US20120183419A1 - Hermetic compressor - Google Patents
Hermetic compressor Download PDFInfo
- Publication number
- US20120183419A1 US20120183419A1 US13/498,791 US201013498791A US2012183419A1 US 20120183419 A1 US20120183419 A1 US 20120183419A1 US 201013498791 A US201013498791 A US 201013498791A US 2012183419 A1 US2012183419 A1 US 2012183419A1
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- United States
- Prior art keywords
- piston
- recessed
- cylindrical hole
- dead center
- hermetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/02—Lubrication
- F04B39/0223—Lubrication characterised by the compressor type
- F04B39/023—Hermetic compressors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/0005—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00 adaptations of pistons
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/02—Lubrication
- F04B39/0207—Lubrication with lubrication control systems
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/02—Lubrication
- F04B39/0223—Lubrication characterised by the compressor type
- F04B39/0276—Lubrication characterised by the compressor type the pump being of the reciprocating piston type, e.g. oscillating, free-piston compressors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/02—Lubrication
- F04B39/0284—Constructional details, e.g. reservoirs in the casing
- F04B39/0292—Lubrication of pistons or cylinders
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/12—Casings; Cylinders; Cylinder heads; Fluid connections
- F04B39/122—Cylinder block
Definitions
- the present invention relates to a hermetic-type compressor for use in a refrigeration cycle system such as a refrigerator freezer.
- a reciprocation-type hermetic compressor has, as a compression mechanism, a cylinder forming a cylindrical compression chamber, a cylindrical piston, and a connecting rod.
- the piston reciprocates in the cylinder.
- an eccentric shaft of a shaft is connected to the piston via a piston pin.
- the shaft is fixed to the shaft center of a rotor of a motor, and the compression mechanism is operated by the rotation of the rotor.
- a gap is necessary between the inner peripheral face of the cylinder and a sliding face of the piston so that the faces slide each other.
- a blowby gas as a leaked high-temperature high-pressure refrigerant gas compressed in the compression chamber is generated, and the compression efficiency deteriorates.
- the gap is small, a sliding loss increases, and input-output efficiency deteriorates.
- FIGS. 16A and 16B are cross sections of a compression part of a conventional hermetic-type compressor described in the patent literature 1.
- FIG. 16A shows a state where the piston is positioned in the bottom dead center
- FIG. 16B shows a state where the piston is positioned in the top dead center.
- Cylinder block 14 includes cylinder 16 having a center axis in an almost horizontal direction. Piston 23 inserted in an almost horizontal direction is connected to connecting rod 26 via a piston pin (not shown), thereby constructing piston assembly 23 A. At an end face (an end face on the right side in the drawing) of cylinder 16 on the side opposite to connecting rod 26 , a valve plate (not shown) is attached. By piston 23 , cylinder 16 , and the valve plate constructed as described above, compression chamber 15 is formed. Piston 23 reciprocates in an almost horizontal direction in cylinder 16 via connecting rod 26 by eccentric motion of an eccentric shaft (not shown) of a shaft (not shown).
- the inner face of cylinder 16 is formed so as to have tapered part 17 whose inner diameter dimension increases from Dt to Db (>Dt) from a some midpoint on the side where piston 23 is positioned in the top dead center toward the side where piston 23 is positioned in the bottom dead center.
- Piston 23 is formed so that its outer diameter dimension is almost the same in full length. Consequently, around the top dead center where the pressure in compression chamber 15 is high, the gap in the sealing part of piston 23 is reduced, and blow-by gas is prevented. On the other hand, around the bottom dead center, the gap increases, so that sliding loss can be reduced.
- piston 23 constructed as described above repeats reciprocating while always slightly vibrating in all directions in the gap with the inner face of cylinder 16 for the following reason.
- a dynamic compressive load the inertia force and gravity of movable members such as piston 23 and connecting rod 26
- a piston lateral pressure load generated by converting the rotational motion to the reciprocating motion act on piston 23 .
- Forces such as sliding resistance of the sliding part exert influences one another, and act on piston 23 while the directions and magnitudes of the forces are changing.
- Such an action is also a factor of slight vibrations in all directions of piston in the gap with the inner face of cylinder 16 .
- the structure that entire piston 23 is disposed in cylinder 16 when piston 23 is in the bottom dead center position relatively improves stability of the behavior in tapered part 17 of cylinder 16 .
- the total length of cylinder 16 is long, and the size of the compression mechanism is inevitably large. Accordingly, the entire hermetic-type compressor becomes large. As a result, it is difficult to reduce the weight, and it is accordingly difficult to save resources.
- the present invention relates to a hermetic-type compressor realizing prevention of noise and improved efficiency and reliability by avoiding a local contact between a piston and an inner face of a cylinder (cylindrical hole), simultaneously, by minimizing sliding area, and preventing generation of noise due to a contact between the piston and the cylinder and a local contact causing abrasion.
- a hermetic-type compressor of the present invention has a sealed container, an electric mechanism, and a compression mechanism.
- the sealed container stores lubricant oil at its bottom.
- the electric mechanism and the compression mechanism are disposed in the sealed container.
- the electric mechanism drives a compression mechanism.
- the compression mechanism includes a shaft, a cylinder block, a piston, and a connecting rod.
- the shaft has a main shaft part rotated by the electric mechanism and an eccentric shaft part formed in the main shaft part.
- the cylinder block has a cylindrical hole constructing a compression chamber and a bearing rotatably supporting the main shaft part. The cylindrical hole and the bearing are disposed so that axis of the cylindrical hole and that of the bearing are orthogonal to each other.
- the piston has a sliding face which slides on an inner wall of the cylindrical hole and is reciprocatably inserted in the cylindrical hole.
- the connecting rod connects the eccentric shaft part and the piston.
- the cylindrical hole has a tapered part, whose inside diameter dimension gradually increases from a top dead center of the piston toward a bottom dead center, and an end part on the shaft side.
- the reciprocation direction of the piston is substantially a horizontal direction.
- a recessed part which is recessed to an inside in a radial direction of the piston and holds the lubricating oil, is provided in the sliding face of the piston.
- the tapered part in the cylindrical hole and the recessed part provided in the piston With the configuration, by the tapered part in the cylindrical hole and the recessed part provided in the piston, the average gap and the sliding area are reduced, and sliding resistance of the piston can be lessened.
- the recessed part in the piston does not come off from the end part on the shaft side of the cylindrical hole. Consequently, the inclination of the piston does not become excessive, and a local collision between the periphery of the recessed part in the piston and the cylinder block can be avoided. Therefore, occurrence of collision sound is suppressed, and increase in noise can be prevented.
- the lubricant oil can be amply supplied to the gap between the inner face of the cylindrical hole and the surface of the piston. As a result, lubricity and sealing performance between the cylinder and the piston are improved, so that the compression efficiency improves. In addition, the total length of the cylindrical hole is short.
- FIG. 1 is a cross section of a main part of a hermetic-type compressor prior to a first embodiment of the present invention.
- FIG. 2 is a vertical cross section of a main part of another hermetic-type compressor prior to the first embodiment of the present invention.
- FIG. 3 is a top view of the main part of the hermetic-type compressor shown in FIG. 2 .
- FIG. 4 is a cross section showing a state where a piston of a hermetic-type compressor in the first embodiment of the invention is positioned at the bottom dead center.
- FIG. 5 is a cross section showing a state where the piston of the hermetic-type compressor illustrated in FIG. 4 is positioned at the top dead center.
- FIG. 6 is a bottom view of the piston of the hermetic-type compressor illustrated in FIG. 4 .
- FIG. 7 is a cross section of a compression part showing a state where the leaned piston of the hermetic-type compressor illustrated in FIG. 4 is positioned at the bottom dead center.
- FIG. 8 is a cross section of a compression part showing a state where a piston of a hermetic-type compressor in a second embodiment of the present invention is positioned at the bottom dead center.
- FIG. 9 is a cross section showing a state where the piston is positioned at the top dead center, of the compression part illustrated in FIG. 8 .
- FIG. 10 is a vertical cross section of a piston assembly of the hermetic-type compressor in the second embodiment of the invention.
- FIG. 11 is a cross section of a top face part of the compression part showing a state where the piston of the hermetic-type compressor in the second embodiment of the invention is in a compression stroke.
- FIG. 12 is a characteristic diagram of the piston lateral pressure load with respect to crank angle of the hermetic-type compressor in the second embodiment of the invention.
- FIG. 13 is a characteristic diagram of coefficient of performance with respect to space volume of a recessed part in the hermetic-type compressor in the second embodiment of the invention.
- FIG. 14 is a characteristic diagram of the coefficient of performance with respect to distance between recessed parts in the hermetic-type compressor in the second embodiment of the invention.
- FIG. 15 is a characteristic diagram of the coefficient of performance with respect to operation frequency of the hermetic-type compressor in the second embodiment of the invention.
- FIG. 16A is a vertical cross section of a compression part showing a state where a piston of a conventional hermetic-type compressor is positioned in the bottom dead center.
- FIG. 16B is a vertical cross section of the compression part showing a state where the piston illustrated in FIG. 16A is positioned in the top dead center.
- FIG. 1 is a cross section of a main part of a hermetic-type compressor and shows a state where piston 123 is in the bottom dead center.
- narrow circular-shaped grooves 141 A and 141 B and a recessed part 141 C which is recessed to an inside in a radial direction are provided in the surface of piston 123 .
- the inside diameter of cylindrical-shaped hole 116 is almost constant.
- lower end part 123 B of piston 123 and recessed part 141 C are exposed from cylindrical-shaped hole 116 .
- Grooves 141 A and 141 B are partially exposed from notch 114 A formed in cylinder block 114 .
- FIG. 2 is a vertical cross section of a main part of a hermetic-type compressor on the assumption of the combination.
- FIG. 2 shows a state where the piston is at the bottom dead center.
- FIG. 3 is a top view of the main part in a state where the piston of the hermetic-type compressor shown in FIG. 2 is in the compression stroke.
- Cylindrical hole 216 has straight part 218 and tapered part 217 .
- straight part 218 the inside diameter of cylindrical-shaped hole 216 is almost constant.
- tapered part 217 the inside diameter dimension increases from Dt to Db (>Dt) from a some midpoint on the side where piston 223 is positioned in the top dead center (the right side in the drawing) toward the side where piston 23 is positioned in the bottom dead center (the left side in the drawing).
- the gap between piston 223 and tapered part 217 is large around the bottom dead center and small around the top dead center.
- grooves 241 A and 241 B and recessed part 241 C which is recessed to the inner side in a radial direction are formed.
- lower end part 223 B of piston 223 and recessed part 241 C are exposed from cylindrical-shaped hole 216 .
- Grooves 241 A and 241 B are partially exposed from notch 214 A formed in cylinder block 214 .
- the sealing part of piston 223 prevents blowby gas by reduction in the gap around the top dead center and the labyrinth seal effect by grooves 241 A and 241 B.
