Patent Description:
In general, a compressor refers to a device that is configured to receive power from a power generator such as a motor or a turbine and compress a working fluid such as air or refrigerant. More specifically, the compressors are widely used in the whole industry or home appliances, such as for a steam compression refrigeration cycle (hereinafter, referred to as "refrigeration cycle").

The compressors may be classified into a reciprocating compressor, a rotary compressor, and a scroll compressor according to a method of compressing the refrigerant.

The reciprocating compressor uses a method in which a compression space is formed between a piston and a cylinder, and the piston linearly reciprocates to compress a fluid. The rotary compressor uses a method of compressing a fluid by a roller that eccentrically rotates inside a cylinder. The scroll compressor uses a method of compressing a fluid by engaging and rotating a pair of spiral scrolls.

Recently, among the reciprocating compressors, the use of linear compressors that uses a linear reciprocating motion without using a crank shaft is gradually increasing. The linear compressor has advantages in that it has less mechanical loss resulting from switching a rotary motion to the linear reciprocating motion and thus can improve the efficiency, and has a relatively simple structure.

The linear compressor is configured such that a cylinder is positioned in a casing forming a sealed space to form a compression chamber, and a piston covering the compression chamber reciprocates in the cylinder. The linear compressor repeats a process in which a fluid in the sealed space is sucked into the compression chamber while the piston is positioned at a bottom dead center (BDC), and the fluid of the compression chamber is compressed and discharged while the piston is positioned at a top dead center (TDC).

A compression unit and a drive unit are installed inside the linear compressor. The compression unit performs a process of compressing and discharging a refrigerant while performing a resonant motion by a resonant spring through a movement generated in the drive unit.

The piston of the linear compressor repeatedly performs a series of processes of sucking the refrigerant into the casing through an intake pipe while reciprocating at high speed inside the cylinder by the resonant spring, and then discharging the refrigerant from a compression space through a forward movement of the piston to move it to a condenser through a discharge pipe.

The linear compressor may be classified into an oil lubricated linear compressor and a gas lubricated linear compressor according to a lubrication method.

The oil lubricated linear compressor is configured to store a predetermined amount of oil in the casing and lubricate between the cylinder and the piston using the oil.

On the other hand, the gas lubricated linear compressor is configured not to store an oil in the casing, induce a part of the refrigerant discharged from the compression space between the cylinder and the piston, and lubricate between the cylinder and the piston by a gas force of the refrigerant.

The oil lubricated linear compressor supplies the oil of a relatively low temperature between the cylinder and the piston and thus can suppress the cylinder and the piston from being overheated by motor heat or compression heat, etc. Hence, the oil lubricated linear compressor suppresses specific volume from increasing as the refrigerant passing through an intake flow path of the piston is sucked into the compression chamber of the cylinder and is heated, and thus can prevent in advance an intake loss from occurring.

<FIG> is a cross-sectional view of an oil feeder according to a related art.

Referring to <FIG>, an oil feeder <NUM> according to a related art includes an oil cylinder <NUM>, an oil piston <NUM> that linearly reciprocates inside the oil cylinder <NUM> in an axial direction or a horizontal direction, first and second elastic members <NUM> and <NUM> supporting the oil piston <NUM>, an intake valve <NUM> coupled to a front end of the oil piston <NUM>, and a discharge valve <NUM> that is coupled to the oil cylinder <NUM> and is disposed at a front end of the intake valve <NUM>.

The oil stored in a bottom surface of a shell according to a vibration of the oil piston <NUM> passes through a first flow path <NUM>, the inside of the oil piston <NUM>, the intake valve <NUM>, the discharge valve <NUM>, and a second flow path <NUM> and is supplied between the piston and the cylinder.

Since the oil feeder <NUM> according to the related art was extended in the axial direction or the horizontal direction, there was a problem in that a length of the linear compressor was increased. <CIT> shows an oil feeder with a free floating piston in a chamber. The device is lacking an accommodation groove and a communication hole to the groove. An elastic member is inside the piston.

An object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of reducing an axial length or a horizontal length of the linear compressor by reducing an axial length of the oil feeder.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of improving the ease of assembly of first ball and the second ball with respect to the oil feeder by inserting the first ball into an oil supply hole and then inserting the second ball into the oil supply hole.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of allowing a first ball to stably move in a vertical direction while stably supporting the first ball.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of allowing a second ball to stably move in a vertical direction while stably supporting the second ball.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of enabling a stable vertical movement of a first ball and a second ball according to vibration of an oil piston.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of reducing a friction between an oil piston and an oil cylinder due to oil stored in a groove between the oil piston and the oil cylinder.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of improving the ease of assembly of an oil piston and an elastic member by assembling a coupling groove exposed to the outside and the elastic member using a fastening member.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of improving structural stability of the oil feeder by preventing an outer portion of an elastic member from moving to an accommodation space.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of reducing interference between an elastic member and a connection area when the elastic member is deformed due to vibration of an oil piston.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of improving the ease of coupling of a fixing member to an oil cylinder while stably fixing an outer portion of an elastic member to the oil cylinder.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of reducing the size of the linear compressor by coupling the oil feeder to a flange portion of a frame.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of improving space efficiency of the linear compressor.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of enabling stable coupling of the oil feeder to a flange portion of a frame.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of improving the ease of assembly of the oil feeder by guiding a coupling position of the oil feeder with respect to a flange portion.

Another object of the present disclosure is to provide an oil feeder and a linear compressor including the same capable of compensating for an assembly tolerance between a flange portion and the oil feeder.

To achieve the above-identified objects, according to an aspect of the present disclosure, there is provided an oil feeder comprising an oil cylinder, which comprises an oil supply hole extending in a first direction and having a first end portion being in connection with an oil inlet of the oil feeder and a second end portion being in connection with an oil outlet of the oil feeder, an accommodation groove spaced apart from the oil supply hole, and a communication hole extending from a portion of the oil supply hole between said first and second end portions and allowing the oil supply hole to be in fluid communication with the accommodation groove; an oil piston accommodated at the accommodation groove and configured to reciprocate in a second direction different from the first direction; a first check valve disposed in the oil supply hole at one side with respect to the communication hole; a second check valve disposed in the oil supply hole at the other side with respect to the communication hole; and an elastic member comprising (i) an outer portion coupled to the accommodation groove and (ii) an inner portion coupled to the oil piston. The first and second check valves are configured in the manner that when one of the first and second check valves is open, the other one of the first and second check valves is closed.

Preferably, the oil supply hole may comprise: a first oil supply hole being in fluid communication with the communication hole; and a second oil supply hole connected to the first oil supply hole and having an inner diameter smaller than an inner diameter of the first oil supply hole, and the first check valve may comprise a first ball disposed between the first and second oil supply holes.

