US20110176942A1 - Sealed compressor - Google Patents

Sealed compressor Download PDF

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Publication number
US20110176942A1
US20110176942A1 US13/119,494 US200913119494A US2011176942A1 US 20110176942 A1 US20110176942 A1 US 20110176942A1 US 200913119494 A US200913119494 A US 200913119494A US 2011176942 A1 US2011176942 A1 US 2011176942A1
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Prior art keywords
piston
cylindrical hole
shaft portion
compression
tapered portion
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US13/119,494
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English (en)
Inventor
Akio Yagi
Ichiro Morita
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Panasonic Corp
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Panasonic Corp
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Publication of US20110176942A1 publication Critical patent/US20110176942A1/en
Abandoned legal-status Critical Current

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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
    • F04B39/125—Cylinder heads
    • 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
    • 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
    • F04B39/126—Cylinder liners

Definitions

  • the present invention relates to a hermetic compressor used in a refrigeration cycle of a fridge-freezer or the like.
  • Patent Literature 1 One conventional hermetic compressor having a reciprocating compression mechanism is disclosed on Patent Literature 1.
  • the hermetic compressor of Patent Literature 1 includes a cylinder, a piston, and a connecting rod.
  • the cylinder has a cylindrical compression space on the inner-diameter side.
  • the piston is cylindrical on the outer-diameter side and reciprocates in the cylinder.
  • the connecting rod connects the piston to an eccentric shaft portion of a shaft via a piston pin.
  • the compression mechanism is driven by the rotation of a rotor of a motor with the shaft fixed to the axial center of the rotor.
  • the hermetic compressor of Patent Literature 1 has a cylinder which is tapered so as to increase its inner diameter from the top dead center to the bottom dead center of the piston.
  • FIGS. 12A and 12B are longitudinal sectional views of a compression section of the hermetic compressor disclosed in Patent Literature 1.
  • FIG. 12A shows a state in which the piston is in the bottom dead center position
  • FIG. 12B shows a state in which the piston is in the top dead center position.
  • the compression section includes cylinder block 14 having cylindrical hole 16 and piston 23 reciprocable therein, and connecting rod 26 connected to piston 23 via piston pin 25 .
  • Connecting rod 26 reciprocates piston 23 between the bottom dead center shown in FIG. 12A and the top dead center shown in FIG. 12B by the eccentric movement of an eccentric shaft portion of a shaft (not shown).
  • the compression section also includes an unillustrated valve plate at an end of cylindrical hole 16 that is opposite (the right side in the drawing) to connecting rod 26 .
  • Piston 23 , cylindrical hole 16 , and the valve plate together form compression space 15 .
  • Cylindrical hole 16 includes tapered portion 17 so as to increase its inner diameter from Dt to Db (>Dt) from the top dead center to the bottom dead center of piston 23 .
  • Piston 23 has a uniform outer diameter throughout its length.
  • piston 23 comes into contact at edge 30 on the compression space 15 side with tapered portion 17 in the compression stroke.
  • piston 23 is reversed in its inclination direction with respect to the axial center of cylindrical hole 16 .
  • the region of the outer surface of piston 23 that did not slide with tapered portion 17 before the reversal comes into contact with tapered portion 17 , possibly making the sliding too much or causing contact noise when the contact is severe at the time of the reversal.
  • Patent Literature 1 Japanese Patent Unexamined Publication No. 2002-89450
  • the hermetic compressor includes an airtight container having lubricating oil therein; an electric element; and a compression element, the compression element being driven by the electric element, and the electric element and the compression element being housed in the airtight container.
  • the compression element includes a shaft, a cylinder block, a piston, and a connection mechanism.
  • the shaft has a main shaft portion and an eccentric shaft portion, the main shaft portion being rotatable by the electric element, and the eccentric shaft portion moving in unison with the main shaft portion.
  • the cylinder block has a cylindrical hole and a bearing, the cylindrical hole forming a compression space, and the bearing supporting the main shaft portion.
  • the piston is reciprocable in the cylindrical hole.
  • the connection mechanism connects the eccentric shaft portion and the piston.
