Stockdorf/Munich. – Vehicle roofs with high-quality, individual design features that offer attractive additional benefits are some of the major trends in automotive construction. The roof module for the Opel Zafira gives this development an additional, new impetus.

The core idea behind the development was to create a symbiosis between the greatest possible feeling of space and additional storage capacity. The extra sensation of spaciousness is created by four large glass elements, while the additional storage volume is principally achieved thanks to an external housing with an integrated storage box system – a system that is also responsible for the striking look of the roof module.

The support frame of the roof module is manufactured using the roving process1 and consists of polyurethane with a glass fibre content of 22 %. This material structure is achieved using a Long Fibre Injection (LFI) process that guarantees excellent resistance to thermal deformation, making it the ideal carrier for units and enabling fastening elements to be integrated without difficulty. In addition, demanding forms can be realised using various cross sections (the wall thicknesses vary according to local requirements).

The outer skin is the part that meets the eye first, therefore development work here focused on achieving first class optical properties. The challenge was to develop a surface that would above all harmonise with the large glass elements and create a perfect overall impression. The 2100 x 1100 mm Opel Zafira roof module is therefore provided with a special plastic foil that blends optimally with the glass look, is scratch-resistant and, at the same time, offers the greatest possible UV and temperature stability. If a repair should be necessary, the foil can be painted over a large area. Minor damage can also be effectively eliminated by polishing. In order to achieve the required perfect surface quality, the most exacting demands are placed on the production process in terms of cleanliness, repeat accuracy and the material composition of the components.

The large area glass panels (1080 x 400 mm) along the two long sides of the roof are tinted; additional sun protection is provided by four electrically driven sun blinds made from a translucent material and operated by a switch in the front area of the roof frame. Five storage boxes of different sizes are integrated in the middle part of the roof. These offer the vehicle occupants a significant bonus in terms of storage space. The boxes have a spring damper function and are lockable; high-quality, glass fibre-reinforced plastics are used here as well and they blend harmoniously into the interior design.

To minimize the installation complexity of the optional roof system for Opel, it was necessary to supply a preassembled roof to the assembly line that would be as complete as possible. The module was therefore designed as a modified top-load system for installation from above. The installation preparations at the vehicle manufacturer are chiefly restricted to welding in an adapter frame that replaces the standard steel roof. The complete module is attached to the adapter frame using PU adhesive. The simplifications offered by this processing technique also lead to additional benefits: In the event that other module variants are called for in the future, it will be significantly easier to achieve them because there will be no need to make any changes to the bodywork and the plant layout can be left untouched. The same thing applies to possible aftermarket variants in which straightforward conversions could be achieved because of the bonding process that is in many respects based on conventional glazing technology.

During each phase of the development of the Opel Zafira module roof, great emphasis was placed on standardising the vehicle interfaces and this has led to decisive advantages: For one thing, it will be much easier to use various additional modules in the future. For another thing, the range of components will be noticeably reduced and this will have a favourable effect on both handling and costs.

1 Term referring to combining spun glass fibres into strands (rovings)
  during the manufacture of fibreglass