Reciprocating compressor

1. A reciprocating compressor, comprising:

a cylinder including a cylinder portion and a cylinder head portion on one side of the cylinder portion; and

a piston mechanism reciprocably fitted on an inner peripheral side of the cylinder portion, the piston mechanism including a piston defining an inside of the cylinder portion into a first side chamber and a second side chamber,

wherein a bottomed hole-shaped valve body housing portion is defined at the cylinder head portion, the bottomed hole-shaped valve body housing portion including an opening that is open to a piston side facing the piston in an axial direction of the cylinder portion,

wherein the bottomed hole-shaped valve body housing portion houses a discharge valve assembly,

wherein the discharge valve assembly is inserted into the bottomed hole-shaped valve body housing portion through the opening of the bottomed hole-shaped valve body housing portion,

wherein the discharge valve assembly includes a valve body unit and a holding mechanism,

wherein the holding mechanism is configured to hold the valve body unit in the bottomed hole-shaped valve body housing portion and includes a communication hole configured to establish communication between the bottomed hole-shaped valve body housing portion and the first side chamber,

wherein the piston mechanism includes:

the piston;

a piston rod which is integral with the piston and connected to a driving device;

a piston ring around the piston, the piston ring being configured to be in sliding contact with the cylinder portion;

an intake valve on a communication passage configured to establish communication between the second chamber and the first chamber; and

a fixation member fixing the intake valve to the piston and partially protruding from the piston toward a cylinder head portion side,

wherein the holding mechanism includes a screw portion that fixes the holding mechanism to the cylinder head portion, and a fixation member housing portion that is defined as a polygonal bottomed hole that houses a protruding portion of the fixation member when the piston reaches a top dead center position,

wherein the communication hole extends through the polygonal bottomed hole,

wherein the valve body unit includes a valve body and a spring member, and the spring member is in abutment with a bottom surface portion of the bottomed hole-shaped valve body housing portion, and

wherein the protruding portion of the fixation member faces the communication hole, and a diameter of the protruding portion of the fixation member is larger than a diameter of the communication hole.

2. The reciprocating compressor according to claim 1 , wherein the spring member is configured to bias the valve body toward the holding mechanism.

3. The reciprocating compressor according to claim 2 , wherein:

the valve body is a discharge valve;

the discharge valve is seated on the communication hole when the discharge valve is closed; and

the discharge valve discharges compressed fluid from the first side chamber via the communication hole when the discharge valve opens.

4. The reciprocating compressor according to claim 1 , wherein the cylinder portion and the cylinder head portion are integral with each other.

5. The reciprocating compressor according to claim 1 , wherein:

a bottom portion of the holding mechanism defines a valve seat onto which the valve body is seated when the valve body is closed;

the communication hole is at a center of the bottom portion of the holding mechanism;

the communication hole defines a discharge port by axially penetrating through the bottom portion of the holding mechanism; and

the first side chamber is a compression chamber on the cylinder head portion side in the inside of the cylinder portion.

6. The reciprocating compressor according to claim 5 , wherein the valve body has a recessed portion that faces the protruding portion of the fixation member through the communication hole.