Pump device with deformable pump ring

Pump device for pumping a liquid, comprising

• a hydraulics housing (12, 212) within which a deformable pump ring (14, 214),
• a pump ring support (16, 216) and
• an eccentric (18) are accommodated, said eccentric (18) being driven by a shaft (20), said shaft defining an axial and a radial direction,
• wherein
• the hydraulics housing (12, 212) has
• an annular portion (22, 222),
• a first lateral section (24, 224), and
• a second lateral section (26), the two lateral sections (24, 26, 224) being arranged opposite each other,
• wherein the pump ring (14, 214) is, at least in some portions, mounted between said first and second lateral sections (24, 26, 224) of the hydraulics housing (12, 212) and has two first projections (28, 28a, 28b, 228) which extend in an axial direction of the shaft (20) on a side facing away from the pump ring support (16, 216) which are, in each case, in contact with one of the two lateral sections (24, 26, 224), and
• wherein cavities (60 260) are defined by the annular portion (22,222) and the two lateral sections 24, 26, 224) of the hydraulics housing (12, 212) into which the cavities the first projections (28, 228) are pressed, and said hydraulics housing section (22, 24, 26) and said first projections (28, 228) are configured such that at least one free space (62, 262) remains in the cavities (60, 260) when the first projections (28, 228) are pressed in.