JP2009062864A - Hermetic compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive assembling method of a reciprocating compressor using a ball joint. <P>SOLUTION: This hermetic compressor has a connecting means 236 for connecting a piston 230 and an eccentric shaft part 222 and using the ball joint in a connecting part 244 with the piston 230. The connecting means 236 has a rod part 238 having a ball part 242 on one end and having a ring part 240 on the other end. The piston 230 has a spherical surface seat 232 inside. Since the connecting part 244 is formed by caulking a side wall of the spherical surface seat 232 by allowing the ball part 242 to abut on the spherical surface seat 232 in a state of storing the piston 230 in a compression space 248, cost reduction and high efficiency can be achieved by a simple assembling method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a compressor mainly used in a refrigeration cycle such as an electric refrigerator-freezer.

  Conventionally, as a compressor using a ball joint as a means for connecting the piston and the eccentric shaft portion, there is one in which the cylinder and the bearing are configured as separate parts in order to assemble the piston and the connecting means assembled in advance to the compression element ( For example, see Patent Document 1). In addition, there is one that employs a method of dividing the connecting means (see, for example, Patent Document 2).

  Hereinafter, a conventional compressor will be described with reference to the drawings.

  FIG. 13 is a longitudinal sectional view of a conventional compressor described in Patent Document 1, and FIG. 14 is a top view of a conventional piston.

  In FIGS. 13 and 14, the lubricating oil 4 is stored at the bottom of the sealed container 2, and the compressor body 6 is elastically supported by the suspension container 8 with respect to the sealed container 2.

  The compressor body 6 includes an electric element 10 and a compression element 12 disposed above the electric element 10. The electric element 10 includes a stator 14 and a rotor 16.

  The shaft 18 of the compression element 12 includes a main shaft portion 20 and an eccentric shaft portion 22. The main shaft portion 20 is rotatably supported by a bearing portion 26 of a block 24 and the rotor 16 is fixed. Further, the shaft 18 is provided with an oil supply passage 28 including a spiral groove provided on the surface of the main shaft portion 20.

  The piston 30 has a spherical seat 32 having a substantially hemispheric inner surface inside, and is reciprocally inserted into a cylinder 34 having a cylindrical inner surface attached to the upper surface of the block 24 using a bolt (not shown). Is done.

  In the connecting means 36, a ring portion 40 and a ball portion 42 formed of a steel ball are joined to both ends of the rod portion 38 by welding so that the shaft portion and the rod portion 38 coincide with each other. Further, the ring portion 40 is fitted and inserted into the eccentric shaft portion 22, and the ball joint portion 44 is formed by the ball portion 42 on the spherical seat 32 of the piston 30, so that the piston 30 and the rod portion 38 swing with each other. Connected as possible.

  The cylinder 34 and the piston 30 form a compression chamber 48 together with the valve plate 46 attached to the opening end surface of the cylinder 34. Further, the cylinder head 50 is fixed so as to cover the valve plate 46 and cover it.

  The suction muffler 52 is molded from a resin such as PBT, forms a silencing space inside, and is attached to the cylinder head 50.

  About the compressor comprised as mentioned above, the operation | movement is demonstrated below.

  When the electric element 10 is energized, the rotor 16 rotates together with the shaft 18 by the rotating magnetic field generated in the stator 14. By the rotation of the main shaft portion 20, the eccentric motion of the eccentric shaft portion 22 is transmitted to the piston 30 via the connecting means 36, and the piston 30 reciprocates in the cylinder 34.

  The refrigerant returned from the refrigeration cycle (not shown) outside the hermetic container 2 is introduced into the compression chamber 48 via the suction muffler 52, and is compressed by the piston 30 in the compression chamber 48, and the compressed refrigerant is sealed. It is sent to a refrigeration cycle (not shown) outside the container 2.

  Next, an assembling procedure of the compression element 12 will be described focusing on the connecting means 36.

  First, the piston 30 and the ball portion 42 of the connecting means 36 are assembled in advance. Specifically, the ball joint type connecting portion 44 is formed by caulking the side wall of the spherical seat 32 with the ball portion 42 housed in the spherical seat 32 of the piston 30.

  Next, the main shaft portion 20 of the shaft 18 is inserted into the bearing portion 26 of the block 24, and the ring portion 40 of the connecting means 36 is inserted into the eccentric shaft portion 22.