  • the cylindrical hole includes a tapered portion so as to increase an inner diameter thereof from the top dead center to the bottom dead center of the piston, and the piston is reversed in the inclination direction thereof with respect to the axial center of the cylindrical hole in the initial stage of the compression stroke.
  • This structure reduces the sliding resistance, that is, the sliding loss between the piston and the cylindrical hole.
  • This structure also reduces the load when the region of the outer surface of the piston, which did not slide with the tapered portion at the time of the reversal, comes into contact with the tapered portion.
  • the load reduction can be achieved because in the initial stage of the compression stroke, the end face on the compression space side of the piston is subjected to only a small compressive load. This reduces the contact between the piston and the tapered portion, as compared with the case in which the piston is reversed in its inclination direction in the middle or later stage of the compression stroke. This results in a reduction in the contact when the piston is reversed in its inclination direction with respect to the axial center of the cylindrical hole, thereby achieving noise reduction.
  • FIG. 1 is a longitudinal sectional view of a hermetic compressor according to a first exemplary embodiment of the present invention.
  • FIG. 2 is a longitudinal sectional view of an essential part of a compression section of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 3 is a longitudinal sectional view of the essential part of the compression section, including its design dimensions, of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 4 is a cross sectional view of the essential part of the compression section, including its design dimensions, of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 5A is a schematic diagram showing a behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 5B is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 6A is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 6B is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 7A is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 7B is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 8A is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 8B is a schematic diagram showing another behavior of piston 123 in the compression stroke of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 9 is a characteristic diagram showing the relationship between rotation angle and noise obtained from an example of the design dimensions of the hermetic compressor according to the first exemplary embodiment.
  • FIG. 10 is a longitudinal sectional view of an essential part of a compression section, including its design dimensions, of a hermetic compressor according to a second exemplary embodiment of the present invention.
  • FIG. 11 is a cross sectional view of the essential part of the compression section, including its design dimensions, of the hermetic compressor according to the second exemplary embodiment.
  • FIG. 12A is a longitudinal sectional view of a compression section of a conventional hermetic compressor.
  • FIG. 12B is another longitudinal sectional view of the compression section of the conventional hermetic compressor.
  • FIG. 1 is a longitudinal sectional view of a hermetic compressor according to a first exemplary embodiment of the present invention.
  • FIG. 2 is a longitudinal sectional view of an essential part of a compression section of the hermetic compressor.
  • FIG. 3 is a longitudinal sectional view of the essential part of the compression section including its design dimensions.
  • FIG. 4 is a cross sectional view of the essential part of the compression section including its design dimensions.
  • the hermetic compressor includes airtight container 103 having electric element 105 and compression element 107 driven by electric element 105 .
  • Electric element 105 includes stator 105 a and rotor 105 b .
  • Airtight container 103 has lubricating oil 101 at its bottom.
  • Compression element 107 includes shaft 113 having main shaft portion 109 and eccentric shaft portion 111 , which is eccentric thereto to move in unison therewith.
  • Main shaft portion 109 is fixed to the axial center of rotor 105 b.
  • Compression element 107 also includes bearing 119 , which forms a cantilever bearing by supporting the end on the eccentric shaft portion 111 side of main shaft portion 109 of shaft 113 .
  • Compression element 107 also includes balance weight 137 between main shaft portion 109 and eccentric shaft portion 111 .
  • Balance weight 137 is eccentric in the direction opposite to the eccentric direction of eccentric shaft portion 111 so as to strike a rotational balance with the eccentric weight attached to main shaft portion 109 .
  • the eccentric weight is the load of eccentric shaft portion 111 or the pressure load of the refrigerant gas in compression space 115 which acts on eccentric shaft portion 111 .
  • Compression element 107 also includes cylinder block 121 having cylindrical hole 117 with a substantially cylindrical shape and bearing 119 , which are arranged in fixed positions relative to each other. Cylindrical hole 117 has piston 123 reciprocable therein.
  • Compression element 107 also includes connecting rod 125 as a connection mechanism, whose one end is connected with eccentric shaft portion 111 , and whose other end is connected with piston 123 via piston pin 136 .
  • Shaft 113 is provided on its inside and outer surface with oil supply passage 128 .
  • Oil supply passage 128 is communicated at one end (upper end) thereof with oil supply hole 128 a formed in eccentric shaft portion 111 .
