Gas guiding mechanism in a piston type compressor

A piston type compressor comprising:

• a housing including a cylinder block;
• a gas suction chamber formed in said housing, for receiving uncompressed gas;
• a rotatable drive shaft mounted in said housing to extend into said cylinder block, said cylinder block having a plurality of axial cylinder bores formed around said drive shaft;
• a plurality of pistons respectively disposed in said cylinder bores, each of said pistons defining a compression chamber in the associated cylinder bore and being capable of reciprocating between a top dead center position where a volume of the associated compression chamber is at a minimum and a bottom dead center position where said volume of the associated compression chamber is at a maximum;
• a piston driving mechanism for causing said pistons to reciprocate in cooperation with said drive shaft;
• a discharge chamber formed in said housing, for receiving compressed gas contained in said compression chambers outside the compressor;
• a valve receiving chamber formed around said drive shaft in said cylinder block and having an inner wall surrounding said drive shaft;
• a rotary valve fittingly received in said valve receiving chamber and having an outer surface urged contacting relationship with said inner wall of said valve receiving chamber, said rotary valve being supported on said drive shaft to rotate in synchronism with the rotation of said drive shaft, said rotary valve having a suction passage formed therein for providing gases contained in said gas suction chamber to a compression chamber during said chamber's gas suction stroke;
• a plurality of communication passages formed in said cylinder block in association with said compression chambers, for providing gas communication between said compression chambers and said valve suction passage;
• each of said communication passages having a first port open to the interior of one of said cylinder bores and a second port open to an interior of said valve receiving chamber and communicable with said valve suction passage, said first port being located at a position (P2) apart by a predetermined distance (L) from a top dead center position (P1) of one of said pistons, wherein before said piston reaches said top dead center position, said first port is closed by an outer surface of said piston;
• and
• said rotary valve having a bypass passage formed therein for permitting one communication passage, isolated from both said compression chambers and said gas suction chamber by said outer surface of the associated piston and said outer surface of said rotary valve, to communicate with another communication passage corresponding to a compression chamber in a compression stroke.