- Lubricant oil scattering around the bottom dead center is held in recessed part 241 C, and supplied from recessed part 241 C to grooves 241 A and 241 B and the sliding part of piston 223 .
- the sealing performance and lubricity can be improved.
- piston 223 is exposed from tapered part 217 of cylindrical-shaped hole 216 around the bottom dead center.
- piston 223 has a cantilever configuration that the sliding part of piston 223 inserted in cylindrical-shaped hole 216 serves as a supporting point, and the deadweight of piston 223 , a piston pin (not shown), and connecting rod 226 is supported by the supporting point.
- piston 223 does not have recessed part 241 C, long support length of the sliding part which supports one side of piston 223 can be assured as shown by L 1 in FIG. 2 .
- recessed part 241 C is formed, leaning of piston 223 increases only by the recess amount of recessed part 241 C. As a result, support length of the sliding part which supports one side of piston 223 becomes shorter as shown by L 2 in FIG. 2 .
- FIG. 4 is a cross section showing a state where the piston of the hermetic-type compressor in the first embodiment of the invention is positioned at the bottom dead center.
- FIG. 5 is a cross section showing a state where the piston of the hermetic-type compressor is positioned at the top dead center.
- FIG. 6 is a bottom view of the piston of the hermetic-type compressor.
- FIG. 7 is a cross section of a compression part showing a state where the piston which leans is positioned at the bottom dead center.
- the hermetic-type compressor has sealed container 301 , electric mechanism 304 , and compression mechanism 305 .
- Lubricant oil 306 is stored at the bottom of sealed container 301 .
- Electric mechanism 304 has stator 302 and rotor 303 and is disposed in sealed container 301 .
- Compression mechanism 305 is also disposed in sealed container 301 and driven by electric mechanism 304 .
- compression mechanism 305 has shaft 310 , cylinder block 314 , piston 423 , and connecting rod 326 .
- Shaft 310 has main shaft part 311 rotated by electric mechanism 304 and eccentric shaft part 312 formed eccentrically at one end of main shaft part 311 .
- Main shaft part 311 is fixed to the shaft center of rotor 303 .
- Oil support path 313 is provided on the inside and the peripheral face of shaft 310 , and one end of oil support path 313 extends in the axial direction in eccentric shaft part 312 .
- Oil support path 313 is communicated with an oil support path (not shown) which is open at the upper end of eccentric shaft part 312 .
- a branch oil path (not shown) which is branched from oil supply path 313 in a radius direction and is open is provided in a some midpoint of eccentric shaft part 312 .
- the lower end of main shaft part 311 extends so that the other end of oil supply path 313 is dipped in predetermined depth in lubricant oil 306 .
- Cylinder block 314 has an almost cylindrical shaped cylindrical hole 316 constructing compression chamber 315 and bearing 320 rotatably supporting main shaft part 311 .
- Cylindrical hole 316 and bearing 320 are disposed so as to be fixed in predetermined positions.
- Cylindrical hole 316 and bearing 320 are disposed so that their axes are orthogonal to each other.
- Bearing 320 serves as a cantilever bearing by axially supporting the end on the side of eccentric shaft part 312 in main shaft part 311 of shaft 310 .
- notch 319 is formed in an upper wall on which lubricant oil 306 falls, in the peripheral wall of cylindrical hole 316 .
- Piston 423 is reciprocatably inserted in cylindrical hole 316 and has sliding face 423 C which slides on the inner wall of cylindrical hole 316 as shown in FIG. 6 .
- the reciprocation direction of piston 423 is substantially the horizontal direction.
- eccentric shaft part 312 and piston 423 are connected to each other.
- one end of connecting rod 326 is coupled to eccentric shaft part 312
- the other end is coupled to piston 423 via piston pin 425 inserted in piston pin hole 423 as shown in FIG. 6 .
- Connecting rod 326 and piston 423 construct piston assembly 440 .
- piston pin hole 423 A is formed in a direction orthogonal to the axis of piston 423 .
- Compression mechanism 305 has piston pin 425 inserted in piston pin hole 423 A.
- Connecting rod 326 is coupled to piston pin 425 so as to be rotatable about the axis of piston pin 425 .
- cylindrical hole 316 and piston 423 will be described in detail with reference to FIGS. 6 and 7 .
- the dimension in the axial direction of cylindrical hole 316 is set so that, when piston 423 is positioned in the bottom dead center, the end on connecting rod 326 side of piston 423 protrudes from end face 316 A on the side of shaft 310 of cylindrical hole 316 .
- cylindrical hole 316 is constructed by, as shown in FIG. 7 , straight part 318 in which the inside diameter dimension is constant in the axial direction only in an interval of predetermined length L from the top dead center side and tapered part 317 whose inside diameter dimension increases from Dt to Db (>Dt) toward the bottom dead center. That is, cylindrical hole 316 has tapered part 317 whose inside diameter dimension gradually increases in a direction in which piston 423 moves from the top dead center to the bottom dead center. Cylindrical hole 316 has end face 316 A as the end on the side of shaft 310 .
- the border between straight part 318 and tapered part 317 is the start point of tapered part 317 , and is inflection part 317 A at which the change rate of taper angle is large.
- piston 423 As shown in FIGS. 6 and 7 , the outside diameter of piston 423 is the same in full length. That is, piston 423 does not have a tapered shape.
- a plurality of recessed parts 441 A, 441 B, 4411 C, and 4412 C are provided in the outer peripheral face (sliding face 423 C) of piston 423 . Recessed parts 441 A and 441 B close to compression chamber 315 are formed in an annular shape extending in the entire outer periphery of piston 423 .
- the space volume of each of recessed parts 441 A and 441 B is 6 mm 3 and the interval between them is set to 2 mm.
- Recessed parts 4411 C and 4412 C furthest from compression chamber 315 do not have an annular shape. Recessed parts 4411 C and 4412 C are formed to, mainly, reduce the area of contact with cylindrical hole 316 of piston 423 and hold lubricant oil 306 . When recessed parts 4411 C and 4412 C hold lubricant oil 306 , the sliding face with cylindrical hole 316 of piston 423 can be made lubricant. Therefore, when it is necessary to further reduce the weight of piston 423 , recessed parts 4411 C and 4412 C may be formed deeper or wider.
- recessed part 4412 C is shown representatively.
- Recessed part 4411 C has a similar shape.
- the outline of recessed part 4412 C extends so that its width is gradually decreased from the part parallel to recessed parts 441 A and 441 B toward end 423 B side on connecting rod 326 side, and the terminating end extends oppositely toward compression chamber 315 side.
- recessed parts 4411 C and 4412 C are formed symmetrically with respect to axis X as the center of piston pin hole 423 A, and their terminating end extends to piston pin hole 423 A. Therefore, recessed parts 4411 C and 4412 C are provided so as to surround piston pin hole 423 A, and extension part 423 D which extends to the inside of recessed parts 4411 C and 4412 C is formed in end part 423 B. Extension part 423 D serves as a part of end part 423 B of piston 423 . Recessed parts 4411 C and 4412 C are formed so as to be recessed to the inside in a radial direction of piston 423 and hold lubricant oil 306 .
- the volume of space formed by the inner face (straight part 318 ) of cylindrical hole 316 of recessed parts 4411 C and 4412 C is set to 6 mm 3 or larger. Since recessed parts 4411 C and 4412 C do not face straight part 318 , an imaginary state is assumed. An interval of 1.5 mm (interval including the dimension of periphery 442 which will be described later) is provided for recessed part 441 B using the deepest point of recessed parts 4411 C and 4412 C as a base point.
- the volume of recessed parts 4411 C and 4412 C can be set arbitrarily as described above.
- Recessed parts 4411 C and 4412 C are provided so as to surround piston pin hole 423 A and are therefore communicated with piston pin hole 423 A. Specifically, recessed parts 4411 C and 4412 C are first and second recessed parts formed in positions symmetrical with respect to axis X of piston 423 passing through the center of piston pin hole 423 A. Recessed parts 4411 C and 4412 C communicate with each other via piston pin hole 423 A.
- a section corner of periphery 442 of recessed parts 4411 C and 4412 C is formed in an inclined face of about 30°.
- Recessed parts 4411 C and 4412 C are provided in positions symmetrical with respect to axis X as a center in the surface of piston 423 . In this case, it is unnecessary to provide recessed part 4411 C with extension part 423 D. However, by employing the same shape, it becomes unnecessary to recognize the side in the vertical direction of piston 423 at the time of assembly, and workability improves.
- piston 423 serves as a component of piston assembly 440 by making piston pin 425 inserted in piston pin hole 423 A penetrate connecting rod 326 , and is assembled as compression mechanism 305 .
- extension part 423 D is disposed so as to be the bottom face as shown in FIG. 7 .
- extension part 423 D faces (comes into contact with) the corner of end face 316 A of cylindrical hole 316 .
- the dimensional relations between piston 423 and end face 316 A on the side of connecting rod 326 in cylindrical hole 316 are set to achieve such a state.
- the lower part in the vertical direction of piston 423 which comes into contact with end face 316 A as an end on the side of shaft 310 of cylindrical hole 316 is extension part 423 D as a part of sliding face 423 C.
- the lower end part of oil supply path 313 functions as a pump using centrifugal force by rotation of shaft 310 .
- lubricant oil 306 at the bottom of sealed container 301 passes through oil supply path 313 , is pumped up, and jets and scatters to respective directions from the oil supply path and the branched oil path provided for eccentric shaft part 312 .
- Lubricant oil 306 jetted from the oil supply path collides with the ceiling face of sealing container 301 and scatters to mainly cool compression mechanism 305 and make the sliding part lubricant.
- Lubricant oil 306 from the branched oil path flies almost horizontally in all circumferences in sealed container 301 , is supplied mainly to piston pin 325 , piston 423 , and the like, and makes the sliding part lubricant.
- lubricant oil 306 is supplied amply from notch 319 formed in the upper wall of cylindrical hole 316 to recessed parts 4411 C and 4412 C formed in sliding face 423 C of piston 423 and is held. A part of lubricant oil 306 is supplied to recessed parts 441 A and 441 B and held. Consequently, also when piston 423 moves to straight part 318 where the gap is narrow, a larger amount of lubricant oil is supplied to the sliding part formed by piston 423 and straight part 318 . Therefore, the lubricant oil makes the sliding part lubricant and sealed. As a result, occurrence of gas leakage is prevented, and the volumetric efficiency can be improved.
- cylindrical hole 316 has straight part 318 provided on the top dead center side of piston 423 relative to tapered part 317 .
- the sealed part of piston 423 around the top dead center where the pressure increases most in the compression stroke can be formed in straight part 318 whose inside diameter dimension is constant in the axial direction.
- the distance in the axial direction of the minimum gap between piston 423 and cylindrical hole 316 is long, so that action of preventing occurrence of gas leakage accompanying increase in pressure of the refrigerant gas is large.
