JP6363849B2 - Hermetic compressor and refrigerator - Google Patents

Description

  The present invention relates to a hermetic compressor with reduced sliding loss of a piston and a refrigerator equipped with the same.

  In recent years, demands for protecting the global environment have accelerated the trend toward energy saving in household refrigerators.

  Under such circumstances, the conventional hermetic compressor forms a non-sliding surface on the outer peripheral surface of the piston to reduce the sliding loss between the piston and the cylinder, thereby improving the compression efficiency ( For example, see Patent Document 1).

  The prior art hermetic compressor will be described below with reference to the drawings. 9 is a longitudinal sectional view of a conventional hermetic compressor described in Patent Document 1, FIG. 10 is a perspective view of a piston of a conventional hermetic compressor, and FIG. 11 is a cylinder, piston, connecting means, shaft, and main bearing. FIG.

  In FIG. 9, the compressor is configured by elastically supporting a compressor main body 6 in an airtight container 2 that stores lubricating oil. The compressor main body 6 includes an electric motor including a stator 14 and a rotor 16. It is composed of an element 10 and a compression element 12 driven by the electric element 10.

  The compression element 12 includes a crankshaft 18, a cylinder block 24, a piston 36, connection means 28, and the like.

  The crankshaft 18 has a main shaft 20 to which the rotor 16 is fixed and an eccentric shaft 22 formed eccentric to the main shaft 20, and the cylinder block 24 is a bearing portion that rotatably supports the cylinder 34 and the main shaft 20. 26.

  The piston 36 is inserted into the cylinder 34 so as to be slidable back and forth, and reciprocates through the connecting means 28 by the rotation of the eccentric shaft 22 to compress the refrigerant in the cylinder 34.

  Here, as shown in FIG. 10, the outer peripheral surface of the piston 36 is a concave non-sliding portion 63 other than the seal portion 60 on the outer peripheral surface and the extension portion 62 that receives a lateral force. As a result, the piston 36 has a reduced sliding area with the inner surface of the cylinder 34, thereby reducing sliding loss.

JP-T-2004-501320

However, the conventional configuration described in Patent Document 1 has a problem that the piston is tilted and uneven wear occurs as shown in the schematic diagram during the general compression operation of FIG. That is, as shown in FIG. 11, the piston 36 first applies a force from the piston 36 to the eccentric shaft portion 22 of the crankshaft 18 via the connecting means 28 due to a load during compression, and the crankshaft 18 18 tilts within the clearance between the bearing 26 and the crankshaft 18. Next, when the shaft 18 is inclined, the piston 3 passes through the connecting means 28.
6 also tilts. Further, as shown in FIG. 10, since the non-sliding portion 63 is provided on the vertical upper and lower surfaces of the outer peripheral surface of the piston 36, the piston 36 does not slide on the tip side of the seal portion 60, the extension portion 62 and the back surface 65. Since it is supported near the boundary 66 of the three points of the moving part 63, a phenomenon occurs in which the inclination of the piston 36 in the cylinder 34 increases. As a result, the piston 36 slides strongly on the front end side of the seal portion 60 that slides with the inner surface of the cylinder 34, and the boundary portion 66 between the extension portion 62, the back surface 65, and the non-sliding portion 63, and uneven wear occurs. As a result, there was room for improvement in efficiency and reliability.

  The present invention solves the above-mentioned conventional problems, and reduces the piston sliding in the cylinder while reducing the sliding loss by reducing the area of the sliding surface of the piston, and the occurrence of uneven wear of the piston. An object of the present invention is to provide a hermetic compressor that is highly efficient and reliable.

In order to solve the above-described conventional problems, a hermetic compressor according to the present invention includes a shaft that is pivotally supported by a main bearing of a cylinder block, and a piston that is reciprocated by the shaft. A cylindrical seal portion having a uniform gap with the surface and forming a sliding surface, and a slide which is located on both side surfaces behind the seal portion and has the same radius as the seal portion and supports a lateral pressure. Two extending portions forming a moving surface, and the center of the width of the extending portion is shifted from the center of reciprocation of the piston toward the main bearing.

