Pump device, respiratory device and method for providing a respiratory gas

A respiratory device comprising at least one pump device, comprising:

• at least two pump chambers and, for each pump chamber, a rotor arranged in the pump chamber, the at least one pump chamber having an inlet and an outlet so that a fluid can flow into the pump chamber via the inlet and can flow out of the pump chamber via the outlet, wherein the inlet and the outlet are connected to the pump chamber by a common duct, wherein a separating element is arranged in the duct to separate the inlet from the outlet, wherein the rotor is drivable on an orbital path inside the pump chamber, wherein the rotor and the pump chamber are shaped to match each other so that an approximately sinusoidal profile of the flow of the fluid flowing out of the outlet is effected by movement of the rotor in the pump chamber at a constant speed, wherein the rotors are arranged in the pump chambers, phase-shifted relative to each other by 180° and wherein the two pump chambers have a common outlet at which the approximately sinusoidal flows of respective out-flowing fluids join together to form a cumulative substantially constant total flow.