[YesAuto Chassis Analysis] After 10 years of transformation, the new generation of Audi Q7 finally met the world in 2015. In terms of visible appearance and interior, the new model has obviously made people feel the novelty. In terms of chassis, there are also many differences between the new Q7 and the previous model. Behind these differences, it also reflects the fact that Audi's flagship SUV model has replaced the model platform. What we have to do today is to take a look at the new Q7, which uses the latest MLB Evo platform, and what changes have taken place in the chassis compared to the previous model.
● Platform changes
As we all know, the first-generation Audi Q7 (hereinafter referred to as the “old Q7”) has a very close “blood relationship” with the Volkswagen Touareg and the Porsche Cayenne. Specifically, it is from the Volkswagen PL71 platform. The PL71 platform was initially jointly developed by Volkswagen and Porsche, and on this basis, the previously mentioned “three brothers” of medium and large luxury SUVs were created. Although the “blood relationship” is the same as brothers and sisters, in the final analysis, the PL71 platform is not Audi's own model platform. The old Q7 is also significantly different from the traditional Audi sedan in the structure of the chassis suspension.
With the birth of the second-generation Q7 (hereinafter referred to as the “new Q7”), Audi’s brand-new MLB Evo platform has gradually surfaced. The new platform adopts brand-new body materials, electronic technology and chassis structure. After the new Q7, brand new The first generation of Audi A4 (B9), Audi A8 (next generation) and Bentley Tim Yue all come from this platform.
● Front suspension structure
The biggest feature of the front suspension of the PL71 platform model is that it adopts a double-wishbone structure, which is a commonly used structure for many luxury cars, sports cars and high-end SUV models. The front suspension structure of the MLB platform (including MLB Evo) is a multi-link structure with Audi characteristics, which Audi officially calls the “five-link”. In fact, the so-called “five-link” structure can also be seen as an evolution from a double wishbone structure. In theory, such a structure can bring a more delicate road handling experience.
When we carefully observe the front suspension structure of the new and old Q7, it is not difficult to see that the new Q7 splits the “A-type” lower control arm (also known as the wishbone) of the old Q7 into two front and rear control arms, so the lower control The physical articulation points of the arm and the steering knuckle have changed from the original one to two; in the same way, the upper wishbone of the old Q7 is also decomposed into two upper control arms on the new Q7, forming two articulation points. This approach can make the kingpin of the vehicle move further out and get closer to the center of the wheel, which is helpful to improve the steering stability of the vehicle. In addition, this structure has a larger adjustable range in the engineering development stage.
In terms of material selection, both the new and old Q7 front suspensions use a large number of lightweight aluminum alloy components, which not only contributes to the lightweight of the vehicle, but also effectively reduces the unsprung mass. A lighter body has a positive effect on dynamic response and handling flexibility, and a smaller unsprung mass can make the suspension better absorb the bumps from the ground and bring better driving comfort. This is for the Q7 For such a “million-class” luxury SUV, it is justified.
Through comparison, it can be seen that due to the change of the model platform, the new and old Q7 has obvious changes in the front suspension structure. The multi-link front suspension of the new Q7 pays more attention to the control experience of the vehicle on the paved road. , At the same time, it has gone further in the application of lightweight materials.
● Front chassis details
In addition to the changes in the front suspension, the new and old Q7 also have many differences in the details of the front chassis: the subframe material of the new Q7 has changed from old steel to aluminum, and the steering system has also changed, and An active engine mount has been added to further improve the NVH level of the vehicle.
In terms of front wheel brakes, the configuration of the new and old Q7 is basically the same, both are a combination of ventilated discs and 6-piston calipers. In addition, in terms of wheel arch sound insulation and engine protection, the two generations also maintained the same level. In terms of tires, the S-Line version of the new Q7 is “convergent” compared to the S-line version of the old Q7. The smaller wheel size is more comfortable and practical.