  Thereby, the sliding area of a piston and a cylinder can be reduced only to a seal part and an extension part, and a sliding loss can be reduced.

  In addition, when the shaft is tilted by the load during compression and the piston is tilted by the tilt of the shaft, the center of the width of the extension portion is shifted from the center of the reciprocating shaft of the piston toward the main bearing side. As a result, it is possible to alleviate the one-sided contact of the piston and suppress the occurrence of uneven wear of the piston.

  The hermetic compressor of the present invention reduces the sliding area between the piston and the cylinder by reducing the sliding area of the piston, and suppresses the inclination of the piston and relaxes the one-sided piston. The occurrence of uneven wear of the piston can be suppressed, and the efficiency and reliability of the hermetic compressor can be improved at the same time.

1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. Top sectional view of the hermetic compressor in the same embodiment (A) Sectional view seen from the back of the piston in the same embodiment, (b) Side view (A) The schematic cross section which showed the attitude | position of the piston in the cylinder in the embodiment seen from the back surface, (b) The schematic side cross section Relationship diagram of piston position and piston tilt in cylinder in the same embodiment (A) (b) Side view (c) of anti-load side and load side of piston in same embodiment, and sectional view seen from back The characteristic view which shows the load which acts on the piston side surface in 1 stroke in the embodiment Schematic sectional view of a refrigerator equipped with a hermetic compressor of the present invention Vertical section of a conventional hermetic compressor Perspective view and longitudinal sectional view showing a piston of a conventional hermetic compressor Schematic diagram of cylinder, piston, connecting means, shaft, main bearing during compression operation

A hermetic compressor according to a first aspect of the present invention stores lubricating oil in a hermetic container, and stores an electric element having a stator and a rotor and a compression element driven by the electric element, and the compression element Includes a shaft having a main shaft portion to which the rotor is fixed and an eccentric shaft portion, a cylinder block including a cylinder and a main bearing that supports the main shaft portion of the shaft, and a reciprocating motion inside the cylinder. A piston inserted in a possible manner, a connecting means for connecting the piston and the eccentric shaft portion, and an oil supply mechanism provided in the shaft, wherein the piston is uniform with an inner peripheral surface of the cylinder. A cylindrical seal portion that has a gap and forms a sliding surface, and a sliding surface that is located on both side surfaces behind the sealing portion, has the same radius as the sealing portion, and supports lateral pressure. It has two extensions and the extension There the center of the width of the parts a configuration in which by shifting from the main bearing side axial center of reciprocation of the piston.

  As a result, the sliding area between the piston and the cylinder can be reduced only to the seal part and the extension part, and the sliding loss can be reduced, so that the efficiency of the hermetic compressor can be improved and the load at the time of compression can be improved. When the piston pushes the eccentric shaft portion of the shaft via the connecting means, the shaft tilts, and when the piston tilts due to the tilt of the shaft, the center of the width of the extension portion of the piston is the axis of reciprocation of the piston. Since it is shifted to the main bearing side from the center, the extension part can contact the cylinder earlier than when it is not shifted, and the inclination of the piston can be reduced, so that the piston contact per side is alleviated and the piston is unevenly worn. Can be suppressed, and the reliability of the hermetic compressor can be improved at the same time.

  In the second invention, in particular, the piston of the hermetic compressor according to the first invention is formed behind the seal portion and the extension portion, and has a non-sliding radius smaller than the radius of the seal portion and the extension portion. It is set as the structure which has the collection part formed in the surface.

  As a result, the lubricating oil from the oil supply mechanism scatters from the upper end of the shaft eccentric shaft part and adheres to the collecting part, and this lubricating oil is supplied from the collecting part to the extension part and the seal part, so that it is more reliable. The seal part can be sealed to reduce leakage between the piston and cylinder, and the lubrication can prevent the sliding surface of the piston seal part and extension part from being worn. The sex can be further improved.