Preferably, the oil supply hole may comprise: a first oil supply hole being in fluid communication with the communication hole; and a third oil supply hole connected to the first oil supply hole and having an inner diameter larger than the inner diameter of the first oil supply hole, and the second check valve may comprise a second ball disposed between the first and third oil supply holes.

According to another aspect of the present disclosure to achieve the above-identified objects, there is provided an oil feeder comprising an oil cylinder comprising an oil supply hole configured to extend in a first direction, an accommodation groove formed concavely at a side, and a communication hole configured to communicate the oil supply hole with the accommodation groove, an oil piston accommodated in the accommodation groove and configured to reciprocate in a second direction perpendicular to the first direction, a first ball accommodated in the oil supply hole and disposed below the communication hole, a second ball accommodated in the oil supply hole and disposed on the communication hole, and an elastic member comprising an outer portion coupled to the accommodation groove and an inner portion coupled to the oil piston.

Hence, the present disclosure can reduce an axial length or a horizontal length of the linear compressor by reducing an axial length of the oil feeder. That is, the linear compressor can be made smaller.

The oil supply hole may comprise a first oil supply hole configured to communicate with the communication hole, a second oil supply hole disposed below the first oil supply hole and having an inner diameter less than an inner diameter of the first oil supply hole, and a third oil supply hole disposed on the first oil supply hole and having an inner diameter greater than the inner diameter of the first oil supply hole.

In this case, a diameter of the first ball may be less than a diameter of the second ball.

Hence, the present disclosure can improve the ease of assembly of the first ball and the second ball with respect to the oil feeder by inserting the first ball into the oil supply hole and then inserting the second ball into the oil supply hole.

The oil supply hole may further comprise a first connection portion configured to connect the first oil supply hole and the second oil supply hole and contact the first ball.

In this case, the first connection portion may have a decreasing inner diameter as it goes downward, and may be formed concavely inward.

Hence, the present disclosure can allow the first ball to stably move in a vertical direction while stably supporting the first ball.

The oil supply hole may further comprise a second connection portion configured to connect the first oil supply hole and the third oil supply hole and contact the second ball.

In this case, the second connection portion may have a decreasing inner diameter as it goes downward, and may be formed concavely inward.

Hence, the present disclosure can allow the second ball to stably move in the vertical direction while stably supporting the second ball.

In an initial state, the first ball and the second ball may entirely overlap the oil piston in the first direction.

Hence, the present disclosure can enable a stable vertical movement of the first ball and the second ball according to vibration of the oil piston.

The oil piston may comprise a groove formed on an outer circumferential surface facing an inner wall of the oil cylinder.

Hence, the present disclosure can reduce a friction between the oil piston and the oil cylinder due to oil stored in a groove between the oil piston and the oil cylinder.

The oil piston may comprise a coupling groove formed on a surface facing the elastic member, and the inner portion of the elastic member and the coupling groove may be penetrated by a fastening member.

Hence, the present disclosure can improve the ease of assembly of the oil piston and the elastic member by assembling a coupling groove exposed to the outside and the elastic member using the fastening member.

The accommodation groove may comprise an accommodation space in which the oil piston is disposed, and a coupling area that is disposed outside the accommodation space and is coupled to the outer portion of the elastic member, and an inner diameter of the coupling area may be greater than an inner diameter of the accommodation space.

Hence, the present disclosure can improve structural stability of the oil feeder by preventing the outer portion of the elastic member from moving to the coupling area.

The accommodation groove may further comprise a connection area configured to connect the accommodation space and the coupling area, and the connection area may be formed concavely inward.

Hence, the present disclosure can reduce interference between the elastic member and the connection area when the elastic member is deformed due to vibration of an oil piston.

The oil feeder may further comprise a fixing member configured to fix the outer portion of the elastic member to the oil cylinder, and the fixing member may be press-fitted and coupled to the accommodation groove.

Hence, the present disclosure can improve the ease of coupling of the fixing member to the oil cylinder while stably fixing the outer portion of the elastic member to the oil cylinder.

To achieve the above-described and other objects, in another aspect of the present disclosure, there is provided a linear compressor comprising a shell, a frame disposed in the shell, the frame comprising a body portion and a flange portion configured to extend radially from a front area of the body portion, a cylinder fixed to the body portion, a piston disposed in the cylinder and configured to reciprocate axially, and an oil feeder coupled to the flange portion and configured to supply an oil stored in a bottom surface of the shell to between the cylinder and the piston.

In this case, the present disclosure can reduce size of the linear compressor by coupling the oil feeder to the flange portion.

The linear compressor may further comprise an inner stator fixed to an outer circumferential surface of the cylinder, an outer stator fixed to a rear surface of the flange portion, and a permanent magnet disposed between the inner stator and the outer stator and connected to the piston.

In this case, the oil feeder may overlap the outer stator in the second direction.

Hence, the present disclosure can improve space efficiency of the linear compressor.

The linear compressor may further comprise a discharge valve coupled to the cylinder and disposed in a front of the piston.

In this case, the oil feeder may overlap the discharge valve in the first direction.

The flange portion may comprise a front portion, a rear portion disposed at a rear of the front portion, and an oil hole disposed between the front portion and the rear portion and configured to communicate with the oil supply hole.

In this case, an upper surface of the oil cylinder may contact an outer end of the front portion, and a rear surface of the oil cylinder may contact a front surface of the rear portion.

The flange portion may comprise a first horizontal portion extending rearward from an outer end of the rear portion, and a vertical portion extending radially outward from a rear end of the first horizontal portion. The rear surface of the oil cylinder may contact a front surface of the vertical portion.

Hence, the present disclosure can enable stable coupling of the oil feeder to the flange portion.

The linear compressor may further comprise a discharge cover coupled to a front end of the cylinder. The oil cylinder may comprise a protrusion configured to protrude upward from an upper surface, and the protrusion may be inserted into a space between the discharge cover and the front portion.

Hence, the present disclosure can improve the ease of assembly of the oil feeder by guiding a coupling position of the oil feeder with respect to the flange portion.

The flange portion may comprise a second horizontal portion configured to extend forward from an inner end of the front portion and contact a rear surface of the discharge cover, and an upper end of the protrusion may be disposed adjacent to the second horizontal portion.

