The present invention relates to a linear compressor, and more particularly to an opening and closing system for an oil path of a linear compressor capable of facilitating smooth oil supply during operation of the compressor and smooth lubrication by an oil which remains in the compressor when re-operating the compressor by having the supplied oil partly remained therein when the operation of the compressor is suspended.
Recently, as in home appliances such as a refrigerator and an air-conditioner, etc. high-efficiency and power-saving products have been produced, the study for developing a compressor constituting a refrigerating cycle machine which is installed in a refrigerator or an air-conditioner is also being lively made.
A linear compressor, which is one of the compressors for sucking and compressing low-pressure air and exhausting the compressed air at high pressure, is illustrated in FIG. 1.
As shown therein, the linear compressor includes a hermetic vessel 1 in which a predetermined amount of oil is filled, a frame 10 formed in a predetermined shape and disposed in the hermetic vessel 1, a cylinder 20 inserted into the frame 10, an inner stator assembly 30 coupled with one side portion of the frame 10 for constituting a motor, an outer stator assembly 31 coupled with the inner stator assembly 30 at a predetermined distance, a magnet 32 inserted between the inner and outer stator assemblys 30, 31, and a piston 40 inserted into the cylinder 20 and coupled to a magnet frame 33 to which the magnet 32 is fixedly connected, and reciprocating in accordance with the linear movement of the magnet 32, wherein there is formed a refrigerant oil path F in the piston 40 through which a refrigerant gas is flowed.
Further, a predetermined-shaped cover 50 is engaged to the other side of the frame 10, and at an inner part of the cover 50 a main spring 51 is provided at both sides of the magnet frame 33 coupled to the piston 40 and thus elastically supports the reciprocation of the piston 40.
While, an exhaust cover 60 formed in a cap type is coupled to one side of the cylinder 20 and an exhaust valve assembly 61 is insertedly disposed in an inner portion of the exhaust cover 60, the exhaust valve assembly 61 switching the one side of the cylinder 20, an suction valve 62 which switches according to the suction of the gas is coupled to an end portion of the piston 40, and an oil supplier 70 which supplies oil to components to be slid to each other is disposed at a lower part of the frame 10.
In the operation of the conventional linear compressor, when an electric current is applied to the motor, the magnet 32 linearly reciprocates and the linear movement accordingly travels through the magnet frame 33 to the piston 40 which also accordingly reciprocates in the cylinder 20.
Here, the refrigerant gas which is flowed into the hermetic vessel 1 in accordance with the linear operation of the piston 40 is flowed into the cylinder 20 through the refrigerant oil path F provided in the piston 40, compressed therein and then exhausted through the exhaust valve assembly 61 and the exhaust cover 60, the above process being repeatedly performed.
Further, in order to achieve the smooth sliding performed while the piston 40 is being reciprocating in the cylinder 20 and also to radiate the heat generated during the compression of the refrigerant gas, the oil pumped out by the oil supplier 70 is supplied to components, for example, which are disposed between the cylinder. 20 and the piston 40.
Here, in the oil supply system in which the oil pumped out by the oil supplier 70 circulates, a first oil groove 12 is formed at predetermined size on a portion of an inner circumferential surface of a through hole 11 of the frame 10 to which the cylinder 20 is inserted, a second oil groove 41 is formed at predetermined size on a portion of an outer circumferential surface of the piston 40 inserted into the cylinder 20, and an oil pass hole 21 is provided in the cylinder 20 so that the first oil groove 12 communicates with the second oil groove 41. In addition, a ring-shaped oil circular path 13 is formed by the exhaust cover 60 connected with an outer circumferential portion of the cylinder 20, the through hole 11 and the cylinder 20 when the cylinder 20 is inserted into the through hole 11 of the frame 10, the oil circular path 13 communicating with the first oil groove 12 through an oil communicating path 14 formed on a portion of the inner circumferential surface of the through hole 11.
Further, an oil inflow path 15 is formed at a portion of the frame 10 so that the oil pumped out in the oil supplier 70 is flowed to the first oil groove 12, and an oil discharge hole 17 is formed at a side portion of the oil circular path 13 so as for the oil which has circulated through the oil circular path 13 to be discharged to a bottom part of the hermetic vessel 1.
In the thusly described oil supply system of the convention linear compressor, as shown in FIG. 2, in the operation of the compressor, when the oil is pumped out in the oil supplier 70 due to vibrations generated in the process of which the compressor compresses the refrigerant gas while reciprocating, the pumped oil is flowed into the first oil groove 12 through the oil inflow path 15 and then flowed to the oil pass hole 21 and the second oil groove 41, so that the flowed oil serves as a lubricant between the piston 40 and the cylinder 20 and also refrigerates the heat generated from the motor.
Further, the oil passed through the first and second oil grooves 12, 41 is flowed into the oil circular path 13 through the oil communicating path 14, heated parts of the exhaust cover 60 and the cylinder 20 are refrigerated by the refrigerant gas which is exhausted when the oil flowed to the path 13 circulates through the oil circular path 13, and the oil flowed to the oil circular path 13 drops to the bottom part of the hermetic vessel 1 in which a predetermined amount of oil is filled and such oil continuously circulates by the above-described process.
In addition, numerals 34 and 2 denote a coil assembly and a suction pipe, respectively.
However, when the operation of the compressor is suspended, the oil being supplied is returned to the bottom part of the vessel 1 due to its self weight. Therefore, when the compressor is restarted to operate in such condition, no oil remains in a portion, for example, between the cylinder and the piston where friction occurs, and thus the operation is performed in a non-lubricative state, which results in abrasion of the components in the system as well as friction loss and also becomes a problem of generation of overload in the initial state of the re-operation.
Further, when the pressure of a compression chamber which compresses the gas increases as the piston moves to a top dead center by the driving of the motor, the high-pressure refrigerant gas may leak from a gap between the piston and the cylinder and be flowed into the oil path. In this case, when the high-pressure refrigerant gas is flowed to the oil supplier side, there is produced noises caused by, for example, a cavitation.
Accordingly, an object of the present invention is to provide an opening and closing system for an oil path of a linear compressor that facilitates smooth oil supply during the operation of the compressor and has the oil which has been supplied to the compressor partly remained therein when suspending the operation of the compressor for smooth lubrication when re-operating the compressor. To achieve the above object, there is provided an opening and closing system for an oil path of a linear compressor which includes a hermetic vessel in which oil is filled in a bottom part thereof, a frame disposed in the hermetic vessel and communicating with a first oil groove and a second oil groove, a cylinder inserted into a through hole formed in a predetermined portion of the frame, a piston linearly reciprocating by the driving of a motor by being inserted into the cylinder, the second oil groove being formed on a portion of an outer circumferential surface of the piston, an exhaust cover coupled to one side of the cylinder, an oil supplier disposed at the frame for pumping out oil and communicating with the first oil groove through an oil inflow path, and a switching means provided between the first oil groove and the oil inflow path for opening and closing the oil inflow path.