  In a third aspect of the invention, particularly in the hermetic compressor according to the first or second aspect of the invention, the side on the side (load side) that is pressed against the inner peripheral surface of the cylinder by the connecting means when the piston moves toward top dead center. The width of the extension portion of the piston is set to be 1.2 times or more wider than the width of the extension portion of the piston on the side not pressed against the inner peripheral surface of the cylinder (the anti-load side).

  Thereby, the surface pressure on the load side, which increases the load acting in the side surface direction of the piston with the compression action, is reduced, and the reliability can be further increased.

  According to a fourth aspect of the invention, in particular, the electric element of the hermetic compressor according to any one of the first to third aspects is driven by an inverter circuit at a plurality of rotational speeds.

  Along with this, by shortening the extension of the piston and accordingly shortening the total length of the piston and reducing the weight of the piston, vibration at a low speed is reduced and the inertial force of the piston is reduced. It is possible to reduce the load on the eccentric shaft portion and the shaft to which the inertial force is applied at the time of the increasing high-speed rotation speed, and further increase the reliability.

  A fifth invention is a refrigerator using the hermetic compressor according to any one of the first to fourth inventions.

  Thereby, since the efficiency of the hermetic compressor is high, the power consumption of the refrigerator can be reduced, and the reliability of the hermetic compressor is improved, so that the reliability of the refrigerator can also be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. FIG. 2 is a top cross-sectional view in the same embodiment, and FIGS. 3A and 3B are a cross-sectional view and a side view as seen from the back surface of the piston in the same embodiment. 4A and 4B are a schematic cross-sectional view and a schematic side cross-sectional view showing the posture of the piston in the cylinder in the same embodiment. FIG. 5 is a relationship diagram between the position of the piston in the cylinder and the inclination of the piston in the same embodiment. 6 (a), 6 (b), and 6 (c) are a side view and a cross-sectional view as seen from the back side of the piston on the anti-load side and the load side of the piston in the same embodiment. FIG. 7 is a characteristic diagram showing the load acting on the piston side surface during one stroke.

  1 to 4, the hermetic compressor 101 stores lubricating oil 104 in the bottom of the hermetic container 102, and a compressor body 106 is suspended by a suspension spring 108. The sealed container 102 is filled with R600a (isobutane), which is a refrigerant gas having a low warming potential.

  The compressor body 106 includes an electric element 110 and a compression element 112 driven by the electric element 110, and a power supply terminal 113 for supplying power to the electric element 110 is attached to the sealed container 102.

  First, the electric element 110 will be described.

  The electric element 110 includes a stator 114 in which a winding (not shown) is directly wound around a plurality of magnetic pole teeth of an iron core in which steel plates are laminated, and an inner diameter side of the stator 114. This is a salient pole concentrated winding type DC brushless motor provided with a rotor 116 (not shown). The windings of the stator 114 are connected to an inverter circuit (not shown) outside the hermetic compressor via a power supply terminal 113 by a conductive wire, and the electric element 110 is driven at a plurality of rotational speeds.

  Next, the compression element 112 will be described.

  In this embodiment, the compression element 112 is disposed above the electric element 110.

  The shaft 118 constituting the compression element 112 includes a main shaft portion 120 and an eccentric shaft portion 122 extending from the upper end of the main shaft portion 120 and parallel to the main shaft portion 120. Further, the rotor 116 is fixed to the main shaft portion 120 by a method such as shrink fitting.

The cylinder block 124 includes a main bearing 126 having a cylindrical inner surface and a cylinder 134 that is a cylindrical hole. The main bearing 126 supports the shaft 118 by inserting the main shaft portion 120 in a rotatable state. The compression element 112 has a configuration of a cantilever bearing that supports the load acting on the eccentric shaft portion 122 by the main shaft portion 120 and the main bearing 126 arranged below the eccentric shaft portion 122. In the cylinder 134, a piston 136 is reciprocally inserted. Further, the connecting means 144 has holes provided at both ends thereof fitted into the piston pin 143 (see FIG. 2) attached to the piston 136 and the eccentric shaft portion 122, so that the eccentric shaft portion 122, the piston 136, Are connected.