Hence, the present disclosure can compensate for an assembly tolerance between the flange portion and the oil feeder.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of reducing an axial length or a horizontal length of the linear compressor by reducing an axial length of the oil feeder.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of improving the ease of assembly of first ball and the second ball with respect to the oil feeder by inserting the first ball into an oil supply hole and then inserting the second ball into the oil supply hole.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of allowing a first ball to stably move in a vertical direction while stably supporting the first ball.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of allowing a second ball to stably move in a vertical direction while stably supporting the second ball.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of enabling a stable vertical movement of a first ball and a second ball according to vibration of an oil piston.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of reducing a friction between an oil piston and an oil cylinder due to oil stored in a groove between the oil piston and the oil cylinder.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of improving the ease of assembly of an oil piston and an elastic member by assembling a coupling groove exposed to the outside and the elastic member using a fastening member.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of improving structural stability of the oil feeder by preventing an outer portion of an elastic member from moving to an accommodation space.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of reducing interference between an elastic member and a connection area when the elastic member is deformed due to vibration of an oil piston.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of improving the ease of coupling of a fixing member to an oil cylinder while stably fixing an outer portion of an elastic member to the oil cylinder.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of reducing the size of the linear compressor by coupling the oil feeder to a flange portion of a frame.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of improving space efficiency of the linear compressor.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of enabling stable coupling of the oil feeder to a flange portion of a frame.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of improving the ease of assembly of the oil feeder by guiding a coupling position of the oil feeder with respect to a flange portion.

The present disclosure can provide an oil feeder and a linear compressor including the same capable of compensating for an assembly tolerance between a flange portion and the oil feeder.

The accompanying drawings, which are included to provide a further understanding of the present disclosure and constitute a part of the detailed description, illustrate embodiments of the present disclosure and serve to explain technical features of the present disclosure together with the description.

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

It should be understood that when a component is described as being "connected to" or "coupled to" other component, it may be directly connected or coupled to the other component or intervening component(s) may be present.

It will be noted that a detailed description of known arts will be omitted if it is determined that the detailed description of the known arts can obscure embodiments of the present disclosure. The accompanying drawings are used to help easily understand various technical features and it should be understood that embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be understood to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings.

In addition, a term of "disclosure" may be replaced by document, specification, description, etc..

<FIG> is a cross-sectional view of a linear compressor according to an embodiment of the present disclosure.

Hereinafter, a linear compressor according to the present disclosure will be described taking, as an example, a linear compressor <NUM> that sucks and compresses a fluid while a piston linearly reciprocates, and discharges the compressed fluid.

The linear compressor <NUM> may be a component of a refrigeration cycle, and a fluid compressed in the linear compressor <NUM> may be a refrigerant circulating the refrigeration cycle. The refrigeration cycle may include a condenser, an expander, an evaporator, etc., in addition to the compressor. The linear compressor <NUM> may be used as a component of a cooling system of a refrigerator, but is not limited thereto. The linear compressor <NUM> can be widely used in the whole industry.

Referring to <FIG>, the linear compressor <NUM> may include a shell <NUM> and a main body accommodated in the shell <NUM>. The main body of the linear compressor <NUM> may include a frame <NUM>, a cylinder <NUM> fixed to the frame <NUM>, a piston <NUM> that linearly reciprocates inside the cylinder <NUM>, a drive unit <NUM> that is fixed to the frame <NUM> and gives a driving force to the piston <NUM>, and the like. Here, the cylinder <NUM> and the piston <NUM> may be referred to as compression units <NUM> and <NUM>.

The shell <NUM> may include a lower shell and an upper shell coupled to an upper part of the lower shell. The inside of the shell <NUM> may form a closed space. Further, the upper shell and the lower shell may be integrally formed.

The shell <NUM> may be formed of a thermally conductive material. Hence, heat generated in an inner space of the shell <NUM> can be quickly dissipated to the outside.

A leg (not shown) may be coupled to a lower side of the shell <NUM>. The leg may be coupled to a base of a product in which the linear compressor <NUM> is installed. For example, the product may include a refrigerator, and the base may include a machine room base of the refrigerator. As another example, the product may include an outdoor unit of an air conditioner, and the base may include a base of the outdoor unit.

The shell <NUM> may have substantially a cylindrical shape and may be disposed to lie in a horizontal direction or an axial direction. <FIG> illustrates that the shell <NUM> is extended in the horizontal direction and has a slightly low height in a radial direction, by way of example. That is, since the linear compressor <NUM> can have a low height, there is an advantage in that a height of the machine room can decrease when the linear compressor <NUM> is installed in, for example, the machine room base of the refrigerator.

In an embodiment of the present disclosure, it can be understood that the axial direction (or axially) means the horizontal direction based on <FIG>, and the radial direction (or radially) means the vertical direction based on <FIG>. In addition, it can be understood that the front means the left direction based on <FIG>, and the rear means the right direction based on <FIG>.

A longitudinal central axis of the shell <NUM> coincides with a central axis of the linear compressor <NUM> to be described below, and the central axis of the linear compressor <NUM> coincides with a central axis of the cylinder <NUM> and the piston <NUM> of the linear compressor <NUM>.

A terminal (not shown) may be installed on an outer surface of the shell <NUM>. The terminal may transmit external electric power to the drive unit <NUM> of the linear compressor <NUM>. More specifically, the terminal may be connected to a lead line of a coil wound on an outer stator <NUM>.

The linear compressor <NUM> may include a plurality of pipes <NUM> and <NUM> that are included in the shell <NUM> and can suck, discharge, or inject the refrigerant.

The plurality of pipes <NUM> and <NUM> may include an intake pipe <NUM> that allows the refrigerant to be sucked into the linear compressor <NUM>, and a loop pipe <NUM> that allows the compressed refrigerant to be discharged from the linear compressor <NUM>.

For example, the intake pipe <NUM> may be coupled to a rear of the shell <NUM>. The refrigerant may be sucked into the linear compressor <NUM> along the axial direction through the intake pipe <NUM>. The loop pipe <NUM> may be coupled to a front of the shell <NUM>. The refrigerant sucked through the intake pipe <NUM> may be compressed while flowing in the axial direction. The compressed refrigerant may be discharged through the loop pipe <NUM>. The intake pipe <NUM> may be coupled to a rear of the lower shell, and the loop pipe <NUM> may be coupled to a front of the lower shell. The loop pipe <NUM> may be disposed below the intake pipe <NUM>.

The linear compressor <NUM> may include a bearing means for reducing a friction between the cylinder <NUM> and the piston <NUM>. The bearing means may be an oil bearing or a gas bearing. Alternatively, a mechanical bearing may be used as the bearing means.

The main body of the linear compressor <NUM> may be elastically supported by support springs <NUM> and <NUM> installed on a lower inner side of the shell <NUM>. The support springs <NUM> and <NUM> may include a front support spring <NUM> for supporting a front of the main body and a rear support spring <NUM> for supporting a rear of the main body. The support springs <NUM> and <NUM> may include a coil spring. The support springs <NUM> and <NUM> can absorb vibrations and impacts generated by a reciprocating motion of the piston <NUM> while supporting internal components of the main body of the linear compressor <NUM>.

The frame <NUM> may include a body portion <NUM> supporting an outer circumferential surface of the cylinder <NUM>, and a first flange portion <NUM> that is connected to one side of the body portion <NUM> and supports the drive unit <NUM>. The frame <NUM> may be elastically supported with respect to the shell <NUM> by the support springs <NUM> and <NUM> together with the drive unit <NUM> and the cylinder <NUM>.

