Reciprocating compressor

Abstract

A reciprocating compressor is disclosed. The reciprocating compressor includes a shell, a driving motor, a crankshaft, a piston, and a bearing protrusion, wherein the bearing protrusion may have at least one oil receiving groove formed in a linear bearing portion extending along a reciprocating direction of the piston in a direction intersecting the reciprocating direction of the piston. Accordingly, a sealing surface using an oil film in the linear bearing portion is reinforced while the refrigerant in a compression chamber is effectively prevented from leaking through a gap between a cylinder and the piston, thereby improving energy efficiency and / or cooling capacity of the compressor.

Description

Reciprocating compressor

[0001] The present invention relates to a reciprocating compressor.

[0002] Compressors can be classified into various types, such as rotary compressors, scroll compressors, and reciprocating compressors, depending on the compression method and the type of refrigerant used. A reciprocating compressor is a method in which a piston reciprocates within a cylinder to compress the refrigerant.

[0003] Reciprocating compressors can be classified into vibrating and connected types depending on the piston driving method. A vibrating reciprocating compressor is a method in which a piston is connected to the actuator of a reciprocating motor and compresses the refrigerant by reciprocating within a cylinder while vibrating. A connected reciprocating compressor is a method in which a piston is connected to the crankshaft of a rotary motor via a connecting rod and compresses the refrigerant by reciprocating within a cylinder. The present invention relates to a connected reciprocating compressor, and hereinafter, a reciprocating compressor may be defined as a connected reciprocating compressor.

[0004] Recently, there has been a trend of reciprocating compressors becoming smaller in size while their compression volume actually increases. Consequently, the overall length of the piston is shortening, while the piston's reciprocating distance is being maintained or increasing. This can lead to a shortened or insufficient piston sealing length, causing refrigerant in the compression chamber to leak between the outer surface of the piston and the inner surface of the cylinder, which may degrade compressor performance.

[0005] The objective of the present invention is to provide a reciprocating compressor capable of suppressing refrigerant leakage in the compression chamber while shortening the overall length of the piston.

[0006] Another objective of the present invention is to provide a reciprocating compressor capable of suppressing refrigerant leakage in the compression chamber by ensuring that oil is smoothly supplied between the inner surface of the cylinder and the outer surface of the piston.

[0007] Another objective of the present invention is to provide a reciprocating compressor that allows oil to be smoothly supplied between the inner surface of the cylinder and the outer surface of the piston while suppressing wear between the inner surface of the cylinder and the outer surface of the piston.

[0008] To achieve the objective of the present invention, a reciprocating compressor comprising a shell, a drive motor, a crankshaft, a piston, and a bearing protrusion may be provided. The drive motor may be provided within the internal space of the shell. The crankshaft may be coupled to the rotor of the drive motor. The piston may be coupled to the crankshaft and reciprocate within a cylinder to form a compression chamber. The bearing protrusion may be provided on the outer circumference of the piston to form a bearing surface together with the inner circumference of the cylinder, and may include a linear bearing portion extending along the reciprocating direction of the piston. At least one oil receiving groove may be formed in the linear bearing portion in a direction intersecting the reciprocating direction of the piston. Through this, the sealing surface using an oil film in the linear bearing portion is reinforced, effectively suppressing the leakage of refrigerant in the compression chamber through the gap between the cylinder and the piston, thereby improving the energy efficiency and / or cooling power of the compressor.

[0009] For example, the oil receiving groove may be formed at a position overlapping with the inner surface of the cylinder at the bottom dead center of the piston. This prevents the oil receiving groove from being exposed to the outside of the inner surface of the cylinder during the intake stroke of the piston, thereby maintaining stable movement of the piston.

[0010] For example, the width of the oil receiving groove can be formed to be 5 to 90% of the reciprocating length of the linear bearing part. Through this, during the suction stroke of the piston, the corners of the oil receiving groove are supported on the inner circumference of the cylinder, thereby stabilizing the movement of the piston, while simultaneously preventing the oil contained in the oil receiving groove from leaking out of the cylinder, which can be advantageous in terms of energy efficiency and cooling power.

[0011] As another example, the oil receiving grooves may be formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston. The multiple oil receiving grooves may be formed with the same width. This not only facilitates the processing of the multiple oil receiving grooves but also allows for the formation of a uniform oil film thickness in each of the grooves.

[0012] As another example, the oil receiving grooves may be formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston. Among the multiple oil receiving grooves, the width of the oil receiving groove located adjacent to the compression chamber may be formed to be greater than the width of the oil receiving groove located far from the compression chamber. Through this, the sealing surface formed by the oil film in the oil receiving groove located adjacent to the compression chamber is formed to be relatively wider than the sealing surface formed by the oil film in the oil receiving groove located far from the compression chamber, thereby more effectively suppressing refrigerant leakage in the compression chamber.

[0013] As another example, the depth of the oil receiving groove may be formed to be less than or equal to the height of the linear bearing portion. Through this, the oil receiving groove is formed within the range of the linear bearing portion, allowing the oil receiving groove to be easily machined while enhancing the substantial sealing effect.

[0014] Specifically, the depth of the oil receiving groove can be formed to be less than 70% of the height of the linear bearing part. Through this, the oil receiving groove can be easily machined while improving the oil retention capacity relative to the amount of oil supplied and increasing the actual sealing effect, thereby improving energy efficiency and / or cooling power.

[0015] Specifically, the oil receiving grooves may be formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston. The multiple oil receiving grooves may be formed with the same depth. This facilitates the machining of the multiple oil receiving grooves and allows for the uniform formation of a sealing surface formed by an oil film in each oil receiving groove.

[0016] Specifically, the oil receiving grooves may be formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston. Among the multiple oil receiving grooves, the depth of the oil receiving groove located adjacent to the compression chamber may be formed to be smaller than the depth of the oil receiving groove located far from the compression chamber. Through this, the sealing force by the oil film in the oil receiving groove located adjacent to the compression chamber is formed to be high, thereby more effectively suppressing refrigerant leakage in the compression chamber, while oil scattered to the upper half of the piston through the oil receiving groove located far from the compression chamber can rapidly move to the lower half of the piston, thereby enhancing the lubrication effect between the cylinder and the piston.

[0017] As another example, the oil receiving groove may be formed longitudinally between the circumferential ends of the linear bearing portion. Through this, oil splashing toward the upper half of the piston can smoothly move toward the lower half of the piston through the oil receiving groove, thereby effectively lubricating the entire bearing surface between the cylinder and the piston.

[0018] For example, the oil receiving groove can be formed with the same cross-sectional area between the circumferential ends of the linear bearing part. This not only facilitates the machining of the oil receiving groove but also ensures a nearly uniform oil film thickness in the oil receiving groove.

[0019] Alternatively, the oil receiving groove may be formed with different cross-sectional shapes between the circumferential ends of the linear bearing portion. This improves the oil retention capacity within the oil receiving groove, which can be advantageous for securing the oil film thickness during initial startup and / or low-speed operation.

[0020] As another example, at least a portion of both inner surfaces of the oil receiving groove may be formed as inclined or curved surfaces in the reciprocating direction of the piston. Through this, the inner angle at the corner between the two inner surfaces of the oil receiving groove forms an obtuse angle, thereby effectively suppressing wear between the two corners of the oil receiving groove and the inner surface of the cylinder during the reciprocating motion of the piston.

[0021] For example, the oil receiving groove may be formed with an inclined or curved shape so that the first side wall and the second side wall, which form the inner surfaces on both sides in the reciprocating direction of the piston, are connected to each other. Through this, the oil receiving groove can be easily formed while reducing wear between the cylinder and the piston.

[0022] Alternatively, the oil receiving groove may include a first side wall and a second side wall forming both inner surfaces in the reciprocating direction of the piston, and a connecting surface connecting the first side wall and the second side wall. The first side wall and the second side wall may be formed inclined or curved so as to be connected to each side of the connecting surface. Through this, the width of the oil receiving groove can be formed as wide as possible, while ensuring a more uniform oil film thickness in the width direction within the oil receiving groove.