  • the end of main shaft portion 109 on the side opposite to eccentric shaft portion 111 that is, the bottom end of main shaft portion 109 is extended so that oil supply passage 128 can reach a predetermined depth of lubricating oil 101 .
  • Compression element 107 also includes valve plate 139 at an end of cylindrical hole 117 .
  • Cylindrical hole 117 is formed in cylinder block 121 in such a manner to form compression space 115 together with piston 123 and valve plate 139 .
  • cylindrical hole 117 includes tapered portion 127 so as to increase its inner diameter from D 1 to D 3 (>D 1 ) from the top dead center to the bottom dead center of piston 123 .
  • Cylindrical hole 117 also includes straight portion 129 in the position corresponding to the end on the compression space 115 side of piston 123 when piston 123 is in the top dead center position.
  • Straight portion 129 has a uniform inner diameter in an axial length L 1 .
  • Piston 123 has a uniform outer diameter D 2 throughout its length.
  • cylindrical hole 117 of cylinder block 121 is formed in such a manner that when piston 123 is in the bottom dead center position, the side opposite to the compression space 115 side of piston 123 is exposed in airtight container 103 .
  • Piston 123 is provided on its outer surface 133 on the compression space 115 side with concave oil supply groove 131 which is substantially annular (including completely annular).
  • Cylindrical hole 117 has notch 120 on its peripheral wall so that oil supply groove 131 is exposed at least partly from cylindrical hole 117 and is communicated with airtight container 103 when piston 123 is in the bottom dead center position.
  • Piston 123 has the outer diameter D 2 , and eccentric shaft portion 111 has an eccentricity “e” with respect to main shaft portion 109 .
  • the center of piston pin 136 and the compression-space-side end face 134 of piston 123 have a distance (hereinafter, main sliding surface length) L 2 therebetween.
  • the center of piston pin 136 corresponds to the connection center between connecting rod 125 and piston 123 .
  • Main shaft portion 109 which has a rotation angle of 0 (zero) degrees when the piston 123 is in the top dead center position, has a rotation angle “ ⁇ ”.
  • the axial center of compression space 115 and tapered portion 127 form an angle “ ⁇ ” therebetween.
  • the inner diameter D 1 of cylindrical hole 117 , the outer diameter D 2 of piston 123 , the length L 1 of straight portion 129 , the main sliding surface length L 2 , the eccentricity “e”, and the rotation angle “ ⁇ ” are design dimensions to find the coordinates of the tip position of piston 123 in cylindrical hole 117 when the behaviors of piston 123 in cylindrical hole 117 are simulated.
  • the angle “ ⁇ ” formed by tapered portion 127 when the above-mentioned design dimensions are selected is set in the range obtained by multiplying a coefficient in the range of 0.4 to 2.0 by a value “ ⁇ ”.
  • the value “ ⁇ ” (hereinafter, dimension value) is obtained by dividing the dimensional numerical value 3/2 of the difference (D 1 ⁇ D 2 ) between the inner diameter D 1 of cylindrical hole 117 and the outer diameter D 2 of piston 123 by the coordinate position ⁇ L 1 ⁇ L 2 +2e(1 ⁇ cos ⁇ ) ⁇ of the tip on the top-dead-center side of piston 123 when the top dead center position is zero.
  • the dimensional numerical value 3/2 is a value derived from the above-mentioned design dimensions (values) to find the coordinates of the tip position of piston 123 in cylindrical hole 117 .
  • the angle “ ⁇ ” defines the dimension value “ ⁇ ” expressed by Mathematical Formula 1 based on the above-mentioned design dimensions: the inner diameter D 1 of cylindrical hole 117 , the outer diameter D 2 of piston 123 , the length L 1 of straight portion 129 , the main sliding surface length L 2 , the eccentricity “e”, and the rotation angle “ ⁇ ”.
  • the angle “ ⁇ ” is defined by Mathematical Formula 2 which is based on the dimension value “ ⁇ ”.
  • the rotation angle “ ⁇ ” of main shaft portion 109 is in the range of ⁇ to 4 ⁇ /3 (rad) in the initial stage of the compression stroke.
