

Phil：是的，这两处的设计是完全不同的，但创新之处在于，我们将如何以最紧凑、最高效的方式将这些轴承应用在我们车桥设计中。

OEMs are increasing their focus on the vehicle driveline, working with Tier 1s to wring out greater efficiencies, mass and NVH reduction and cost. Making drive axles as efficient, light and ‘intelligent’ as possible was the impetus behind the new Quantum technology now being demonstrated by American Axle & Manufacturing. Quantum is a family of drive axles that AAM claims deliver a 30 to 40% mass reduction and 20% greater power density as incumbent axles with the same torque capacity. Phil Guys, AAM’s Vice President and CTO, recently spoke with AE about Quantum developments.

Where did the Quantum concept come from?

From a brainstorming session with AAM’s advanced engineering team. We’d just been through an internal project aimed at seeking greater efficiencies—new bearings, lighter weight lubes, superfinished hypoid gears. A very iterative exercise, but we concluded that all of us in the Tier-1 axle space can do that. From a product-functional perspective there’s not a lot of differentiation.

We had a significant dialogue about how do we truly differentiate ourselves in the market, knowing that customers want less weight, more efficiency, quiet operation, reliability and durability, at reduced cost. So our advanced team benchmarked products outside the automotive space, including aerospace, medical—anything with a torque element to it that had to transfer energy.

Six months later—this was in 2014—they came up with a proposal. And the idea that came out of it, now called Quantum, was so radical that we thought no one would want to buy it. Quantum technology is all about a totally different approach to the axle’s gear-support structure. The concept encompasses beam-axle and IRS [independent rear suspension] versions for rear-drive applications, and an AWD derivative.

What makes it ‘radical’?

Well, it doesn’t look like a traditional axle so there was a bit of skepticism from some of our customers. It is a different-looking animal so we were right to gather a tremendous amount of validation, development, efficiency, NVH and durability data in support of the technology. We also built models to prove that it’s a quiet axle when installed in a vehicle.

We built a beam axle, the biggest product in AAM’s portfolio. It’s the first application of this technology; we felt the truck market would be looking for weight and efficiency improvements as a priority. And in our prototype we saw a 30-35% weight reduction. A benchmark beam axle for a 1500-series pickup weighs 82 kg [180 lb]; the Quantum is 57 kg [125 lb]; that’s a 30% mass reduction. A benchmark 2500-series axle is 144 kg [317 lb]; Quantum is 98 kg [180 lb], so we took 30-40 pounds out of that. We haven’t even tried to quantify the savings on the vehicle side that can come from the “cascade” benefits we bring; we’ll let the customers do that.

Each time we applied the technology in a different application we saw weight-reduction improvements. On the AWD version the weight savings is about 40% relative to current-market technology. And we’re seeing on the order of 40% reduction in parasitic losses. We quantify that as about a 1% improvement in label-type fuel economy to the vehicle. We went through one iteration and found more opportunities to make it even better. We did a second iteration, tweaked it a bit more and started taking that technology to our customers about 14 months ago.

What’s AAM’s ‘secret sauce’ for Quantum?

I’m not ready to show the insides just yet. The center section is heat-treated 356. I can tell you that while the new ball bearings we’re using for ring-and-pinion support are from aerospace applications, their cost isn’t! We use tapered roller bearings for the differential. All of our efficiencies are coming out of the ring-and-pinion support. Those bearings are not double-row and are not preloaded, so we don’t use shims [typically used in axles to set pinion bearing preload]. The design is radical in this regard.

Is the IP in the case design and bearing saddles?

Yes, they’re totally different. But the innovation is in how we apply these bearings in an axle in the most compact, efficient manner.

Author: Lindsay Brooke
Source: SAE Automotive Engineering Magazine