Electrical connector assembly

1. An electrical connector assembly, comprising;

a plug with a plug body comprising a contact holder portion;

an annular locking ring movable about a plug-in axis, attached to the plug body, and concentrically surrounding the contact holder portion, wherein an elastic element holds the locking ring in a rest position and wherein the locking ring has a first recess at a first end extending opposite a direction of insertion diagonally to the plug-in axis, wherein it creates a guide surface; and

a mating connector having a plug-receiving portion configured to receive the contact holder portion of the plug, wherein the plug-receiving portion is surrounded by a collar, on the outside of which a projection is provided, which, when mating the plug and the mating connector, engages the guide surface and rotates the locking ring against a spring force of the elastic element about the plug-in axis in a first direction, wherein the locking ring has a second recess at a second end, wherein the projection and the second recess are in a plane perpendicular to the plug-in axis in fully assembled state, wherein the spring force rotates the locking ring against the first direction, so that the projection is received in the second recess and locks the plug body with the plug-receiving portion.

2. The electrical connector assembly according to claim 1 , wherein a clearance is formed between the contact holder portion and the locking ring that completely receives the collar when the plug is inserted into the mating connector.

3. The electrical connector assembly according to claim 1 , wherein a circumference of the contact holder portion facing said locking ring comprises a rib which is configured to engage a groove in the mating connector while the plug is inserted into the mating connector.

4. The electrical connector assembly according to claim 3 , wherein the rib engages the groove before the projection engages the guide surface.

5. The electrical connector assembly according to claim 4 , wherein a plurality of ribs is distributed unevenly about the circumference.

6. The electrical connector assembly according to claim 1 , wherein the first recess and the second recess are provided on the inside of the locking ring.

7. The electrical connector assembly according to claim 1 , wherein the elastic element is formed as torsion spring.

8. The electrical connector assembly according to claim 7 , wherein the torsion spring has a winding that winds about the plug-in axis.

9. The electrical connector assembly according to claim 8 , wherein one end of the torsion spring is connected with the plug body and the second end is connected with the locking ring.

10. The electrical connector assembly according to claim 1 , wherein the plug body has a flat, elongate shape having a first dimension along a housing axis perpendicular to the plug-in axis, is larger than a second dimension in a direction of the plug-in axis.

11. The electrical connector assembly according to claim 1 , wherein the first and second recesses are evenly distributed about a circumference of the locking ring.

12. The electrical connector assembly according to claim 1 , wherein the guide surface extends in a linear direction.

13. The electrical connector assembly according to claim 1 , wherein the guide surface extends in a curved manner.

14. The electrical connector assembly according to claim 1 , wherein an angle at which the guide surface extends opposite to an insertion direction varies along the plug-in axis.