  • the coefficients of the dimension value “ ⁇ ” are values properly determined in view of the machining tolerance of tapered portion 127 and the like, and can be set according to the material of cylinder block 121 .
  • Rotor 105 b of electric element 10 rotates shaft 113 , and the rotational motion of eccentric shaft portion 111 is transmitted to piston 123 via connecting rod 125 , allowing piston 123 to reciprocate in cylindrical hole 117 .
  • the reciprocation of piston 123 allows refrigerant gas to be suctioned into compression space 115 from an unillustrated cooling system, to be compressed, and to be discharged into the cooling system.
  • oil supply passage 128 performs a pumping action at its bottom end so that lubricating oil 101 at the bottom of airtight container 103 is pumped through oil supply passage 128 and reaches oil supply hole 128 a .
  • Lubricating oil 101 reached oil supply hole 128 a is sprinkled all around airtight container 103 horizontally from the upper end of shaft 113 so as to be supplied to piston pin 136 , piston 123 , and other components, thereby lubricating them.
  • the pressure in compression space 115 does not increase very much while piston 123 is moving from the bottom dead center shown in FIG. 3 toward the top dead center in the compression stroke to compress the refrigerant gas. Therefore, even when the gap is comparatively large between outer surface 133 of piston 123 and tapered portion 127 , there is almost no leakage of the refrigerant gas, and piston 23 has low sliding resistance due to the sealing effect of lubricating oil 101 .
  • piston 123 When piston 123 is in the bottom dead center position, the connecting rod 125 side of piston 123 is exposed from cylinder block 121 . This allows lubricating oil 101 sprinkled from the upper end of shaft 113 to be sufficiently supplied to outer surface 133 of piston 123 and to be held there.
  • concave substantially annular oil supply groove 131 formed on outer surface 133 on the compression space 115 side of piston 123 is also exposed at least partly from cylindrical hole 117 via notch 120 . This allows lubricating oil 101 sprinkled from the upper end of shaft 113 to be sufficiently supplied to oil supply groove 131 and to be held therein.
  • Substantially annular oil supply groove 131 can move to the position facing straight portion 129 of cylindrical hole 117 , making it easy to carry lubricating oil 101 to straight portion 129 in which the sliding resistance becomes the largest.
  • FIGS. 5A , 5 B to 8 A, 8 B are schematic diagrams showing the behaviors of piston 123 in the present exemplary embodiment.
  • FIGS. 5A , 5 B to 8 A, 8 B are schematic diagrams showing the behaviors of piston 123 in the compression stroke.
  • FIGS. 5A to 8A are schematic diagrams showing a side surface of compression space 115 .
  • FIGS. 5B to 8B are schematic diagrams showing a side surface of shaft 113 .
  • FIGS. 5A , 5 B to 7 A, 7 B show the initial stage of the compression stroke, and
  • FIGS. 8A and 8B show the latter stage of the compression stroke.
  • FIG. 9 is a characteristic diagram showing the relationship between rotation angle and noise obtained from an example of the design dimensions of the hermetic compressor according to the present exemplary embodiment.
  • bearing 119 forms a cantilever bearing which supports the end on the eccentric shaft portion 111 side of main shaft portion 109 of shaft 113 . Therefore, shaft 113 is inclined in the clearance between main shaft portion 109 and bearing 119 . It is known that shaft 113 has intricate behaviors, changing its direction and inclination angle according to operating and other conditions.
  • shaft 113 is affected by various forces such as the pressure load in compression space 115 or the inertia force of piston 123 and connecting rod 125 . Therefore, the schematic diagrams of FIGS. 5B to 8B showing inclinations of shaft 113 are inferentially drawn by the applicant.
  • shaft 113 is inclined in the initial stage of the compression stroke.
  • shaft 113 has intricate inclination behaviors, and hence, piston 123 is considered to have intricate behaviors.
  • piston 123 In the initial stage of the compression stroke, piston 123 is near the bottom dead center and in the region of tapered portion 127 in cylindrical hole 117 . In this case, piston 123 is easily inclined only by a small force, so that, under normal conditions, piston 123 is considered to slide along somewhere on the inner wall surface of tapered portion 127 .
  • piston 123 is inclined nearly in the same manner as shaft 113 and is slid along an upper region of tapered portion 127 in cylindrical hole 117 .
