The pump has a flow outlet opening (16) from which an uncontrollable outlet volume flow emerges, directly connected with an outlet connection (20) by an outlet channel (19) in a pump housing (1). The outlet opening from which controllable outlet volume flow emerges, is connected with an outflow opening (22) by an outflow channel (21). The outflow opening is arranged in a region of a rear wall (12) of a valve disk (13) in a pump chamber rear wall (7), and enclosed by a ring seal (23). The seal is arranged in the chamber rear wall and actively connected with the disk in a rear end position.