  Finally, the cylinder 34 is fixed to the block 24 with the piston 30 inserted into the cylinder 34.

  Next, another conventional compressor will be described with reference to the drawings.

  FIG. 15 is an enlarged view of the main part in the vicinity of the connecting means of the conventional compressor described in Patent Document 2.

  In FIG. 15, the block 124 and the cylinder 134 are integrally formed. A ball portion 142 is attached to one end of the rod portion 138 of the connecting means 136, and a connection projection 138a is formed at the other end. A connection hole 140 a is provided on the outer peripheral surface of the ring portion 140.

  A method for assembling the compressor configured as described above will be described focusing on the connecting means 136.

  First, the piston 30 and the ball part 142 are connected in advance to form a ball joint type connection part 144.

  Then, the ring portion 140 is inserted into the eccentric shaft portion 22 of the shaft 18 inserted into the bearing portion 126 of the block 124, and the piston 30 is inserted into the cylinder 134.

Finally, the piston 30 and the eccentric shaft portion 22 are connected by connecting the connecting protrusion 138a of the rod portion 138 and the connecting hole 140a of the ring portion 140, and the rotational motion of the shaft 18 is converted into the reciprocating motion of the piston 30. It becomes possible.
JP 59-040063 A Japanese Patent Laid-Open No. 62-294784

  However, in order to use the ball joint type coupling means 36 and 136 in the conventional configuration, the block 24 and the cylinder 34 are separate parts, or the rod part 138 and the ring part 140 of the coupling means 136 are separate parts. In other words, it is necessary to divide any part for assembly. Therefore, in order to assemble the divided parts, the weight increases to form the mounting surface, the processing of the mounting surface and screw holes for fixing, and parts such as screws for fixing the parts are also added. Since it is necessary, it has a problem of high cost.

  In addition, since the parts are divided, the dimensional accuracy after assembly is lowered, and there is a problem that the performance is lowered due to, for example, an increase in the clearance volume at the top dead center.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a low-cost and high-efficiency compressor by assembling compression elements by a simple method.

  In order to solve the above-described conventional problems, the hermetic compressor according to the present invention has a side wall of a spherical seat in which a connecting means is brought into contact with the spherical seat in a state where a piston having a spherical seat is accommodated in the compression chamber. Since the connecting portion is formed by caulking, the cost can be reduced by minimizing the division of the parts, and the lowering of the assembly accuracy of each part can be suppressed and the lowering of the performance can be prevented.

  In the hermetic compressor according to the present invention, since the connecting portion is formed with the piston housed in the compression chamber, the division of the parts is minimized, the cost is reduced, and the deterioration of the assembly accuracy of each part is suppressed. A decrease in performance can be prevented.

  The invention according to claim 1 stores lubricating oil in an airtight container, accommodates an electric element including a stator and a rotor, and a compression element driven by the electric element. A shaft having a main shaft portion and an eccentric shaft portion, a cylinder that forms a compression chamber, a bearing portion that supports the main shaft portion of the shaft, a piston that reciprocates in the compression chamber, the piston, and the eccentric shaft And a connecting means using a ball joint at the connecting portion with the piston, the connecting means comprises a rod portion having a ball portion at one end and a ring portion at the other end, The piston has a spherical seat inside, and in a state where the piston is housed in the compression chamber, the ball portion is brought into contact with the spherical seat and the side wall of the spherical seat is caulked to form the connecting portion. What , It is possible to prevent a decrease in suppressing a decrease in assembly accuracy of each part performance can be suppressed cheaper costs by suppressing division of the parts to a minimum.

  According to a second aspect of the present invention, in the first aspect of the present invention, the height of the ball portion in the axial direction of the shaft is 1/3 or less of the diameter of the compression chamber. Since the ball part can be arranged at the center of the piston after the operation is performed, the load due to the pressure in the compression chamber acts symmetrically with respect to the ball part, and no moment is generated to rotate the piston. Since tilting with respect to the cylinder can be prevented, in addition to the effect of the invention according to claim 1, it is possible to further prevent the end portion of the piston from being strongly pressed against the cylinder, and friction at this end portion can be prevented. In addition to reducing the loss caused by this, it is possible to prevent the occurrence of wear, and the efficiency is high and the reliability is improved.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the rod portion is sandwiched between two divided molds and the mold is pressed by pressing the mold against the side wall of the spherical seat. Therefore, by inserting the mold along the rod portion into the back surface of the piston, the mold can be inserted straight and the joint can be securely crimped in the cylinder. Alternatively, in addition to the effects of the invention described in claim 2, by further preventing the caulking failure due to the oblique insertion of the mold, the occurrence of noise vibration and wear due to rattling at the joint portion is prevented. Can be prevented and reliability is improved.

