Injection system with stratified fuel charge

Claim 1

A high pressure fuel injection system including an injection pump connected by means with at least one nozzle, said nozzle including a high pressure channel connected to the injection pump by said means, a pressure chamber connected with said high pressure channel and with the delivery channel of the nozzle, said delivery channel being closed by means between consecutive injections, said high pressure fuel injection system including also two fuel tanks, one tank to which the injection pump is connected containing a fuel, called first fuel, whose characteristics are suitable for the operation of a diesel engine, the other tank containing a fuel, called second fuel, whose characteristics are not suitable for the operation of a diesel engine, the high pressure fuel injection system having the capability to inject periodically first fuel together with second fuel, said high pressure fuel injection system being characterized by the capacity to stratify the second fuel charge between portions of first fuel called pilots, the stratification occurring between consecutive injections in a region of the high pressure channel, said region where the stratification of the two fuels occurs being so selected that the second fuel charge is injected in the next cycle interspersed with pilots of first fuel, starting and ending with pilots of first fuel, said high pressure fuel injection system being also characterized by the capacity to switch from dual fuel operation to the operation with first fuel only and vice-versa from cycle to cycle, these capacities being achieved by several means including a nozzle provided with two additional channels, called the first and the second additional channels, said additional channels being connected with said high pressure channel close to said pressure chamber, each additional channel being provided with a one-way check valve, said nozzle having a pressure chamber of very small volume, and a configuration of the high pressure channel which prevent the mixing between the second fuel charge and the pilots of first fuel during their stratification as well as during their injection, a source of second fuel which delivers second fuel from the respective tank into said second additional channel, the second fuel being delivered between consecutive injections at controllable pressure and temperature, in controllable amount, and with controllable timing, said source of second fuel being electronically programmable, a main source of first fuel which delivers first fuel from the respective tank into said first additional channel, the first fuel being delivered between consecutive injections at controllable pressure and temperature, in controllable amount, and with controllable timing, said main source of first fuel being electronically programmable, means which connect the high pressure section of the injection system with the tank of first fuel between consecutive injections for a period between selected instants of the cycle, means which ensure a selected pressure in the high pressure section of the injection system between consecutive injections, a drain provided with means which direct the fuel leakages, either to the tank of second fuel or to the tank of first fuel, dependent upon the operation of the injection system with first fuel and second fuel, or with first fuel only.