  • outer surface 133 a which is an upper region of outer surface 133 of piston 123 , moves toward compression space 115 while sliding with the upper region of tapered portion 127 in cylindrical hole 117 . Then, as shown in FIGS. 6A and 6B , edge 135 on the outer surface 133 b side of outer surface 133 of piston 123 that does not slide with tapered portion 127 comes into contact with the region of tapered portion 127 that faces outer surface 133 b.
  • piston 123 is reversed in its inclination direction with respect to the axial center of cylindrical hole 117 , and consequently, outer surface 133 b that did not slide with tapered portion 127 before that slides with tapered portion 127 .
  • the inventors have another supposition as follows. Edge 135 on the outer surface 133 b side of piston 123 that does not slide with tapered portion 127 comes into contact with tapered portion 127 . At this moment, shaft 113 is inclined largely toward the side opposite to the compression space 115 side, making piston 123 reversed in its inclination direction with respect to the axial center of cylindrical hole 117 .
  • piston 123 is adjusted in such a manner that its axial center substantially coincides with the axial center of straight portion 129 in cylindrical hole 117 , and then piston 123 further moves toward the compression space 115 side.
  • compression is performed in such a manner as to reduce the leakage of the refrigerant gas that has increased to reach the predetermined discharge pressure, as compared with the case in which straight portion 129 is tapered.
  • piston 123 in the initial stage of the compression stroke, piston 123 is inclined nearly in the same manner as shaft 113 and is slid along the upper region of tapered portion 127 in cylindrical hole 117 . Even when piston 123 and shaft 113 are inclined differently, however, at least piston 123 is considered to be inclined along some region of tapered portion 127 . As a result, it is likely that piston 123 is reversed in its inclination direction, and consequently, the region of outer surface 133 that did not slide with tapered portion 127 before that slides with tapered portion 127 .
  • piston 123 should be designed to be reversed in its inclination direction with respect to the axial center of cylindrical hole 117 in the initial stage of the compression stroke. This reduces the contact between piston 123 and cylindrical hole 117 at the time of the reversal, as compared with the case in which piston 123 is reversed in its inclination direction in the middle or later stage of the compression stroke. As a result, noise reduction can be achieved.
  • tapered portion 127 and compression element 107 can be designed to meet the following requirements.
  • edge 135 of outer surface 133 b of piston 123 that does not slide with tapered portion 127 comes into contact with the region of tapered portion 127 with which outer surface 133 does not slide.
  • piston 123 is reversed in its inclination direction without edge 135 of piston 123 coming into contact with tapered portion 127 . Even in such a case, noise reduction is expected to be achieved in the initial stage of the compression stroke.
  • straight portion 129 is formed in cylindrical hole 117 as follows.
  • Straight portion 129 is formed in a region which is adjacent to tapered portion 127 and corresponds to the upper end on the compression space 115 side of piston 123 .
  • Straight portion 129 is uniform in the inner diameter direction.
  • straight portion 129 designed as above can reduce the leakage of the refrigerant gas that has increased to reach the predetermined discharge pressure, as compared with the case in which straight portion 129 is tapered.
  • edge 135 of piston 123 comes into contact with tapered portion 127 at the timing at which the difference between the outer diameter D 2 of piston 123 and the minimum inner diameter of compression space 115 (the inner diameter D 1 of straight portion 129 in the present exemplary embodiment) is reduced. This means that edge 135 of piston 123 comes into geometric contact with the region of tapered portion 127 that is in the vicinity of straight portion 129 .
  • providing straight portion 129 advances the timing at which edge 135 of piston 123 comes into contact with tapered portion 127 as early as the initial stage of the compression stroke.
  • Increasing the axial length of straight portion 129 can more advance the timing at which edge 135 of piston 123 comes into contact with tapered portion 127 . This reduces, however, the axial length of tapered portion 127 by just that much, decreasing the effect of reducing the sliding resistance in tapered portion 127 .
  • One action is to reduce the refrigerant gas leakage in compression space 115 by providing straight portion 129 , and also to make the timing at which edge 135 of piston 123 comes into contact with tapered portion 127 in the initial stage of the compression stroke.