- piston 423 is positioned in tapered part 317 around the bottom dead center, the gap in the radius direction is wide, so that the sliding loss is small. As a result, higher efficiency can be achieved.
- periphery 442 of recessed parts 4411 C and 4412 C an inclined face, the wedge film effect of lubricant oil 306 is obtained, and an oil film can be reliably formed in the gap between piston 423 and cylindrical hole 316 .
- piston assembly 440 leans due to its own weight, so that periphery 442 is deviated vertically downward from cylindrical hole 316 and does not collide with the lower corner of end face 316 A. Therefore, occurrence of collision noise is suppressed, and reduction in noise can be achieved.
- Connecting rod 326 is coupled to piston pin 425 so as to be rotatable about the axis of piston pin 425 . Consequently, piston 423 does not rotate about the axis, and extension part 423 D reliably comes into contact with the corner of end face 316 A.
- recessed parts 4411 C and 4412 C communicate with piston pin hole 423 A, a circulation path is formed by lubricant oil 306 scattered and supplied around the bottom dead center of piston 423 , and piston 423 is cooled by lubricant oil 306 .
- the temperature of piston 423 decreases. Accordingly, temperature rise in compression chamber 315 is suppressed, and deterioration in the volume efficiency caused by heat reception is prevented.
- the refrigeration capacity and efficiency at the time of operating the hermetic-type compressor in a low operation frequency range equal to or less than the power-supply frequency can be increased.
- the effect will be described specifically in a second exemplary embodiment.
- FIG. 8 is an enlarged cross section of a compression part showing a state where a piston of a hermetic-type compressor in a second embodiment of the present invention is positioned at the bottom dead center.
- FIG. 9 is an enlarged cross section of the compression part, showing a state where the piston is positioned at the top dead center.
- FIG. 10 is a vertical cross section of a piston assembly of the hermetic-type compressor in the second embodiment.
- FIG. 11 is a top view of the compression part, showing a state where the piston of the hermetic-type compressor in the second embodiment is in a compression stroke.
- FIG. 12 is a characteristic diagram of the piston lateral pressure load with respect to crank angle of the hermetic-type compressor in the second embodiment.
- the part different from the first embodiment is the configuration of recessed parts formed in a piston, and the other configuration is similar to the first embodiment. Therefore, the piston having the different configuration will be mainly described.
- the outside diameter of piston 323 is constant in full length.
- three recessed parts 341 A, 341 B, and 341 C are provided at predetermined intervals.
- Each of recessed parts 341 A, 341 B, and 341 C is formed in an annular shape in the entire circumference in the surface of piston 323 .
- the volume of space formed by each of recessed part 341 A formed in a position closest to compression chamber 315 and recessed part 341 B in the second closest position and the inner face (straight part 318 ) of cylindrical hole 316 is set to 6 mm 3 .
- the interval between recessed parts 341 A and 341 B is set to 2 mm.
- the volume of space formed by recessed part 341 C in a third position and the inner face (straight part 318 ) of cylindrical hole 316 is set to 6 mm 3 or larger. However, since recessed part 341 C does not face straight part 318 , an imaginary state is assumed. Between recessed parts 341 C and 341 B, the interval of 1.5 mm (interval including the dimension of periphery 342 which will be described later) is provided using the deepest point of recessed part 341 C as a base point. A part of recessed part 341 C is communicated with piston pin hole 323 A. Recessed part 341 C is formed for purposes similar to those of recessed parts 4411 C and 44112 C in the first embodiment. Therefore, the volume of recessed part 341 C can be arbitrarily set.
- end part 323 B on the side opposite to the compression chamber (on the side of connecting rod 326 ) of piston 323 positioned at the bottom dead center is exposed only by length A from end face 316 A on the shaft side of cylinder block 314 .
- Piston 323 is formed in such dimensions. In other words, the dimension in the axial direction of cylindrical hole 316 is set so that, when piston 323 is positioned at the bottom dead center, the corner of end face 316 A of cylindrical hole 316 comes into contact with end part 323 B.
- End part 323 B is the outer peripheral face between the end on the side of connecting rod 326 in piston 323 and recessed part 341 C having the annular shape.
- notch 319 is provided in the upper wall on which lubricant oil 306 falls in the peripheral wall of cylindrical hole 316 in a manner similar to the first embodiment.
- notch 319 at least recessed part 341 C is exposed in a state where piston 323 is positioned at the bottom dead center.
- recessed part 341 C is defined as a part of recesses in the configuration having the plurality of recesses 341 A, 341 B, and 341 C.
- recessed part 341 C is formed so that, in a state where piston 323 reaches the position of the bottom dead center, all of recessed part 341 C is positioned on the side of the top dead center only by length B from end face 316 A of cylindrical hole 316 . End face 323 C on the side of compression chamber 315 of piston 323 is positioned on the side of tapered part 317 only by distance of length C. Further, as shown in FIG. 10 , periphery 342 of recessed part 341 C has a shape inclined at almost 30° in cross section.
- FIG. 11 shows disposition of piston 323 when the crank angle is 320 degrees in the compression stroke.
- the crank angle of 320 degrees is the angle at which the lateral pressure load of piston 320 becomes the maximum.
- the maximum lateral pressure load acts on the lateral pressure load sliding part on the side face in the horizontal direction of cylindrical hole 316 .
- inflection part 317 A between straight part 318 and tapered part 317 is positioned in the range of the width of recessed part 341 C in piston 323 .
- FIG. 11 to clearly show that inflection part 317 A is positioned in the range of the width of recessed part 341 C, the clearance between piston 323 and straight part 318 of cylindrical hole 316 is illustrated largely.
- Piston 323 shifts from the bottom dead center position shown in FIG. 8 to the compression stroke of compressing the refrigerant gas.
- rise of pressure in compression chamber 315 is small. Consequently, even if the clearance between tapered part 317 formed in cylindrical hole 316 and the sliding face (peripheral face) of piston 323 is relatively large, blowby gas is hardly generated by the sealing effect of the lubricant oil. Since the clearance is large, sliding resistance of piston 323 is also small.
- piston 323 When the compression stroke progresses and the crank angle becomes 320 degrees, piston 323 is in the position shown in FIG. 11 . At this time, the lateral pressure load of piston 323 becomes the maximum value as shown in FIG. 12 .
- inflection part 317 A having high change rate of the taper angle as the start point of tapered part 317 is positioned in the range of the width of recessed part 341 C in piston 323 .
- inflection part 317 A is apart from the bottom of recessed part 341 C in a state where inflection part 317 A faces recessed part 341 C. Therefore, even when the lateral pressure load increases, the lubricant state does not decrease in inflection part 317 A in which an oil film is not easily formed, inflection part 317 A does not locally slide, and no sliding sound is generated.
- Lubricant oil 306 scattered from the upper end of shaft 310 is amply supplied from notch 319 formed in the upper wall of cylindrical hole 316 to recessed part 341 C formed in the sliding face of piston 323 and is held. A part of lubricant oil 306 is supplied to recessed parts 341 A and 341 B. Consequently, the lubricant oil supplied to the gap between the inner peripheral face of cylindrical hole 316 of cylinder block 314 and the sliding face of piston 323 becomes large in the compression stroke.
- end face 323 C on the side of the compression chamber of piston 323 is positioned on the side of tapered part 317 only by distance of length C in FIG. 8 at the bottom dead center. Consequently, when piston 323 moves from the bottom dead center to the top dead center in the compression stroke, a part of lubricant oil 306 adhered to the surface of piston 323 moves to the top dead center side, and a part of lubricant oil 306 adhered to the surface of cylindrical hole 316 is also taken and supplied to the gap between piston 323 and cylindrical hole 316 as piston 323 moves.
- recessed part 341 C is provided in the annular shape in the sliding face of piston 323 , for example, by widening the width of recessed part 341 C in the axial direction of piston 323 , the area of recessed part 341 C can be maximized.
- periphery 342 of recessed part 341 C is constructed as a face inclined from the surface in the axial direction of piston 323 by about 30° in a sectional shape. Consequently, when piston 323 reciprocates, lubricant oil 306 held in recessed part 341 C gains force in recessed part 341 C. Along the inclination of periphery 342 of recessed part 341 C, lubricant oil 306 is pulled in the gap between piston 323 and cylindrical hole 316 , enters the gap, and acts so as to correct the inclination of piston 323 . In such a manner, a so-called wedge film effect is produced in the gap between piston 323 and cylindrical hole 316 .
- the angle of periphery 342 of recessed part 341 C is not limited to about 30°.
- the angle may be any angle at which the wedge film effect such that, as described above, when piston 323 reciprocates, lubricant oil 306 held in recessed part 341 C is pulled in the gap between piston 323 and cylindrical hole 316 is easily produced. That is, it is sufficient to the angle properly in accordance with the reciprocation speed of piston 323 and the like.
- the angle with respect to the surface in the axial direction of piston 323 , of periphery 342 is preferably in the range of 25° to 35°.
- the angle may be any angle at which lubricant oil 306 held in recessed part 341 C is pulled in the gap between piston 323 and cylindrical hole 316 .
- lubricant oil 306 As a result, a larger amount of lubricant oil 306 can be supplied to the gap between cylindrical block 314 and piston 323 , lubricant oil 306 is excellently held, and sealing performance can be improved. Further, with ample supply of lubricant oil 306 , the sliding resistance of piston 323 can be reduced, so that the compression efficiency is improved, an input is reduced, and higher efficiency can be achieved.
- the configuration may be applied to recessed parts 4411 C and 4412 C of the first embodiment.
- Piston assembly 340 has a cantilever configuration that the deadweight of piston assembly 340 is supported only by the sliding part of piston 323 inserted in cylindrical hole 316 . Consequently, around the bottom dead center at which piston 323 is exposed from cylindrical hole 316 most, the bottom dead center side of piston 323 leans downward in the vertical direction in the gap between piston 323 and cylindrical hole 316 .
- periphery 342 on the connecting rod side of recessed part 341 C is positioned on the top dead center side relative to end face 316 A of cylindrical hole 316 .
- End part 323 B of piston 323 and the corner of end face 316 A of cylindrical hole 316 are in contact with each other. Consequently, periphery 342 of recessed part 341 C is not deviated vertically downward from cylindrical hole 316 and does not collide with the lower corner of end face 316 A. Therefore, occurrence of collision noise is suppressed, and reduction in noise can be achieved.
- a part of recessed part 341 C is communicated with piston pin hole 323 A. That is, preferably, the upper and lower sides of recessed part 341 C communicate with each other via piston pin hole 323 A.
- a circulating path that lubricant oil 306 scattered and supplied to the upper part of piston 323 around the bottom dead center passes through circular shaped recessed part 341 C and is ejected downward via the end face of piston pin hole 323 A is formed.
- Piston 323 heated by high-temperature, high-pressure refrigerant gas is cooled by relatively-low-temperature lubricant oil 306 passing through the circulating path. By the cooling, the temperature of piston 323 decreases. Accordingly, temperature rise in compression chamber 315 is suppressed, and deterioration in the volume efficiency caused by heat reception can be prevented.
