Internal gear machine with variable capacity

A fluidic machine comprising:

• a fixed body (1,2;101,102);
• an external orbital member (7;107) installed in said fixed body (1;101), supported and guided by said fixed body for rotation around a first rotational axis, said external orbital member (7;107) having internal gear teeth comprising a first teeth number;
• a transmission member (3;103) installed in said fixed body (2;102), supported and guided by said fixed body for rotation around a second rotational axis not coincident with said first rotational axis;
• an internal orbital member (5;105) supported by said transmission member (3;103) and solid in rotation therewith, said internal orbital member (5;105) having external gear teeth comprising a second teeth number different from said first teeth number, and said internal orbital member (5;105) extending within said external orbital member (7;107) and having its own external gear teeth meshing, with relative (namely, only partial) fluid seal, with the internal gear teeth of the external orbital member (7;107), thus determining among the gear teeth of the two orbital members spaces whose volume is variable during the rotation;
• said fixed body (1;102) having two chambers (22,23;122,123), connected with a low pressure connection (20;120) and to a high pressure connection (21;121), respectively;
• and one of said internal and external orbital members being so shaped as to act as a distributor among said variable volume spaces and said chambers of the fixed body;
• characterized in that one of said internal and external orbital members (5,7;105,107) is mounted axially displaceable, with relative fluid seal, in a component part (3,1;103,101) by which it is supported;
• that the machine comprises a push member (6;106) acting against said axially displaceable orbital member (5,7;
• 105,107) for pushing the same in the direction producing a more extended engagement with the other orbital member (7,5;107,105);
• and that the machine comprises a piston (8;108), which is mounted displaceable, with relative fluid seal, within the non-axially displaceable orbital member (7,5;107,105), rests against said axially displaceable orbital member (5,7;105,107), and is subjected, on the side opposite the axially displaceable orbital member, to the pressure of the high pressure connection (21;121);
• whereby said axially displaceable orbital member is pushed by the pressure of the high pressure connection (21;121) to withdraw, against the action of said push member, within the part supporting the same, this latter along with said piston delimiting the operatively active portion of the two mutually meshing orbital members (5,7;
• 105,107), namely, the swept volume of the fluidic machine,
• characterized in that the external orbital member (7;107) is mounted in a fixed axial position, and the internal orbital member (5;105) is mounted axially displaceable, with relative fluid seal, within the transmission member (3;103), this latter having an internal outline corresponding to the external outline of the internal orbital member (5;105), which penetrates in part therein with relative fluid seal, and
• characterized in that the internal orbital member is mounted in a fixed axial position, and the external orbital member is mounted axially displaceable, with relative fluid seal, within said machine body.