  The invention according to claim 4 is the invention according to claim 3, wherein the rod part is sandwiched so that the dividing direction of the mold coincides with the axial direction of the shaft. Even without complicated movements such as rotating the mold, the mold can be inserted into the back of the piston without interfering with the block and shaft, and the mold can be pushed with a simple structure, In addition to the effect of the invention according to claim 3, since the caulking of the joint can be reliably performed in the cylinder, the generation of noise vibration and the occurrence of wear due to the rattling of the joint can be prevented, Reliability is improved.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a concave portion is provided on a surface of the mold that contacts the ball, and lubricating oil is supplied between the side wall of the spherical seat facing the concave portion and the ball. 5. A passage is formed, and the lubricating oil scattered from the eccentric shaft portion flows in from the lubricating oil supply passage, and oil can be supplied to the ball portion and the sliding portion of the spherical seat. In addition, since an oil film is further formed on the sliding portion, the occurrence of wear can be prevented, so that the reliability is improved.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the cylinder is offset so that the axis of the compression chamber does not intersect with the axis of the main shaft, and the rod The rod part is offset so that the axis of the part does not intersect the center of the ring part, and the offset direction of the cylinder and the rod part is the same, and the axis of the compression chamber and the main shaft part is offset. Since the loss can be reduced by reducing the load by which the piston is pressed against the cylinder inner wall during compression, in addition to the effects of the invention according to any one of claims 1 to 5, Efficiency is improved by reducing the friction of the cylinder inner wall.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the ball portion of the connecting means is formed with a flat portion on the side opposite to the bearing portion. Since the diameter can be increased and the surface pressure of the contact portion between the ball portion and the spherical seat can be reduced, in addition to the effect of the invention according to any one of claims 1 to 6, the ball portion is further reduced. And more reliably prevent wear on the contact portion of the spherical seat and improve reliability.

  The invention according to claim 8 is the invention according to any one of claims 1 to 8, wherein R600a is used as the refrigerant, and the cylinder volume is larger than the capacity as compared with other refrigerants. In the compressor using the R600a refrigerant, which has a large piston, a simple structure using a ball joint can reduce the size and weight of moving parts, and the piston is low because the operating pressure is low even if the cylinder volume is large. The load acting on R600a is the same, and even if a ball of 1/3 or less of the cylinder inner diameter is used, a ball with a larger diameter can be used for the same load as the piston diameter is larger. Since the surface pressure of the contact portion of the seat can be reduced, in addition to the effect of the invention according to any one of claims 1 to 8, vibration is further reduced by reducing the size and weight of the movable parts. It is possible to reduce, it is possible to ensure reliability by preventing wear of the contact portion of the ball portion and the spherical seat.

  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)
1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention, FIG. 2 is a rear view of a piston, FIG. 3 is a sectional view taken along line AA of FIG. 2, and FIG. FIG. 5 is a cross-sectional view taken along line -B, FIG. 5 is a cross-sectional view of the main part of the compression element, FIG. 6 is a schematic view showing the assembly method of the compression element, FIG. 7 is a perspective view of the mold, and FIG. FIG. 9 is a schematic view showing a state of scattering of lubricating oil, and FIG. 10 is a schematic view showing details of the contact portion.

  1 to 5 and 8, the lubricating oil 204 is stored in the bottom of the sealed container 202, and the compressor body 206 including the electric element 210 and the compression element 212 driven by the electric element 210 is accommodated. As R600a (isobutane) having a low warming potential. The compressor body 206 is suspended inside the sealed container 202 by a suspension spring 208. A power supply terminal 203 for supplying power to the electric element 210 is attached to the sealed container 202.

  First, the electric element 210 will be described.

  The electric element 210 includes a stator 214 formed by winding a copper coil around an iron core in which thin plates are laminated, and a rotor 216 disposed on the inner diameter side of the stator 214. Is connected to a power supply (not shown) outside the compressor via a power supply terminal 203 by a conductive wire.

  Next, the compression element 212 will be described.