The body portion <NUM> may wrap the outer circumferential surface of the cylinder <NUM>. The body portion <NUM> may be formed in a cylindrical shape. The first flange portion <NUM> may radially extend from a front end of the body portion <NUM>.

The cylinder <NUM> may be coupled to an inner circumferential surface of the body portion <NUM>. The body portion <NUM> may be penetrated by an inner stator <NUM>. For example, the cylinder <NUM> may be press-fitted and fixed to the inner circumferential surface of the body portion <NUM>, and the inner stator <NUM> may pass through the body portion <NUM> and may be fixed to the outer circumferential surface of the cylinder <NUM>.

An outer stator <NUM> may be coupled to a rear surface of the first flange portion <NUM>, and a discharge cover <NUM> may be coupled to a front surface of the first flange portion <NUM>. For example, the outer stator <NUM> and the discharge cover <NUM> may be fixed through a mechanical coupling means.

In an outer circumferential surface of the first flange portion <NUM>, an oil hole forming a part of the oil bearing may be formed, and a first bearing communication hole penetrating from a bearing inlet groove to the inner circumferential surface of the body portion <NUM> may be formed. The first bearing communication hole may communicate with a second bearing communication hole of the cylinder <NUM>. The first bearing communication hole and the second bearing communication hole may be formed to be inclined toward the inner circumferential surface of the cylinder <NUM>. The second bearing communication hole of the cylinder <NUM> may communicate with an oil groove formed in the inner circumferential surface of the cylinder <NUM>. The oil groove of the cylinder <NUM> may be formed in an annular shape having a predetermined depth and a predetermined axial length in the inner circumferential surface of the cylinder <NUM>.

An oil O stored in a bottom surface of the shell <NUM> through an oil feeder <NUM> may sequentially pass through the oil hole, the first bearing communication hole, the second bearing communication hole, and the oil groove and may be supplied between the inner circumferential surface of the cylinder <NUM> and an outer circumferential surface of the piston <NUM>.

The frame <NUM> and the cylinder <NUM> may be formed of aluminum or an aluminum alloy material.

The cylinder <NUM> may be formed in a cylindrical shape in which both ends are opened. The piston <NUM> may be inserted through a rear end of the cylinder <NUM>. A front end of the cylinder <NUM> may be closed via the discharge cover <NUM>.

A discharge valve <NUM> may be disposed between a front end of the piston <NUM>, the discharge cover <NUM>, and the cylinder <NUM>. A compression space P may be formed between the front end of the piston <NUM>, the discharge valve <NUM>, and the cylinder <NUM>. Here, the front end of the piston <NUM> may be referred to as a head portion. The volume of the compression space P may increase when the piston <NUM> moves backward, and may decrease as the piston <NUM> moves forward. That is, the refrigerant introduced into the compression space P may be compressed while the piston <NUM> moves forward, and may be discharged through the discharge valve <NUM>.

The cylinder <NUM> may include a second flange portion disposed at its front end. The second flange portion may bend to the outside of the cylinder <NUM>. The second flange portion may extend in an outer circumferential direction of the cylinder <NUM>. The second flange portion of the cylinder <NUM> may be coupled to the frame <NUM>.

An oil bearing means may be provided to supply the oil to a gap between the outer circumferential surface of the piston <NUM> and the inner circumferential surface of the cylinder <NUM> and to lubricate between the cylinder <NUM> and the piston <NUM> with the oil. The oil between the cylinder <NUM> and the piston <NUM> may reduce a friction generated between the piston <NUM> and the cylinder <NUM>.

The piston <NUM> is inserted into the opened end at the rear of the cylinder <NUM> and is provided to seal the rear of the compression space P.

The piston <NUM> may include a head portion and a guide portion. The head portion may be formed in a disc shape. The head portion may be partially open. The head portion may partition the compression space P. The guide portion may extend rearward from an outer circumferential surface of the head portion. The guide portion may be formed substantially in a cylindrical shape. The inside of the guide portion may be empty, and a front of the guide portion may be partially sealed by the head portion. A rear of the guide portion may be opened and connected to a muffler unit <NUM>. The head portion may be provided as a separate member coupled to the guide portion. Alternatively, the head portion and the guide portion may be integrally formed as one body.

The piston <NUM> may include an intake port. The intake port may pass through the head portion. The intake port may extend in an axial direction of the piston <NUM>. The intake port may communicate an intake space inside the piston <NUM> with the compression space P. For example, the refrigerant flowing and introduced into the intake space inside the piston <NUM> may pass through the intake port and may be sucked into the compression space P between the piston <NUM> and the cylinder <NUM>.

The plurality of intake ports may be provided along one or more directions of a radial direction and a circumferential direction of the head portion.

The head portion of the piston <NUM> adj acent to the compression space P may be provided with an intake valve <NUM> for selectively opening and closing the intake port. The intake valve <NUM> may operate by elastic deformation to open or close the intake port. That is, the intake valve <NUM> may pass through the intake port and may be elastically deformed to open the intake port by a pressure of the refrigerant flowing into the compression space P.

The piston <NUM> may be connected to a permanent magnet <NUM>. The piston <NUM> may reciprocate forward and backward in response to the movement of the permanent magnet <NUM>. The inner stator <NUM> and the cylinder <NUM> may be disposed between the permanent magnet <NUM> and the piston <NUM>. The permanent magnet <NUM> and the piston <NUM> may be connected to each other by a magnet frame <NUM> formed by detouring the cylinder <NUM> and the inner stator <NUM> to the rear.

The muffler unit <NUM> may be coupled to the rear of the piston <NUM> and can reduce noise generated in the process of introducing the refrigerant into the piston <NUM>. The refrigerant sucked through the intake pipe <NUM> may flow into the intake space <NUM> in the piston <NUM> via the muffler unit <NUM>.

A discharge valve spring <NUM> may be provided at a front side of the discharge valve <NUM> and may elastically support the discharge valve <NUM>. The discharge valve <NUM> may selectively discharge the compressed refrigerant in the compression space P. Here, the compression space P means a space between the intake valve <NUM> and the discharge valve <NUM>.

The discharge valve <NUM> may be disposed to be supportable on the cylinder <NUM>. The discharge valve <NUM> may selectively open and close a front opening of the cylinder <NUM>. The discharge valve <NUM> may operate by elastic deformation to open or close the compression space P. The discharge valve <NUM> may be elastically deformed to open the compression space P by a pressure of the refrigerant that passes through the compression space P and flows into a discharge space.

The discharge valve spring <NUM> may be provided between the discharge valve <NUM> and the discharge cover <NUM> to provide axially an elastic force. The discharge valve spring <NUM> may be provided as a compression coil spring, or may be provided as a leaf spring in consideration of an occupied space or reliability.