  • the other action is to ensure the axial length of tapered portion 127 by reducing the axial length of straight portion 129 , thereby reducing the sliding resistance in tapered portion 127 .
  • the inventors have examined the angle “ ⁇ ” formed by the axial center of compression space 115 and tapered portion 127 , and other design dimensions of compression element 107 , while watching the timing at which edge 135 of piston 123 comes into contact with tapered portion 127 in the initial stage of the compression stroke.
  • the angle “ ⁇ ” of tapered portion 127 and the design dimensions of compression element 107 can be determined so that the dimension value “ ⁇ ” and the angle “ ⁇ ” of tapered portion 127 satisfy Mathematical Formula 2.
  • the dimension value “ ⁇ ” is expressed by the Mathematical Formula 1 when the design dimensions of compression element 107 are used as parameters, and the rotation angle “ ⁇ ” of main shaft portion 109 is set in the range of ⁇ to 4 ⁇ /3 (rad) in the initial stage of the compression stroke.
  • FIG. 9 Experimental results of an example of the design dimensions are shown in FIG. 9 .
  • solid line 91 represents a noise level in the case of using the design dimensions of the present invention.
  • Dotted line 92 represents a noise level in the case of using conventional design dimensions.
  • Solid line 93 represents the range of rotation angle ⁇ 1 in the case of using the design dimensions of the present invention.
  • Dotted line 94 represents the range of rotation angle ⁇ 1 in the case of using the conventional design dimensions.
  • the experimental results have been obtained by measuring noise values under the following conditions: the inner diameter D 1 of cylindrical hole 117 is about 22.01 mm, the outer diameter D 2 of piston 123 is about 22 mm (D 1 >D 2 ), the main sliding surface length L 2 is about 13 mm, the eccentricity “e” is 10 mm, and the length L 1 of straight portion 129 , which is one of the design dimensions, is about 4 mm, about 8 mm, or about 10 mm (the rotation angle “ ⁇ ” is about 190 degrees, about 210 degrees, or about 225 degrees).
  • the angle “ ⁇ ” obtained in this experiment is in the range of 0.03 to 0.05 degrees. It goes without saying that this range includes some tolerance.
  • the design dimensions in the conventional design are determined to be used over a wide range including the middle stage of the compression stroke, and therefore, the design dimensions include those having high noise levels.
  • the dimension value “ ⁇ ” is defined by Mathematical Formula 1 above, and the timing at which edge 135 of piston 123 comes into contact with tapered portion 127 is set in the range of ⁇ to 4 ⁇ /3 (rad).
  • lubricating oil 101 sufficiently supplied to outer surface 133 of piston 123 reduces the contact between outer surface 133 of piston 123 and tapered portion 127 , thereby achieving efficiency improvement and noise reduction.
  • piston 123 is provided on its outer surface with concave oil supply groove 131 , and cylindrical hole 117 has notch 120 on its peripheral wall so that oil supply groove 131 can be communicated with airtight container 103 near the bottom dead center of piston 123 .
  • lubricating oil 101 sprinkled all around airtight container 103 from the upper end of oil supply hole 128 a formed at eccentric shaft portion 111 of shaft 113 can be held in oil supply groove 131 and sufficiently supplied to tapered portion 127 and straight portion 129 of cylindrical hole 117 .
  • the sealing effect of lubricating oil 101 is achieved, which prevents the refrigerant gas leakage.
  • lubricating oil 101 sufficiently supplied to outer surface 133 of piston 123 reduces the contact between outer surface 133 of piston 123 and tapered portion 127 , thereby achieving efficiency improvement and noise reduction.
  • eccentric shaft portion 111 and piston 123 are connected using connecting rod 125 as a connection mechanism, but the same effect can be obtained by using a connection mechanism having a movable portion such as a ball joint.
  • a present exemplary embodiment has the same structure as the first exemplary embodiment except that bearing 119 and compression space 115 are arranged differently. Therefore, the following description of the present exemplary embodiment will be mainly focused on the difference.
  • FIG. 10 is a longitudinal sectional view of an essential part of a compression section, including its design dimensions, of a hermetic compressor according to the present exemplary embodiment.