  The compression element 212 is disposed above the electric element 210.

  The shaft 218 constituting the compression element 212 includes a main shaft portion 220 and an eccentric shaft portion 222 that is eccentric from the main shaft portion 220 by an eccentric amount E.

  The shaft 218 includes an oil supply passage 228 formed of a spiral groove or the like provided on the surface of the main shaft portion 220. The oil supply passage 228 opens from the introduction portion 228 a that opens to the lubricating oil 204 at the lower end of the shaft 218 to the space in the sealed container 202 at the upper end of the eccentric shaft portion 222 via a spiral groove of the main shaft portion 220. It communicates with the portion 228b.

  An oil supply protrusion 258, which is a protrusion provided in the direction opposite to the upper end surface of the eccentric shaft part 222, that is, the bearing part 226, is provided adjacent to the opening 228 b of the oil supply path 228 on the upper end surface of the eccentric shaft part 222. . In the oil supply protrusion 258, the shaft center side of the eccentric shaft portion 222 is inclined in a direction away from the rotation center of the main shaft portion 220 from the opening 228b. In addition, the height of the apex portion of the oil supply protrusion 258 with respect to the horizontal plane substantially coincides with the upper end portion of the compression chamber 248. Further, the outer peripheral portion of the oil supply protrusion 258 forms the same surface as the outer peripheral portion of the eccentric shaft portion 222.

  The block 224 includes a bearing portion 226 having a cylindrical inner surface, and the main shaft portion 220 is rotatably inserted into and supported by the bearing portion 226.

  The block 224 includes a cylinder 234 that is a cylindrical hole, and the cylinder 234 forms a compression chamber 248 together with the piston 230 and the like. The cylinder 234 is arranged in an offset state by an offset amount C so that the axis of the compression chamber 248 does not intersect with the axis of the main shaft 220. The direction of the offset of the cylinder 234 is the same as the direction of the eccentric shaft portion 222 with respect to the center of the main shaft portion 220 during the compression stroke.

  The piston 230 has a cup-like shape with an open back surface, and has a hemispherical spherical seat 232 on the inner diameter side of the back surface. The piston 230 is made of carbon steel having a carbon content of about 0.10 to 0.20%, and is manufactured by forging.

  A valve plate 246 and a cylinder head 250 are fixed to the end face of the cylinder 234, and the suction muffler 252 is molded from a resin such as PBT, forms a sound deadening space, and is attached to the cylinder head 250.

  A ring part 240 and a ball part 242 are joined to both ends of the rod part 238 of the connecting means 236 by welding. The ball portion 242 is good in terms of strength and accuracy when using a ball bearing steel ball shown in JIS B1501, etc., and is easily available and inexpensive.

  Further, the height DB of the ball portion 242 and the height H of the ring portion 240 are both ３ or less with respect to the inner diameter D of the cylinder 234.

  Further, the axis of the rod portion 238 is offset with respect to the axis of the ring portion 240, and this direction is the same as the direction in which the cylinder 234 is offset with respect to the axis of the main shaft 220, and the offset amount Is the same C.

  As a result, when the eccentric shaft portion 222 is positioned in the direction opposite to the cylinder head 250 in the axial direction of the compression chamber 248 with respect to the main shaft portion 220, that is, when the piston 230 is at the bottom dead center position, the rod portion 238 and the compression chamber 248 are disposed. The axes are aligned.

  Next, a method for assembling the compression element 212 will be described with reference to FIGS.

  First, the main shaft portion 220 of the shaft 218 is inserted into the bearing portion 226 and the piston 230 is inserted into the cylinder 234. The tetrafluoroethylene resin ring 256 is attached to the inner surface of the side wall of the spherical seat 232 of the piston 230 in advance.

  Next, the ball portion 242 is inserted into the cylinder 234 while the connecting means 236 is inclined, and then the oil supply protrusion 258 at the tip of the eccentric shaft portion 222 is inserted into the ring portion 240 ((1) in FIG. 6). At this time, a pressing member 262 having an outer diameter equal to or smaller than the outer diameter of the piston 230 is brought into contact with the end face of the piston 230 on the compression chamber 248 side.

  In the state immediately before the ring portion 240 is inserted into the eccentric shaft portion 222, the eccentric shaft portion 222 and the axis of the ring portion 240 need to be parallel, but the height DB of the ball portion 242 and the height of the ring portion 240 are required. Since H is 1/3 or less of the inner diameter D of the cylinder 234, the ball portion 242 can be assembled without interfering with the inner surface of the cylinder 234 ((2) in FIG. 6).

