Coupling bushing with smooth-running seal

A coupling bushing, comprising a bushing body and a retainer, wherein the bushing body comprises a connecting section and a coupling section, wherein the retainer is arranged in the coupling section, wherein the coupling section is designed to incorporate a complementary coupling plug, wherein the connecting section is configured to be connected with a tube or an aggregate, wherein a fluid channel of the bushing body fluidically connects the coupling section and the connecting section with each other, wherein a middle axis (M) of the coupling section defines an axial, a radial and a peripheral direction of the coupling section,

• wherein the coupling bushing comprises at least one sealing ring, wherein the coupling bushing has a sealing groove, wherein the sealing ring is arranged in the sealing groove, wherein the sealing groove comprises a groove base and, in an axial direction, an inner groove wall as well as an outer groove wall, wherein, as viewed in a longitudinal section of the coupling bushing, the inner groove wall and/or the outer groove wall has at least one point or each have at least one point, whose complete circulation as viewed in the longitudinal section of the coupling bushing at least sectionally deviates from a-perpendicular to the middle axis (M),
• wherein the bushing body has a head part and a sealing part, wherein the head part and the sealing part are manufactured separately from each other and connected with each other, wherein the head part at least partially comprises the coupling section, wherein the sealing part at least partially comprises the connecting section, wherein the sealing part has the groove base and the inner groove wall, and
• wherein the coupling bushing or the bushing body comprises a decoupling ring for decoupling the head part from the sealing groove, wherein the decoupling ring is manufactured separately from the head part, so that the decoupling ring is not integrally connected with the head part, wherein the decoupling ring forms at least one section of the outer groove wall with at least a portion of an axially inwardly facing rear side.