[0023] Alternatively, the oil receiving groove may include a first side wall and a second side wall forming both inner surfaces in the reciprocating direction of the piston, and a connecting surface connecting the first side wall and the second side wall. The first side wall and the second side wall may be formed parallel to each other so as to be orthogonal to each other on both sides of the connecting surface. Through this, not only can the oil receiving groove be easily machined, but the width of the oil receiving groove can also be formed as wide as possible while ensuring a more uniform oil film thickness in the width direction within the oil receiving groove.

[0024] As another example, the oil receiving groove may be formed along a direction perpendicular to the reciprocating direction of the piston. Through this, the oil receiving groove is formed to be located within the inner circumference of the cylinder at the bottom dead center of the piston, while the width of the oil receiving groove is formed wide to enhance the sealing effect.

[0025] As another example, the oil receiving groove may be formed in a direction that intersects obliquely with respect to the reciprocating direction of the piston. Through this, the sealing effect in the linear bearing part is improved, and at the same time, as the length of the oil receiving groove increases, the oil retention amount in the oil receiving groove increases, thereby enhancing the lubrication effect between the cylinder and the piston.

[0026] For example, the oil receiving grooves may be composed of multiple grooves, and the multiple oil receiving grooves may be formed to be spaced apart from each other or intersect each other in the reciprocating direction of the piston. Through this, the sealing surface is formed in multiple stages, thereby more effectively suppressing the leakage of refrigerant from the compression chamber while further enhancing the lubrication effect between the cylinder and the piston, and some oil receiving grooves are exposed to the outside of the cylinder, allowing oil splashed from the crankshaft to be supplied more quickly and smoothly to the oil receiving grooves.

[0027] As another example, the bearing protrusion may further include an annular bearing portion that is connected to one end of the linear bearing portion and extends annularly along the circumferential direction from the outer surface of the piston. The oil receiving groove may be formed on the linear bearing portion outside the annular bearing portion. Through this, while securing the sealing area in the annular bearing portion, an additional sealing surface formed by the oil film in the linear bearing portion is added, thereby enhancing the overall sealing effect.

[0028] The reciprocating compressor according to the present invention comprises a shell, a drive motor, a crankshaft, a piston, and a bearing protrusion, wherein the bearing protrusion may have at least one oil receiving groove formed in a linear bearing portion extending along the reciprocating direction of the piston in a direction intersecting the reciprocating direction of the piston. Through this, the sealing surface using an oil film in the linear bearing portion is reinforced, thereby effectively suppressing the leakage of refrigerant in the compression chamber through the gap between the cylinder and the piston, which can improve the energy efficiency and / or cooling power of the compressor.

[0029] In the reciprocating compressor according to the present invention, an oil receiving groove may be formed at a position where it overlaps with the inner surface of the cylinder at the bottom dead center of the piston. By doing so, the oil receiving groove is prevented from being exposed to the outside of the inner surface of the cylinder during the suction stroke of the piston, thereby maintaining stable movement of the piston.

[0030] In the reciprocating compressor according to the present invention, the depth of the oil receiving groove can be formed to be less than or equal to the height of the linear bearing part. Through this, the oil receiving groove is formed within the range of the linear bearing part, thereby allowing the oil receiving groove to be easily machined while enhancing the substantial sealing effect.

[0031] In the reciprocating compressor according to the present invention, an oil receiving groove may be formed longitudinally between the two circumferential ends of the linear bearing portion. Through this, oil scattered toward the upper half of the piston can smoothly move toward the lower half of the piston through the oil receiving groove, thereby effectively lubricating the entire bearing surface between the cylinder and the piston.

[0032] In the reciprocating compressor according to the present invention, at least a portion of the inner surfaces of both sides of the oil receiving groove may be formed as inclined or curved surfaces in the reciprocating direction of the piston. Through this, the inner angle at the corner between the two inner surfaces of the oil receiving groove forms an obtuse angle, thereby effectively suppressing wear between the two corners of the oil receiving groove and the inner circumferential surface of the cylinder during the reciprocating motion of the piston.

[0033] In the reciprocating compressor according to the present invention, an oil receiving groove can be formed along a direction perpendicular to the reciprocating direction of the piston. Through this, the oil receiving groove is formed to be located within the inner circumference of the cylinder at the bottom dead center of the piston, while the width of the oil receiving groove is formed wide to enhance the sealing effect.

[0034] The reciprocating compressor according to the present invention further comprises an annular bearing portion in which one end of a linear bearing portion is connected to a bearing protrusion and extends annularly along the circumferential direction from the outer surface of a piston, wherein an oil receiving groove may be formed in the linear bearing portion outside the annular bearing portion. Through this, the sealing surface formed by the oil film in the linear bearing portion can be enhanced overall sealing effect while securing a sealing area in the annular bearing portion.

[0035] FIG. 1 is a perspective view showing the interior of a reciprocating compressor according to the present embodiment through the shell.

[0036] FIG. 2 is a cross-sectional view showing the interior of a reciprocating compressor according to FIG. 1.

[0037] FIG. 3 is a perspective view showing a piston in a reciprocating compressor according to the present embodiment.

[0038] Fig. 4 is a plan view of Fig. 3.

[0039] Fig. 5 is a side view of Fig. 3.

[0040] FIG. 6 is a cross-sectional view along "VI-VI" of FIG. 5.

[0041] FIG. 7a is a plan view showing a comparison of the width of the oil receiving groove relative to the length of the linear bearing part in this embodiment.

[0042] Figure 7b is a graph showing the change in energy efficiency and the change in cooling power according to the width of the oil receiving groove in Figure 7a, respectively.

[0043] FIG. 8a is a front view showing a comparison of the depth of the oil receiving groove relative to the height of the linear bearing part in this embodiment.

[0044] FIG. 8b is a graph showing the change in energy efficiency and the change in cooling power according to the depth of the oil receiving groove in FIG. 8a, respectively.

[0045] FIG. 9 is a perspective view showing another embodiment of the oil passage groove of the piston.

[0046] FIGS. 10a and FIGS. 10b are perspective views showing other embodiments of the oil passage groove of the piston.

[0047] FIG. 11 is a perspective view showing another embodiment of the oil passage groove of the piston.

[0048] FIG. 12 is a perspective view showing another embodiment of the oil passage groove of the piston.

[0049] FIG. 13 is a perspective view showing another embodiment of the oil passage groove of the piston.

[0050] FIG. 14 is a side view showing another embodiment of the oil passage groove of the piston.

[0051] FIGS. 15a and FIGS. 15b are side views showing other embodiments of FIG. 14.

[0052] Hereinafter, a reciprocating compressor according to the present invention will be described in detail based on an embodiment illustrated in the attached drawings. In the following description, the side facing the compression chamber will be defined as the front and the opposite side as the rear, respectively, with respect to the piston.

[0053] FIG. 1 is a perspective view showing the interior of a reciprocating compressor according to the present embodiment, and FIG. 2 is a cross-sectional view showing the interior of a reciprocating compressor according to FIG. 1.

[0054] Referring to FIGS. 1 and 2, the reciprocating compressor according to the present embodiment may include a shell (110) forming an exterior, an electric motor (120) provided in the internal space (110a) of the shell (110) and providing driving force, a compression unit (130) that receives driving force from the electric motor (120) and compresses a refrigerant, an intake / discharge unit (140) that guides the refrigerant to a compression chamber (130a) and discharges the compressed refrigerant, and a damping unit (150) that cushions the impact generated when there is a collision between the shell (110) and the compressor body.

[0055] The shell (110) may include a lower shell (111) and an upper shell (112). The lower shell (111) and the upper shell (112) may be combined to form a sealed internal space (110a). The internal space (110a) of the shell (110) may accommodate a driving unit (120) and a compression unit (130). The shell (110) may be made of a lightweight aluminum alloy with a high thermal conductivity (hereinafter abbreviated as aluminum).

