Element, device and method for compressing a gas

An element for compressing a gas,

• wherein the element comprises a housing enclosing an internal space in which a helical first rotor and a helical second rotor are mounted rotatably and adjacent to a wall of the internal space,
• such that, during a rotation cycle of the first rotor and the second rotor in opposite directions of rotation, a first lobe of the first rotor and a second lobe of the second rotor rotate in contact with each other at a location between the first rotor and the second rotor,
• wherein the housing is provided with an inlet for guiding gas to be compressed toward and into the internal space and an outlet for guiding compressed gas out of and away from the internal space,
• wherein the outlet comprises an axial outlet opening abutting the internal space,
• wherein, viewed in a direction parallel to a first rotational axis of the first rotor and a second rotational axis of the second rotor, the outlet opening is formed by:
• a first distal edge situated entirely within a first angle of rotation around the first rotational axis in which an end surface of the first lobe facing the outlet opening rotates during the rotation cycle toward or within a maximum turning circle of an end surface of the second lobe facing the outlet opening;
• a second distal edge situated entirely within a second angle of rotation around the second rotational axis in which said end surface of the second lobe rotates during the rotation cycle toward or within a maximum turning circle of said end surface of the first lobe;
• a first proximal edge situated entirely within the first angle of rotation at a smaller distance from the first rotational axis than the first distal edge;
• a second proximal edge situated entirely within the second angle of rotation at a smaller distance from the second rotational axis than the second distal edge;
• a tongue-shaped protrusion between the first proximal edge and the second proximal edge, which protrusion is positioned within, firstly, a third angle of rotation around the first rotational axis in which said end surface of the first lobe and said end surface of the second lobe rotate in contact with each other during the rotation cycle and, secondly, a fourth angle of rotation around the second rotational axis in which said end surface of the first lobe and said end surface of the second lobe rotate in contact with each other during the rotation cycle,
• wherein the tongue-shaped protrusion is fastened to a base piece of the housing and extends from the base piece in a direction opposite to a direction in which the first rotor and the second rotor rotate right between the first rotational axis and the second rotational axis during the rotation cycle,
• wherein an edge of the tongue-shaped protrusion is formed by at least a first tongue edge and a second tongue edge which extend from the base piece, wherein the first tongue edge is further from the rotational axis of the first rotor than the second tongue edge and the second tongue edge is further from the rotational axis of the second rotor than the first tongue edge;
• and
• wherein a first tongue edge radius of the first tongue edge relative to the first rotational axis over an entire length of the first tongue edge is smaller than a radius, parallel to the first tongue edge radius, of a first geometric path relative to the first rotational axis, which first geometric path is described by a point of contact, situated furthest from the first rotational axis, between said end surface of the first lobe and said end surface of the second lobe during the rotation cycle.