  Next, by moving the connecting means 236 downward by the height DB of the ball portion 242, the center position of the ball portion 242 and the axis of the compression chamber 248 coincide (FIG. 6 (3)).

  In addition, it is possible to assemble while preventing the sliding portion of the inner surface of the ring portion 240 from being damaged by inserting the oil supply protrusion portion 258 along the inner surface of the ring portion 240 into the eccentric shaft portion 222.

  Next, by moving the pressing member 262 in the direction of the bearing portion 226, the piston 230 is moved so that the ball portion 242 is accommodated in the spherical seat 232 provided on the back surface of the piston 230, and the ball portion 242 and the spherical seat 232 are moved. (Fig. 6 (4)).

  Strictly speaking, the inner surface of the spherical seat 232 is not a spherical surface, but is a curved surface having a radius 10 to 20% larger than that of the ball portion 242, and the spherical seat 232 and the ball portion 242 are in linear contact with the annular contact portion 233. It has become.

  Next, the taper portion 260d of the two molds 260 is arranged to face the piston 230 and the rod portion 238 is sandwiched between them. After the divided surfaces 260a of the mold 260 are pressed against each other, the mold 260 is combined. It moves to the anti-bearing part 226 direction along the rod part 238, and the metal mold | die 260 is inserted in the back surface of the piston 230 (FIG. 6 (4), FIG. 8).

  Next, a load is applied by sandwiching the piston 230 and the ball portion 242 between the mold 260 and the pressing member 262. As a result, the ball portion 242 and the piston 230 can be caulked and connected by being plastically deformed so that the side wall of the spherical seat 232 is bent inward (FIG. 6 (5)).

  Thereafter, after the mold 260 is moved to the ring part 240 side behind the piston 230 along the rod part 238, the mold 260 is divided by the dividing surface 206a and removed from the rod part 238, and the pressing member 262 is also removed. (FIG. 6 (6)).

  With the above assembly method, the connection between the connecting means 236 and the piston 230 is completed.

  Among the above-described assembly methods, the caulking work will be supplementarily described below.

  As shown in FIG. 7, the mold 260 has a shape in which a cylinder is divided into two by a dividing surface 206 a, a cylindrical portion 260 b in which the rod portion 238 is sandwiched on the dividing surface 206 a side, and a spherical surface portion having a larger radius than the ball portion 242. 260c and a taper portion 260d extending to the upper end of the mold 260 are provided.

  Further, a concave portion 260e is provided in the spherical portion 260c of the mold 260. Since the recessed portion 260e is located at the ridge line portion between the dividing surface 206a and the spherical surface portion 260c, the edge portion of the mold 260 is easily processed, and the accuracy and quality during production are improved.

  First, such a mold 260 is disposed on the ring portion 240 side of the rod portion 238 so as to sandwich the rod portion 238. Since the mold 260 is divided into two by a plane including the central axis, the mold 260 can be easily arranged at a predetermined position even when the connecting means 236 is assembled to the block 224.

  Further, since the mold 260 is divided in the axial direction of the shaft 218, the rod part 238 is sandwiched from the side surface so that the mold 260 is rotated around the rod part 238 when the mold 260 is inserted. There is no need to move, and the mold 260 can be arranged more easily by only linear movement.

  Furthermore, since the mold 260 is inserted linearly, the structure of the caulking device is simplified, so that a load can be reliably applied to the mold 260 and the caulking is not insufficient. In addition, no backlash occurs in the connecting portion 244, and generation of noise vibration and wear can be prevented.

  Further, productivity is improved because the operation when caulking is simple.

  As described above, the ball joint type connecting portion 244 in which the piston 230 and the rod portion 238 are connected in a swingable state can be assembled with the piston 230 inserted into the cylinder 234.

  Further, although the compression chamber 248 is offset with respect to the main shaft portion 220 axis, the rod portion 238 is similarly offset with respect to the axial center of the ring portion 240, so that the rod portion 238 and the compression chamber 248 can be securely connected. It is possible to prevent the occurrence of caulking failure due to tilting of the mold 260 pushed along the rod portion 238, and the generation of noise vibration and wear due to rattling at the joint portion. , Reliability can be improved.

