Door closer

1. A door closer, including at least one of a locking function and a free-swing function, comprising:

a door closer housing;

an output shaft configured to be connected to a door;

a piston assembly connected to the output shaft and guided in the door closer housing;

a closer spring;

a fluid-tight separating wall arranged in the door closer housing between the piston assembly and the closer spring;

a piston rod that couples the piston assembly to the closer spring, wherein the piston rod passes through the separating wall in a fluid-tight manner

a hydraulic lock compartment configured to lock the closer spring; and

a free-swing assembly configured to enable a translational motion of the piston assembly decoupled from the closer spring when the closer spring is locked;

a closer spring tension piston guided in the door closer housing and abutting on the closer spring;

wherein the lock compartment is arranged between the separating wall and the closer spring tension piston.

2. The door closer of claim 1 , wherein the free-swing assembly is formed as a sliding-coupling formed by a pocket arranged in the piston assembly that exclusively transmits compressive force between the closer spring and the piston assembly.

3. The door closer according to claim 1 , further comprising a solenoid control valve,

wherein a closure damping compartment is formed between the door closer housing and the piston assembly on a side of the piston assembly facing away from the piston rod, and

wherein the solenoid control valve controls at least the pressures in the closure damping compartment and in the lock compartment.

4. The door closer according to claim 3 , wherein the solenoid control valve is a 3/2-solenoid control valve.

5. The door closer according to claim 1 , wherein the door closer is a hinge door closer.

6. A door closer configured as a hinge door closer, including at least one of a locking function and a free-swing function, comprising:

a door closer housing;

an output shaft configured to be connected to a door;

a piston assembly connected to the output shaft and guided in the door closer housing;

a closer spring;

a fluid-tight separating wall arranged in the door closer housing between the piston assembly and the closer spring;

a piston rod that couples the piston assembly to the closer spring, wherein the piston rod passes through the separating wall in a fluid-tight manner

a hydraulic lock compartment configured to lock the closer spring;

a free-swing assembly configured to enable a translational motion of the piston assembly decoupled from the closer spring when the closer spring is locked;

a closer spring tension piston guided in the door closer housing and abutting on the closer spring;

wherein the lock compartment is arranged between the separating wall and the closer spring tension piston; and

a hydraulic solenoid control valve having a valve housing;

a valve chamber integrated into the valve housing including:

a first valve seat bore as a connection to a first pressure line;

a second valve seat bore as a connection to a second line configured as an operating line; and

a free aperture configured as a connection to a third line configured as a tank line;

a solenoid; and

a valve spindle moved by said solenoid and partially arranged in the valve chamber, the valve spindle comprises, within the valve chamber, a first sealing surface facing the first valve seat bore and a second sealing surface facing the second valve seat bore, such that the first valve seat bore or the second valve seat bore can be selectively closed,

wherein the valve spindle extends from the valve chamber through the second valve seat bore toward the solenoid, and

when the second valve seat bore is closed, the valve spindle is pulled into the second valve seat bore by a differential-area-ratio by a pressure in the operating line,

wherein the valve adapter is formed in the door closer.