Piezo injector
A piezo injector includes an actuator space in which a piezo actuator is arranged, a control piston bore in which a control piston with an end face is arranged, a leakage pin arranged between the piezo actuator and the end face to couple the piezo actuator with the control piston, and a union for fluidic communication with the control piston bore which union has a hydraulic throttle.
1. A piezo injector of an internal combustion engine, the piezo injector comprising:
an actuator chamber,
a piezo actuator arranged in the actuator chamber,
a control piston bore,
a control piston arranged in the control piston bore, the control piston having a face side and a perimeter in sliding contact with walls of the control piston bore,
a first control chamber delimited by the walls of the control piston bore having straight sides and the face side of the control piston, the first control chamber disposed between the face side of the control piston and the actuator chamber,
a rigid leakage pin sliding within an intermediate plate arranged between the piezo actuator and the face side of the control piston to transmit an increase in length of the piezo actuator to the control piston through direct physical contact with both the piezo actuator and the control piston,
a nozzle needle guided in a high-pressure region of the piezo injector by a nozzle needle sleeve,
a second control chamber formed within the nozzle needle sleeve and delimited by a face side of the nozzle needle,
a connection for fluid communication between the first control chamber and the second control chamber, and
a hydraulic throttle disposed in the connection for fluid communication,
wherein the control piston, the first control chamber, the second control chamber, and the connection are physically interrelated such that a movement of the control piston toward the nozzle needle increases a volume of the first control chamber to thereby reduce a fluid pressure in both the first control chamber and the second control chamber to thereby reduce a pressure exerted on the face side of the nozzle needle.
2. The piezo injector of claim 1 , further comprising:
a spring chamber formed by a section of the control piston bore that faces away from the piezo actuator and by the control piston,
wherein a second connection for fluid communication is formed between the spring chamber and the high-pressure region.
3. The piezo injector of claim 1 , in which the throttle exhibits a throughflow in the range from 300 ml/min to 600 ml/min.
4. The piezo injector of claim 1 , wherein the throttle has a minimum diameter in the range from 0.2 mm to 0.4 mm.
5. The piezo injector of claim 1 , in which the throttle is designed such that a throughflow rate through the throttle in one direction differs from a throughflow rate through the throttle in the opposite direction.
6. The piezo injector of claim 5 , wherein
the throughflow rate of the connection for fluid communication in the direction of the second control chamber is lower than the throughflow rate in the direction of the first control chamber.
7. The piezo injector of claim 5 , further comprising:
a spring chamber formed by a section of the control piston bore that faces away from the piezo actuator and by the control piston,
a second connection for fluid communication between the spring chamber and the high-pressure region, and
wherein the throughflow rate of the second connection in the direction of the spring chamber is lower than the throughflow rate in the direction of the high-pressure region.
8. The piezo injector of claim 1 , wherein a diameter of the first control chamber is defined by a diameter of the face side of the control piston.