  Further, since the recess 260e is provided on the surface of the mold 260 that contacts the side wall of the spherical seat 232, a gap is formed between the side wall of the spherical seat 232 that faces the recess 260e and the ball portion 242, and a lubricating oil supply passage is provided. 254 is formed.

  As shown in FIG. 4, in portions other than the lubricating oil supply passage 254, a tetrafluoroethylene resin ring 256 is interposed between the ball portion 242 and the portion of the side wall of the spherical seat 232 that is caulked, and is in close contact with each other. There are almost no gaps.

  However, as shown in FIG. 3, in the lubricating oil supply passage 254, a gap is formed between the side wall of the spherical seat 232 and the ball portion 242.

  The recess 260e is formed on the dividing surface 206a of the mold 260, and the mold 260 is divided in the axial direction of the shaft 218. Therefore, the lubricating oil supply passage 254 is formed above and below the connecting portion 244.

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

  When the electric element 210 is energized from the power terminal 203, the rotor 216 rotates together with the shaft 218 by the magnetic field generated in the stator 214. As the main shaft portion 220 rotates, the eccentric shaft portion 222 rotates in an eccentric state, and this eccentric motion is converted into a reciprocating motion via the connecting means 236, causing the piston 230 to reciprocate within the cylinder 234. The compression operation is performed by changing the volume of the compression chamber 248 by the reciprocating motion of the piston 230.

  In this compression operation, the refrigerant in the hermetic container 202 is sucked into the compression chamber 248 through the suction muffler 252, then the refrigerant in the compression chamber 248 is compressed, and finally the compressed high-temperature and high-pressure refrigerant is discharged. The operation is repeated alternately.

  When the refrigerant is compressed in the compression chamber 248, the piston 230 is pushed out by the eccentric shaft portion 222 through the connecting means 236 in the direction of the top dead center, but the eccentric shaft portion 222 is swung with the eccentric amount E. Therefore, the piston 230 is pushed in an oblique direction with respect to the axis, and a force that is pushed against the side wall of the cylinder 234 acts.

  However, in the present embodiment, the compression chamber 248 is displaced (offset) in the same direction as the eccentric shaft portion 222 during compression with respect to the center of the main shaft portion 220, so that the load on the piston 230 becomes the largest. During compression, the piston 230 can be pushed in the direction of top dead center in a state close to straight. Therefore, the load with which the piston 230 is pressed against the cylinder 234 can be reduced, and the friction generated at the sliding portion is also reduced, so that the loss can be reduced and the efficiency is improved.

  Further, as shown in FIG. 9, the lubricating oil 204 is conveyed from the bottom of the sealed container 202 to the compression element 212 as the shaft 218 rotates. The lubricating oil 204 carried to the opening 228b at the upper end of the eccentric shaft 222 rises upward along the inclined surface 258a of the oil supply protrusion 258 by the centrifugal force and scatters from the oil supply protrusion 258 tip 258b.

  Since the height of the oil supply protrusion 258 coincides with the upper end of the compression chamber 248, as shown by 204a in FIG. 9, the lubricating oil 204 scattered in a substantially horizontal direction by the centrifugal force adheres to the upper end of the inner wall of the cylinder 234. . The lubricating oil 204 adhering to the upper part of the cylinder 234 flows downward due to gravity, so that the entire outer surface of the piston 230 and the entire inner wall of the cylinder 234 can be sufficiently lubricated, thereby preventing wear due to insufficient lubrication. , Reliability can be improved.

  Further, the lubricating oil 204 overflowing from the sliding part of the ring part 240 is similarly scattered as shown in 204b and 204c in FIG. At this time, since the lubricating oil supply path 254 is provided above and below the connecting portion 244, the lubricating oil 204 is supplied to the sliding portions of the ball portion 242 and the spherical seat 232 to perform lubrication, so that wear due to insufficient lubrication occurs. And can improve reliability.

  In addition, for example, the processing accuracy such as the perpendicularity of the bearing portion 226 and the cylinder 234 is low, and even if the shaft 218 is inclined with respect to the bearing portion 226, the inclination can be absorbed by the ball joint portion. It is possible to prevent the cylinder 234 from being inclined and to prevent the end of the piston 230 from being pressed against the cylinder 234. Therefore, wear due to piece contact can be prevented, and manufacturing can be easily and inexpensively.