- lubricant oil 306 is reserved mainly in recessed part 341 C and supplied to the sealing part.
- the oil retentivity is maintained by the capillary action of recessed parts 341 A and 341 B, and eddying flow by the labyrinth effect is formed.
- decelerating flow by contraction flow is formed.
- the coefficient of performance is the ratio of refrigeration capacity to an applied input and is generally used as an index indicating the efficiency of a compressor.
- R600a isobutane
- the operation frequency was 27 r/sec, and operation conditions close to operation conditions in a refrigerator were evaporation temperature of ⁇ 30° C. and condensation temperature of 40° C.
- FIG. 13 is a characteristic diagram of coefficient of performance with respect to space volume of recessed parts 341 A and 341 B.
- FIG. 14 is a characteristic diagram of the coefficient of performance with respect to distances among neighboring recessed parts 341 A, 341 B, and 341 C.
- FIG. 15 is a characteristic diagram of the coefficient of performance with respect to operation frequency of the compressor.
- the vertical axis denotes the coefficient of performance of the compressor
- the horizontal axis denotes the sum of volume of space surrounded by the section of recessed parts 341 A and 341 B and the extension face of the outside diameter of piston 323 .
- the test result shown in FIG. 13 is a result of conducting the test using the recessed parts on the side of compression chamber 315 as a plurality of recessed parts 341 A and 341 B having small sectional area.
- the invention is not limited to a plurality of recessed parts.
- One recessed part formed in a volume with which the result shown in FIG. 13 is obtained may be employed.
- the space volume of recessed parts 341 A and 341 B in a range T of 0.25 mm 3 to 25 mm 3 (inclusive).
- the vertical axis denotes the coefficient of performance of the compressor
- the horizontal axis denotes distance S between neighboring recessed parts 341 A, 341 B, and 341 C.
- the coefficient of performance increases. It is assumed that, by setting distance S between neighboring recessed parts 341 A, 341 B, and 341 C to 1 mm or larger, the gap between the surface of piston 323 and cylindrical hole 316 becomes a reducer. Consequently, the flow rate of a mixed fluid of the refrigerant gas and lubricant oil 306 increases so that the pressure of the mixed fluid is reduced. As a result, the leakage amount from the gap between piston 323 and cylindrical hole 316 further decreases. Therefore, by further reducing the amount of leakage to the side opposite to the compression chamber, reduction in the volumetric efficiency is prevented, and the efficiency of the compressor can be increased.
- recessed parts 341 A, 341 B, and 341 C are formed by setting the distance between neighboring recessed parts 341 A, 341 B, and 341 C to 1 mm or larger. Consequently, in addition to the above-described effects, even in the case where oil in any one of recessed parts 341 A, 341 B, and 341 C becomes discontinuous and the sealing performance deteriorates, the sealing performance can be maintained by the other recessed parts.
- the vertical axis indicates the coefficient of performance of the compressor
- the horizontal axis indicates the operation frequency at which the piston is driven.
- the operation frequency is set in the range of about 20 r/sec to about 45 r/sec in a state where a compressor having specifications (cylinder volume: 10 ml and capability at the time of operation of 27 r/sec: 74 W) equivalent to those of the embodiment is assembled in a similar refrigeration cycle is shown.
- the cylindrical hole does not have a tapered part, and recessed part 341 C is not formed in the piston.
- lubricant oil 306 contributing to the performance of sealing between piston 323 and cylindrical hole 316 is stably supplied to the gap between piston 323 and cylindrical hole 316 and can be reliably assured between piston 323 and cylindrical hole 316 .
- the full length of cylindrical hole 316 is shortened and the hermetic-type compressor is downsized and, moreover, occurrence of contact noise is prevented, and occurrence of abrasion can be reduced. Consequently, higher efficiency, lower noise, and higher reliability of the hermetic-type compressor can be simultaneously achieved.
- the compression efficiency of the hermetic-type compressor is increased, and sound of collision between the piston and the cylindrical hole can be suppressed.
- the hermetic-type compressor can be widely applied as a hermetic-type compressor for use in a machine using a refrigeration cycle such as an air conditioner or an automatic vending machine.
Abstract
Description
- The present invention relates to a hermetic-type compressor for use in a refrigeration cycle system such as a refrigerator freezer.
- A reciprocation-type hermetic compressor has, as a compression mechanism, a cylinder forming a cylindrical compression chamber, a cylindrical piston, and a connecting rod. The piston reciprocates in the cylinder. By the connecting rod, an eccentric shaft of a shaft is connected to the piston via a piston pin. The shaft is fixed to the shaft center of a rotor of a motor, and the compression mechanism is operated by the rotation of the rotor.
- In such a hermetic-type compressor, a gap is necessary between the inner peripheral face of the cylinder and a sliding face of the piston so that the faces slide each other. However, when the gap is large, a blowby gas as a leaked high-temperature high-pressure refrigerant gas compressed in the compression chamber is generated, and the compression efficiency deteriorates. On the other hand, when the gap is small, a sliding loss increases, and input-output efficiency deteriorates.
- Consequently, a hermetic-type compressor using a cylinder formed so that the inside diameter dimension of a compression chamber is gradually increased from a side on which a piston is positioned in a top dead center toward a side on which the piston is positioned in a bottom dead center has been proposed (refer to, for example, patent literature 1).
FIGS. 16A and 16B are cross sections of a compression part of a conventional hermetic-type compressor described in the patent literature 1.FIG. 16A shows a state where the piston is positioned in the bottom dead center, andFIG. 16B shows a state where the piston is positioned in the top dead center. -
Cylinder block 14 includescylinder 16 having a center axis in an almost horizontal direction. Piston 23 inserted in an almost horizontal direction is connected to connectingrod 26 via a piston pin (not shown), thereby constructingpiston assembly 23A. At an end face (an end face on the right side in the drawing) ofcylinder 16 on the side opposite to connectingrod 26, a valve plate (not shown) is attached. Bypiston 23,cylinder 16, and the valve plate constructed as described above,compression chamber 15 is formed. Piston 23 reciprocates in an almost horizontal direction incylinder 16 via connectingrod 26 by eccentric motion of an eccentric shaft (not shown) of a shaft (not shown). - The inner face of
cylinder 16 is formed so as to have taperedpart 17 whose inner diameter dimension increases from Dt to Db (>Dt) from a some midpoint on the side wherepiston 23 is positioned in the top dead center toward the side wherepiston 23 is positioned in the bottom dead center. Piston 23 is formed so that its outer diameter dimension is almost the same in full length. Consequently, around the top dead center where the pressure incompression chamber 15 is high, the gap in the sealing part ofpiston 23 is reduced, and blow-by gas is prevented. On the other hand, around the bottom dead center, the gap increases, so that sliding loss can be reduced. - However,
piston 23 constructed as described above repeats reciprocating while always slightly vibrating in all directions in the gap with the inner face ofcylinder 16 for the following reason. At the time of operation, a dynamic compressive load, the inertia force and gravity of movable members such aspiston 23 and connectingrod 26, and a piston lateral pressure load generated by converting the rotational motion to the reciprocating motion act onpiston 23. Forces such as sliding resistance of the sliding part exert influences one another, and act onpiston 23 while the directions and magnitudes of the forces are changing. Such an action is also a factor of slight vibrations in all directions of piston in the gap with the inner face ofcylinder 16. - Particularly, in a state where
piston 23 is positioned around the bottom dead center, the gap withtapered part 17 ofcylinder 16 becomes larger than the gap around the top dead center. Since the center axis ofcylinder 16 is disposed in an almost horizontal direction, by the influence of the gravity ofpiston assembly 23A, the bottom dead center side ofpiston 23 leans more vertically downward. As a result, connectingrod 26 side ofpiston 23 leans more vertically downward. - Due to occurrence of the slight vibration behavior by the reciprocating motion of
piston 23 and pressure applied topiston 23, the sliding part ofpiston 23 and taperedpart 17 ofcylinder 16 locally slide each other. There is the possibility that such a local sliding generates a contact sound and causes abrasion starting from the contact part. - The structure that
entire piston 23 is disposed incylinder 16 whenpiston 23 is in the bottom dead center position relatively improves stability of the behavior intapered part 17 ofcylinder 16. However, in the structure, the total length ofcylinder 16 is long, and the size of the compression mechanism is inevitably large. Accordingly, the entire hermetic-type compressor becomes large. As a result, it is difficult to reduce the weight, and it is accordingly difficult to save resources. - PTL 1: Unexamined Japanese Patent Publication No. 2002-89450
- The present invention relates to a hermetic-type compressor realizing prevention of noise and improved efficiency and reliability by avoiding a local contact between a piston and an inner face of a cylinder (cylindrical hole), simultaneously, by minimizing sliding area, and preventing generation of noise due to a contact between the piston and the cylinder and a local contact causing abrasion.
- A hermetic-type compressor of the present invention has a sealed container, an electric mechanism, and a compression mechanism. The sealed container stores lubricant oil at its bottom. The electric mechanism and the compression mechanism are disposed in the sealed container. The electric mechanism drives a compression mechanism. The compression mechanism includes a shaft, a cylinder block, a piston, and a connecting rod. The shaft has a main shaft part rotated by the electric mechanism and an eccentric shaft part formed in the main shaft part. The cylinder block has a cylindrical hole constructing a compression chamber and a bearing rotatably supporting the main shaft part. The cylindrical hole and the bearing are disposed so that axis of the cylindrical hole and that of the bearing are orthogonal to each other. The piston has a sliding face which slides on an inner wall of the cylindrical hole and is reciprocatably inserted in the cylindrical hole. The connecting rod connects the eccentric shaft part and the piston. The cylindrical hole has a tapered part, whose inside diameter dimension gradually increases from a top dead center of the piston toward a bottom dead center, and an end part on the shaft side. The reciprocation direction of the piston is substantially a horizontal direction. A recessed part, which is recessed to an inside in a radial direction of the piston and holds the lubricating oil, is provided in the sliding face of the piston. A part on the lower side in the vertical direction of the piston, which comes into contact with the end part on the shaft side of the cylindrical hole when the piston is positioned in the bottom dead center, is a part of the sliding face.
- With the configuration, by the tapered part in the cylindrical hole and the recessed part provided in the piston, the average gap and the sliding area are reduced, and sliding resistance of the piston can be lessened. Around the bottom dead center of the piston, the recessed part in the piston does not come off from the end part on the shaft side of the cylindrical hole. Consequently, the inclination of the piston does not become excessive, and a local collision between the periphery of the recessed part in the piston and the cylinder block can be avoided. Therefore, occurrence of collision sound is suppressed, and increase in noise can be prevented. By holding a large amount of lubricant oil scattered and supplied from the shaft in the recessed part, the lubricant oil can be amply supplied to the gap between the inner face of the cylindrical hole and the surface of the piston. As a result, lubricity and sealing performance between the cylinder and the piston are improved, so that the compression efficiency improves. In addition, the total length of the cylindrical hole is short.