[0056] The lower shell (111) can be formed in a roughly hemispherical shape. A suction pipe (115), a discharge pipe (116), and a process pipe (117) can each be connected to the lower shell (111) by penetrating through it. These suction pipe (115), discharge pipe (116), and process pipe (117) can each be connected to the lower shell (111) by an insert die-casting method.

[0057] The upper shell (112) can be formed in a roughly hemispherical shape, similar to the lower shell (111). The upper shell (112) can be coupled to the lower shell (111) on the upper side of the lower shell (111) to form the internal space (110a) of the shell (110) described above.

[0058] Referring to FIGS. 1 and 2, the electric motor (or drive motor) (120) according to the present embodiment may include a stator (121) and a rotor (122). The stator (121) is elastically supported against the internal space (110a) of the shell (110), i.e., the bottom surface of the lower shell (111), and the rotor (122) may be rotatably installed inside the stator (121).

[0059] The stator (121) may include a stator core (1211) and a stator coil (1212).

[0060] The stator core (1211) is made of a metal material such as electrical steel, and when voltage is applied from the outside to the motor unit (120), it performs electromagnetic interaction through electromagnetic force together with the stator coil (1212) and rotor (122) to be described later.

[0061] The stator core (1211) is formed in a roughly rectangular shape. For example, the inner surface of the stator core (1211) may be formed in a circular shape, and the outer surface may be formed in a rectangular shape. The stator core (1211) may be fixed to the lower surface of the cylinder block (131) described later by a stator fastening bolt (not shown).

[0062] The stator core (1211) can be elastically supported by a support spring (123) on the bottom surface of the shell (110) while being spaced axially and radially apart from the inner surface of the shell (110). Accordingly, vibrations generated during operation can be suppressed from being directly transmitted to the shell (110).

[0063] The stator coil (1212) can be wound inside the stator core (1211). As previously described, when voltage is applied from the outside, the stator coil (1212) generates an electromagnetic force and performs electromagnetic interaction with the stator core (1211) and the rotor (122). Through this, the motor unit (120) generates a driving force for the reciprocating motion of the compression unit (130).

[0064] The rotor (122) may include a rotor core (1221) and a magnet (1222).

[0065] The rotor core (1221), like the stator core (1211), is made of a metal material such as electrical steel and can be formed in a roughly cylindrical shape. A crank shaft (125), which will be described later, can be press-fitted and connected to the center of the rotor core (1221).

[0066] The magnet (1222) is made of a permanent magnet and can be inserted and coupled at equal intervals along the circumferential direction of the rotor core (1221). When voltage is applied, the rotor (122) rotates through electromagnetic interaction with the stator core (1211) and the stator coil (1212). Accordingly, the crank shaft (125) rotates together with the rotor (122) and transmits the rotational force of the electric motor (120) to the compression unit (130) through the connecting rod (126).

[0067] Referring to FIGS. 1 and 2, the compression unit (130) according to the present embodiment may include a cylinder block (131) and a piston (132). The cylinder block (131) is elastically supported by a shell (110), and the piston (132) is coupled to a crankshaft (125) by a connecting rod (126) and moves relative to the cylinder block (131).

[0068] The cylinder block (131) may be provided on one axial side of the electric motor (120), for example, on the upper side. The cylinder block (131) may be connected to the stator (121) by a stator-fastening bolt (not shown) and elastically supported on the lower shell (111) together with the stator (121) of the electric motor (120).

[0069] A cylinder (1311) may be formed radially eccentrically at one edge of the cylinder block (131). The cylinder (1311) is radially penetrated, and a piston (132) connected to a connecting rod (126) is inserted into the inner opening, and a suction / discharge part (140) may be mounted at the outer opening.

[0070] The piston (132) is formed in a cylindrical shape, but the side facing the connecting rod (126) (rear side) is open, while the opposite side facing away from the connecting rod (126) (front side) is formed in a closed shape. Accordingly, the connecting rod (126) is inserted into the rear side of the piston (132) and rotatably coupled, and the front side of the piston (132) forms a compression chamber (130a) inside the cylinder (1311).

[0071] Additionally, a bearing protrusion (1322) that slides in contact with the inner surface (1311a) of the cylinder (1311) may be formed on the outer surface of the piston (132). The bearing protrusion (1322) may include an annular bearing portion (1325) and a linear bearing portion (1326). The annular bearing portion (1325) may extend annularly along the circumferential direction on the outer surface of the piston (132), and the linear bearing portion (1326) may extend long along the reciprocating direction of the piston (132) on the outer surface of the piston (132).

[0072] The annular bearing portion (1325) is formed annularly at the front end of the piston (132) and can be formed to have a sealing length (L2) equal to a predetermined width in the reciprocating direction of the piston (132). For example, the sealing length (L2) of the annular bearing portion (1325) can be formed to be approximately half the total length (L1) of the piston (132). Accordingly, while the total length (L1) of the piston (132) is shortened, the bearing area of ​​the bearing protrusion (1322) is secured widely, thereby effectively suppressing refrigerant leakage between the cylinder (1311) and the piston (132) due to the increase in compression volume.

[0073] The linear bearing portion (1326) can be formed lengthwise along the reciprocating direction of the piston (132) between the upper and lower portions of the piston (132). In other words, the linear bearing portion (1326) can be extended lengthwise along the reciprocating direction of the piston (132) from the rear end of the annular bearing portion (1325) to the rear end of the piston (132). Accordingly, the linearity of the piston (132) can be maintained during the reciprocating motion of the piston (132) by the linear bearing portion (1326).

[0074] In this case, multiple linear bearing portions (1326) may be formed along the circumferential direction on the outer surface of the piston (132) at predetermined intervals. For example, the linear bearing portions (1326) may be formed on both sides in a direction orthogonal to the axial direction of the crankshaft (125). Accordingly, one annular bearing portion (1325) is formed at the front end of the piston (132), and multiple linear bearing portions (1326) are formed at the rear end of the piston (132), so that they make sliding contact with the inner surface (1311a) of the cylinder (1311), thereby maintaining straightness during the reciprocating motion of the piston (132). The linear bearing portions (1326) will be explained again later along with the oil receiving groove (1326b).

[0075] In the drawing, the unexplained symbols are 1251 (oil passage), 1255 (oil feeder), 127 (balance weight), 1321 (connecting receiving groove), and 1323 (friction avoidance groove).

[0076] The reciprocating compressor according to the present embodiment as described above operates as follows.

[0077] That is, when power is applied to the electric motor (120), the rotor (122) rotates. When the rotor (122) rotates, the crankshaft (125) connected to the rotor (122) rotates and transmits rotational force to the piston (132) through the connecting rod (126). The piston (132) reciprocates in the forward and backward directions relative to the cylinder (1311) by means of the connecting rod (126).

[0078] For example, when the piston (132) moves backward (intake stroke) in the cylinder (1311), the volume of the compression chamber (130a) increases, causing the refrigerant to be drawn into the compression chamber (130a), and when the piston (132) moves forward (discharge stroke) in the cylinder (1311), the volume of the compression chamber (130a) decreases, and the refrigerant filled in the compression chamber (130a) is compressed and discharged through the loop pipe (118) and the discharge pipe (116) to the refrigeration cycle, repeating this series of processes.

[0079] At this time, a bearing protrusion (1322) is partially formed on the outer surface of the piston (132) to minimize friction loss between the cylinder (1311) and the piston (132), while also suppressing leakage of the refrigerant in the compression chamber through the gap between the cylinder (1311) and the piston (132).

[0080] However, as previously explained, as the compressor becomes smaller while the compression volume increases, the overall length (L1) of the piston (132) becomes shorter, whereas the reciprocating distance of the piston (132) is maintained or increased. As a result, the sealing length (L2) of the annular bearing portion (1325) forming part of the bearing protrusion (1322) is limited, and the refrigerant in the compression chamber (130a) may leak through the gap between the cylinder (1311) and the piston (132).