When the pressure of the compression space P is equal to or greater than a discharge pressure, the discharge valve spring <NUM> may open the discharge valve <NUM> while deforming forward, and the refrigerant may be discharged from the compression space P and discharged into a discharge space inside the discharge cover <NUM>. When the discharge of the refrigerant is completed, the discharge valve spring <NUM> may provide a restoring force to the discharge valve <NUM> and allow the discharge valve <NUM> to be closed.

A process of introducing the refrigerant into the compression space P through the intake valve <NUM> and discharging the refrigerant of the compression space P into the discharge space through the discharge valve <NUM> is described as follows.

In the process in which the piston <NUM> linearly reciprocates inside the cylinder <NUM>, when the pressure of the compression space P is equal to or less than a predetermined intake pressure, the intake valve <NUM> is opened and thus the refrigerant is sucked into the compression space P. On the other hand, when the pressure of the compression space P exceeds the predetermined intake pressure, the refrigerant of the compression space P is compressed in a state in which the intake valve <NUM> is closed.

When the pressure of the compression space P is equal to or greater than a predetermined discharge pressure, the discharge valve spring <NUM> deforms forward and opens the discharge valve <NUM> connected to the discharge valve spring <NUM>, and the refrigerant is discharged from the compression space P to the discharge space inside the discharge cover <NUM>. When the discharge of the refrigerant is completed, the discharge valve spring <NUM> provides a restoring force to the discharge valve <NUM> and allows the discharge valve <NUM> to be closed, thereby sealing the front of the compression space P.

The discharge cover <NUM> is installed at the front of the compression space P to form a discharge space <NUM> for accommodating the refrigerant discharged from the compression space P, and is coupled to the front of the cylinder <NUM> and/or the frame <NUM> to reduce noise generated in the process of discharging the refrigerant from the compression space P. The discharge cover <NUM> may be coupled to the front end of the cylinder <NUM> while accommodating the discharge valve <NUM>.

An O-ring may be provided between the discharge cover <NUM> and the front end of the cylinder <NUM> to suppress the refrigerant in a gasket for thermal insulation and the discharge space from leaking.

The discharge cover <NUM> may be formed of a thermally conductive material. Therefore, when a high temperature refrigerant is introduced into the discharge cover <NUM>, heat of the refrigerant may be transferred to the shell <NUM> through the discharge cover <NUM> and dissipated to the outside of the linear compressor.

The discharge cover <NUM> may include one discharge cover, or may be arranged so that a plurality of discharge covers sequentially communicates with each other. When the discharge cover <NUM> includes the plurality of discharge covers, the discharge space may include a plurality of spaces partitioned by the respective discharge covers. The plurality of spaces may be disposed in a front-rear direction and may communicate with each other. Hence, as the refrigerant discharged from the compression space P sequentially passes through the plurality of discharge spaces, a discharge noise can be reduced, and the refrigerant can be discharged to the outside of the shell <NUM> through the loop pipe <NUM>.

The drive unit <NUM> may include the outer stator <NUM> that is disposed between the shell <NUM> and the frame <NUM> and surrounds the body portion <NUM> of the frame <NUM>, the inner stator <NUM> that is disposed between the outer stator <NUM> and the cylinder <NUM> and surrounds the cylinder <NUM>, and the permanent magnet <NUM> disposed between the outer stator <NUM> and the inner stator <NUM>. The drive unit <NUM> may be referred to as a `linear motor'.

The outer stator <NUM> may be coupled to the rear of the first flange portion <NUM> of the frame <NUM>, and the inner stator <NUM> may be coupled to the outer circumferential surface of the cylinder <NUM>. The inner stator <NUM> may be spaced apart from the inside of the outer stator <NUM>, and the permanent magnet <NUM> may be disposed in a space between the outer stator <NUM> and the inner stator <NUM>.

The outer stator <NUM> may be provided with a winding coil. The permanent magnet <NUM> may consist of a single magnet with one pole or may be configured by combining a plurality of magnets with three poles.

The outer stator <NUM> may include a coil winding body surrounding the axial direction in the circumferential direction, and a stator core laminated while surrounding the coil winding body. The coil winding body may include a hollow cylindrical bobbin and a coil wound in a circumferential direction of the bobbin. Alternatively, the coil winding body may include a bobbin extending to the inside of the stator core and a coil wound on the bobbin. A cross section of the coil may be formed in a circular or polygonal shape and, for example, may have a hexagonal shape. In the stator core, a plurality of lamination sheets may be laminated radially, or a plurality of lamination blocks may be laminated along the circumferential direction.

The front side of the outer stator <NUM> may be supported by the first flange portion <NUM> of the frame <NUM>, and the rear side of the outer stator <NUM> may be supported by a stator cover <NUM>. For example, a front surface of the stator cover <NUM> may be supported by the outer stator <NUM>, and a rear surface of the stator cover <NUM> may be coupled to a back cover <NUM>.

The inner stator <NUM> may be configured by radially laminating a plurality of laminations on the outer circumferential surface of the cylinder <NUM>.

The permanent magnet <NUM> may be supported as one side of the permanent magnet <NUM> is coupled to the magnet frame <NUM>. The magnet frame <NUM> has substantially a cylindrical shape and may be inserted into a space between the outer stator <NUM> and the inner stator <NUM>. The magnet frame <NUM> may be coupled to the rear side of the piston <NUM> and may move together with the piston <NUM>.

As an example, a rear end of the magnet frame <NUM> may be bent and extended inward radially and may be coupled to the rear of the piston <NUM>.

When a current is applied to the drive unit <NUM>, a magnetic flux may be formed in the winding coil, and an electromagnetic force may occur by an interaction between the magnetic flux formed in the winding coil of the outer stator <NUM> and a magnetic flux formed by the permanent magnet <NUM> to move the permanent magnet <NUM>. At the same time as the axially reciprocating movement of the permanent magnet <NUM>, the piston <NUM> connected to the magnet frame <NUM> may also axially reciprocate integrally with the permanent magnet <NUM>.

The drive unit <NUM> and the compression units <NUM> and <NUM> may be axially supported by a shaft support spring <NUM>. The shaft support spring <NUM> may be a coil spring extending in the axial direction or the horizontal direction. A front end of the shaft support spring <NUM> may support the muffler unit <NUM> that is seated on a stepped portion of the piston <NUM>, and a rear end of the shaft support spring <NUM> may be supported by the back cover <NUM>. The shaft support spring <NUM> may cover an outer diameter of the muffler unit <NUM>.

An operation of the linear compressor <NUM> described above is as follows.