  A valve plate 146 is attached to the end surface of the cylinder 134 and forms a compression chamber 148 together with the cylinder 134 and the piston 136. Further, the cylinder head 150 is fixed so as to cover the valve plate 146 and cover it. The suction muffler 152 is molded from a resin such as PBT, forms a silencing space inside, and is attached to the cylinder head 150.

  In the shaft 118, the lower end of the main shaft portion 120 is immersed in the lubricating oil 104 stored in the inner bottom portion of the sealed container 102, and the oil supply from the lower end to the upper end of the shaft 118 including the spiral groove 128 on the outer surface of the main shaft portion 120 is performed. A mechanism 130 is provided.

  Next, the piston 136 will be described.

  As shown in FIG. 3, a cylindrical seal portion 160 having a radius smaller than the radius of the cylinder 134 is formed on the outer peripheral surface of the piston 136 so as to ensure a small clearance with respect to the inner peripheral surface of the cylinder 134. Further, on both side surfaces on the rear side of the seal portion 160, extension portions 162 having the same radius as the seal portion 160 and forming a sliding surface for supporting a lateral pressure extended with a constant width in the axial direction of the piston 136 are installed. ing. Further, behind the seal portion 160 and the extension portion 162, a collecting portion 164 that is a non-sliding surface having a radius smaller than the radius of the extension portion 162 is provided. Further, the center of the width of the extension 162 is shifted from the center of the reciprocating shaft of the piston 136 toward the main bearing 126 (lower side in this figure).

  As shown in FIG. 6, the width of the extension portion 162 of the piston 136 is such that the piston 136 is pressed against the inner peripheral surface of the cylinder 134 and the extension portion 162 is loaded (downward direction in FIG. Side) is wider than the opposite side (hereinafter referred to as the anti-load side). Specifically, when the piston 136 moves from the bottom dead center toward the top dead center to compress the refrigerant gas, the piston 136 is pressed against the inner peripheral surface of the cylinder 134 by the connecting means 144 and slides on the load side. The width F is set wider than the sliding width G on the non-load side. In this embodiment, the width F is about 1.6 times the width G.

  The operation and action of the hermetic compressor configured as described above will be described below.

  When the electric element 110 is energized from the power supply terminal 113, the rotor 116 rotates together with the shaft 118 in the direction of the arrow in FIG. 2 due to the magnetic field generated in the stator 114. The eccentric rotation of the eccentric shaft portion 122 accompanying the rotation of the main shaft portion 120 is converted by the connecting means 144 and causes the piston 136 to reciprocate within the cylinder 134. Then, when the volume of the compression chamber 148 is changed, the refrigerant gas in the sealed container 102 is sucked into the compression chamber 148 and compressed.

  When this compression operation is performed, the piston 136 includes a collecting portion 164 having a diameter smaller than that of the seal portion 160 and the extension portion 162. Therefore, the sliding area between the piston 136 and the cylinder 134 is only the seal portion 160 and the extension portion 162. The sliding loss can be reduced, and the efficiency of the hermetic compressor can be improved.

Further, since the piston 136 reciprocates against the pressure of the compression chamber 148, the force is transmitted from the piston 136 to the eccentric shaft portion 122 via the connecting means 144, and the shaft 118 is moved to the main bearing on the anti-compression chamber 148 side. Tilt within the clearance between 126 and the main shaft 120. As shown in FIG. 4, the inclination is supported at three points, that is, the upper surface near the tip of the seal portion 160 of the piston 136 and the lower side 166 of the extension portion 162 on the collecting portion 164 side, as shown in FIG. The piston 136 is inclined because it hits the inner peripheral surface of the cylinder 134.