[0081] Accordingly, in this embodiment, an oil receiving groove (1326b) is formed on the bearing surface (1326a) of the linear bearing part (1326) to increase the sealing force between the bearing surface (1326a) of the linear bearing part (1326) and the inner circumferential surface (1311a) of the cylinder (1311). By securing the sealing length (L2) of the linear bearing part (1322a), refrigerant leakage in the compression chamber (130a) can be suppressed as much as possible even if the overall length (L1) of the piston (132) is reduced.

[0082] FIG. 3 is a perspective view showing a piston in a reciprocating compressor according to the present embodiment, FIG. 4 is a plan view of FIG. 3, FIG. 5 is a side view of FIG. 3, and FIG. 6 is a cross-sectional view taken along line "VI-VI" of FIG. 5.

[0083] Referring to FIG. 3, the piston (132) according to the present embodiment is formed in a cylindrical shape having a connecting receiving groove (1321) inside, and the side facing the connecting rod (126) (rear side) is open, while the side facing away from the connecting rod (126) (front side) is closed. Accordingly, the connecting rod (126) can be inserted into the rear side of the piston (132) and rotatably coupled to the piston (132) by a piston pin (not shown).

[0084] Additionally, a bearing protrusion (1322) that makes sliding contact with the inner surface (1311a) of the cylinder (1311) may be formed on the outer surface of the piston (132) by protruding to a predetermined height. Accordingly, the portion of the outer surface of the piston (132) excluding the bearing protrusion (1322) may be recessed to a predetermined depth when viewed from the bearing protrusion (1322) to form a friction avoidance groove (1323). Accordingly, only the portion of the outer surface of the piston (132) forming the bearing protrusion (1322) makes sliding contact with the inner surface (1311a) of the cylinder (1311), thereby reducing friction loss between the cylinder (1311) and the piston (132).

[0085] For example, the bearing protrusion (1322) may be composed of an annular bearing portion (1325) extending along the circumferential direction from the outer surface of the piston (132) as described above, and a plurality of linear bearing portions (1326) extending linearly from the annular bearing portion (1325).

[0086] The annular bearing portion (1325) can be formed to have a sealing length (L2) equal to a predetermined width from the front end to the rear end of the piston (132). For example, the sealing length (L2) of the annular bearing portion (1325) can be formed to be approximately half the total length (L1) of the piston (132) by taking into account the compression volume as previously described.

[0087] In this case, the annular bearing portion (1325) may overlap the pin hole (1324) into which the piston pin is inserted and the crankshaft (125) in the axial direction. In other words, the piston pin may be spaced apart from the rear end of the piston (132) by an appropriate distance for reliability, while the piston pin may be formed so that both ends of the pin hole (1324) overlap with the annular bearing portion (1325) while being coupled to the piston (132) at approximately the middle position of the piston (132) in the reciprocating direction of the piston (132). Accordingly, the outer diameter of the piston pin (not shown) inserted into the pin hole (1324) is formed as large as possible so that the reliability of the connection with the connecting rod (126) can be increased even if the compression volume of the compression chamber (130a) increases.

[0088] Although not illustrated in the drawing, the pin hole (1324) may be formed in multiple stages. For example, the inner diameters at both ends of the pin hole (1324) may be formed differently. In other words, at one end of the pin hole (1324), the pin hole (1324) interferes with the annular bearing part (1325), thereby reducing the sealing length (L2) of the annular bearing part (1325), whereas at the other end of the pin hole (1324), the pin hole (1324) is formed outside the annular bearing part (1325), allowing the annular bearing part (1325) to maintain its original sealing length (width of the annular bearing part) (L2). Accordingly, the overall length (L1) of the piston (132) is shortened, and the bearing area of ​​the bearing protrusion (1322) is widened, thereby effectively suppressing refrigerant leakage between the cylinder (1311) and the piston (132) due to the increase in compression volume.

[0089] Meanwhile, as previously described, the linear bearing portion (1326) can be formed along the reciprocating direction of the piston (132) between the upper and lower halves of the piston (132) with respect to the axial direction of the crankshaft (125). In other words, the linear bearing portion (1326) can be extended along the reciprocating direction of the piston (132) from the rear end of the annular bearing portion (1325) to the rear end of the piston (132). Accordingly, when viewed from the side, the linear bearing portion (1326) can form a "T" shaped bearing protrusion (1322) together with the annular bearing portion (1325).

[0090] In this case, as previously described, a plurality of linear bearing sections (1326) are formed at predetermined intervals along the circumferential direction, and the plurality of linear bearing sections (1326) may be formed symmetrically at equal intervals from each other. Accordingly, the center of gravity of the piston (132) coincides with the geometric center of the piston (132), thereby stabilizing the behavior of the piston (132). In this embodiment, the description focuses on an example in which two linear bearing sections (1326) are located in a direction orthogonal to the axial direction of the crankshaft (125) with a phase difference of approximately 180°. However, the number and location of the linear bearing sections (1326) may not be limited to this embodiment.

[0091] Referring to FIGS. 3 to 5, at least one oil receiving groove (1326b) may be formed in the linear bearing portion (1326) according to the present embodiment. For example, at least one oil receiving groove (1326b) that is recessed to a predetermined depth may be formed in the bearing surface (1326a) forming the outer circumference of the linear bearing portion (1326). Accordingly, the arc-shaped sealing surface extending along the circumferential direction is reinforced on the bearing surface (1326a) of the linear bearing portion (1326), thereby more effectively suppressing refrigerant leakage in the compression chamber (130a).

[0092] The oil receiving groove (1326b) is formed on the outside of the linear bearing portion (1326), but can be formed to be located inside the cylinder (1311) at the bottom dead center (P1) of the piston (132). For example, the oil receiving groove (1326b) can be formed at a position that overlaps with the inner surface (1311a) of the cylinder (1311) at the bottom dead center (P1) of the piston (132). Accordingly, during the intake stroke of the piston (132), the oil receiving groove (1326b) is prevented from being exposed to the outside of the cylinder (1311), specifically to the outside of the inner surface (1311a) of the cylinder (1311), thereby maintaining stable movement of the piston (132).

[0093] Referring to FIGS. 4 and 5, the width (W) of the oil receiving groove (1326b) can be formed to be approximately 5 to 90% of the reciprocating length (hereinafter abbreviated as length) (L3) of the linear bearing portion (1326). In other words, the oil receiving groove (1326b) can be formed such that the edge adjacent to the rear end of the piston (132) among the reciprocating side edges of the piston (132) is located inside the inner surface (1311a) of the cylinder (1311) at a certain distance from the edge (1311b) of the inner surface (1311a) of the rear end of the cylinder (1311) at the bottom dead center (P1) of the piston (132), for example, approximately 10% of the length of the linear bearing portion (1326). Accordingly, during the suction stroke of the piston (132), the edge of the oil receiving groove (1326b) is supported by the inner surface (1311a) of the cylinder (1311), thereby stabilizing the movement of the piston (132) and preventing the oil contained in the oil receiving groove (1326b) from leaking out of the cylinder (1311).

[0094] The oil receiving groove (1326b) can be extended in a direction intersecting the reciprocating direction of the piston (132), for example, in a direction perpendicular to the reciprocating direction of the piston (132). Accordingly, the oil receiving groove (1326b) is formed to be located within the inner surface (1311a) of the cylinder (1311) at the bottom dead center (P1) of the piston (132), while the width of the oil receiving groove (1326b) is formed wide to enhance the sealing effect.

[0095] In this case, the two ends of the oil receiving groove (1326b) may be formed to extend between the two circumferential ends of the linear bearing portion (1326), or the upper end of the two circumferential ends of the linear bearing portion (1326) may be open in the axial direction of the crankshaft (125), while the lower end may be closed. In the former case, oil splashed onto the upper half of the piston (132) can move smoothly to the lower half of the piston (132) through the oil receiving groove (1326b), thereby effectively lubricating the entire bearing surface between the cylinder (1311) and the piston (132). In the latter case, a certain amount of oil can be retained in the oil receiving groove (1326b), thereby enhancing the sealing effect during initial startup and / or low-speed operation. In this embodiment, the description focuses on an example in which both ends of the oil receiving groove (1326b) are formed to extend between the circumferential ends of the linear bearing part (1326).