First, when a current is applied to the drive unit <NUM>, a magnetic flux may be formed in the outer stator <NUM> by the current flowing in the coil. The magnetic flux formed in the outer stator <NUM> may generate an electromagnetic force, and the permanent magnet <NUM> may linearly reciprocate by the generated electromagnetic force. The electromagnetic force may be alternately generated in a direction (forward direction) in which the piston <NUM> is directed toward a top dead center (TDC) during a compression stroke, and in a direction (rearward direction) in which the piston <NUM> is directed toward a bottom dead center (BDC) during an intake stroke. That is, the drive unit <NUM> may generate a thrust which is a force for pushing the permanent magnet <NUM> and the piston <NUM> in a moving direction.

The piston <NUM> linearly reciprocating inside the cylinder <NUM> may repeatedly increase or reduce the volume of the compression space P.

When the piston <NUM> moves in a direction (rearward direction) of increasing the volume of the compression space P, a pressure of the compression space P may decrease. Hence, the intake valve <NUM> mounted in front of the piston <NUM> is opened, and the refrigerant remaining in the intake space may be sucked into the compression space P along the intake port. The intake stroke may be performed until the piston <NUM> is positioned in the bottom dead center by maximally increasing the volume of the compression space P.

The piston <NUM> reaching the bottom dead center may perform the compression stroke while switching its motion direction and moving in a direction (forward direction) of reducing the volume of the compression space P. As the pressure of the compression space P increases during the compression stroke, the sucked refrigerant may be compressed. When the pressure of the compression space P reaches a setting pressure, the refrigerant can be discharged into the discharge space as the discharge valve <NUM> is pushed out by the pressure of the compression space P. The compression stroke may continue while the piston <NUM> moves to the top dead center at which the volume of the compression space P is minimized.

As the intake stroke and the compression stroke of the piston <NUM> are repeated, the refrigerant introduced into the linear compressor <NUM> through the intake pipe <NUM> may be introduced into the piston <NUM> via the muffler unit <NUM>, and the refrigerant in the piston <NUM> may be introduced into the compression space P in the cylinder <NUM> during the intake stroke of the piston <NUM>. A flow may be formed in which after the refrigerant of the compression space P is compressed and discharged into the discharge space during the compression stroke of the piston <NUM>, the refrigerant is discharged to the outside of the linear compressor <NUM> via the loop pipe <NUM>.

<FIG> is an enlarged view of a portion 'A' in <FIG>. <FIG> is a perspective view of an oil feeder according to an embodiment of the present disclosure. <FIG> is an exploded perspective view of an oil feeder according to an embodiment of the present disclosure. <FIG> is a cross-sectional view of an oil feeder according to an embodiment of the present disclosure.

Referring to <FIG>, an oil feeder <NUM> according to an embodiment of the present disclosure may include an oil cylinder <NUM>, an oil piston <NUM>, an elastic member <NUM>, a first ball <NUM>, a second ball <NUM>, a fixing member <NUM>, and a fastening member <NUM>, but can be implemented except some of these components and does not exclude additional components.

The oil feeder <NUM> may be coupled to the frame <NUM>. Specifically, the oil feeder <NUM> may be coupled to the first flange portion <NUM> of the frame <NUM>. Through this, the linear compressor <NUM> can be made smaller due to a reduction in an axial length of the oil feeder <NUM>. In this case, the oil feeder <NUM> may be fixed to the first flange portion <NUM> of the frame <NUM> through an adhesive means such as an adhesive. Alternatively, the oil feeder <NUM> may be fixed to the first flange portion <NUM> of the frame <NUM> through a mechanical coupling means such as bolting coupling.

The oil feeder <NUM> may overlap the outer stator <NUM> in the axial direction or the horizontal direction. Through this, the space efficiency of the linear compressor <NUM> can be improved. In this case, the oil feeder <NUM> may not overlap the outer stator <NUM> in the vertical direction. Through this, magnetic interference that may occur when the oil feeder <NUM> is disposed below the outer stator <NUM> can be prevented.

The oil feeder <NUM> may vertically overlap the discharge valve <NUM>. Through this, the space efficiency of the linear compressor <NUM> can be improved.

The first flange portion <NUM> may include a front portion <NUM>, a rear portion <NUM> disposed at the rear of the front portion <NUM>, and an oil hole <NUM> that is disposed between the front portion <NUM> and the rear portion <NUM> and communicates with an oil supply hole <NUM> of the oil feeder <NUM>.

The first flange portion <NUM> may further include a first horizontal portion <NUM> extending rearward from an outer end of the rear portion <NUM>, and a vertical portion <NUM> extending from a rear end of the first horizontal portion <NUM> radially outward (downward direction with reference to <FIG>). The first flange portion <NUM> may further include a second horizontal portion <NUM> that extends forward from an inner end of the front portion <NUM> and contacts a rear surface of the discharge cover <NUM>.

An upper surface of the oil feeder <NUM> may contact an outer end of the front portion <NUM> of the first flange portion <NUM>. A rear surface of the oil feeder <NUM> may contact a front surface of the rear portion <NUM> of the first flange portion <NUM>. Specifically, the rear surface of the oil feeder <NUM> may contact a front surface of the vertical portion <NUM> of the first flange portion <NUM>. Through this, it is possible to enable the stable coupling of the oil feeder <NUM> to the first flange portion <NUM>.

The oil cylinder <NUM> may form a main body of the oil feeder <NUM>. The oil cylinder <NUM> may form an appearance of the oil feeder <NUM>. An oil piston <NUM>, an elastic member <NUM>, a first ball <NUM>, a second ball <NUM>, a fixing member <NUM>, and a fastening member <NUM> may be disposed in the oil cylinder <NUM>.

The oil cylinder <NUM> may be coupled to the frame <NUM>. The oil cylinder <NUM> may be coupled to the first flange portion <NUM> of the frame <NUM>. Through this, the linear compressor <NUM> can be made smaller due to a reduction in an axial length of the oil cylinder <NUM>. In this case, the oil cylinder <NUM> may be fixed to the first flange portion <NUM> of the frame <NUM> through an adhesive means such as an adhesive. Alternatively, the oil cylinder <NUM> may be fixed to the first flange portion <NUM> of the frame <NUM> through a mechanical coupling means such as bolting coupling.

The oil cylinder <NUM> may overlap the outer stator <NUM> in the axial direction or the horizontal direction. Through this, the space efficiency of the linear compressor <NUM> can be improved. In this case, the oil cylinder <NUM> may not overlap the outer stator <NUM> in the vertical direction. Through this, magnetic interference that may occur when the oil cylinder <NUM> is disposed below the outer stator <NUM> can be prevented.

The oil cylinder <NUM> may vertically overlap the discharge valve <NUM>. Through this, the space efficiency of the linear compressor <NUM> can be improved.

