Generally, a compressor is a device for changing a mechanical energy into a compressive energy of compressible fluid. And a refrigerating compressor can be classified into a reciprocating compressor, a scroll compressor, a centrifugal type compressor, and a rotary compressor.
Among those compressors, a compressor which reciprocates in a compression space, in which a volume is formed eccentrically, and divides the compression space into a suction area and a compression area will be described as follows.
FIG. 1 is a longitudinal cross-sectional view showing an example of the compressor according to the conventional art, and FIG. 2 is a cut perspective view showing a compression unit of the compressor in FIG. 1.
The compressor shown in FIGS. 1 and 2 was developed and applied to Korean Intellectual Property Office (application No. 10-1999-0042381, date Oct. 1, 1999) by the present applicant, and registered on Korean Intellectual Property Office at Nov. 14, 2001 (registration No. 10-0315954).
As shown in FIGS. 1 and 2, the compressor according to the conventional art can be classified as the rotary compressor, and comprises: a sealed chamber 10 to which a suction pipe 1 and a discharge pipe 2 are connected; a motor unit 12 disposed in the sealed chamber 10 to generate rotary force; and a compression unit 14 disposed in the sealed chamber 10 to be apart a predetermined distance from the motor unit 12 for sucking, compressing and discharging compressible fluid by the rotary force generated in the motor unit 12.
The motor unit 12 comprises: a stator 16 fixedly adhered on an inner circumferential surface of the sealed chamber 10 same as general electric motor, and a rotor 18 disposed to maintain a predetermined air gap from an inner circumferential surface of the stator 16 and rotated by an electromagnetic interaction with the stator 16.
The compression unit 14 comprises: a cylinder assembly 31 disposed in the sealed chamber 10 for forming a compression space (V) in which the sucked compressible fluid is compressed on outer part; a rotary shaft 20 fixed on the cylinder assembly 31 to be rotatable and fixedly adhered to an inner circumferential surface of the rotor to be rotated with the rotor 18 when the rotor 18 is rotated; a cam member 23 rotating with the rotary shaft 20 as coupled to the rotary shaft 20 and dividing the compression space (V) in the cylinder assembly 31 into a first space (V1) and a second space (V2); a first vane 60 and a second vane 70 contacted to upper and lower sides of the cam member 23 for reciprocating toward inner and outer sides of the compression space (V) along with a cam surface of the cam member 23 when the cam member 23 is rotated and dividing the first and second spaces (V1 and V2) into suction areas and compression areas respectively.
The cylinder assembly 31 comprises a cylinder 30, and a first and a second bearing plates 40 and 50 fixed on both sides of the cylinder 30 for forming the compression space (V) with the cylinder 30.
The first and second bearing plates 40 and 50 are formed as discs having predetermined thickness and area, and comprise: journal portions 42 and 52, which are extended and penetrate centers of the discs to have predetermined heights and outer diameters, having the rotary shaft 20 inserted therein to be rotatable, and a first and a second vane slots 44 and 54 formed on one sides of the journal portions 42 and 52 for guiding the reciprocating movements of the first and second vanes 60 and 70.
Herein, the first and second vane slots 44 and 54 are formed as square holes corresponding to sizes of the first and second vanes 60 and 70 from outer circumferences of the first and the second bearing plates 40 and 50 toward center sides.
The rotary shaft 20 is formed to have a certain outer diameter and a predetermined length, and consists of a shaft portion 21 inserted into the first and second bearing plates 40 and 50 and into the journal portions 42 and 52, and a hub portion 22 extendedly formed on one side of the shaft portion 21 to be coupled to the cam member 23 in the cylinder assembly 31.
The cam member 23 is formed as a disc when it is projected on a plane so that the outer circumferential surface thereof is slidably contacted to the inner circumferential surface of the cylinder 30, and is formed as a cam surface of sinuous wave having same thickness from the inner circumferential surface to the outer circumferential surface when a side surface thereof is projected. And the surface making an top dead center (D1) is rotated as sliding on a bottom surface of the first bearing plate 40, and the surface making a bottom dead center (D2) is rotated as sliding on an upper surface of the second bearing plate 50.
The first and second vanes 60 and 70 are formed as square plates, and disposed to be adhered to the sinuous wave of the cam member 23 in the compression space (V) of the cylinder assembly 31.
Also, the first and the second vanes 60 and 70 are elastically supported by an elastic supporting member 90 mounted on the first and second bearing plates 40 and 50, respectively.
Therefore, the first and the second vanes 60 and 70 respectively divide the compression spaces (V1 and V2) into the suction areas and the compression areas as reciprocating up-and-down direction along with the height of the cam surface of the cam member 23, when the cam member 23 is rotated.
Also, a first discharge muffler 46 and a second discharge muffler 56 are fixed respectively on upper side of the first bearing plate 40 and on lower side of the second bearing plate 50, so as to reduce discharge noise of fluid which is discharged after compressed.
Operations of the compressor according to the conventional art constructed as above will be described as follows.
First, when the rotary shaft 20 is rotated by the rotating force of the motor unit 12, the cam member 23 coupled to the rotary shaft 20 in the cylinder assembly 31 is also rotated.
At that time, the first space (V1) located on upper part of the cam member 23 is divided into the suction area and the compression area as making the top dead center (D1) and the first vane 60 boundaries, and the second space (V2) located on the lower part of the cam member 23 is also divided into the suction area and the compression area as making the bottom dead center (D2) and the second vane 70 of the cam member 23 boundaries.
