Displacement machine according to the spiral principle, method to regulate pressure in the counter-pressure chamber by using a pressure difference and characteristic curve

A method for operating a displacement machine, the method comprising:

• a) ascertaining a pressure value PD in a high-pressure chamber of the displacement machine or in a high-pressure section of a system in which the displacement machine has been installed,
• b) forwarding the ascertained pressure value PD to a computing unit,
• c) determining a differential pressure value Δ PBP between a counter-pressure PBP prevailing in a counter-pressure chamber and a low-pressure PS prevailing in a low-pressure chamber by way of a characteristic line and/or a characteristic field with the aid of the pressure value PD, wherein the characteristic line and/or the characteristic field is stored in the computing unit, wherein the counter-pressure chamber is formed between the low-pressure chamber and an orbiting displacement spiral such that chambers are formed between the displacement spiral and a counter-spiral for receiving a working medium, and wherein a pressure regulating device fluidically connected to the counter-pressure chamber sets a pressure difference between the counter-pressure chamber and the low-pressure chamber by means of a set value specified by the computing unit, and
• d) controlling the pressure regulating device by means of a control current applied to a magnetic coil and autonomously adjusting the differential pressure value Δ PBP by means of an electrically controllable regulating valve, wherein the pressure regulating device comprises the electrically controllable regulating valve and a throttle, wherein the electrically controllable regulating valve includes a movable valve needle which can be electrically activated.