[0096] The oil receiving groove (1326b) can be formed with the same cross-sectional area between both ends along the circumferential direction of the linear bearing portion (1326). For example, the width (W) and depth (D) between both ends in the circumferential direction of the oil receiving groove (1326b) can be formed equally. Accordingly, not only is the processing of the oil receiving groove (1326b) easy, but the oil film thickness in the oil receiving groove (1326b) can also be secured almost uniformly. However, in some cases, the circumferential ends of the oil receiving groove (1326b) may be formed with different cross-sectional areas. This will be explained again later in another embodiment.

[0097] Referring to FIGS. 4 to 6, the oil receiving groove (1326b) may be formed such that at least a portion of both inner surfaces is inclined in the reciprocating direction of the piston (132). For example, the oil receiving groove (1326b) may be formed in a wedge cross-sectional shape that is approximately a 'V' or 'U' shape when projected in the reciprocating direction of the piston (132). In other words, the first side wall surface (1326c) forming the front inner surface of the oil receiving groove (1326b) and the second side wall surface (1326d) forming the rear inner surface of the oil receiving groove (1326b) may each be formed as inclined surfaces having a predetermined angle of inclination. Accordingly, the outer end of the first side wall surface (1326c) and the outer end of the second side wall surface (1326d) are spaced apart from each other, while the inner end of the first side wall surface (1326c) and the inner end of the second side wall surface (1326d) can be connected to each other.

[0098] As described above, when the first side wall surface (1326c) and the second side wall surface (1326d) forming the front inner surface and the rear inner surface of the oil receiving groove (1326b) are formed at an angle, the interior angle (θ) at the corner between the bearing surface (1325a) of the annular bearing part (1325) and the two inner surfaces of the oil receiving groove (1326b) in contact therewith forms an obtuse angle. Accordingly, as the two corners of the oil receiving groove (1326b) are formed gently, wear between the two corners of the oil receiving groove (1326b) and the inner surface (1311a) of the cylinder (1311) can be effectively suppressed during the reciprocating motion of the piston (132).

[0099] Although not illustrated in the drawing, the two side walls (1326c) (1326d) of the oil receiving groove (1326b) may be formed as curved surfaces. In this case, the two side walls (1326c) (1326d) of the oil receiving groove (1326b) may be formed concavely in opposite directions. Accordingly, the two corners described above can be formed to form obtuse angles while being easily machined.

[0100] In these cases, as shown in FIG. 6, the radial depth (hereinafter abbreviated as depth) (D) of the oil receiving groove (1326b) can be formed to be smaller than or equal to the height (H) of the linear bearing part (1326). For example, the depth (D) of the oil receiving groove (1326b) can be formed to be smaller than the height (H) of the linear bearing part (1326). In other words, the depth (D) of the oil receiving groove (1326b) can be formed to be less than 70% of the height (H) of the linear bearing part (1326). Accordingly, the oil receiving groove (1326b) can be formed within the range of the linear bearing part (1326) while avoiding the friction avoidance groove (1323). Through this, the oil receiving groove (1326b) can be easily machined, while the oil retention capacity relative to the amount of oil supplied is improved, thereby increasing the actual sealing effect.

[0101] As described above, when an oil receiving groove (1326b) is formed in the linear bearing part (1326), the sealing surface by the oil surface in the linear bearing part (1326) is reinforced, and the leakage of the refrigerant in the compression chamber (130a) through the gap between the cylinder (1311) and the piston (132) can be effectively suppressed, thereby improving the energy efficiency and / or cooling power of the compressor.

[0102] Here, the sealing effect of the oil receiving groove (1326b) can be increased or decreased depending on the width (W) of the oil receiving groove (1326b). For example, the larger the width (W) of the oil receiving groove (1326b), the larger the sealing area and the greater the sealing effect; however, if it is formed to be exposed to the outside of the cylinder (1311), the sealing effect may be reduced by half. This can also be seen through FIGS. 7a and 7b. FIGS. 7a is a plan view showing a comparison of the width of the oil receiving groove relative to the length of the linear bearing part in this embodiment, and FIGS. 7b is a graph showing the change in energy efficiency and the change in cooling power according to the width of the oil receiving groove in FIGS. 7a, respectively.

[0103] Referring to FIGS. 7a and 7b, it can be seen that forming the width (W) of the oil receiving groove (1326b) to approximately 5 to 90% of the length (L3) of the linear bearing part (1326), as previously explained, is advantageous in terms of energy efficiency and cooling power. In other words, it can be seen that if the width (W) of the oil receiving groove (1326b) is less than 5% or more than 90% of the length (L3) of the linear bearing part (1326), the increase in energy efficiency and cooling power slows down or is even halved. This can be seen as being because when the width (W) of the oil receiving groove (1326b) is less than 5% of the length of the linear bearing part (1326), the effect of increasing the sealing area of ​​the linear bearing part (1326) decreases, and when it exceeds 90% of the length (L3) of the linear bearing part (1326), the oil in the oil receiving groove (1326b) leaks to the rear side of the piston (132), thereby reducing the sealing effect by half. Accordingly, it may be desirable for the oil receiving groove (1326b) to be formed with an appropriate width (W), for example, about 5 to 90% of the length (L3) of the linear bearing part (1326).

[0104] Meanwhile, the sealing effect of the oil receiving groove (1326b) can be increased or decreased depending not only on the width (W) of the oil receiving groove (1326b) but also on the depth (D). For example, if the depth (D) of the oil receiving groove (1326b) increases beyond the appropriate depth, the sealing effect may be reduced by half. This can also be seen through FIGS. 8a and 8b. FIGS. 8a is a front view showing a comparison of the depth of the oil receiving groove relative to the height of the linear bearing part in this embodiment, and FIGS. 8b is a graph showing the change in energy efficiency and the change in cooling power according to the depth of the oil receiving groove in FIGS. 8a, respectively.

[0105] Referring to FIGS. 8a and 8b, it can be seen that forming the depth (D) of the oil receiving groove (1326b) to be less than 70% of the height (H) of the linear bearing part (1326), as previously explained, is advantageous in terms of energy efficiency and cooling power. In other words, if the depth (D) of the oil receiving groove (1326b) exceeds 70% of the height (H) of the linear bearing part (1326), the amount of oil retained in the oil receiving groove (1326b) decreases compared to the amount of oil supplied by scattering from the crankshaft (125), and thus the increase in energy efficiency and cooling power slows down or is even halved. This can be seen as being because when the depth (D) of the oil receiving groove (1326b) exceeds 70% of the height (H) of the linear bearing part (1326), oil is not retained in the oil receiving groove (1326b) or the oil film thickness becomes thin, thereby reducing the sealing effect. Accordingly, it may be desirable for the oil receiving groove (1326b) to be formed to an appropriate depth (D), for example, less than 70% of the height (H) of the linear bearing part (1326).

[0106] Meanwhile, other embodiments of the oil receiving groove are as follows.

[0107] That is, in the above-described embodiment, only one oil receiving groove is formed, but in some cases, multiple oil receiving grooves may be formed at predetermined intervals along the reciprocating direction of the piston.

[0108] FIG. 9 is a perspective view showing another embodiment of the oil passage groove of the piston, and FIG. 10a and FIG. 10b are perspective views showing yet other embodiments of the oil passage groove of the piston.

