Hot runner injection nozzle and actuator for injection molding device

An injection nozzle with

• a. a nozzle head including at least one discharge opening for injecting melted plastic material into a mold cavity of a thereto interconnected injection mold and forming therein a molded body,
• b. at least one positively controlled closure element which is movably supported in the nozzle head for closing a communication opening in the thereto connected injection mold, and
• c. an actuator cylinder comprising
• i. a first piston which is interconnected to the at least one closure element is arranged movable between
• 1. a first position in which the closure element is fully closed and
• 2. a second position in which the closure element is fully open, and
• ii. a second piston is arranged movable between a third position in which the second piston is not interconnected to the closure element and a fourth position in which the second piston is interconnected to the closure element and the closure element is thereby limited in an intermediate position between the fully opened and the fully closed position;
• wherein an active surface of the first piston is smaller than a corresponding active surface of the second piston, such that when pressurized with the same pressure the second piston has priority over the movement of the first piston;
• wherein the second piston comprises a first part and a second part that are axially spaced with respect to each other by a bushing that interconnects the first part and the second part, wherein the bushing extends between the first part and the second part of the second piston and wherein the first part and the second part of the second piston are arranged around the bushing and the first piston extends inside the bushing;
• wherein the second piston is in the fourth position interconnected to the first piston by the bushing;
• wherein the bushing acts as linear bearing for the first piston;
• wherein the first piston delimits with respect to a cylinder housing a first fluid chamber and a second fluid chamber and the second piston delimits with respect to the cylinder housing a third fluid chamber and a fourth fluid chamber, wherein
• the first fluid chamber when pressurized by a fluid causes the first piston to go to the first position,
• the second fluid chamber when pressurized by a fluid causes the first piston to go to the second position,
• the third fluid chamber when pressurized by a fluid causes the second piston to go to the third position, and
• the fourth fluid chamber, when pressurized by a fluid, causes the second piston to go to the fourth position;
• and
• wherein the fourth chamber comprises two segments which are interconnected to each other by a connection channel.