  Also, by assembling the ball joint connecting portion 244 in the cylinder 234, for example, additional parts such as screws required in the conventional structure for mounting the cylinder, which is a separate part from the block, and for mounting the block and the cylinder Since it is not necessary to process the provided smooth processed surface or screw holes, a lightweight and inexpensive hermetic compressor can be manufactured.

  Furthermore, since it is not necessary to divide the parts such as the connecting means 236 for assembly, the number of parts does not decrease and the accuracy of the combination does not decrease. For example, the performance decreases due to an increase in clearance volume at the top dead center. Can be prevented.

  Further, since the diameter of the ball portion 242 is set to 1/3 or less of the diameter of the compression chamber 248, the ball portion 242 can be disposed at the center of the piston 230 after assembly. For this reason, the pressure of the compression chamber 248 acting on the end face of the piston 230 acts symmetrically on the ball portion 242, and a moment that causes the piston 230 to rotate in the cylinder 234 is not generated. Accordingly, the end of the piston 230 can be prevented from being strongly pressed against the inner wall of the cylinder 234, loss due to friction at this end can be reduced, and wear can be prevented from occurring, so that performance and reliability can be improved. .

  Furthermore, the R600a refrigerant has a lower cylinder capacity than the capacity of other refrigerants such as HFC134a, but its capacity is larger. Therefore, the piston 230 and the cylinder 234 are larger, the weight of the reciprocating motion part is increased, and the vibration is increased. There is a problem that the cost increases due to the cause or the compression element 212 becoming large. However, according to the present invention, a simple structure using a ball joint can reduce the size and weight, reduce the cost, and reduce the vibration especially by reducing the weight of the movable parts.

  Further, when the diameter of the ball portion 242 is reduced, the area of the contact portion 233 between the ball portion 242 and the spherical seat 232 is reduced, so that the surface pressure is increased and wear is likely to occur. Even if the diameter of 242 is small, it is possible to ensure reliability.

  Hereinafter, the contact portion 233 of the ball portion 242 and the spherical seat 232 will be described in detail with reference to FIG.

  The spherical seats 232 have a radius that is about 10% larger than the radius R of the ball portion 242 and are in line contact with each other at the contact portion 233. If the direction of the contact portion 233 relative to the axial direction of the piston 230 is θ, the contact portion 233 forms a circle centered on the axial center of the piston 230, and the circumferential length L is expressed by (Equation 1). The

  Here, when the acting force on the piston 230 is W and the contact load per unit width of the contact portion 233 is F, the contact load F is expressed by (Equation 2) from the balance of the axial load of the piston 230. .

  Therefore, regardless of the size of the ball portion 242, it can be seen that the contact load F is minimized when θ is about 45 degrees.

  Further, the larger the radius R of the ball portion 242 is, the smaller the contact load F of the contact portion 233 is.

  When R600a is used as a refrigerant, the operating pressure is low even if the cylinder volume is large, so the load W acting on the piston 230 is equivalent to that of other refrigerants, but the diameter (2R) of the ball portion 242 is relative to the inner diameter D of the cylinder 234. Therefore, the radius R of the ball portion 242 can be made larger in R600a than in other refrigerants. Therefore, in R600a, the contact load F per unit width of the contact portion 233 can be reduced.

  Further, the contact portion 233 will be described in detail. Although the ball portion 242 and the spherical seat 232 are in line contact, the radius of curvature of the spherical seat 232 is 10% larger than the radius R of the ball portion 242. Assuming 1R, the contact width b based on Hertz's contact theory with respect to the contact load F per unit width is expressed by (Equation 3).

  That is, the contact width b is proportional to the contact load F and the square root of the radius R. When the radius R of the ball portion 242 is large, not only the contact load F is decreased but also the contact width b is increased.

  Therefore, when R600a is used, the radius R of the ball portion 242 is increased, so that the contact load F per unit width of the contact portion 233 in line contact is reduced, while the contact width b is increased by increasing the radius R. Therefore, since the surface pressure is reduced, the wear of the sliding portion can be prevented and the reliability is improved.

  Further, by providing the flat portions 264 at the upper and lower ends of the ball portion 242, the curvature radius R of the ball portion 242 is increased while maintaining the height DB of the ball portion 242 at 1/3 or less of the inner diameter D of the cylinder 234. be able to.

  Specific examples thereof are shown in FIGS.