  • FIG. 11 is a cross sectional view of the essential part of the compression section, including its design dimensions, of the hermetic compressor.
  • bearing 119 and compression space 115 are arranged in such a manner that third center line 142 and second center line 143 cross each other.
  • Third center line 142 is parallel with first center line 141 representing the axial center of bearing 119 .
  • Second center line 143 represents the axial center of compression space 115 .
  • each of first and third center lines 141 and 142 is illustrated as a dot because FIG. 11 is a cross sectional view.
  • second center line 143 and offset line 144 which passes through first center line 141 and is parallel with second center line 143 have a distance (hereinafter, offset distance) “s” therebetween.
  • offset distance a distance (hereinafter, offset distance) “s” therebetween.
  • bearing 119 is arranged offset with respect to compression space 115 .
  • the first exemplary embodiment does not have this offset.
  • the offset distance “s” is one of the design dimensions in the present exemplary embodiment, additional to the design dimensions of the first exemplary embodiment. More specifically, the offset distance “s” is designed in the range of 1 to 4 mm, and is designed to be 2 mm in a hermetic compressor for a refrigerator.
  • the angle “ ⁇ ” formed by the axial center of compression space 115 and tapered portion 127 is defined by Mathematical Formula 2 described in the first exemplary embodiment.
  • the angle “ ⁇ ” is set based on the following design dimensions: the inner diameter D 1 of cylindrical hole 117 , the outer diameter D 2 of piston 123 , the length L 1 of straight portion 129 , the main sliding surface length L 2 , the eccentricity “e”, and the rotation angle “ ⁇ ” of main shaft portion 109 , which are defined in the first exemplary embodiment, and also offset distance “s”.
  • the angle “a” is set in the range obtained by multiplying a coefficient in the range of 0.4 to 2.0 by the dimension value “ ⁇ ”.
  • the dimension value “ ⁇ ” is obtained by dividing the dimensional numerical value 3/2 of the difference (D 1 ⁇ D 2 ) between the inner diameter D 1 of cylindrical hole 117 and the outer diameter D 2 of piston 123 by the coordinate position ⁇ L 1 ⁇ L 2 +2A ⁇ of the tip on the top-dead-center side of piston 123 when the top dead center position of piston 123 is 0 (zero).
  • the “A” is an assignment expression used to simplify the calculation formula because the offset arrangement of bearing 119 and compression space 115 makes it necessary to correct the coordinate position of the tip of the piston.
  • the dimensional numerical value 3/2 is a value derived from the design dimensions (values) to find the coordinates of the tip position of piston 123 in cylindrical hole 117 in the same manner as in the first exemplary embodiment.
  • bearing 119 is arranged offset with respect to compression space 115 . This makes it possible to reduce the sliding loss between cylinder block 121 and piston 123 in addition to the effect of the first exemplary embodiment.
  • the hermetic compressor of the present invention includes an airtight container having lubricating oil therein; an electric element; and a compression element, the compression element being driven by the electric element, and the electric element and the compression element being housed in the airtight container.
  • the compression element includes a shaft, a cylinder block, a piston, and a connection mechanism.
  • the shaft has a main shaft portion and an eccentric shaft portion, the main shaft portion being rotatable by the electric element, and the eccentric shaft portion moving in unison with the main shaft portion.
  • the cylinder block has a cylindrical hole and a bearing, the cylindrical hole forming a compression space, and the bearing supporting the main shaft portion.
  • the piston is reciprocable in the cylindrical hole.
  • the connection mechanism connects the eccentric shaft portion and the piston.
  • the cylindrical hole includes a tapered portion so as to increase an inner diameter thereof from the top dead center to the bottom dead center of the piston, and the piston is reversed in the inclination direction thereof with respect to the axial center of the cylindrical hole in the initial stage of the compression stroke.
  • This structure reduces the sliding resistance, that is, the sliding loss between the piston and the cylindrical hole.
  • This structure also reduces the load when the region of the outer surface of the piston that did not slide with the tapered portion before the reversal comes into contact with the tapered portion.
  • the load reduction can be achieved because in the initial stage of the compression stroke, the end face on the compression space side of the piston is subjected to only a small compressive load.