-
FIG. 1 is a cross section of a main part of a hermetic-type compressor prior to a first embodiment of the present invention. -
FIG. 2 is a vertical cross section of a main part of another hermetic-type compressor prior to the first embodiment of the present invention. -
FIG. 3 is a top view of the main part of the hermetic-type compressor shown inFIG. 2 . -
FIG. 4 is a cross section showing a state where a piston of a hermetic-type compressor in the first embodiment of the invention is positioned at the bottom dead center. -
FIG. 5 is a cross section showing a state where the piston of the hermetic-type compressor illustrated inFIG. 4 is positioned at the top dead center. -
FIG. 6 is a bottom view of the piston of the hermetic-type compressor illustrated inFIG. 4 . -
FIG. 7 is a cross section of a compression part showing a state where the leaned piston of the hermetic-type compressor illustrated inFIG. 4 is positioned at the bottom dead center. -
FIG. 8 is a cross section of a compression part showing a state where a piston of a hermetic-type compressor in a second embodiment of the present invention is positioned at the bottom dead center. -
FIG. 9 is a cross section showing a state where the piston is positioned at the top dead center, of the compression part illustrated inFIG. 8 . -
FIG. 10 is a vertical cross section of a piston assembly of the hermetic-type compressor in the second embodiment of the invention. -
FIG. 11 is a cross section of a top face part of the compression part showing a state where the piston of the hermetic-type compressor in the second embodiment of the invention is in a compression stroke. -
FIG. 12 is a characteristic diagram of the piston lateral pressure load with respect to crank angle of the hermetic-type compressor in the second embodiment of the invention. -
FIG. 13 is a characteristic diagram of coefficient of performance with respect to space volume of a recessed part in the hermetic-type compressor in the second embodiment of the invention. -
FIG. 14 is a characteristic diagram of the coefficient of performance with respect to distance between recessed parts in the hermetic-type compressor in the second embodiment of the invention. -
FIG. 15 is a characteristic diagram of the coefficient of performance with respect to operation frequency of the hermetic-type compressor in the second embodiment of the invention. -
FIG. 16A is a vertical cross section of a compression part showing a state where a piston of a conventional hermetic-type compressor is positioned in the bottom dead center. -
FIG. 16B is a vertical cross section of the compression part showing a state where the piston illustrated inFIG. 16A is positioned in the top dead center. - Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.
- The inventors of the present invention have proposed another configuration for compression efficiency improvement and reduction in sliding loss (Unexamined Japanese Patent Publication No. 2006-169998).
FIG. 1 is a cross section of a main part of a hermetic-type compressor and shows a state wherepiston 123 is in the bottom dead center. - In the surface of
piston 123, narrow circular-shapedgrooves part 141C which is recessed to an inside in a radial direction are provided. The inside diameter of cylindrical-shapedhole 116 is almost constant. At a position around the bottom dead center,lower end part 123B ofpiston 123 and recessedpart 141C are exposed from cylindrical-shapedhole 116.Grooves notch 114A formed incylinder block 114. By forminggrooves part 141C in the sliding face (outer peripheral face) ofpiston 123 in such a manner, whenpiston 123 reciprocates, the amount of oil supplied to a sealing part and a sliding part increases. Consequently, the sealing performance improves, and the sliding loss can be reduced while improving the compression efficiency and decreasing the sliding area. - By combining the configuration of
FIG. 1 to the configuration ofFIG. 16A , further improvement in compression efficiency and reduction in the sliding loss can be expected.FIG. 2 is a vertical cross section of a main part of a hermetic-type compressor on the assumption of the combination.FIG. 2 shows a state where the piston is at the bottom dead center.FIG. 3 is a top view of the main part in a state where the piston of the hermetic-type compressor shown inFIG. 2 is in the compression stroke. -
Cylindrical hole 216 hasstraight part 218 andtapered part 217. Instraight part 218, the inside diameter of cylindrical-shapedhole 216 is almost constant. Intapered part 217, the inside diameter dimension increases from Dt to Db (>Dt) from a some midpoint on the side wherepiston 223 is positioned in the top dead center (the right side in the drawing) toward the side wherepiston 23 is positioned in the bottom dead center (the left side in the drawing). The gap betweenpiston 223 andtapered part 217 is large around the bottom dead center and small around the top dead center. - In the surface of
piston 223,grooves part 241C which is recessed to the inner side in a radial direction are formed. In a position around the bottom dead center,lower end part 223B ofpiston 223 and recessedpart 241C are exposed from cylindrical-shapedhole 216.Grooves notch 214A formed incylinder block 214. - Therefore, the sealing part of
piston 223 prevents blowby gas by reduction in the gap around the top dead center and the labyrinth seal effect bygrooves part 241C, and supplied from recessedpart 241C togrooves piston 223. By increasing the oil supply amount in such a manner, the sealing performance and lubricity can be improved. - As a result, by enlargement of the average clearance of the sliding part of
piston 223 and reduction in sliding area, a hermetic-type compressor with largely reduced sliding loss, high sealing performance, and high compression efficiency can be expected. In the configuration,piston 223 is exposed fromtapered part 217 of cylindrical-shapedhole 216 around the bottom dead center. At this time,piston 223 has a cantilever configuration that the sliding part ofpiston 223 inserted in cylindrical-shapedhole 216 serves as a supporting point, and the deadweight ofpiston 223, a piston pin (not shown), and connectingrod 226 is supported by the supporting point. This is because the clearance of a connection part of connectingrod 226 and an eccentric shaft (not shown) of the crankshaft and the clearance of a connection part of a bearing and the crankshaft (which are not shown) are larger than the gap of the sealing part ofpiston 223. - Due to the cantilever configuration, at the bottom dead center at which
piston 223 is exposed most from cylindrical-shapedhole 216, the bottom dead center side ofpiston 223 leans vertically downward in the gap formed bytapered part 217 andpiston 223. This is because, since it is formed to have taperedpart 217 in which the inside diameter dimension of cylindrical-shapedhole 216 increases from Dt to Db, the gap betweentapered part 217 andpiston 223 increases around the bottom dead center. - If
piston 223 does not have recessedpart 241C, long support length of the sliding part which supports one side ofpiston 223 can be assured as shown by L1 inFIG. 2 . However, when recessedpart 241C is formed, leaning ofpiston 223 increases only by the recess amount of recessedpart 241C. As a result, support length of the sliding part which supports one side ofpiston 223 becomes shorter as shown by L2 inFIG. 2 . - Therefore, in the configuration shown in
FIG. 2 , the leaning ofpiston 223 becomes excessive. Consequently, whenperiphery 242 of recessedpart 241C enters cylindrical-shape hole 216 in the compression stroke, there is the possibility thatperiphery 242 locally collides withend face 216A of cylindrical-shapedhole 216, and noise increases. - Next, a configuration solving such a problem will be described with reference to
FIGS. 4 to 7 .FIG. 4 is a cross section showing a state where the piston of the hermetic-type compressor in the first embodiment of the invention is positioned at the bottom dead center.FIG. 5 is a cross section showing a state where the piston of the hermetic-type compressor is positioned at the top dead center.FIG. 6 is a bottom view of the piston of the hermetic-type compressor.FIG. 7 is a cross section of a compression part showing a state where the piston which leans is positioned at the bottom dead center. - As shown in
FIGS. 4 and 5 , the hermetic-type compressor has sealedcontainer 301,electric mechanism 304, andcompression mechanism 305.Lubricant oil 306 is stored at the bottom of sealedcontainer 301.Electric mechanism 304 hasstator 302 androtor 303 and is disposed in sealedcontainer 301.Compression mechanism 305 is also disposed in sealedcontainer 301 and driven byelectric mechanism 304. - Concretely,
compression mechanism 305 hasshaft 310,cylinder block 314,piston 423, and connectingrod 326.Shaft 310 hasmain shaft part 311 rotated byelectric mechanism 304 andeccentric shaft part 312 formed eccentrically at one end ofmain shaft part 311.Main shaft part 311 is fixed to the shaft center ofrotor 303. -
Oil support path 313 is provided on the inside and the peripheral face ofshaft 310, and one end ofoil support path 313 extends in the axial direction ineccentric shaft part 312.Oil support path 313 is communicated with an oil support path (not shown) which is open at the upper end ofeccentric shaft part 312. A branch oil path (not shown) which is branched fromoil supply path 313 in a radius direction and is open is provided in a some midpoint ofeccentric shaft part 312. The lower end ofmain shaft part 311 extends so that the other end ofoil supply path 313 is dipped in predetermined depth inlubricant oil 306. -
Cylinder block 314 has an almost cylindrical shapedcylindrical hole 316 constructingcompression chamber 315 and bearing 320 rotatably supportingmain shaft part 311.Cylindrical hole 316 and bearing 320 are disposed so as to be fixed in predetermined positions.Cylindrical hole 316 and bearing 320 are disposed so that their axes are orthogonal to each other. Bearing 320 serves as a cantilever bearing by axially supporting the end on the side ofeccentric shaft part 312 inmain shaft part 311 ofshaft 310. Incylinder block 314,notch 319 is formed in an upper wall on whichlubricant oil 306 falls, in the peripheral wall ofcylindrical hole 316. -
Piston 423 is reciprocatably inserted incylindrical hole 316 and has slidingface 423C which slides on the inner wall ofcylindrical hole 316 as shown inFIG. 6 . The reciprocation direction ofpiston 423 is substantially the horizontal direction. By connectingrod 326,eccentric shaft part 312 andpiston 423 are connected to each other. Specifically, one end of connectingrod 326 is coupled toeccentric shaft part 312, and the other end is coupled topiston 423 viapiston pin 425 inserted inpiston pin hole 423 as shown inFIG. 6 .Connecting rod 326 andpiston 423construct piston assembly 440. - In
piston 423,piston pin hole 423A is formed in a direction orthogonal to the axis ofpiston 423.Compression mechanism 305 haspiston pin 425 inserted inpiston pin hole 423A.Connecting rod 326 is coupled topiston pin 425 so as to be rotatable about the axis ofpiston pin 425. - Next,
cylindrical hole 316 andpiston 423 will be described in detail with reference toFIGS. 6 and 7 . As shown inFIG. 7 , the dimension in the axial direction ofcylindrical hole 316 is set so that, whenpiston 423 is positioned in the bottom dead center, the end on connectingrod 326 side ofpiston 423 protrudes from end face 316A on the side ofshaft 310 ofcylindrical hole 316. - The inner face of
