Multi piston machine with at least three switchable displacement volumes

A multi piston machine comprising:

• a casing having a first working port and a second working port, the casing defining a cam surface having a second number of lobes;
• a rotor located within the casing and configured for rotation about an axis of rotation, the rotor defining a first control surface;
• a plurality of pistons;
• a first control valve;
• and
• a second control valve,
• wherein:
• a first number of pistons of the plurality of pistons are received in the rotor in a linearly movable manner,
• the pistons are configured to contact the cam surface of the casing,
• a number of strokes of a single piston during one revolution of the rotor equals the second number,
• each piston has one associated first control opening at the first control surface of the rotor,
• the first control openings are located along a first circle having a center defined by the axis of rotation,
• a distributor defines a second control surface configured to abut against the first control surface,
• the second control surface has a third number of second control openings located along a second circle having a center defined by the axis of rotation,
• each of the first control openings overlap each of the second control openings in at least one rotational position of the rotor respectively,
• there is a first, a second, a third, and fourth fluid chamber,
• each of the second control openings is permanently connected to a single one of the first to fourth fluid chambers,
• the multi piston machine is switchable between at least three non-zero displacement volumes using the first control valve and the second control valve,
• the first control valve is connected to the first and the third fluid chambers,
• the second control valve is connected to the second and the fourth fluid chambers,
• the first and the second control valves are connected to the first and the second working ports respectively,
• the third number is twice the second number,
• there is a first and a second group of the second control openings,
• adjacent second control openings belong to a different first or second group,
• the second control openings of the first group are either connected to the first or the second fluid chamber,
• the second control openings of the second group are either connected to the third or the fourth fluid chamber,
• the first control valve has a first and a second position,
• in the first position of the first control valve, the first fluid chamber is connected to the first working port, and the third fluid chamber is connected to the second working port,
• in the second position of the first control valve, the first and the third fluid chambers are directly connected to each other, and the connection to the first and the second working ports is blocked,
• the first control valve has a first control port,
• a pressure at the first control port urges the first control valve into the second position of the first control valve,
• in the second position of the first control valve, the first control port is connected to the first and the third fluid chambers, and
• in the first position of the first control valve, the connection of the first control port to the first and the third fluid chambers is blocked.

A multi piston machine comprising:

• a casing having a first working port and a second working port, the casing defining a cam surface having a second number of lobes;
• a rotor located within the casing and configured for rotation about an axis of rotation, the rotor defining a first control surface;
• a plurality of pistons;
• a first control valve;
• and
• a second control valve,
• wherein:
• a first number of pistons of the plurality of pistons are received in the rotor in a linearly movable manner,
• the pistons are configured to contact the cam surface of the casing,
• a number of strokes of a single piston during one revolution of the rotor equals the second number,
• each piston has one associated first control opening at the first control surface of the rotor,
• the first control openings are located along a first circle having a center defined by the axis of rotation,
• a distributor defines a second control surface configured to abut against the first control surface,
• the second control surface has a third number of second control openings located along a second circle having a center defined by the axis of rotation,
• each of the first control openings overlap each of the second control openings in at least one rotational position of the rotor respectively,
• there is a first, a second, a third, and fourth fluid chamber,
• each of the second control openings is permanently connected to a single one of the first to fourth fluid chambers, and each of the first to fourth fluid chambers is permanently connected to at least one of the second control openings,
• the multi piston machine is switchable between at least three non-zero displacement volumes using the first control valve and the second control valve,
• the first control valve is connected to the first and the third fluid chambers,
• the second control valve is connected to the second and the fourth fluid chambers,
• the first and the second control valves are connected to the first and the second working ports respectively,
• the third number is twice the second number,
• there is a first and a second group of the second control openings,
• adjacent second control openings belong to a different first or second group,
• the second control openings of the first group are either connected to the first or the second fluid chamber,
• the second control openings of the second group are either connected to the third or the fourth fluid chamber,
• the first control valve has a first and a second position,
• in the first position of the first control valve, the first fluid chamber is connected to the first working port, and the third fluid chamber is connected to the second working port, and
• in the second position of the first control valve, the first and the third fluid chambers are directly connected to each other, and the connection to the first and the second working ports is blocked.