In above status, the cam member 23 is rotated, and thereby the top dead center (D1) and the bottom dead center (D2) of the cam member 23 are moved and the volumes of the suction areas and of the compression areas of the first and second spaces (V1 and V2) are variable.
At that time, the first vane 60 and the second vane 70 reciprocate toward opposite directions of each other for the cam surface height of the cam member 23.
Therefore, when the top dead center (D1) or the bottom dead center (D2) of the cam member 23 reaches to a discharge starting point after the compressible fluid is sucked into the respective suction areas of the first and second spaces (V1 and V2) simultaneously through the suction passage 1 and gradually compressed, at the same time, the compressed fluid is discharged out of the cylinder assembly 31 through discharge passages (not shown) of the respective compression spaces (V1 and V2).
In addition, the fluid discharged as above passes through the respective discharge mufflers 46 and 56 and the sealed chamber 10, and exhausted out of the compressor through the discharge pipe 2.
On the other hand, another examples of the conventional compressor will be described with reference to FIGS. 3 and 4 as follows. FIG. 3 is a longitudinal cross-sectional view showing another example of the conventional compressor, and FIG. 4 is a cross-sectional view in line IV-IV direction of FIG. 3.
As shown in FIGS. 3 and 4, the compressor according to the conventional art comprises: a sealed case 110 connected to a suction pipe 101 and to a discharge pipe 102, and making an outer case of the compressor; a motor unit 112 comprising a stator 116 fixedly adhered to an inner circumferential surface of the sealed chamber 110 and a rotor 118 installed inside the stator 116; and a compression unit 114 for sucking, compressing and discharging compressible fluid by being transmitted the rotating force of the motor unit 112.
The compression unit 114 comprises: a cylinder assembly 131 disposed in the sealed chamber 110 for forming a compression space (V) in which the compressible fluid which is sucked from outer side is compressed; a rotary shaft 120 comprising a shaft portion 121 press-fitted into the inner circumferential surface of the rotor 118 and an eccentric portion 122 formed to be eccentric for the shaft portion 121 in the compression space (V), coupled to the cylinder assembly 131 to be rotatable and rotated with the rotor 118; a cam member 123 connected to an outer circumferential surface of the eccentric portion 122 of the rotary shaft 120 to be contacted to an inner diameter of the cylinder assembly 131 for rotating and revolving centering around the rotary shaft 120; and a vane 160 reciprocating along with a cam surface of the cam member 123 for dividing the compression space (V) into a suction area and a compression area.
The cylinder assembly 131 comprises a cylinder 130 and a first and second bearing plates 140 and 150 fixed on both sides of the cylinder 130 for forming the compression space (V) with the cylinder 130.
A vane slot 144 for guiding the reciprocating movements of the vane 160 is formed as cut in the cylinder 130, and an elastic supporting means 190 for elastically supporting the vane 160 from outer part of the vane slot 144 is disposed.
In addition, a discharge passage 185 through which the compressed fluid is discharged is formed on one side of the inner circumferential surface where the cylinder 130 and the first and second bearing plates 140 and 150 are contacted.
Also, the first and second bearing plates are formed as disc having predetermined thickness and area, and journal portions 142 and 152, to which the rotary shaft 120 is inserted therein to be rotatable, extended and penetrated on center portion to have predetermined height and outer diameter.
Operations of the another example of compressor according to the conventional art will be described as follows.
When electric power is applied to the stator 116 and the rotor 118 is rotated, the rotary shaft 120 which is press-fitted and fixed on the inner circumferential surface of the rotor 118 is rotated so that the cam member 123 coupled to the eccentric portion 122 of the rotary shaft 120 is rotated in the cylinder assembly 131 in a state that the cam member 123 is contacted to the vane 160.
In above status, the cam member 123 is rotated, and thereby volumes of the suction area and the compression area made by the cam member 123 and the vane 160 are variable.
Therefore, the compressible fluid is sucked into the compression space (V) of the cylinder assembly 131 through a suction hole 101, and compressed. In addition, the fluid compressed as above is discharged out of the cylinder assembly 131 through the discharge passage 185, and discharged out of the sealed chamber 110 through the discharge hole 102.
In the compressor constructed and operated as above according to the conventional art, the motor unit and the compression unit are installed on upper and lower parts with a certain distance therebetween, and therefore, size of the compressor is increased in length direction and the cam member is coupled as apart a predetermined distance from the center of the rotor, and therefore, the transmission length of the rotating force which is generated by the rotor is increased.
That is, as the transmission length of the rotating force is increased as described above, loss of power is generated, and efficiency of the compressor for inputted energy into the rotor is lowered.
Also, as the transmission length of the rotating power is increased as above, the moment of inertia is increased, and accordingly, vibration noise of the compressor is also increased.
On the other hand, in order to reduce the moment of inertia on the rotary shaft, the journal portions are formed on the first and second bearing plates for supporting the rotary shaft, however, frictional loss between the outer circumferential surface of the rotary shaft and the inner circumferential surface of the journal portions is increased, and the efficiency of the compressor is also decreased.
Also, the device, in which the compressor is installed, becomes compact and low weight, and production cost is reduced. Accordingly, the size of the compressor is also needed to be reduced under same function. However, the conventional compressor is formed long in the length direction, and therefore, a lot of installation space is required for the compressor.