This is how Rheinmetall technology balances excess or negative pressure in the fuel tank system

Restraint systems for fuel vapors, so-called EVAP systems, are now common components of modern combustion engines. In today's hybrid vehicles, the fuel tank system is sealed off from the outside and so excess or negative pressure can build up. Yet in certain situations this pressure must be balanced out again. Pierburg has developed two new valves for this purpose: both the Fuel Tank Isolation Valve (FTIV) and the Fuel Vapor Valve (FVV) are based on a modular system.

The FTIV is normally placed between the fuel tank and the activated carbon filter and controls the flow to the filter. In addition, additional valves are required to open and close the complete system, for example during OBDII tests. The FTIV is a normally closed valve that can be opened electrically as required. It has two mechanical bypasses which reduce the built up pressure or underpressure as soon as a pre-defined threshold is exceeded. In addition, the volume flow of fuel vapors in the direction of the activated carbon filter can be limited to a maximum value by a flow limiter. The valve meets the non-leakage and flow requirements of modern fuel tank systems with a compact design and low weight.

Thanks to the modular build, it is possible to equip the FTIV with any functions required by the customer. For example, there is an option in which the valve is closed without current and only has an overpressure bypass.

Another variant of the valve, the FVV, is normally open. This type can be closed by simply applying power, if desired, so that the path of the fuel vapors in the EVAP system is sealed, for example, during an OBDII test.