  11 is a longitudinal sectional view of another compressor, and FIG. 12 is a sectional view of the piston of FIG.

  By configuring as shown in FIGS. 11 and 12, the area of the contact portion 233 between the ball portion 242 and the spherical seat 232 can be increased, so that the surface pressure of the contact portion 233 is lowered to prevent the occurrence of wear. Can improve reliability.

  Furthermore, the connecting means 236 swings in the horizontal direction with respect to the piston 230, but hardly moves in the vertical direction. Therefore, the swinging movement is hindered by the flat portion 264, or the flat portion is positioned at the position of the contact portion 233. Since H.264 does not move, there is no problem that the sliding area becomes small or wear occurs.

  As described above, since the hermetic compressor according to the present invention has a simple structure and can be manufactured at low cost, it is not limited to an electric refrigerator-freezer for home use, but is an air conditioner, a vending machine, other refrigeration apparatuses, and the like. Widely applicable to.

1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. Rear view of piston in the same embodiment Sectional drawing in the AA line of FIG. Sectional drawing in the BB line of FIG. Sectional drawing of the principal part of the compression element in the embodiment The schematic diagram which shows the assembly method of the compression element in the embodiment The perspective view of the metal mold | die in the embodiment The top view which shows the pressing state of the metal mold | die in the embodiment Schematic diagram showing the state of lubricant scattering in the same embodiment Schematic diagram showing details of contact area Longitudinal sectional view of another compressor in the same embodiment Sectional view of the piston of FIG. Vertical section of a conventional compressor Top view of conventional piston Enlarged view of the main parts near the connecting means of a conventional compressor

Explanation of symbols

202 Sealed container 204 Lubricating oil 210 Electric element 212 Compression element 214 Stator 216 Rotor 218 Shaft 220 Main shaft part 222 Eccentric shaft part 226 Bearing part 228 Oil supply passage 230 Piston 232 Spherical seat 234 Cylinder 236 Connecting means 238 Rod part 240 Ring part 242 Ball portion 244 Connection portion 248 Compression chamber 254 Lubricating oil supply passage 258 Oil supply protrusion 260 Mold 260e Recess 264 Flat portion

Claims (9)

  The lubricating oil is stored in an airtight 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 has a main shaft portion and an eccentric shaft portion. A shaft, a cylinder that forms a compression chamber, a bearing portion that supports the main shaft portion of the shaft, a piston that reciprocates in the compression chamber, and the piston and the eccentric shaft portion; Connecting means using a ball joint in the connecting part, the connecting means comprising a rod part having a ball part at one end and a ring part at the other end, and the piston having a spherical seat inside. In a state where the piston is housed in the compression chamber, the ball portion is brought into contact with the spherical seat and the side wall of the spherical seat is caulked to form the hermetic compressor.   The hermetic compressor according to claim 1, wherein the height of the ball portion in the axial direction of the shaft is 1/3 or less of the diameter of the compression chamber.   3. The hermetic compressor according to claim 1, wherein the rod portion is sandwiched between two molds and the mold is caulked by pressing the mold against a side wall of a spherical seat.   The hermetic compressor according to claim 3, wherein the rod portion is sandwiched so that the dividing direction of the mold coincides with the axial direction of the shaft.   5. The hermetic compressor according to claim 4, wherein a concave portion is provided on a surface of the die that contacts the ball, and a lubricating oil supply passage is formed between the side wall of the spherical seat facing the concave portion and the ball.   The cylinder is offset so that the axis of the compression chamber does not intersect with the axis of the main shaft, and the rod is offset so that the axis of the rod does not intersect with the center of the ring. The hermetic compressor according to any one of claims 1 to 5, wherein the offset directions are the same.   The hermetic compressor according to any one of claims 1 to 6, wherein the ball portion of the connecting means is formed with a flat portion on the side opposite to the bearing portion.   An oil supply passage having a lower end communicating with the lubricating oil and having the other end opened into the sealed container at the end surface of the eccentric shaft portion, and an end surface of the eccentric shaft portion projecting from the end surface of the eccentric shaft portion to the opposite bearing portion side 8. The oil supply protrusion according to claim 1, further comprising an oil supply protrusion that scatters the lubricating oil guided to the outer periphery of the compression chamber using a centrifugal force generated by rotation of the shaft. Hermetic compressor.   The hermetic compressor according to any one of claims 1 to 8, wherein R600a is used as a refrigerant.