[0109] Referring again to FIG. 3, the basic configuration of the piston (132) according to the present embodiment and the resulting effects are similar to the previously described embodiment. For example, a bearing protrusion (1322) including an annular bearing portion (1325) and a plurality of linear bearing portions (1326) is formed on the outer surface of the piston (132), and a friction avoidance groove (1323) may be formed in a portion not belonging to the bearing protrusion (1322) so as to be shallower than the bearing protrusion (1322). Accordingly, the total bearing area of ​​the bearing protrusion (1322) is reduced, thereby suppressing friction loss while preventing leakage of the refrigerant in the compression chamber (130a).

[0110] Additionally, an oil receiving groove (1326b) may be formed in an arc shape along the circumferential direction of the linear bearing part (1326). Accordingly, oil is filled into the oil receiving groove (1326b), and a strip-shaped sealing surface is reinforced on the bearing surface (1326a) of the linear bearing part (1326), thereby more effectively suppressing the leakage of refrigerant from the compression chamber (130a).

[0111] However, in this embodiment, as shown in FIGS. 9 to 10b, the oil receiving grooves (1326b) may be formed in multiple numbers. In other words, multiple oil receiving grooves (1326b1) (1326b2) may be formed spaced apart from each other at predetermined intervals along the reciprocating direction of the piston (132). Accordingly, a band-shaped sealing surface is formed in multiple stages on the bearing surface (1326a) of the linear bearing part (1326), thereby more effectively suppressing the leakage of the refrigerant in the compression chamber (130a).

[0112] In this case, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed with the same shape or with different shapes. In the former case, the plurality of oil receiving grooves (1326b1) (1326b2) can be easily processed, and in the latter case, as the plurality of oil receiving grooves (1326b1) (1326b2) are formed with different shapes, the oil film shape in each oil receiving groove (1326b1) (1326b2) is formed in various ways, and the sealing effect of the oil receiving groove (1326b) may be improved. This embodiment illustrates an example in which the plurality of oil receiving grooves (1326b1) (1326b2) are formed with the same shape.

[0113] In this case, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed with the same specifications or with different specifications. For example, as shown in FIG. 9, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed to have the same cross-sectional area along the reciprocating direction of the piston (132) (or the longitudinal direction of the linear bearing part). In other words, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed in a shape having the same width (W1) (W2) and the same depth (D1) (D2) along the reciprocating direction of the piston (132). Accordingly, not only is it easy to machine the plurality of oil receiving grooves (1326b1) (1326b2), but a sealing surface formed by the oil surface in each oil receiving groove (1326b1) (1326b2) can also be formed uniformly.

[0114] However, depending on the case, multiple oil receiving grooves (1326b1) (1326b2) may be formed to have different cross-sectional areas along the reciprocating direction of the piston (132). In other words, with respect to the compression chamber (130a), the front oil receiving groove (1326b1) located adjacent to the compression chamber (130a) and the rear oil receiving groove (1326b2) located far from the compression chamber (130a) may be formed to have different cross-sectional areas.

[0115] For example, as shown in FIG. 10a, a plurality of oil receiving grooves (1326b1) (1326b2) may be formed with different widths (W1) (W2). In other words, the width (W1) of the front oil receiving groove (1326b1) located adjacent to the compression chamber (130a) may be formed larger than the width (W2) of the rear oil receiving groove (1326b2) located far from the compression chamber (130a). Accordingly, the sealing surface formed by the oil surface in the front oil receiving groove (1326b1) located adjacent to the compression chamber (130a) is formed relatively wider than the sealing surface formed by the oil surface in the rear oil receiving groove (1326b2) located far from the compression chamber (130a), thereby more effectively suppressing refrigerant leakage in the compression chamber (130a).

[0116] Additionally, as shown in FIG. 10b, the depths (D1) and (D2) of the multiple oil receiving grooves (1326b1) and (1326b2) may be formed differently from each other. In other words, the depth (D1) of the front oil receiving groove (1326b1) located adjacent to the compression chamber (130a) may be formed smaller than the depth (D2) of the rear oil receiving groove (1326b2) located far from the compression chamber (130a). Accordingly, a high sealing force is formed by the oil surface in the oil receiving groove (1326b1) located adjacent to the compression chamber (130a), thereby more effectively suppressing refrigerant leakage in the compression chamber (130a), while oil scattered to the upper half of the piston (132) through the oil receiving groove (1326b2) located far from the compression chamber (130a) moves quickly to the lower half of the piston (132), thereby increasing the lubrication effect between the cylinder (1311) and the piston (132).

[0117] As described above, when the oil receiving grooves (1326b) are formed in multiple numbers, the sealing surface in the linear bearing part (1326) is formed in multiple stages, thereby increasing the sealing effect relative to the same sealing area. Through this, the leakage of the refrigerant in the compression chamber (130a) through the gap between the cylinder (1311) and the piston (132) can be suppressed more effectively.

[0118] Meanwhile, another embodiment of the oil receiving groove is as follows.

[0119] That is, in the above-described embodiment, the two inner surfaces of the oil receiving groove are formed to be connected to each other, but in some cases, the two inner surfaces of the oil receiving groove may be formed spaced apart from each other.

[0120] FIG. 11 is a perspective view showing another embodiment of the oil passage groove of the piston.

[0121] Referring again to FIG. 3, the basic configuration of the piston (132) according to the present embodiment and the resulting effects are similar to the previously described embodiment. For example, a bearing protrusion (1322) including an annular bearing portion (1325) and a plurality of linear bearing portions (1326) is formed on the outer surface of the piston (132), and a friction avoidance groove (1323) may be formed in a portion not belonging to the bearing protrusion (1322) so as to be shallower than the bearing protrusion (1322). Accordingly, the total bearing area of ​​the bearing protrusion (1322) is reduced, thereby suppressing friction loss while preventing leakage of the refrigerant in the compression chamber (130a).

[0122] Additionally, an oil receiving groove (1326b) may be formed in an arc shape along the circumferential direction of the linear bearing part (1326). Accordingly, oil is filled into the oil receiving groove (1326b), and a strip-shaped sealing surface is reinforced on the bearing surface (1326a) of the linear bearing part (1326), thereby more effectively suppressing the leakage of refrigerant from the compression chamber (130a).

[0123] However, in this embodiment, as shown in FIG. 11, the oil receiving groove (1326b) may include a first side wall surface (1326c), a second side wall surface (1326d), and a connecting surface (1326e). In other words, the oil receiving groove (1326b) may be composed of a first side wall surface (1326c) and a second side wall surface (1326d) that form both inner sides in the reciprocating direction of the piston (132), and a connecting surface (1326e) that connects the inner ends of the first side wall surface (1326c) and the second side wall surface (1326d) to each other.

[0124] In this case, the first side wall surface (1326c) and the second side wall surface (1326d) are formed as inclined surfaces or curved surfaces that are inclined in a direction in which the space between the two side walls narrows toward the connecting surface (1326e) as previously described, and the connecting surface (1326e) can be formed as a straight surface or a concave curved surface.

[0125] As described above, when the oil receiving groove (1326b) is formed with a first side wall surface (1326c), a second side wall surface (1326d), and a connecting surface (1326e), the width (W) of the oil receiving groove (1326b) can be formed as wide as possible, while ensuring a more uniform oil film thickness in the width direction within the oil receiving groove (1326b). Through this, the leakage of the refrigerant in the compression chamber (130a) through the gap between the cylinder (1311) and the piston (132) can be suppressed more effectively.

[0126] Although not illustrated in the drawing, the oil receiving groove (1326b) according to the present embodiment can be applied in the same way even when a plurality of oil receiving grooves (1326b) are arranged at predetermined intervals along the reciprocating direction of the piston (132).

[0127] Meanwhile, another embodiment of the oil receiving groove is as follows.

[0128] That is, in the aforementioned embodiments, both inner surfaces of the oil receiving groove are formed in the shape of inclined or curved surfaces, but in some cases, both inner surfaces of the oil receiving groove may be formed parallel to each other.

[0129] FIG. 12 are perspective views showing different embodiments of the oil passage groove of the piston, respectively.

