Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2002-05-23
2003-09-30
Tyler, Cheryl J. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S044100, C417S363000, C310S012060
Reexamination Certificate
active
06626651
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a linear compressor used in an air conditioner and the like for reciprocating a piston in a cylinder by a linear motor to compress gas, and more particularly, to a linear compressor in which a load is not applied, almost at all, to a direction perpendicular to a reciprocating direction of a piston.
(2) Description of the Prior Art
In refrigeration cycle, HCFC refrigerants such as R22 are stable compound and decompose the ozone layer. In recent years, HFC refrigerants begin to be utilized as alternative refrigerants of HCFCs, but these HFC refrigerants have the nature for facilitating the global warming. Therefore, a study is started to employ HC refrigerants which do not decompose the ozone layer or largely affect the global warming. However, since this HC refrigerant is flammable, it is necessary to prevent explosion or ignition so as to ensure the safety. For this purpose, it is required to reduce the amount of refrigerant to be used as small as possible. On the other hand, the HC refrigerant itself does not have lubricity and is easily melted into lubricant. For these reasons, when the HC refrigerant is used, an oilless or oil-poor compressor is required. A linear compressor in which a load applied in a direction perpendicular to an axis of its piston is small and a sliding surface pressure is small is known as a compressor which can easily realize oilless as compared with a reciprocal type compressor, a rotary compressor and a scroll compressor.
However, the linear motor used for the linear compressor has such a loss of end effect that if the piston receives a gas pressure which is being compressed, the axial length center of the moving member is deviated from the axial length center of the stator, and the thrust is lowered. If the displacement amount is further increased, a behavior of the moving member becomes unstable, and it is difficult to stably operate the linear motor.
SUMMARY OF THE INVENTION
Thereupon, it is an object of the present invention to provide an efficient and reliable linear compressor in which an axial length center of the moving member connected to a piston is previously deviated toward a compression chamber with respect to an axial length center of the stator, the axial length center of the moving member and the axial length center of the stator are substantially aligned with each other at the time of operation of the linear compressor.
It is another object of the invention to provide a reliable linear compressor in which a DC bias current is fed to a linear motor, thereby substantially aligning the axial length center of the moving member and the axial length center of the stator of the linear motor with each other at the time of operation of the linear compressor.
According to a first aspect of the present invention, there is provided a linear compressor comprises a cylinder supported in a hermetic vessel by a support mechanism, a piston which is supported concentrically with the cylinder such that the piston can move in an axial direction of the cylinder, and which forms a compression chamber between the cylinder and the piston, a spring mechanism for applying an axial force to the piston, and a linear motor portion having a moving member connected to the piston through a holding member and a stator fixed to the cylinder to form a magnetic path between the stator and the moving member, the linear motor portion generating thrust for moving the piston in its axial direction, wherein the linear compressor further comprises aligning means for aligning an axial length center of the stator and an axial length center of the moving member with each other at the time of operation.
According to a second aspect of the invention, in the linear compressor of the first aspect, the aligning means deviates the axial length center of the moving member toward the compression chamber with respect to the axial length center of the stator in expectation of a length through which the axial length center of the stator is displaced with respect to the axial length center of the moving member at the time of operation, and mounts the moving member thereon.
According to a third aspect of the invention, in the linear compressor of the second aspect, the length to be displaced is determined by a pressure fluctuation of a refrigerant gas in the compression chamber.
According to a fourth aspect of the invention, in the linear compressor of the second aspect, the length to be displaced is determined by a pressure difference between a suction pressure and a discharge pressure.
According to a fifth aspect of the invention, in the linear compressor of the first aspect, the aligning means feeds a DC bias current to the linear motor portion so that the spring mechanism receives a gas pressure to act against a displacing force of the spring mechanism.
According to a sixth aspect of the invention, in the linear compressor of the fifth aspect, the DC bias current is fed in proportion to a pressure difference between the suction pressure and the discharge pressure.
According to a seventh aspect of the invention, in the linear compressor of the fourth or sixth aspect, the suction pressure is defined as a suction pressure of a predetermined cooling condition or heating condition, and the discharge pressure is defined as a discharge pressure of a predetermined cooling condition or heating condition.
According to an eighth aspect of the invention, in the linear compressor of the fourth or sixth aspect, the suction pressure is defined as an average suction pressure between a suction pressure of a predetermined cooling condition and a suction pressure of a predetermined heating condition, and the discharge pressure is defined as an average discharge pressure between a discharge pressure of a predetermined cooling condition and a discharge pressure of a predetermined heating condition.
According to a ninth aspect of the invention, in the linear compressor of the seventh or eighth aspect, the predetermined cooling condition is set to an indoor set temperature of 27° C. and an outdoor temperature of 35° C., and the predetermined heating condition is set to an indoor set temperature of 20° C. and an outdoor temperature of 7° C.
According to a tenth aspect of the invention, there is provided a linear compressor comprises a cylinder supported in a hermetic vessel by a support mechanism, a piston which is supported concentrically with the cylinder such that the piston can move in an axial direction of the cylinder, and which forms a compression chamber between the cylinder and the piston, a spring mechanism for applying an axial force to the piston, and a linear motor portion having a moving member connected to the piston through a holding member and a stator fixed to the cylinder to form a magnetic path between the stator and the moving member, the linear motor portion generating thrust for moving the piston in its axial direction, wherein the linear compressor further comprises a position sensor for detecting a displacement of the axial length center of the moving member caused by a gas pressure.
According to a first aspect of the present invention, since the linear compressor comprises the aligning means which aligns the axial length center of the moving member with the axial length center of the stator during operation, even if the compressed gas force during operation is applied to the piston and the amplitude center of the piston is moved in a direction opposite from the compression chamber, the axial length center of the moving member and the axial length center of the stator are not largely deviated from each other and thus, the linear compressor can be driven efficiently.
According to a second aspect of the invention, in the linear compressor of the first aspect, the aligning means deviates the axial length center of the moving member toward the compression chamber with respect to the axial length center of the stator in expectation of a length through which the axial length center of the stator is disp
Akazawa Teruyuki
Hasegawa Sugimatsu
Kawahara Sadao
Armstrong Westerman & Hattori, LLP
Gray Michael K.
Tyler Cheryl J.
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