An upper surface of the oil cylinder <NUM> may contact the outer end of the front portion <NUM> of the first flange portion <NUM>. A rear surface of the oil cylinder <NUM> may contact the front surface of the rear portion <NUM> of the first flange portion <NUM>. Specifically, the rear surface of the oil cylinder <NUM> may contact the front surface of the vertical portion <NUM> of the first flange portion <NUM>. Through this, it is possible to enable the stable coupling of the oil cylinder <NUM> to the first flange portion <NUM>.

The oil cylinder <NUM> may include a protrusion <NUM> protruding upward from the upper surface. The protrusion <NUM> may be inserted into a space between the discharge cover <NUM> and the front portion <NUM>. Through this, it is possible to improve the ease of assembly of the oil feeder <NUM> by guiding the coupling position of the oil feeder <NUM> with respect to the first flange portion <NUM>.

In this case, an upper end of the protrusion <NUM> may be disposed adjacent to the second horizontal portion <NUM>. The upper end of the protrusion <NUM> may be vertically spaced apart from the second horizontal portion <NUM>. Through this, an assembly tolerance between the first flange portion <NUM> and the oil feeder <NUM> can be compensated.

The oil cylinder <NUM> may include the oil supply hole <NUM>. The oil supply hole <NUM> may extend in a vertical direction (first direction). The first ball <NUM> and the second ball <NUM> may be disposed in the oil supply hole <NUM>. A lower end of the oil supply hole <NUM> may contact the oil O stored in the bottom surface of the shell <NUM>. An upper end of the oil supply hole <NUM> may communicate with the oil hole <NUM> of the first flange portion <NUM>.

The oil supply hole <NUM> may include a first oil supply hole <NUM> communicating with a communication hole <NUM>, a second oil supply hole <NUM> disposed below the first oil supply hole <NUM>, a first connection portion <NUM> connecting the first oil supply hole <NUM> and the second oil supply hole <NUM>, a third oil supply hole <NUM> disposed on the first oil supply hole <NUM>, and a second connection portion <NUM> connecting the first oil supply hole <NUM> and the third oil supply hole <NUM>.

An inner diameter of the second oil supply hole <NUM> may be less than an inner diameter of the first oil supply hole <NUM>. An inner diameter of the first connection portion <NUM> may decrease as it goes downward. Through this, the first ball <NUM> may be seated on the first connection portion <NUM>.

An inner diameter of the third oil supply hole <NUM> may be greater than the inner diameter of the first oil supply hole <NUM>. An inner diameter of the second connection portion <NUM> may decrease as it goes downward. Through this, the second ball <NUM> may be seated on the second connection portion <NUM>.

The oil cylinder <NUM> may include an accommodation groove <NUM>. The accommodation groove <NUM> may be concavely formed at a side surface or a rear surface of the oil cylinder <NUM>. The oil piston <NUM>, the elastic member <NUM>, the fixing member <NUM>, and the fastening member <NUM> may be disposed in the accommodation groove <NUM>.

The accommodation groove <NUM> may include an accommodation space V1 in which the oil piston <NUM> is disposed. The accommodation groove <NUM> may communicate with the oil supply hole <NUM> through the communication hole <NUM>.

The accommodation groove <NUM> may include a coupling area <NUM> that is disposed outside the accommodation space V1 and is coupled to an outer portion of the elastic member <NUM>. An inner diameter of the coupling area <NUM> may be greater than an inner diameter of the accommodation space V1. Hence, the present disclosure can improve the structural stability of the oil feeder <NUM> by preventing the outer portion of the elastic member <NUM> from moving to the accommodation space V1.

The accommodation groove <NUM> may include a connection area <NUM> connecting the accommodation space V1 and the coupling area <NUM>.

The oil cylinder <NUM> may include the communication hole <NUM>. The communication hole <NUM> may communicate the oil supply hole <NUM> with the accommodation groove <NUM>. The communication hole <NUM> may extend horizontally. A horizontal central axis of the communication hole <NUM> may be understood to be the same as an axial central axis of the oil piston <NUM>.

The oil piston <NUM> may be disposed in the oil cylinder <NUM>. The oil piston <NUM> may be accommodated in the accommodation groove <NUM>. The oil piston <NUM> may reciprocate in a horizontal direction or an axial direction (second direction) perpendicular to the vertical direction (first direction). Specifically, an outer circumferential surface of the oil piston <NUM> may slide in the axial direction with respect to an inner circumferential surface of the oil cylinder <NUM>.

In an initial state in which the oil feeder <NUM> does not operate, the oil piston <NUM> may overlap the first ball <NUM> and the second ball <NUM> in the axial direction. Through this, it is possible to enable the stable vertical movement of the first ball <NUM> and the second ball <NUM> according to the vibration of the oil piston <NUM>.

The oil piston <NUM> may include a groove <NUM> formed on an outer circumferential surface facing an inner wall of the oil cylinder <NUM>. The groove <NUM> may be formed in an annular shape formed along the periphery of the central area on the outer circumferential surface of the oil piston <NUM>. Hence, the present disclosure can reduce a friction between the oil piston <NUM> and the oil cylinder <NUM> due to the oil stored in the groove <NUM> between the oil piston <NUM> and the oil cylinder <NUM>.

The oil piston <NUM> may include a coupling groove <NUM> that is concavely formed on a surface or a rear surface facing the elastic member <NUM>. The coupling groove <NUM> may be penetrated by the fastening member <NUM> passing through an inner portion of the elastic member <NUM>. Hence, the present disclosure can improve the ease of assembly of the oil piston <NUM> and the elastic member <NUM> by assembling the coupling groove <NUM> exposed to the outside and the elastic member <NUM> using the fastening member <NUM>.

A rear surface of the oil piston <NUM> may be coupled to the elastic member <NUM>. Specifically, the rear surface of the oil piston <NUM> may be coupled to the inner portion of the elastic member <NUM>. Through this, the oil piston <NUM> can be elastically supported in the horizontal direction by the elastic member <NUM>.

The outer portion of the elastic member <NUM> may be coupled to the accommodation groove <NUM>, and the inner portion of the elastic member <NUM> may be coupled to the oil piston <NUM>. Specifically, the outer portion of the elastic member <NUM> may be fixed to the coupling area <NUM> of the accommodation groove <NUM>, and the inner portion of the elastic member <NUM> may be fixed to the rear surface of the oil piston <NUM>. The elastic member <NUM> may be a leaf spring. Through this, the oil piston <NUM> can be elastically supported in the axial direction with respect to the oil cylinder <NUM>.

The first ball <NUM> may be accommodated in the oil supply hole <NUM>. The first ball <NUM> may be disposed below the communication hole <NUM>. The first ball <NUM> may be seated on the first connection portion <NUM>. A diameter of the first ball <NUM> may be less than the inner diameter of the first oil supply hole <NUM>. The diameter of the first ball <NUM> may be greater than the inner diameter of the second oil supply hole <NUM>.