[0130] Referring again to FIG. 3, the basic configuration of the piston (132) according to the present embodiment and the resulting effects are similar to the previously described embodiment. For example, a bearing protrusion (1322) including an annular bearing portion (1325) and a plurality of linear bearing portions (1326) is formed on the outer surface of the piston (132), and a friction avoidance groove (1323) may be formed in a portion not belonging to the bearing protrusion (1322) so as to be shallower than the bearing protrusion (1322). Accordingly, the total bearing area of ​​the bearing protrusion (1322) is reduced, thereby suppressing friction loss while preventing leakage of the refrigerant in the compression chamber (130a).

[0131] Additionally, an oil receiving groove (1326b) may be formed in an arc shape along the circumferential direction of the linear bearing part (1326). Accordingly, oil is filled into the oil receiving groove (1326b), and a strip-shaped sealing surface is reinforced on the bearing surface (1326a) of the linear bearing part (1326), thereby more effectively suppressing the leakage of refrigerant from the compression chamber (130a).

[0132] The oil receiving groove (1326b) may be formed with a first side wall surface (1326c) and a second side wall surface (1326d) forming both inner sides in the reciprocating direction of the piston (132), and a connecting surface (1326e) connecting the inner ends of the first side wall surface (1326c) and the second side wall surface (1326d). Accordingly, the width (W) of the oil receiving groove (1326b) can be formed as wide as possible, while ensuring a more uniform oil film thickness in the width direction within the oil receiving groove (1326b).

[0133] However, in this embodiment, as shown in FIG. 12, the first side wall surface (1326c) and the second side wall surface (1326d) forming the inner sides of the oil receiving groove (1326b) may be formed by being bent parallel to each other at the bearing surface (1326a) of the linear bearing part (1326). In other words, the inner ends of the first side wall surface (1326c) and the second side wall surface (1326d) may be connected so as to be orthogonal to the connecting surface (1326e).

[0134] As described above, when the first side wall surface (1326c) and the second side wall surface (1326d) are formed parallel to each other, the oil receiving groove (1326b) including the first side wall surface (1326c) and the second side wall surface (1326d) can be easily processed, and the width of the oil receiving groove (1326b) can be formed as wide as possible while ensuring a more uniform oil film thickness in the width direction within the oil receiving groove (1326b).

[0135] Although not illustrated in the drawing, the oil receiving groove (1326b) according to the present embodiment can be applied in the same way even when a plurality of oil receiving grooves (1326b) are arranged at predetermined intervals along the reciprocating direction of the piston (132).

[0136] Meanwhile, another embodiment of the oil receiving groove is as follows.

[0137] That is, in the aforementioned embodiments, both ends of the oil receiving groove are formed with the same specifications along the circumferential direction of the piston, but in some cases, both ends of the oil receiving groove may be formed with different specifications along the circumferential direction of the piston.

[0138] FIG. 13 is a perspective view showing another embodiment of the oil passage groove of the piston.

[0139] Referring again to FIG. 3, the basic configuration of the piston (132) according to the present embodiment and the resulting effects are similar to the previously described embodiment. For example, a bearing protrusion (1322) including an annular bearing portion (1325) and a plurality of linear bearing portions (1326) is formed on the outer surface of the piston (132), and a friction avoidance groove (1323) may be formed in a portion not belonging to the bearing protrusion (1322) so as to be shallower than the bearing protrusion (1322). Accordingly, the total bearing area of ​​the bearing protrusion (1322) is reduced, thereby suppressing friction loss while preventing leakage of the refrigerant in the compression chamber (130a).

[0140] Additionally, an oil receiving groove (1326b) may be formed in an arc shape along the circumferential direction of the linear bearing part (1326). Accordingly, oil is filled into the oil receiving groove (1326b), and a strip-shaped sealing surface is reinforced on the bearing surface (1326a) of the linear bearing part (1326), thereby more effectively suppressing the leakage of refrigerant from the compression chamber (130a).

[0141] However, in this embodiment, as shown in FIG. 13, the oil receiving groove (1326b) may be formed such that a plurality of oil receiving grooves (1326b3) (1326b4) arranged along the circumferential direction of the piston (132) are connected to each other. For example, the oil receiving groove (1326b) may consist of an upper oil receiving groove (1326b3) located on the upper side and a lower oil receiving groove (13264) located on the lower side with respect to the axial direction of the crankshaft (125), and the lower oil receiving groove (13264) may be connected at the bottom of the upper oil receiving groove (1326b3). Accordingly, the oil receiving groove (1326b) may be formed with a step difference in the middle of the circumferential direction.

[0142] In this case, the upper oil receiving groove (1326b3) and the lower oil receiving groove (1326b4) may be formed on the same axis or on different axes. In the former case, the machining of the upper oil receiving groove (1326b3) and the lower oil receiving groove (1326b4) is easy, and in the latter case, the oil retention capacity in the oil receiving groove (1326b) can be improved. This embodiment illustrates an example in which the upper oil receiving groove (1326b3) and the lower oil receiving groove (1326b4) are formed on the same axis.

[0143] In addition, in this case, the upper oil receiving groove (1326b3) and the lower oil receiving groove (1326b4) are formed with the same depth, but the width (W12) of the lower oil receiving groove (1326b4) may be formed smaller than the width (W11) of the upper oil receiving groove (1326b3). Accordingly, the sealing area in the upper oil receiving groove (1326b3) is expanded while minimizing the reduction in oil retention capacity, thereby improving the sealing strength in the overall oil receiving groove (1326b).

[0144] As described above, among the plurality of oil receiving grooves (1326b3) (1326b4) arranged along the circumferential direction, if the width (W12) of the lower oil receiving groove (1326b4) is formed to be smaller than the width (W11) of the upper oil receiving groove (1326b3), the oil retention capacity within the oil receiving groove (1326b) is improved, which may be advantageous for securing the oil film thickness during initial startup and / or low-speed operation. In this case, the length (L41) of the upper oil receiving groove (1326b3) may be formed to be larger than the length (L42) of the lower oil receiving groove (1326b4). Through this, the actual sealing area in the linear bearing part (1326) is secured to be wider, thereby effectively suppressing refrigerant leakage in the compression chamber (130a).

[0145] Although not illustrated in the drawing, the oil receiving groove (1326b) may be formed in a tapered shape such that the cross-sectional area gradually decreases from the upper side to the lower side. In this case as well, as previously explained, it may be advantageous to increase the oil retention capacity within the oil receiving groove (1326b) to secure the oil film thickness during initial startup and / or low-speed operation.

[0146] Additionally, although not illustrated in the drawing, the oil receiving groove (1326b) according to the present embodiment can be applied in the same way even when a plurality of oil receiving grooves (1326b) are arranged at predetermined intervals along the reciprocating direction of the piston (132).

[0147] Meanwhile, another embodiment of the oil receiving groove is as follows.

[0148] That is, in the aforementioned embodiments, the oil receiving groove is formed in a direction orthogonal to the reciprocating direction of the piston, but in some cases, the oil receiving groove may be formed in a direction that intersects obliquely with respect to the reciprocating direction of the piston.

[0149] FIG. 14 is a side view showing another embodiment of the oil passage groove of the piston, and FIG. 15a and FIG. 15b are side views showing other embodiments of FIG. 14.

[0150] Referring again to FIG. 3, the basic configuration of the piston (132) according to the present embodiment and the resulting effects are similar to the previously described embodiment. For example, a bearing protrusion (1322) including an annular bearing portion (1325) and a plurality of linear bearing portions (1326) is formed on the outer surface of the piston (132), and a friction avoidance groove (1323) may be formed in a portion not belonging to the bearing protrusion (1322) so as to be shallower than the bearing protrusion (1322). Accordingly, the total bearing area of ​​the bearing protrusion (1322) is reduced, thereby suppressing friction loss while preventing leakage of the refrigerant in the compression chamber (130a).