cylindrical hole 316 is constructed by, as shown inFIG. 7 ,straight part 318 in which the inside diameter dimension is constant in the axial direction only in an interval of predetermined length L from the top dead center side andtapered part 317 whose inside diameter dimension increases from Dt to Db (>Dt) toward the bottom dead center. That is,cylindrical hole 316 has taperedpart 317 whose inside diameter dimension gradually increases in a direction in whichpiston 423 moves from the top dead center to the bottom dead center.Cylindrical hole 316 hasend face 316A as the end on the side ofshaft 310. - The border between
straight part 318 andtapered part 317 is the start point oftapered part 317, and isinflection part 317A at which the change rate of taper angle is large. - As shown in
FIGS. 6 and 7 , the outside diameter ofpiston 423 is the same in full length. That is,piston 423 does not have a tapered shape. In the outer peripheral face (slidingface 423C) ofpiston 423, a plurality of recessedparts parts compression chamber 315 are formed in an annular shape extending in the entire outer periphery ofpiston 423. The space volume of each of recessedparts - Recessed
parts compression chamber 315 do not have an annular shape. Recessedparts cylindrical hole 316 ofpiston 423 and holdlubricant oil 306. When recessedparts lubricant oil 306, the sliding face withcylindrical hole 316 ofpiston 423 can be made lubricant. Therefore, when it is necessary to further reduce the weight ofpiston 423, recessedparts - In
FIG. 6 , recessedpart 4412C is shown representatively. Recessedpart 4411C has a similar shape. The outline of recessedpart 4412C extends so that its width is gradually decreased from the part parallel to recessedparts end 423B side on connectingrod 326 side, and the terminating end extends oppositely towardcompression chamber 315 side. - As shown in
FIG. 6 , recessedparts piston pin hole 423A, and their terminating end extends topiston pin hole 423A. Therefore, recessedparts piston pin hole 423A, andextension part 423D which extends to the inside of recessedparts end part 423B.Extension part 423D serves as a part ofend part 423B ofpiston 423. Recessedparts piston 423 and holdlubricant oil 306. - The volume of space formed by the inner face (straight part 318) of
cylindrical hole 316 of recessedparts parts straight part 318, an imaginary state is assumed. An interval of 1.5 mm (interval including the dimension ofperiphery 442 which will be described later) is provided for recessedpart 441B using the deepest point of recessedparts parts - Recessed
parts piston pin hole 423A and are therefore communicated withpiston pin hole 423A. Specifically, recessedparts piston 423 passing through the center ofpiston pin hole 423A. Recessedparts piston pin hole 423A. - Further, a section corner of
periphery 442 of recessedparts - Recessed
parts piston 423. In this case, it is unnecessary to provide recessedpart 4411C withextension part 423D. However, by employing the same shape, it becomes unnecessary to recognize the side in the vertical direction ofpiston 423 at the time of assembly, and workability improves. - In the configuration,
piston 423 serves as a component ofpiston assembly 440 by makingpiston pin 425 inserted inpiston pin hole 423A penetrate connectingrod 326, and is assembled ascompression mechanism 305. In this case,extension part 423D is disposed so as to be the bottom face as shown inFIG. 7 . - As shown in
FIG. 7 , in a state wherepiston 423 is positioned at the bottom dead center,extension part 423D faces (comes into contact with) the corner ofend face 316A ofcylindrical hole 316. The dimensional relations betweenpiston 423 and end face 316A on the side of connectingrod 326 incylindrical hole 316 are set to achieve such a state. Specifically, whenpiston 423 is positioned at the bottom dead center, the lower part in the vertical direction ofpiston 423 which comes into contact with end face 316A as an end on the side ofshaft 310 ofcylindrical hole 316 isextension part 423D as a part of slidingface 423C. - The operation of the hermetic-type compressor constructed as mentioned above will now be described. By applying current to
electric mechanism 304,rotor 303 ofelectric mechanism 304 rotatesshaft 310, rotary motion ofeccentric shaft part 312 is converted to reciprocating motion via connectingrod 326 and the reciprocating motion is transmitted topiston 423. Consequently,piston 423 inserted in cylindrical hole 316 (compression chamber 315) ofcylinder block 314 reciprocates incylindrical hole 316. By the reciprocating motion ofpiston 423, refrigerant gas from a cooling system (not shown) is taken intocompression chamber 315 and compressed. After that the gas is discharged again to the cooling system. - The lower end part of
oil supply path 313 functions as a pump using centrifugal force by rotation ofshaft 310. By the pumping action,lubricant oil 306 at the bottom of sealedcontainer 301 passes throughoil supply path 313, is pumped up, and jets and scatters to respective directions from the oil supply path and the branched oil path provided foreccentric shaft part 312. -
Lubricant oil 306 jetted from the oil supply path collides with the ceiling face of sealingcontainer 301 and scatters to mainlycool compression mechanism 305 and make the sliding part lubricant.Lubricant oil 306 from the branched oil path flies almost horizontally in all circumferences in sealedcontainer 301, is supplied mainly topiston pin 325,piston 423, and the like, and makes the sliding part lubricant. - In the reciprocating motion of
piston 323, in the beginning of a compression stroke (around the bottom dead center), blowby gas is hardly generated, and sliding resistance ofpiston 423 is small. Just beforepiston 423 reaches a position around the top dead center, the pressure incompression chamber 315 further increases. Since the gap between slidingface 423C ofpiston 423 andtapered part 317 becomes small at the top dead center side, occurrence of blowby gas can be reduced. - In other words, in a state where
piston 423 is positioned in the bottom dead center,lubricant oil 306 is supplied amply fromnotch 319 formed in the upper wall ofcylindrical hole 316 to recessedparts face 423C ofpiston 423 and is held. A part oflubricant oil 306 is supplied to recessedparts piston 423 moves tostraight part 318 where the gap is narrow, a larger amount of lubricant oil is supplied to the sliding part formed bypiston 423 andstraight part 318. Therefore, the lubricant oil makes the sliding part lubricant and sealed. As a result, occurrence of gas leakage is prevented, and the volumetric efficiency can be improved. - Further, preferably,
cylindrical hole 316 hasstraight part 318 provided on the top dead center side ofpiston 423 relative totapered part 317. With the configuration, the sealed part ofpiston 423 around the top dead center where the pressure increases most in the compression stroke can be formed instraight part 318 whose inside diameter dimension is constant in the axial direction. In the sealed part, the distance in the axial direction of the minimum gap betweenpiston 423 andcylindrical hole 316 is long, so that action of preventing occurrence of gas leakage accompanying increase in pressure of the refrigerant gas is large. Whenpiston 423 is positioned intapered part 317 around the bottom dead center, the gap in the radius direction is wide, so that the sliding loss is small. As a result, higher efficiency can be achieved. - In a state where
piston 423 is positioned at the bottom dead center, the end part on the side of connectingrod 326 ofpiston 423 is exposed from the end part on the side ofshaft 310 ofcylindrical hole 316. Consequently, a large amount oflubricant oil 306 scattered and supplied is adhered to the surface of exposedpiston 423 and can be supplied to the sliding part and the sealed part aspiston 423 reciprocates. As a result, sliding loss is reduced, and higher efficiency can be achieved together with the above-described prevention of occurrence of gas leakage. - By making
periphery 442 of recessedparts lubricant oil 306 is obtained, and an oil film can be reliably formed in the gap betweenpiston 423 andcylindrical hole 316. - When
piston 423 is positioned at the bottom dead center, the bottom dead center side ofpiston 423 leans downward in the vertical direction in the gap betweencylindrical hole 316 andpiston 423. However,extension part 423D is in contact with the corner ofend face 316A ofcylindrical hole 316. Consequently,piston assembly 440 leans due to its own weight, so thatperiphery 442 is deviated vertically downward fromcylindrical hole 316 and does not collide with the lower corner ofend face 316A. Therefore, occurrence of collision noise is suppressed, and reduction in noise can be achieved.Connecting rod 326 is coupled topiston pin 425 so as to be rotatable about the axis ofpiston pin 425. Consequently,piston 423 does not rotate about the axis, andextension part 423D reliably comes into contact with the corner ofend face 316A. - Since recessed
parts piston pin hole 423A, a circulation path is formed bylubricant oil 306 scattered and supplied around the bottom dead center ofpiston 423, andpiston 423 is cooled bylubricant oil 306. By the cooling, the temperature ofpiston 423 decreases. Accordingly, temperature rise incompression chamber 315 is suppressed, and deterioration in the volume efficiency caused by heat reception is prevented. - Further, in the case of driving an inverter at operation frequency equal to or less than power-supply frequency, by the synergetic effect of maintenance of oil retentivity by the capillary action of recessed
parts parts - As a result, particularly, the refrigeration capacity and efficiency at the time of operating the hermetic-type compressor in a low operation frequency range equal to or less than the power-supply frequency can be increased. The effect will be described specifically in a second exemplary embodiment.
-
FIG. 8 is an enlarged cross section of a compression part showing a state where a piston of a hermetic-type compressor in a second embodiment of the present invention is positioned at the bottom dead center.FIG. 9 is an enlarged cross section of the compression part, showing a state where the piston is positioned at the top dead center.FIG. 10 is a vertical cross section of a piston assembly of the hermetic-type compressor in the second embodiment.FIG. 11 is a top view of the compression part, showing a state where the piston of the hermetic-type compressor in the second embodiment is in a compression stroke.FIG. 12 is a characteristic diagram of the piston lateral pressure load with respect to crank angle of the hermetic-type compressor in the second embodiment. - In the embodiment, a general configuration of a compressor will be described mainly with respect to parts different from the first embodiment by quoting the description (including the reference numerals) of the first embodiment and
FIGS. 4 and 5 . - The part different from the first embodiment is the configuration of recessed parts formed in a piston, and the other configuration is similar to the first embodiment. Therefore, the piston having the different configuration will be mainly described.