The second ball <NUM> may be accommodated in the oil supply hole <NUM>. The second ball <NUM> may be disposed on the first ball <NUM>. The second ball <NUM> may be disposed above the communication hole <NUM>. The second ball <NUM> may be seated on the second connection portion <NUM>. A diameter of the second ball <NUM> may be greater than the inner diameter of the first oil supply hole <NUM>. The diameter of the second ball <NUM> may be less than the inner diameter of the third oil supply hole <NUM>. The diameter of the second ball <NUM> may be greater than the diameter of the first ball <NUM>.

Through this, the present disclosure can improve the ease of assembly of the first ball <NUM> and the second ball <NUM> with respect to the oil feeder <NUM> by inserting the first ball <NUM> into the oil supply hole <NUM> and then inserting the second ball <NUM> into the oil supply hole <NUM>.

The fixing member <NUM> may fix the outer portion of the elastic member <NUM> to the oil cylinder <NUM>. The fixing member <NUM> may be formed in an annular ring shape. The fixing member <NUM> may be press-fitted and coupled to an inner circumferential surface of the coupling area <NUM> of the accommodation groove <NUM>. Through this, the present disclosure can improve the ease of coupling of the fixing member <NUM> to the oil cylinder <NUM> while stably fixing the outer portion of the elastic member <NUM> to the oil cylinder <NUM>.

The fastening member <NUM> may couple the inner portion of the elastic member <NUM> to the oil piston <NUM>. A fastening portion <NUM> of the fastening member <NUM> may extend axially, may pass through a central area of the inner portion of the elastic member <NUM>, and may be coupled to the coupling groove <NUM> of the oil piston <NUM>.

A head portion <NUM> of the fastening member <NUM> may extend radially from a rear end of the fastening portion <NUM>. A front end of the head portion <NUM> may be seated on the rear surface of the inner portion of the elastic member <NUM>. The head portion <NUM> of the fastening member <NUM> may include a tool groove <NUM> that is concavely formed from the rear to the front. The tool groove <NUM> allows a tool inserted by a user to rotate the fastening member <NUM>.

Through this, the present disclosure can improve the ease of assembly of the oil piston <NUM> and the elastic member <NUM> by assembling the coupling groove <NUM> exposed to the outside and the elastic member <NUM> by the fastening member <NUM>.

<FIG> and <FIG> illustrate an operation of an oil feeder according to an embodiment of the present disclosure.

With reference to <FIG> and <FIG>, an operation of the oil feeder <NUM> is described.

When the linear compressor <NUM> is operated, the piston <NUM> linearly reciprocates in the cylinder <NUM> to thereby generate vibration in the axial direction in the frame <NUM>. In this case, vibration is transmitted to the oil feeder <NUM> connected to the frame <NUM> in the axial direction, and the oil piston <NUM> vibrates in the axial or horizontal direction relative to the oil cylinder <NUM>.

Referring to <FIG>, the oil piston <NUM> moves rearward in the axial direction with respect to the oil cylinder <NUM>. In this case, the pressure of the accommodation space V1 is reduced, and the first ball <NUM> moves upward. Through this, the oil O stored in the bottom surface of the shell <NUM> passes through a first oil flow path V4 in the second oil supply hole <NUM> and is introduced into a second oil flow path V2 at an upper part of the first oil flow path V4.

Referring to <FIG>, the oil piston <NUM> moves forward in the axial direction with respect to the oil cylinder <NUM>. In this case, the pressure of the accommodation space V1 increases, and thus the first ball <NUM> is seated on the first connection portion <NUM> and the second ball <NUM> moves upward. Through this, the oil introduced into the second oil flow path V2 passes through a third oil flow path V3 and is introduced into the oil hole <NUM>.

The oil feeder <NUM> according to an embodiment of the present disclosure can reduce the size of the linear compressor <NUM> by reducing its axial length.

<FIG> and <FIG> illustrate a modified example of an oil feeder according to an embodiment of the present disclosure.

Referring to <FIG>, the first connection portion <NUM> may be formed concavely inward. Through this, the present disclosure can allow the first ball <NUM> to stably move in the vertical direction while stably supporting the first ball <NUM>.

Further, the second connection portion <NUM> may be formed concavely inward. Through this, the present disclosure can allow the second ball <NUM> to stably move in the vertical direction while stably supporting the second ball <NUM>.

The connection area <NUM> may be formed concavely inward. Through this, when the elastic member <NUM> is deformed due to the vibration of the oil piston <NUM>, interference between the elastic member <NUM> and the connection area <NUM> can be reduced.

Referring to <FIG>, the first connection portion <NUM> may be formed to be convex inward. Through this, the oil O stored in the bottom surface of the shell <NUM> can be smoothly introduced into the second oil flow path V2.

Further, the second connection portion <NUM> may be formed to be convex inward. Through this, the oil introduced into the second oil flow path V2 can be smoothly introduced into the oil hole <NUM>.

Further, the connection area <NUM> may be formed to be convex inward. Through this, when the elastic member <NUM> is deformed due to the vibration of the oil piston <NUM>, the present disclosure can guide a deformed area of the elastic member <NUM> to limit the axial movement of the oil piston <NUM> according to the intention of the designer.

Some embodiments or other embodiments of the present disclosure described above are not exclusive or distinct from each other. Some embodiments or other embodiments of the present disclosure described above can be used together or combined in configuration or function.

For example, configuration "A" described in an embodiment and/or the drawings and configuration "B" described in another embodiment and/or the drawings can be combined with each other. That is, even if the combination between the configurations is not directly described, the combination is possible except in cases where it is described that it is impossible to combine.

Claim 1:
An oil feeder comprising:
an oil cylinder (<NUM>) comprising:
an oil supply hole (<NUM>) extending in a first direction and having a first end portion being in connection with an oil inlet of the oil feeder and a second end portion being in connection with an oil outlet of the oil feeder,
an accommodation groove (<NUM>) spaced apart from the oil supply hole (<NUM>), and
a communication hole (<NUM>) extending from a portion of the oil supply hole (<NUM>) between the first and second end portions and allowing the oil supply hole (<NUM>) to be in fluid communication with the accommodation groove (<NUM>);
an oil piston (<NUM>) accommodated at the accommodation groove (<NUM>) and configured to reciprocate in a second direction different from the first direction;
a first check valve disposed in the oil supply hole (<NUM>) at one side with respect to the communication hole (<NUM>);
a second check valve disposed in the oil supply hole (<NUM>) at the other side with respect to the communication hole (<NUM>), wherein the first and second check valves (<NUM>, <NUM>) are configured in the manner that when one of the first and second check valves (<NUM>, <NUM>) is open, the other one of the first and second check valves (<NUM>), <NUM>) is closed; and
an elastic member (<NUM>) comprising (i) an outer portion coupled to the accommodation groove (<NUM>) and (ii) an inner portion coupled to the oil piston (<NUM>).