Method for actuating a piezo injector of a fuel injection system
View Patent ↗A method for actuating a piezoelectric actuator and a piezo injector of a fuel injection system having a nozzle needle which can be moved between the closed position and an open position by the piezoelectric actuator are disclosed. Current is applied to the piezoelectric actuator from a source for the duration of a charging time as a function of a required quantity of fuel, in order to move the nozzle needle into its opened position for a time period which is dependent on the required quantity of fuel. The charging time is selected according to the following relationships: t charge (p)=t nom,charge (p) for TI>t EP,p and t charge (p, TI)≦Ti for TI≦t EP,p .
1. A method for actuating a piezo injector of a fuel injection system, the piezo injector having a piezoelectric actuator and a nozzle needle configured for movement by the piezoelectric actuator between a closed position and an open position, comprising:
applying current to the piezoelectric actuator from a source for the duration of a charging time selected as a function of a requested quantity of fuel to move the nozzle needle into the open position for a time period dependent on the requested quantity of fuel,
wherein the charging time is selected according to the following relationships:
t charge ( p )= t nom,charge ( p ) for TI>t EP,p and
t charge ( p,TI )≦ Ti for TI≦t EP,p ,
where t nom,charge (p) is a nominal charging time given a pressure p, TI is an opening time for the piezo injector and t EP,p is an end time of an influence of bouncing for the pressure p.
2. A control system for a piezo injector having a piezoelectric actuator and a nozzle needle configured for movement by the piezoelectric actuator between a closed position and an open position, comprising:
a current source configured to supply current to the piezoelectric actuator, and
a control device configured to control a charging time during which the current source applies current to the piezoelectric actuator, wherein the charging time is selected as a function of a requested quantity of fuel to move the nozzle needle into the open position for a time period dependent on the requested quantity of fuel, and wherein the charging time is selected according to the following relationships:
t charge ( p )= t nom,charge ( p ) for TI>t EP,p and
t charge ( p,TI )≦ Ti for TI≦t EP,p ,
where t nom,charge (p) is a nominal charging time given a pressure p, TI is an opening time for the piezo injector and t EP,p is an end time of an influence of bouncing for the pressure p.
3. A fuel injector system, comprising:
a piezo injector comprising a piezoelectric actuator and a nozzle needle configured for movement by the piezoelectric actuator between a closed position and an open position,
a current source configured to supply current to the piezoelectric actuator, and
a control device configured to control a charging time during which the current source applies current to the piezoelectric actuator, wherein the charging time is selected as a function of a requested quantity of fuel to move the nozzle needle into the open position for a time period dependent on the requested quantity of fuel, and wherein the charging time is selected according to the following relationships:
t charge ( p )= t nom,charge ( p ) for TI>t EP,p
and
t charge ( p,TI )≦ Ti for TI≦t EP,p ,
where t nom,charge (p) is a nominal charging time given a pressure p, TI is an opening time for the piezo injector and t EP,p is an end time of an influence of bouncing for the pressure p.