- As illustrated in
FIGS. 8 and 9 , the outside diameter ofpiston 323 is constant in full length. In the surface ofpiston 323, three recessedparts parts piston 323. - The volume of space formed by each of recessed
part 341A formed in a position closest tocompression chamber 315 and recessedpart 341B in the second closest position and the inner face (straight part 318) ofcylindrical hole 316 is set to 6 mm3. The interval between recessedparts - The volume of space formed by recessed
part 341C in a third position and the inner face (straight part 318) ofcylindrical hole 316 is set to 6 mm3 or larger. However, since recessedpart 341C does not facestraight part 318, an imaginary state is assumed. Between recessedparts periphery 342 which will be described later) is provided using the deepest point of recessedpart 341C as a base point. A part of recessedpart 341C is communicated withpiston pin hole 323A. Recessedpart 341C is formed for purposes similar to those of recessedparts 4411C and 44112C in the first embodiment. Therefore, the volume of recessedpart 341C can be arbitrarily set. - As shown in
FIG. 8 , endpart 323B on the side opposite to the compression chamber (on the side of connecting rod 326) ofpiston 323 positioned at the bottom dead center is exposed only by length A from end face 316A on the shaft side ofcylinder block 314.Piston 323 is formed in such dimensions. In other words, the dimension in the axial direction ofcylindrical hole 316 is set so that, whenpiston 323 is positioned at the bottom dead center, the corner ofend face 316A ofcylindrical hole 316 comes into contact withend part 323B.End part 323B is the outer peripheral face between the end on the side of connectingrod 326 inpiston 323 and recessedpart 341C having the annular shape. - Further, in
cylinder block 314,notch 319 is provided in the upper wall on whichlubricant oil 306 falls in the peripheral wall ofcylindrical hole 316 in a manner similar to the first embodiment. Bynotch 319, at least recessedpart 341C is exposed in a state wherepiston 323 is positioned at the bottom dead center. In other words, recessedpart 341C is defined as a part of recesses in the configuration having the plurality ofrecesses - As shown in
FIG. 8 , recessedpart 341C is formed so that, in a state wherepiston 323 reaches the position of the bottom dead center, all of recessedpart 341C is positioned on the side of the top dead center only by length B fromend face 316A ofcylindrical hole 316.End face 323C on the side ofcompression chamber 315 ofpiston 323 is positioned on the side oftapered part 317 only by distance of length C. Further, as shown inFIG. 10 ,periphery 342 of recessedpart 341C has a shape inclined at almost 30° in cross section. -
FIG. 11 shows disposition ofpiston 323 when the crank angle is 320 degrees in the compression stroke. As shown inFIG. 12 , the crank angle of 320 degrees is the angle at which the lateral pressure load ofpiston 320 becomes the maximum. The maximum lateral pressure load acts on the lateral pressure load sliding part on the side face in the horizontal direction ofcylindrical hole 316. At this time,inflection part 317A betweenstraight part 318 andtapered part 317 is positioned in the range of the width of recessedpart 341C inpiston 323. InFIG. 11 , to clearly show thatinflection part 317A is positioned in the range of the width of recessedpart 341C, the clearance betweenpiston 323 andstraight part 318 ofcylindrical hole 316 is illustrated largely. - The operation of the hermetic-type compressor constructed as mentioned above will now be described. By applying current to
electric mechanism 304,rotor 303 ofelectric mechanism 304 rotatesshaft 310, rotary motion ofeccentric shaft part 312 is converted to reciprocating motion via connectingrod 326, and the reciprocating motion is transmitted topiston 323. By the motion,piston 323 reciprocates incylindrical hole 316. -
Piston 323 shifts from the bottom dead center position shown inFIG. 8 to the compression stroke of compressing the refrigerant gas. In a compression initial state during the shift to the top dead center side shown inFIG. 9 , rise of pressure incompression chamber 315 is small. Consequently, even if the clearance betweentapered part 317 formed incylindrical hole 316 and the sliding face (peripheral face) ofpiston 323 is relatively large, blowby gas is hardly generated by the sealing effect of the lubricant oil. Since the clearance is large, sliding resistance ofpiston 323 is also small. - When the compression stroke progresses and the crank angle becomes 320 degrees,
piston 323 is in the position shown inFIG. 11 . At this time, the lateral pressure load ofpiston 323 becomes the maximum value as shown inFIG. 12 . - In the configuration shown in
FIG. 3 described in the first embodiment, when the lateral pressure load becomes the maximum, the surface pressure of a sliding part in the side face ofpiston 223 locally rises andinflection part 217A as the start point oftapered part 217 easily slides on the sliding part. As a result, a lubricant state deteriorates, and there is the possibility such that sliding sound increases. - In the second embodiment, however,
inflection part 317A having high change rate of the taper angle as the start point oftapered part 317 is positioned in the range of the width of recessedpart 341C inpiston 323. In addition, since the depth of recessedpart 341C is assured,inflection part 317A is apart from the bottom of recessedpart 341C in a state whereinflection part 317A faces recessedpart 341C. Therefore, even when the lateral pressure load increases, the lubricant state does not decrease ininflection part 317A in which an oil film is not easily formed,inflection part 317A does not locally slide, and no sliding sound is generated. - When the compression stroke further progresses, the pressure of the refrigerant gas in
compression chamber 315 gradually increases. Just beforepiston 323 reaches a position near the top dead center shown inFIG. 9 , the pressure incompression chamber 315 further rises. On the top dead center side, the gap between the sliding face ofpiston 323 andtapered part 317 becomes small, so that generation of blowby gas can be reduced. At this time,straight part 318 formed incylindrical hole 316 reduces leakage of the refrigerant gas increased to predetermined discharge pressure more thantapered part 317. - In the state where
piston 323 is positioned at the bottom dead center, the side of connectingrod 326 ofpiston 323 is exposed fromcylinder block 314.Lubricant oil 306 scattered from the upper end ofshaft 310 is amply supplied fromnotch 319 formed in the upper wall ofcylindrical hole 316 to recessedpart 341C formed in the sliding face ofpiston 323 and is held. A part oflubricant oil 306 is supplied to recessedparts cylindrical hole 316 ofcylinder block 314 and the sliding face ofpiston 323 becomes large in the compression stroke. - During movement of
piston 323 to the top dead center, all ofpiston 323 is positioned incylindrical hole 316. Due to this, escape oflubricant oil 306 held in recessedparts cylindrical hole 316 is suppressed. In addition,lubricant oil 306 is easily carried tostraight part 318 in which sliding resistance is highest. - Further, end face 323C on the side of the compression chamber of
piston 323 is positioned on the side oftapered part 317 only by distance of length C inFIG. 8 at the bottom dead center. Consequently, whenpiston 323 moves from the bottom dead center to the top dead center in the compression stroke, a part oflubricant oil 306 adhered to the surface ofpiston 323 moves to the top dead center side, and a part oflubricant oil 306 adhered to the surface ofcylindrical hole 316 is also taken and supplied to the gap betweenpiston 323 andcylindrical hole 316 aspiston 323 moves. - In the state shown in
FIG. 8 , the end face on the side ofcompression chamber 315 ofpiston 323 is positioned intapered part 317. Consequently, the gap betweenpiston 323 andcylindrical hole 316 is larger than that in the case wherepiston 323 is positioned instraight part 318. The amount oflubricant oil 306 held in the space of the gap is accordingly larger. - Therefore, also when
piston 323 moves tostraight part 318 in which the gap is narrow, a larger amount of lubricant oil is supplied to the sliding part formed bypiston 323 andstraight part 318, and the sliding part can be made lubricant and sealed. As a result, occurrence of gas leakage is prevented, and volume efficiency can be improved. The configuration can be applied also to the first embodiment. - Since recessed
part 341C is provided in the annular shape in the sliding face ofpiston 323, for example, by widening the width of recessedpart 341C in the axial direction ofpiston 323, the area of recessedpart 341C can be maximized. - With the configuration as described above, the sliding area between cylindrical hole 316 (compression chamber 315) and
piston 323 is reduced maximally, and sliding resistance can be decreased. In addition,lubricant oil 306 can be supplied uniformly and stably to the lubricant part and the sealing part in the entire circumference ofpiston 323. Consequently, poor lubrication and deterioration in sealing performance caused by nonuniform and unstable oil supply can be prevented. - Further,
periphery 342 of recessedpart 341C is constructed as a face inclined from the surface in the axial direction ofpiston 323 by about 30° in a sectional shape. Consequently, whenpiston 323 reciprocates,lubricant oil 306 held in recessedpart 341C gains force in recessedpart 341C. Along the inclination ofperiphery 342 of recessedpart 341C,lubricant oil 306 is pulled in the gap betweenpiston 323 andcylindrical hole 316, enters the gap, and acts so as to correct the inclination ofpiston 323. In such a manner, a so-called wedge film effect is produced in the gap betweenpiston 323 andcylindrical hole 316. - As a result, by the wedge film effect of
lubricant oil 306, the inclination ofpiston 323 is corrected so as to be reduced, and the gap withcylindrical hole 316 in the entire circumference ofpiston 323 is made uniform. Therefore, lubricatingoil 306 is carried more easily to the sliding part and the sealing part around the top dead center in which the gap is particularly formed narrow, and the frequency of inevitable local metal contact can be reduced. - The angle of
periphery 342 of recessedpart 341C is not limited to about 30°. The angle may be any angle at which the wedge film effect such that, as described above, whenpiston 323 reciprocates,lubricant oil 306 held in recessedpart 341C is pulled in the gap betweenpiston 323 andcylindrical hole 316 is easily produced. That is, it is sufficient to the angle properly in accordance with the reciprocation speed ofpiston 323 and the like. In the embodiment, the angle with respect to the surface in the axial direction ofpiston 323, ofperiphery 342 is preferably in the range of 25° to 35°. However, in a sectional shape having an inclination angle of 45° or less or an equivalent curved shape, the angle may be any angle at whichlubricant oil 306 held in recessedpart 341C is pulled in the gap betweenpiston 323 andcylindrical hole 316. - As a result, a larger amount of
lubricant oil 306 can be supplied to the gap betweencylindrical block 314 andpiston 323,lubricant oil 306 is excellently held, and sealing performance can be improved. Further, with ample supply oflubricant oil 306, the sliding resistance ofpiston 323 can be reduced, so that the compression efficiency is improved, an input is reduced, and higher efficiency can be achieved. The configuration may be applied to recessedparts -
Piston assembly 340 has a cantilever configuration that the deadweight ofpiston assembly 340 is supported only by the sliding part ofpiston 323 inserted incylindrical hole 316. Consequently, around the bottom dead center at whichpiston 323 is exposed fromcylindrical hole 316 most, the bottom dead center side ofpiston 323 leans downward in the vertical direction in the gap betweenpiston 323 andcylindrical hole 316. - However,
periphery 342 on the connecting rod side of recessedpart 341C is positioned on the top dead center side relative to endface 316A ofcylindrical hole 316.End part 323B ofpiston 323 and the corner ofend face 316A ofcylindrical hole 316 are in contact with each other. Consequently,periphery 342 of recessedpart 341C is not deviated vertically downward fromcylindrical hole 316 and does not collide with the lower corner ofend face 316A. Therefore, occurrence of collision noise is suppressed, and reduction in noise can be achieved. - A part of recessed