  However, in the present invention, as shown in FIG. 3, the extension 162 is shifted to the main bearing 126 side from the center of the reciprocating movement of the piston 136, so that the extension 162 is not displaced. The surface can be quickly contacted, and the inclination of the piston 136 can be reduced accordingly. FIG. 5 shows the position of the piston 136 and the inclination of the piston 136. As shown in FIG. 5, when the extension 162 is shifted to the main bearing 126 side (A> B), it is not shifted (A = B). In comparison, it can be seen that the inclination of the piston 136 is reduced. As a result, the degree of contact of the piston 136 with one piece can be reduced, and uneven wear of the piston 136 can be suppressed.

  Further, when the compression operation is performed, the piston 136 reciprocates against the pressure of the compression chamber 148 and the inertial force of the piston 136, so that the acting force is connected from the connecting means 144 that connects the eccentric shaft portion 122 and the piston pin 143 to the piston. To 136. Since the direction of the acting force is oblique with respect to the axial direction of the cylinder 134, the piston 136 is pressed against the inner peripheral surface of the cylinder 134 by this component force.

  FIG. 7 is a characteristic diagram showing the load by which the piston 136 is pressed against the inner peripheral surface of the cylinder 134 during one stroke of the main shaft portion 120. The upper direction in the figure is the load side load and the lower direction is the anti-load side load. Show. The characteristic indicated by the broken line is the load when the rotational speed is low under normal operating pressure conditions, and the characteristic indicated by the solid line is the load when the compression ratio is high and the rotational speed is high. Yes.

  The side pressure load applied to the piston 136 varies depending on the operating pressure conditions and the number of rotations, the mass of components such as the piston 136, the offset amount of the shaft between the cylinder 134 and the main bearing 126, etc. Is often larger than the anti-load side.

  Under the condition of the high compression ratio shown by the solid line in FIG. 7 and at a high speed, the ratio of the maximum values of the loads on the load side and the anti-load side is about 1.6: 1. Further, in the case of normal pressure and low speed rotation speed, the ratio of the maximum values of the load on the load side and the counter load side is approximately 1.2: 1.

  Therefore, the width of the sliding surface of the extension 162 may be at least 1.2 times the width G, and more preferably, the maximum load is achieved by setting the width F to about 1.6 times the width G. Since the left and right surface pressures when the pressure acts can be made equal, the surface pressure of the sliding surface 162A is reduced, and the durability can be ensured.

  In this series of compression operations, the refrigerant gas in the hermetic container 102 is intermittently sucked into the compression chamber 148 through the suction muffler 152 in the suction process, compressed in the compression chamber 148 in the compression stroke, and then heated. The high-pressure refrigerant gas is sent from the sealed container 102 to a refrigeration cycle (not shown) via a discharge pipe or the like.

  Next, refueling will be described.

  Due to the action of the oil supply mechanism 130 accompanying the rotation of the shaft 118, the lubricating oil 104 stored at the bottom of the sealed container 102 is conveyed upward from the lower end of the shaft 118, lubricates each part, and scatters from the tip of the eccentric shaft part 122.

Part of the scattered lubricating oil 104 adheres to the collecting portion 164 of the piston 136 exposed to the outside from the cylinder 134 near the bottom dead center. Thereafter, as the piston 136 reciprocates, the collecting portion 164 is pulled back into the cylinder 134, so that the lubricating oil 104 can more reliably lubricate the sliding surfaces of the piston 136 and the cylinder 134, and the seal portion 160. In addition, the lubricating oil 104 can be reliably supplied, and the airtightness of the compression chamber 148 at the seal portion 160 can be maintained.

  In particular, since the lubrication state of the extension portion 162 where the load acts greatly is improved, the occurrence of wear can be prevented and the reliability can be improved.

(Embodiment 2)
FIG. 8 is a schematic cross-sectional view of a refrigerator equipped with the hermetic compressor described in the first embodiment.

