30 November 2013

Volkswagen Golf Mk7 Cut Model at KLIMS2013 - A Demonstration of German Engineering

Volkswagen took a prime floor space at KLIMS 2013, a vast portion of the hall previously occupied by Proton in the KLIMS 2010. It brings the whole lot of its car together with the yet-to-be launched CKD Volkswagen Polo hatchback. However, the item that really catch my eyes is the cut model of the Volkswagen Golf, a car that won accolades of awards, triple award I would say; European Car of The Year, World Car of The Year and Car of The Year Japan. Award does not fall from the sky, so this car ought to be quite something.

The cut model of Volkswagen Golf Mk7 is very fascinating to look at. It is the free demonstration of Volkswagen engineering design which is very useful to be benchmarked. After all, Volkswagen Golf Mk7 is significantly 100kg lighter than the model it replaced. The savings are achieved via 3.0kg lighter electrical system, 12.0kg of car's equipment, 22.0kg from engine, 26.0kg from the drivetrain and a whopping 37.0kg from the body structure. The culmination of the savings is the result of finite element analysis which optimize the load path and reduce the redundant structure. The main structure is a hybrid of high strength steel with hot formed steel among other conventional materials.

Lets start with the front. While I don't bring the gauge to check the thickness, I am pretty sure it is quite a standard thickness as far as the hood inner and outer panel is concern. However what can be seen is the hood inner panel is quite mainstream in the design and generously structured near the cowl section. In addition to the hood inner beaded section close by, the hood outer is further augmented by stiffener, so even the rearward right section alone is supported by 3 reinforcements.

The section below shows the front bumper assembly consists of bumper fascia, bumper beam and its foam insert as well as the lower radiator grille louvre design. Also consistent with the current trend, the bumper itself is very thin, around 2mm and usually can't support its own weight is disassembled. Bulk of the loading is taken by the beam, while the yield can be support by the fascia, the springback is aided by the foam.

Moving further downward, one can clearly see the floor is fully covered to aid aerodynamics. The fairing covers even the lowest point of the car which is the oil sump, which seems to be insulated this this example. The next photo shows the main body structure of Volkswagen Golf Mk7, which is the side structure, a structure that envelope the occupants inside the car. The A, B and C pillar are exposed here, although only the critical section of B-pillar is cut out for us to see. 

Closer inspection through the web reveals the B-pillar inner panel is off the TWB type, i.e Tailor Weld Blank which means the panel comes as multi thickness along the length. This is particularly useful in saving weight as it isolates the need for an additional reinforcement of metal sheet to add strength, which also requires spot weld. For TWB, the sheet is rolled in the desired thickness at desired location, the concept which is as per illustrated. This technology is nothing new, as our local grown Proton Saga BLM employs the same technology in its door panel. More details after the jump.

Downwards of A-pillar lies the structure that holds the door and fender. It can be seen that the outer fender panel has at least two mounting on the side structure inner panel, which also holds the front door hinge upper and lower. Door hinge is very vital as it prevent door from sagging over time, and it set the locus of the door movement. Volkswagen item is compact but sturdy, I have seen similar kind of design from Audi A2 8 years ago and it seems the VAG maybe commonizing its hardware. Closer look at the hinge can be seen below.
From the A-pillar, lets have a look at the roof section. The design is more or less similar to the other cars in terms of the way roof outer and inner panel is designed, but there is only one roof bow. Older national cars have more than one bow. We can safely assumed with the advancement in Finite Element Analysis, the redundant structure can really be eliminated.
The side structure inner panel is visibly very busy at the back. Hatchback is typically a bit flimsy at the back as there is no cross member that run mid-way of the car to help resisting bends. Thus it is not a surprise to see a sturdy looking C-pillar section comprises of many reinforced section. The tailgate is one-piece affair, as can be seen in the photo below.
Done with the exterior main panels, the interior showcase is devoid of any door cut out. So we can't see the fascinating bits inside the door which is pity, because Volkswagen door has one of the best feel in the business. 7 years back, I measured the operating force and force-displacement trending of Volkswagen Golf, Passat, Touran and Phaeton and it was distinctly different compared to the Japanese.
 Most C Segment cars has a soft touch padded dashboard. Wonder how it is made? As can be seen above there is a thin layer of pliant material beneath the plastic part. This molded part is usually obtained via slush mold, which is more complicated than the normal injection molding that is used to make hard plastic. Also visible here is the cross section of the HVAC and audio system.
The central hump and side sill are made of hot-formed high strength steel. As a product of modular platform, there is distinct indication that the structure is modular For one, the front floor is isolated and connected to the dash panel, and pieces are joined at quite a number of places. For a different car based on the same platform, these floor panels will be different and quite commonly they are attached to a common corner nodes.
Above is the front-most floor called dash panel. It isolates the occupants cabin from the engine compartment. Below photo depicted rear floor panel, which is protrudes inwards to accommodate fuel tank.
Volkswagen cars are famed for their rigid and high quality cabin. This is the German wonder that most companies outside VAG is keen to find out how. No these next few photos won't reveal much, but at least it gives a clue.
The armrest opening lid is very thick and quite stiffly designed. The inner ribs are generous, and the padded material is thick too. Typical of Volkswagen, all storage space are lined so you won't see a bare compartment. The cupholder is covered by a sliding cover. The cover can't just simply more rearward as it will hit the the armrest storage. Rather, I think it slides over the rotary slider before being curled to the bottom. Many eastern manufacturer took a short cut in this matter by sliding a solid door forward or rearward. Closer photos of these storage space can be found below.

Volkswagen Golf Mk7 can be obtained in our Malaysian market. Two variants are on offer, Golf TSI with 1.4L turbocharged direct injection at RM159,888 and scorching GTI at RM211,888 offering 220PS thanks to a turbocharged 2.0L mill.

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