part 341C is communicated withpiston pin hole 323A. That is, preferably, the upper and lower sides of recessedpart 341C communicate with each other viapiston pin hole 323A. With the configuration, a circulating path thatlubricant oil 306 scattered and supplied to the upper part ofpiston 323 around the bottom dead center passes through circular shaped recessedpart 341C and is ejected downward via the end face ofpiston pin hole 323A is formed.Piston 323 heated by high-temperature, high-pressure refrigerant gas is cooled by relatively-low-temperature lubricant oil 306 passing through the circulating path. By the cooling, the temperature ofpiston 323 decreases. Accordingly, temperature rise incompression chamber 315 is suppressed, and deterioration in the volume efficiency caused by heat reception can be prevented. - Further, in the case of driving an inverter at operation frequency equal to or less than power-supply frequency, particularly, in a low-speed operation of 30 r/sec or less, the reciprocating motion speed of
piston 323 becomes slow and, in addition, the supply amount oflubricant oil 306 supplied by the pumping action ofshaft 310 decreases. Consequently, the amount of lubricatingoil 306 sprayed fromeccentric shaft part 312 intohermetic container 301 decreases. - However, around the bottom dead center, at least recessed
part 341C is exposed fromcylindrical hole 316. Consequently,lubricant oil 306 is reserved mainly in recessedpart 341C and supplied to the sealing part. The oil retentivity is maintained by the capillary action of recessedparts parts - Hereinafter, a result of conducting a confirmatory experiment of coefficient of performance (C.O.P.) of the hermetic-type compressor in the embodiment will be described with reference to
FIGS. 13 to 15 . The coefficient of performance is the ratio of refrigeration capacity to an applied input and is generally used as an index indicating the efficiency of a compressor. In tests, R600a (isobutane) was used as the refrigerant. The operation frequency was 27 r/sec, and operation conditions close to operation conditions in a refrigerator were evaporation temperature of −30° C. and condensation temperature of 40° C. -
FIG. 13 is a characteristic diagram of coefficient of performance with respect to space volume of recessedparts FIG. 14 is a characteristic diagram of the coefficient of performance with respect to distances among neighboring recessedparts FIG. 15 is a characteristic diagram of the coefficient of performance with respect to operation frequency of the compressor. - In
FIG. 13 , the vertical axis denotes the coefficient of performance of the compressor, and the horizontal axis denotes the sum of volume of space surrounded by the section of recessedparts piston 323. - The test result shown in
FIG. 13 is a result of conducting the test using the recessed parts on the side ofcompression chamber 315 as a plurality of recessedparts FIG. 13 is obtained may be employed. - As obvious from
FIG. 13 , it is preferable to set the space volume of recessedparts - Referring now to
FIG. 14 , the influence of distance S between neighboring recessedparts FIG. 14 , the vertical axis denotes the coefficient of performance of the compressor, and the horizontal axis denotes distance S between neighboring recessedparts - As shown in
FIG. 14 , by setting the distance between neighboring recessedparts parts piston 323 andcylindrical hole 316 becomes a reducer. Consequently, the flow rate of a mixed fluid of the refrigerant gas andlubricant oil 306 increases so that the pressure of the mixed fluid is reduced. As a result, the leakage amount from the gap betweenpiston 323 andcylindrical hole 316 further decreases. Therefore, by further reducing the amount of leakage to the side opposite to the compression chamber, reduction in the volumetric efficiency is prevented, and the efficiency of the compressor can be increased. - In the embodiment, recessed
parts parts parts - Next, with reference to
FIG. 15 , the characteristics of the coefficient of performance when the compressor of the embodiment is assembled in a refrigeration cycle and the operation frequency of the compressor is changed under predetermined operation load conditions (certain conditions) will be described. The vertical axis indicates the coefficient of performance of the compressor, and the horizontal axis indicates the operation frequency at which the piston is driven. For comparison, as a conventional technique, a result of the case where the operation frequency is set in the range of about 20 r/sec to about 45 r/sec in a state where a compressor having specifications (cylinder volume: 10 ml and capability at the time of operation of 27 r/sec: 74 W) equivalent to those of the embodiment is assembled in a similar refrigeration cycle is shown. In the conventional compressor, the cylindrical hole does not have a tapered part, and recessedpart 341C is not formed in the piston. - As obvious from
FIG. 15 , in the case of low operation frequency at which the effect of reducing power consumption is large in a cooling system such as a refrigerator, the coefficient of performance is largely improved as compared with that in the conventional compressor. It is therefore understood that the sealing performance ofpiston 323 andcylindrical hole 316 improves dramatically, and the leakage amount can be reduced. - Generally, in a low-speed rotation range, refrigeration capacity is small and the ratio of loss of leakage from the gap between
piston 323 andcylindrical hole 316 to the refrigeration capacity becomes high, so that the efficiency of the compressor deteriorates. However, in the embodiment, by the stable sealing bylubricant oil 306 and the labyrinth effect, the amount of leakage from the gap betweenpiston 323 andcylindrical hole 316 can be reduced. Consequently, extreme deterioration in the efficiency of the compressor accompanying deterioration in volume efficiency can be prevented, and power consumption of the cooling system can be largely reduced. - As described above, in the hermetic-type compressor according to the embodiment, a local contact between
piston 323 andcylindrical hole 316 is avoided and, simultaneously, the sliding area is minimized and the sliding loss can be minimized. Moreover,lubricant oil 306 contributing to the performance of sealing betweenpiston 323 andcylindrical hole 316 is stably supplied to the gap betweenpiston 323 andcylindrical hole 316 and can be reliably assured betweenpiston 323 andcylindrical hole 316. - As a result, a metal contact causing abrasion and noise is prevented, reliability is improved and, moreover, occurrence of noise can be reduced. Further, by assurance of the sealing performance accompanying assurance of stability of
lubricant oil 306, the volumetric efficiency is increased and, as a result, the efficiency of the compressor can be improved. Therefore, higher efficiency and reliability and prevention of occurrence of noise can be simultaneously achieved, and partly contradictory challenges can be solved. - As described above, according to the first and second embodiments, the full length of
cylindrical hole 316 is shortened and the hermetic-type compressor is downsized and, moreover, occurrence of contact noise is prevented, and occurrence of abrasion can be reduced. Consequently, higher efficiency, lower noise, and higher reliability of the hermetic-type compressor can be simultaneously achieved. - According to the present invention, the compression efficiency of the hermetic-type compressor is increased, and sound of collision between the piston and the cylindrical hole can be suppressed. The hermetic-type compressor can be widely applied as a hermetic-type compressor for use in a machine using a refrigeration cycle such as an air conditioner or an automatic vending machine.
- 114, 214, 314 cylinder blocks
- 114A, 214A, 319 notches
- 116, 216, 316 cylindrical holes
- 123, 223, 323, 423 pistons
- 123B, 223B lower end parts
- 226, 326 connecting rods
- 141A, 141B, 241A, 241B grooves
- 141C, 241C, 341A, 341B, 341C, 441A, 441B, 4411C, 4412C recessed parts
- 216A, 316A, 323C end faces
- 217, 317 tapered parts
- 217A, 317A inflection parts
- 218, 318 straight parts
- 242, 342, 442 peripheries
- 301 sealed container
- 302 stator
- 303 rotor
- 304 electric mechanism
- 305 compression mechanism
- 306 lubricant oil
- 310 shaft
- 311 main shaft part
- 312 eccentric shaft part
- 313 oil supply path
- 315 compression chamber
- 320 bearing
- 323A, 423A piston pin holes
- 323B end part
- 340, 440 piston assemblies
- 325, 425 piston pins
- 423B end part
- 423C sliding face
- 423D extension part
Claims (12)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2009246173 | 2009-10-27 | ||
JP2009-246173 | 2009-10-27 | ||
PCT/JP2010/006337 WO2011052195A1 (en) | 2009-10-27 | 2010-10-27 | Hermetic compressor |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120183419A1 true US20120183419A1 (en) | 2012-07-19 |
Family
ID=43921629
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/498,791 Abandoned US20120183419A1 (en) | 2009-10-27 | 2010-10-27 | Hermetic compressor |
Country Status (4)
Country | Link |
---|---|
US (1) | US20120183419A1 (en) |
JP (1) | JP5753983B2 (en) |
CN (2) | CN102597518B (en) |
WO (1) | WO2011052195A1 (en) |
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US20120090461A1 (en) * | 2010-10-14 | 2012-04-19 | Panasonic Corporation | Compressor |
US20160195078A1 (en) * | 2013-09-24 | 2016-07-07 | Illinois Tool Works Inc. | Compressor |
US20160201661A1 (en) * | 2013-09-03 | 2016-07-14 | Panasonic Intellectual Property Management Co., Ltd. | Sealed compressor and freezer device or refrigerator equipped with same |
US20170009758A1 (en) * | 2014-02-25 | 2017-01-12 | Panasonic Intellectual Property Management Co., Ltd. | Sealed compressor and refrigeration device |
US10352312B2 (en) | 2013-01-22 | 2019-07-16 | Panasonic Appliances Refrigeration Devices Singapore | Hermetic compressor and refrigerator |
US11396872B2 (en) * | 2017-03-10 | 2022-07-26 | Hitachi Construction Machinery Co., Ltd. | Axial piston-type hydraulic rotary machine |
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JP5579676B2 (en) * | 2011-08-23 | 2014-08-27 | 日立アプライアンス株式会社 | Hermetic compressor and refrigerator using the same |
CN104165133A (en) * | 2014-09-03 | 2014-11-26 | 安徽美芝制冷设备有限公司 | Compressor crankcase and compressor with same |
JP7258710B2 (en) * | 2019-10-01 | 2023-04-17 | ジーエムシーシー アンド ウェリング アプライアンス コンポーネント (タイランド) カンパニー リミテッド | Compressor and equipment using this |
CN114109773A (en) * | 2021-12-01 | 2022-03-01 | 宁波慕品电器科技有限公司 | Inflating machine core |
CN114962221B (en) * | 2022-06-09 | 2023-02-17 | 珠海格力电器股份有限公司 | Cylinder assembly and compressor |
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- 2010-10-27 JP JP2011538247A patent/JP5753983B2/en active Active
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US20120090461A1 (en) * | 2010-10-14 | 2012-04-19 | Panasonic Corporation | Compressor |
US9074591B2 (en) * | 2010-10-14 | 2015-07-07 | Panasonic Intellectual Property Management Co., Ltd. | Compressor cylinder block and cylinder head distortion prevention |
US10352312B2 (en) | 2013-01-22 | 2019-07-16 | Panasonic Appliances Refrigeration Devices Singapore | Hermetic compressor and refrigerator |
US20160201661A1 (en) * | 2013-09-03 | 2016-07-14 | Panasonic Intellectual Property Management Co., Ltd. | Sealed compressor and freezer device or refrigerator equipped with same |
US11236740B2 (en) * | 2013-09-03 | 2022-02-01 | Panasonic Appliances Refrigeration Devices Singapore | Sealed compressor and freezer device or refrigerator equipped with same |
US20160195078A1 (en) * | 2013-09-24 | 2016-07-07 | Illinois Tool Works Inc. | Compressor |
US20170009758A1 (en) * | 2014-02-25 | 2017-01-12 | Panasonic Intellectual Property Management Co., Ltd. | Sealed compressor and refrigeration device |
US11396872B2 (en) * | 2017-03-10 | 2022-07-26 | Hitachi Construction Machinery Co., Ltd. | Axial piston-type hydraulic rotary machine |
Also Published As
Publication number | Publication date |
---|---|
CN102597518B (en) | 2016-03-30 |
CN105464936A (en) | 2016-04-06 |
WO2011052195A1 (en) | 2011-05-05 |
CN102597518A (en) | 2012-07-18 |
JPWO2011052195A1 (en) | 2013-03-14 |
JP5753983B2 (en) | 2015-07-22 |
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