  In FIG. 8, a heat insulation box 180 injects foam insulation 186 into a space formed by an inner box 182 formed by vacuum molding a resin body such as ABS and an outer box 184 using a metal material such as a pre-coated steel plate. Insulated walls are formed. For the heat insulator 186, for example, rigid urethane foam, phenol foam, styrene foam, or the like is used. Use of hydrocarbon-based cyclopentane as the foaming material is better from the viewpoint of preventing global warming.

  The heat insulation box 180 is divided into a plurality of heat insulation sections, and has a configuration in which the upper part is a revolving door type and the lower part is a drawer type. From the top, there are a refrigerating room 188, a drawer type switching room 190 and an ice making room 192 arranged side by side, a drawer type vegetable room 194, and a drawer type freezing room 196. Each heat insulation section is provided with a heat insulation door via a gasket. From the top are the refrigerating room rotary door 198, the switching room drawer door 200, the ice making room drawer door 202, the vegetable room drawer door 204, and the freezer compartment drawer door 206.

  Moreover, the outer box 184 of the heat insulation box 180 is provided with the recessed part 208 which dented the top surface back. The refrigeration cycle includes a hermetic compressor 210 elastically supported in the recess 208, a condenser (not shown) provided on the side surface of the heat insulating box 180, a capillary 212 as a decompressor, and moisture removal. A dryer (not shown) to be performed, an evaporator 216 provided with a cooling fan 214 disposed in the vicinity on the back of the vegetable compartment 194 and the freezing compartment 196, and an intake pipe 218 are connected in an annular shape.

  About the refrigerator comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, the temperature setting and cooling method of each heat insulation section will be described. The refrigerator compartment 188 is normally set at 1 to 5 ° C. with the temperature not frozen for refrigerated storage as the lower limit.

  Switching room 190 can change temperature setting by a user's setting, and can be made into predetermined temperature setting from a freezer compartment temperature zone to refrigeration and a vegetable compartment temperature zone. In addition, the ice making chamber 192 is an independent ice storage chamber, and includes an automatic ice making device (not shown) to automatically produce and store ice. Although it is a freezing temperature zone for storing ice, it can also be set at a freezing temperature of −18 ° C. to −10 ° C., which is relatively higher than the freezing temperature zone for the purpose of storing ice.

  The vegetable room 194 is often set to 2 ° C. to 7 ° C., which is a temperature setting equal to or slightly higher than that of the refrigerator room 188. It is possible to maintain the freshness of leafy vegetables for a long period of time as the temperature is lowered so as not to freeze. The freezer compartment 196 is normally set at −22 to −18 ° C. for frozen storage, but may be set at a low temperature of −30 or −25 ° C., for example, to improve the frozen storage state.

  Each chamber is divided by a heat insulating wall in order to efficiently maintain different temperature settings. However, as a method of improving the heat insulating performance at a low cost, it is possible to perform foam filling with the heat insulating body 186 integrally. Compared to the use of a heat insulating member such as polystyrene foam, the heat insulating performance can be increased by about twice, and the storage volume can be increased by thinning the partition.

  Next, the operation of the refrigeration cycle will be described.

  The cooling operation is started and stopped by a signal from a temperature sensor (not shown) and a control unit according to the set temperature in the refrigerator. The hermetic compressor 210 performs a predetermined compression operation according to the instruction of the cooling operation, and the discharged high-temperature and high-pressure refrigerant gas is radiated by the condenser (not shown) to be condensed and liquefied, and the pressure is reduced by the capillary 212. It becomes a low-temperature and low-pressure liquid refrigerant and reaches the evaporator 216.

  By the operation of the cooling fan 214, heat is exchanged with the air in the cabinet, the refrigerant gas in the evaporator 216 is evaporated, and the low-temperature cold air after the heat exchange is distributed by a damper (not shown) or the like. Cooling is performed.

  The hermetic compressor 210 of the refrigerator that performs the above operation uses the hermetic compressor described in the first embodiment.