Overall, the front chassis details of the two generations of models have maintained a high level, and there has been no “shrinking” phenomenon. At the same time, the new models are also superior in the application of new technologies, aerodynamic optimization and lightweighting. . Generally speaking, in the first half of the vehicle, the MLB Evo model platform shows many differences from the old PL71 platform. What are the differences between the two vehicles in the rear suspension part?
● Rear suspension structure
Whether it is the old Q7 using the PL71 platform or the new Q7 from the MLB Evo platform, their rear suspension adopts a multi-link structure. However, in terms of specific form and details, the two multi-link structures still have a clear distinction. The rear suspension of the new Q7 pays more attention to lightweight design. Under the premise of ensuring the structural strength, the components are designed to be lighter as possible.
From the perspective of component material selection, the rear suspension of the new Q7 is one of the places where the weight reduction of the chassis is relatively concentrated. In addition to the more compact sub-frame, the steering knuckle of the new Q7 is also replaced with cast aluminum. In addition, the new Q7 adopts an extruded aluminum alloy lower front control arm instead of the old Q7's large steel A-shaped lower control arm. Compared with cast aluminum, the extruded aluminum is lighter in weight and stronger, which guarantees the strength. Under the circumstance, a more obvious lightweight effect can be obtained.
The old Q7 adopts the “mechanical spring integrated” structure in terms of elastic elements, that is, the air spring and the CDC shock absorber are integrated. Although the new Q7 also uses the CDC shock absorber and the air spring, it adopts a split arrangement. In theory, the adjustable range of the spring is longer, which is helpful for improving comfort and passing performance.
In addition, the separate layout can be more flexible to deal with a variety of models, and it is also applicable to cars on the same platform. It can match cars and SUVs of different levels by replacing the corresponding springs and shock absorbers, eliminating the need for redesign and development. Process.
● Other details of the chassis
Due to the electronic parking function, the new Q7 is different from the old Q7 in terms of rear wheel brakes: the front and rear brake calipers of the old Q7 are all made by Brembo, and the rear brake uses four-piston calipers and is equipped with mechanical parking. Braking system: Due to the need to match the electronic handbrake system, the rear wheel brake of the new Q7 uses a single-piston caliper with an integrated parking control motor, provided by TRW. At present, the electronic handbrake control motor still cannot be integrated with the multi-piston caliper. In order to take into account the electronic handbrake and the multi-piston caliper, some models have added a parking brake drum with motor control to the brake disc, but this is not conducive to the vehicle. Lightweight performance. Therefore, Audi chose to abandon the multi-piston brake calipers in the rear wheel brakes when it can meet the braking performance requirements.
In terms of the four-wheel drive system, the new Q7 still continues the purely mechanical torque-sensing central differential. The internal structure adopts a turbo-worm structure and is used in the RS 5 and other high-performance coupes. Audi’s own-developed crown gear-type central differential The devices are not the same.
On the whole, the most prominent aspect of the new Q7's rear suspension design is its light weight. Compared with the old Q7, it uses more lightweight aluminum alloy components, while also further optimizing comfort. Although the rear-wheel brake configuration seems to be “shrinked”, in exchange for more convenient electronic handbrake and AUTOHOLD function, the braking effect is still excellent.
to sum up:
Through the interpretation of the chassis, it can be seen that the changes between the new Q7 and the predecessor after 10 years of replacement are not only in the appearance and interior improvement. From the perspective of the model platform, the new Q7 is already a complete evolution from the bones. New models. The result of changing from the PL71 platform to the MLB Evo platform not only includes more advanced electronic configurations and intelligent systems, but also includes a lighter chassis structure and further improvements in handling and comfort, thus ensuring the new The first generation of Q7 still has a strong competitive strength in the same level of market. In addition, because Bentley Bentayga, the next generation of Volkswagen Touareg, Porsche Cayenne, and Lamborghini SUV Urus are all derived from the MLB Evo platform, the chassis of the new Q7 also has a direct reference for us to understand the mechanical structure of the above models.