The present invention relates to a compressor, and more particularly, to a compressor having an improved structure of a valve unit for controlling the suction and discharge of fluid.
There are several kinds of conventional compressors such as a scroll type compressor, a rotary type compressor, a wobble plate type compressor, or a piston reciprocating type compressor according to its driving method. FIG. 1 is a schematic of one example of a reciprocating airtight type compressor among such compressors.
The reciprocating airtight type compressor has a motor 12, a cylinder 14, a piston 15 reciprocating inside cylinder 14, a crank shaft 13 rotated by motor 12 and a connecting rod 16 for connecting piston 15 and crank shaft 13, inside an airtight main body 11. Reference numeral 20 denotes a valve unit.
In the airtight reciprocating compressor structured as above, piston 15 reciprocates inside cylinder 14 by the drive of motor 12 to compress fluid.
A valve unit 20 for controlling the suction and discharge of fluid into and from a compression chamber of the cylinder is mounted between a cylinder block 17 and a cylinder head 25. Referring to FIGS. 1 and 2, valve unit 20 comprises a valve plate 21 in which a suction hole 21d, a groove portion 21c having a predetermined depth on which a valve coupling groove 21b and discharge hole 21a are formed, a discharge valve 22 for opening and closing discharge hole 21a supported by coupling groove 21b of groove portion 21c at its one end, a stop 23 for supporting discharge valve 22 and defining an opening and closing region of discharge valve 22, a supporting plate 24 for preventing the detachment of discharge valve 22 and stop 23 from groove portion 21c, and a suction valve 27 and a gasket 28 disposed between valve plate 21 and cylinder block 17. An annular shoulder 21e for preventing a backward flow of refrigerant gas is formed on an edge of discharge hole 21a. Reference numeral 26 denotes a gasket interposed between valve plate 21 and a cylinder head 25.
The conventional compressor 1 having such a structure operates as follows. At the time of a suction stroke, piston 15 is moved to a bottom dead point so that vacuum is formed in the compression chamber. As a result, a suction valve plate 27a is opened due to the suction force of the vacuum so that the fluid flows into the compression chamber through suction hole 21d. At this time, discharge valve 22 is maintained to 20 block discharge hole 21a.
In this state, an exhaustion stroke in which the fluid is compressed while piston 15 is moved to a top dead center and the compressed fluid is discharged, proceeds. In such a process, suction valve plate 27a blocks suction hole 21d and discharge valve 22 facing discharge hole 21a is opened by the pressure of the compressed fluid so that the fluid is discharged. Then, when piston 15 is moved to the bottom dead point again, discharge valve 22 is closed and suction valve plate 27a is opened. A continuous compression operation is performed by the above reciprocating of piston 15. The conventional compressor has annular shoulder 21e formed on the edge of discharge hole 21a for preventing the discharged fluid (the refrigerant gas) from flowing reversely, as shown in FIGS. 2 and 3. Accordingly, the refrigerant gas is remained as much as the volume corresponding to the thickness (H) of annular shoulder 21e plus valve plate 21.
Accordingly, since new refrigerant gas and the remaining refrigerant gas are mixed and reexpanded at the time of a subsequent suction stroke, there is a problem in that a refrigeration efficiency is lowered.