  That is, the outer peripheral surface of the piston 136 of the hermetic compressor 210 has a uniform gap with the inner peripheral surface of the cylinder 134, and a cylindrical seal portion 160 that forms a sliding surface, and a rear portion of the seal portion 160. And an extension portion 162 that forms the sliding surface that supports the lateral pressure and has the same radius as the seal portion 160, and a collection portion 164 that is a non-sliding surface that has a smaller radius than the seal portion 160 and the extension portion 162. And.

  As a result, the lubricating oil adheres to the collecting portion 164, and the collecting portion 164 is pulled back into the cylinder 134 as the piston 136 reciprocates, so that the lubricating oil 104 moves the sliding surface between the piston 136 and the cylinder 134. Lubricating can be performed more reliably, and the lubricating oil 104 can be reliably supplied to the seal portion 160, so that the airtightness of the compression chamber 148 at the seal portion 160 is also reliably maintained, By preventing the leakage of the refrigerant gas and providing the extension 162 behind the seal portion 160, the area of the sliding surface is reduced and the sliding loss is reduced while supporting the load in the side direction acting on the piston 136. The efficiency of the hermetic compressor 210 can be improved and the power consumption of the refrigerator can be reduced.

  Further, since the center of the width of the extension 162 is shifted to the main bearing 126 side from the center of the reciprocating movement of the piston 136, the inclination of the piston can be suppressed, and the piston contact per side can be reduced. Uneven wear can be suppressed.

  In addition, by supplying the lubricating oil 104 from the collection unit 164 and lubricating the sliding surface, it is possible to prevent wear of the sliding surface and improve the reliability of the hermetic compressor 210. The reliability of the refrigerator can be improved.

  As described above, the hermetic compressor according to the present invention improves efficiency and reliability by reducing the sliding loss of the piston while preventing the occurrence of wear on the sliding surface of the piston seal and extension. Therefore, the present invention can be widely applied not only to home electric refrigerator-freezers but also to air conditioners, vending machines and other freezers.

DESCRIPTION OF SYMBOLS 101,210 Sealed compressor 102 Sealed container 104 Lubricating oil 110 Electric element 112 Compression element 114 Stator 116 Rotor 120 Main shaft part 122 Eccentric shaft part 118 Shaft 124 Cylinder block 126 Main bearing 130 Oil supply mechanism 134 Cylinder 136 Piston 144 Connection means 160 Sealing part 162 Extension part 164 Collection part

Claims (5)

Lubricating oil is stored in a sealed container, and an electric element having a stator and a rotor and a compression element driven by the electric element are accommodated, and the compression element is a main shaft portion to which the rotor is fixed. A cylinder block including a shaft having a shaft and an eccentric shaft portion, a cylinder and a main bearing that supports the main shaft portion of the shaft, a piston inserted in a reciprocating manner inside the cylinder, and the piston And a connecting means for connecting the eccentric shaft portion and an oil supply mechanism provided on the shaft, and the piston has a uniform gap with the inner peripheral surface of the cylinder to form a sliding surface. A cylindrical seal portion and two extension portions located on both side surfaces behind the seal portion, having the same radius as the seal portion, and forming a sliding surface for supporting a lateral pressure, and the extension The piston at the center of the width of the part Hermetic compressor shifted on the main bearing side of the axial center of the reciprocating. 2. The hermetic compression according to claim 1, wherein the piston has a collecting portion formed behind the seal portion and the extension portion and formed by a non-sliding surface having a radius smaller than the radius of the seal portion and the extension portion. Machine. The piston is configured such that, when the piston moves toward the top dead center, the width of the extension portion of the piston on the side (load side) pressed against the inner peripheral surface of the cylinder by the connecting means is not pressed (the anti-load side). 3) The hermetic compressor according to claim 1 or 2, which is wider than a width of the extension portion of the piston by 1.2 times or more. The hermetic compressor according to any one of claims 1 to 3, wherein the electric element is driven by an inverter circuit at a plurality of rotation speeds. A refrigerator using the hermetic compressor according to any one of claims 1 to 4.

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