Liquid filter and filter element

1 . A liquid filter comprising:

a filter housing comprising a housing cup having a drainage opening;

a filter element comprising a filter medium annularly surrounding a longitudinal axis of the filter element, wherein the filter element comprises an extension part provided with a circumferential lock groove, the extension part extending outward from the filter medium axially in relation to the longitudinal axis; and

a lock device comprising at least one lock means movable radially in relation to the longitudinal axis and arranged at the housing cup, wherein the at least one lock means engages the lock groove in a locked state of the lock device and is disengaged from the lock groove in a release state of the lock device,

wherein the filter housing further comprises a closure screw configured to close the drainage opening of the housing cup in a mounted state Ire screw,

wherein the extension part of the filter element comprises a nose and a compensation element movable in relation to the nose, and

wherein the closure screw is coupled to the compensation element in the mounted state.

2 . The liquid filter according to claim 1 , wherein the lock groove comprises a rounded cross section.

3 . The liquid filter according to claim 2 , wherein the rounded cross section is circular segment-shaped.

4 . The liquid filter according to claim 1 , wherein the filter element further comprises a support tube and/or an end disk, and

wherein the extension part and the support tube and/or the end disk are formed together as one piece.

5 . The liquid filter according to claim 1 , wherein the at least one lock means is a ball.

6 . The liquid filter according to claim 1 , further comprising a holder movable between a locked position and a release position,

wherein the at least one lock means is guided in the holder.

7 . The liquid filter according to claim 6 , wherein the holder is pretensioned into the locked position.

8 . The liquid filter according to claim 6 , further comprising a receptacle,

wherein the holder is received in the receptacle.

9 . The liquid filter according to claim 8 , wherein the receptacle is locked at the housing cup.

10 . The liquid filter according to claim 8 , wherein the at least one lock means is supported at the receptacle in the locked state.

11 . The liquid filter according to claim 6 , wherein the lock device comprises a grip piece configured to move the holder, and wherein the grip piece is movable in relation to the holder.

12 . The liquid filter according to claim 11 , wherein the grip piece is pretensioned toward an outer side of the housing cup.

13 . The liquid filter according to claim 11 ,

wherein the lock device is arranged at the drainage opening of the housing cup.

14 . The liquid filter according to claim 13 , wherein the grip piece is supported at the closure screw when the closure screw closes the drainage opening in the mounted state.

15 . The liquid filter according to claim 13 , wherein the extension part comprises a continuous longitudinal opening, and

wherein the closure screw closes the drainage opening of the housing cup and the continuous longitudinal opening in the mounted state.

16 . A liquid filter comprising:

a filter housing comprising a filter head and a housing cup;

a filter element comprising a filter medium annularly surrounding a longitudinal axis of the filter element, wherein the filter element comprises an extension part provided with a lock groove;

a lock device comprising at least one lock means movable radially in relation to the longitudinal axis and arranged at the housing cup, wherein the at least one lock means engages the lock groove in a locked state of the lock device and is disengaged from the lock groove in a release state of the lock device; and

a holder movable between a locked position and a release position, the at least one lock means being guided in the holder,

wherein the lock device comprises a grip piece configured to move the holder, and wherein the grip piece is movable in relation to the holder,

wherein the housing cup comprises a drainage opening, and wherein the lock device is arranged at the drainage opening of the housing cup,

wherein the filter housing further comprises a closure screw configured to close the drainage opening of the housing cup in a mounted state of the closure screw,

wherein the extension part comprises a nose and a compensation element movable in relation to the nose, and

wherein the closure screw is coupled to the compensation element in the mounted state.

17 . The liquid filter according to claim 16 , wherein the closure screw is coupled to the compensation element by a seal element.

18 . A filter element for a liquid filter, the filter element comprising:

a filter medium annularly surrounding a longitudinal axis of the filter element; and

an extension part extending outward from the filter medium axially in relation to the longitudinal axis and provided with a circumferential lock groove, wherein the lock groove comprises a rounded cross section, and wherein the lock groove is configured to:

be engaged by at least one lock device of a housing cup of a filter housing movable radially in relation to the longitudinal axis in a locked state of the at least one lock device; and

be disengaged by the at least one lock device in a release state of the at least one lock device; and

wherein the extension part comprises a nose and a compensation element movable in relation to the nose; and

wherein a closure screw of the filter housing of the liquid filter is coupled to the compensation element in a mounted state of the closure screw.

19 . The filter element according to claim 18 , wherein the rounded cross section is circular segment-shaped.

20 . The filter element according to claim 18 , further comprising a support tube and/or an end disk,

wherein the extension part and the support tube and/or the end disk are formed together as one piece with the extension part extending outward from the support tube and/or the end disk axially in relation to the longitudinal axis.