Reciprocating compressor and oxygen concentrator

A reciprocating compressor comprising:

• a motor having a motor shaft;
• a casing accommodating the motor shaft;
• four cylinders provided in perpendicular directions relative to an axial direction of the motor shaft, the four cylinders being a first cylinder, a second cylinder, a third cylinder and a fourth cylinder;
• and
• four pistons, with each piston having
• a piston head part fitted into one of the four cylinders in a reciprocal fashion, and
• a rod part formed integrally with the piston head part, the rod part being rotatably mounted to an eccentric shaft that is fixed to the motor shaft,
• a plurality of exhaust passages each connected to inside of one of the four cylinders;
• a plurality of intake passages each connected to inside of one of the four cylinders,
• two of the exhaust passages respectively connected to the first cylinder and the second cylinder adjacent to each other share a first conduit formed inside the casing parallel to the motor shaft and disposed between the first cylinder and a second cylinder,
• two of the exhaust passages respectively connected to the third cylinder and the fourth cylinder adjacent to each other share another first conduit formed inside the casing parallel to the motor shaft and disposed between the third cylinder and the fourth cylinder,
• two of the intake passage respectively connected to the second cylinder and the third cylinder adjacent to each other share a second conduit formed inside the casing parallel to the motor shaft and disposed between the second cylinder and the third cylinder, and
• two of the intake passages respectively connected to the first cylinder and the fourth cylinder adjacent to each other share another second conduit formed inside the casing parallel to the motor shaft and disposed between the first cylinder and the fourth cylinder.