Development of Multi-Layer Plastic Membrane (Bladder Membrane) for Vapor Reducing Fuel Tank

The Vapor Reducing Fuel Tank System (Bladder Tank System) using a flexible plastic membrane (Bladder Membrane) was newly developed in order to reduce the amount of vaporized gasoline in a steel fuel tank. This Bladder Membrane is flexible to expand in proportion to a fuel volume and prevents the permeation of the vaporized gasoline.

As a result of our initial study for various materials, we decided to apply a multi-layer plastic material which could achieve both low fuel permeability and good flexibility.

This multi-layer material consists of polyethylene(PE) for structural material and polyamide(PA) for low permeability. The modulus of the PE needs to achieve a sufficient flexibility in order to keep the movement of the membrane. While PA material must have not only low fuel permeability but also strong adhesion with the structural material of PE.

We also clarify the membrane design to keep a good flexibility and to reduce a strain. Especially, the optimized design of the bead could be determined by our CAE analysis.

This tank system was introduced to Toyota Hybrid System(THS) released in May 2000.