[0151] Additionally, an oil receiving groove (1326b) may be formed in an arc shape in the linear bearing portion (1326). Accordingly, oil is filled in the oil receiving groove (1326b), and a strip-shaped sealing surface is reinforced on the bearing surface (1326a) of the linear bearing portion (1326), thereby more effectively suppressing the leakage of refrigerant from the compression chamber (130a).

[0152] However, in this embodiment, the oil receiving groove (1326b) may be formed at an angle as shown in FIG. 14. For example, the upper end of the oil receiving groove (1326b) may be formed to be located on the front or rear side, respectively, with respect to the reciprocating direction of the piston (132) compared to the lower end of the oil receiving groove (1326b). In this embodiment, an example is illustrated in which the upper end of the oil receiving groove (1326b) is located on the rear side with respect to the reciprocating direction of the piston (132) compared to the lower end of the oil receiving groove (1326b). Accordingly, the oil receiving groove (1326b) may be formed at an angle of inclination by a preset angle, with the upper and lower ends located on different lines with respect to the axial direction of the crankshaft (125).

[0153] In addition, even when the oil receiving groove (1326b) is formed at an angle as in the present embodiment, the oil receiving groove (1326b) can be formed to be located within the inner surface (1311a) of the cylinder (shown in FIG. 7a) (1311) at the bottom dead center (P1) of the piston (132). Accordingly, the stability of the piston's movement can be secured as in the previously described embodiments.

[0154] However, in some cases, a portion of the oil receiving groove (1326b) may be formed so as to be exposed outside the inner surface (1311a) of the cylinder (1311) at the bottom dead center (P1) of the piston (132). In this case, the other portion of the oil receiving groove (1326b) is located inside the inner surface (1311a) of the cylinder (1311) at the bottom dead center (P1) of the piston (132), thereby ensuring the stability of the piston's movement as in the previously described embodiments.

[0155] As described above, when the oil receiving groove (1326b) is formed at an angle with respect to the axial direction of the crankshaft (125), the total length of the oil receiving groove (1326b) increases by the angle of the angle of the oil receiving groove (1326b). Through this, the sealing effect in the linear bearing part (1326) is improved, and at the same time, as the length of the oil receiving groove (1326b) increases, the amount of oil retained in the oil receiving groove (1326b) increases, thereby increasing the lubrication effect between the cylinder (1311) and the piston (132).

[0156] In addition, in this case, the oil receiving groove (1326b) may be formed as a single groove or as a plurality. For example, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed at predetermined intervals along the reciprocating direction of the piston (132), or the plurality of oil receiving grooves (1326b1) (1326b2) may be formed to intersect each other. In other words, as shown in FIG. 15a, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed to be inclined in the same direction and spaced apart from each other, and as shown in FIG. 15b, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed to be inclined in opposite directions and intersect each other. In the former case, the sealing surface is formed in multiple stages, thereby more effectively suppressing the leakage of refrigerant from the compression chamber (130a) while further enhancing the lubrication effect between the cylinder (1311) and the piston (132), and in the latter case, as a plurality of oil receiving grooves (1326b1) (1326b2) are connected to each other, some of the oil receiving grooves (1326b1) (1326b2) are exposed to the outside of the cylinder (1311), allowing oil splashed from the crankshaft (125) to be supplied more quickly and smoothly to the oil receiving grooves (1326b1) (1326b2).

[0157] In these cases as well, as in the above-described embodiment, the plurality of oil receiving grooves (1326b1) (1326b2) may be formed with the same specifications or with different specifications.

Claims

1. Shell; A driving motor provided in the internal space of the above shell; A crankshaft coupled to the rotor of the above-mentioned drive motor; A piston coupled to the crankshaft and reciprocating inside the cylinder to form a compression chamber; and It includes a bearing projection that is provided on the outer surface of the piston and forms a bearing surface together with the inner surface of the cylinder, and has a linear bearing portion that extends along the reciprocating direction of the piston. In the above linear bearing part, A reciprocating compressor having at least one oil receiving groove formed in a direction intersecting the reciprocating direction of the piston.

2. In Paragraph 1, The above oil receiving groove is, A reciprocating compressor formed at a position overlapping with the inner surface of the cylinder at the bottom dead center of the piston.

3. In Paragraph 2, The width of the above oil receiving groove is, A reciprocating compressor formed such that the length of the linear bearing portion is 5 to 90% of the reciprocating direction length.

4. In Paragraph 1, The above oil receiving grooves are formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston, and The above plurality of oil receiving grooves are, Reciprocating compressors formed with equal widths.

5. In Paragraph 1, The above oil receiving grooves are formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston, and The above plurality of oil receiving grooves are, A reciprocating compressor in which the width of an oil receiving groove located adjacent to the compression chamber is formed to be greater than the width of an oil receiving groove located far from the compression chamber.

6. In Paragraph 1, The depth of the above oil receiving groove is, A reciprocating compressor formed to be smaller than or equal to the height of the linear bearing part.

7. In Paragraph 6, The depth of the above oil receiving groove is, A reciprocating compressor formed to be less than 70% of the height of the linear bearing part.

8. In Paragraph 6, The above oil receiving groove is, Multiple pistons are formed at predetermined intervals along the reciprocating direction of the piston, and The above plurality of oil receiving grooves are, Reciprocating compressors formed at equal depths.

9. In Paragraph 6, The above oil receiving grooves are formed in multiple numbers at predetermined intervals along the reciprocating direction of the piston, and The above plurality of oil receiving grooves are, A reciprocating compressor in which the depth of an oil receiving groove located adjacent to the compression chamber is formed to be smaller than the depth of an oil receiving groove located far from the compression chamber.

10. In Paragraph 1, The above oil receiving groove is, A reciprocating compressor formed by longitudinally extending between the two circumferential ends of the above-mentioned linear bearing section.

11. In Paragraph 10, The above oil receiving groove is, A reciprocating compressor formed with the same cross-sectional area between the circumferential ends of the above-mentioned linear bearing section.

12. In Paragraph 10, The above oil receiving groove is, A reciprocating compressor formed with different cross-sectional areas between the circumferential ends of the linear bearing section.

13. In Paragraph 1, The above oil receiving groove is, A reciprocating compressor in which at least a portion of both inner surfaces in the reciprocating direction of the piston is formed as an inclined or curved surface.

14. In Paragraph 13, The above oil receiving groove is, A reciprocating compressor formed such that the first side wall and the second side wall, which form the inner surfaces on both sides in the reciprocating direction of the piston, are inclined or curved so as to be connected to each other.

15. In Paragraph 13, The above oil receiving groove is, It includes a first side wall surface and a second side wall surface forming both inner surfaces in the reciprocating direction of the piston, and a connecting surface connecting the first side wall surface and the second side wall surface to each other. A reciprocating compressor in which the first side wall surface and the second side wall surface are formed to be inclined or curved so as to be connected to each side of the connecting surface.

16. In Paragraph 1, The above oil receiving groove is, It includes a first side wall surface and a second side wall surface forming both inner surfaces in the reciprocating direction of the piston, and a connecting surface connecting the first side wall surface and the second side wall surface to each other. A reciprocating compressor in which the first side wall surface and the second side wall surface are formed parallel to each other and perpendicular to each other on both sides of the connecting surface.

17. In Paragraph 1, The above oil receiving groove is, A reciprocating compressor formed along a direction perpendicular to the reciprocating direction of the piston.

18. In Paragraph 1, The above oil receiving groove is, A reciprocating compressor formed in a direction that intersects obliquely with respect to the reciprocating direction of the above piston.

19. In Paragraph 18, The above oil receiving grooves are composed of multiple grooves, and The above plurality of oil receiving grooves are, A reciprocating compressor formed to be spaced apart from or intersecting each other in the reciprocating direction of the above pistons.

20. In any one of paragraphs 1 through 19, The above bearing protrusion is, One end of the linear bearing part is connected, and an annular bearing part is further included that extends annularly along the circumferential direction from the outer surface of the piston. The above oil receiving groove is, A reciprocating compressor formed on the linear bearing portion outside the annular bearing portion.

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