  • the piston is revered in its inclination direction with respect to the axial center of the cylindrical hole at the moment when the edge on the compression space side of the piston comes into contact with the tapered portion.
  • the cylindrical hole includes the straight portion designed as follows.
  • the straight portion has a uniform inner diameter in the axial direction, and is formed in the region which is adjacent to the tapered portion and corresponds to the upper end on the compression space side of the piston when the piston is near the top dead center position.
  • This structure advances the timing at which the piston is reversed in its inclination direction with respect to the axial center of the cylindrical hole as early as the initial stage of the compression stroke, much earlier than the middle or later stage.
  • the end face on the compression space of the piston is subjected to only a small compressive load. Therefore, this structure also reduces the load when the region of the outer surface of the piston that did not slide with the tapered portion before the reversal comes into contact with the tapered portion. This reduces the contact between the outer surface of the piston and the tapered portion when the piston is reversed in its inclination direction with respect to the axial center of the cylindrical hole, thereby achieving efficiency improvement and noise reduction.
  • the axial length of the straight portion is L 1
  • the minimum inner diameter of the compression space is D 1
  • the outer diameter of the piston is D 2
  • the eccentricity of the eccentric shaft portion with respect to the main shaft portion is “e”
  • the distance from the connection center of the connection mechanism and the piston to the compression-space-side end face of the piston is L 2
  • the rotation angle of the main shaft portion whose rotation angle is 0 (zero) degrees when the piston is in the top dead center position is “ ⁇ ”
  • the angle formed by the axial center of the compression space and the tapered portion is “ ⁇ ”.
  • the angle “ ⁇ ” defines the dimension value “ ⁇ ” expressed by Mathematical Formula 1 based on the design dimensions: the inner diameter D 1 of the cylindrical hole, the outer diameter D 2 of the piston, the length L 1 of the straight portion, the main sliding surface length L 2 , the eccentricity “e”, and the rotation angle “ ⁇ ”.
  • the angle “ ⁇ ” is defined by Mathematical Formula 2 which is based on the dimension value “ ⁇ ”.
  • the design dimensions of the hermetic compressor that are involved in the behaviors of the piston can be determined in such a manner as to reduce the contact between the outer surface of the piston and the tapered portion when the piston is reversed in its inclination direction with respect to the axial center of the cylindrical hole. As a result, this reduces the contact between the outer surface of the piston and the tapered portion when the piston is reversed in its inclination direction, as compared with the case in which the piston is reversed in its inclination direction in the middle or later stage of the compression stroke.
  • the angle “ ⁇ ” formed by the axial center of the compression space and the tapered portion can be determined by setting the rotation angle “ ⁇ ” of the main shaft portion with respect to which the piston is reversed in its inclination direction, and also by setting the following design values: the inner diameter D 1 of the cylindrical hole, the outer diameter D 2 of the piston, the length L 1 of the straight portion, the main sliding surface length L 2 , and the eccentricity “e”.
  • the rotation angle “ ⁇ ” of the main shaft portion is in the range of ⁇ to 4 ⁇ /3 (rad).
  • the bottom end of the piston is exposed from the cylindrical hole when the piston is returned to the bottom dead center position.
  • This allows a large amount of lubricating oil to be supplied and held, thereby reducing the sliding loss between the piston and the cylindrical hole, and hence, achieving efficiency improvement.
  • the region of the outer surface of the piston that did not slide with the tapered portion before the reversal comes into contact with the tapered portion.
  • a sufficient amount of lubricating oil is supplied.
  • the lubricating oil can reduce the contact between the outer surface of the piston and the tapered portion, thereby achieving efficiency improvement and noise reduction.
  • the piston is provided on its outer surface with the concave oil supply groove, which is communicated with the airtight container near the bottom dead center of the piston.
  • the lubricating oil lubricates the sliding portion, thereby achieving a hermetic compressor having high freezing capacity and reliability.
  • the lubricating oil reduces the contact between the outer surface of the piston and the tapered portion, and ensures the sealing between the outer surface of the piston and the tapered portion, thereby achieving efficiency improvement and noise reduction.
  • the bearing and the compression space are arranged in such a manner that the third center line and the second center line cross each other.
  • the third center line is parallel with the first center line representing the axial center of the bearing.
  • the second center line represents the axial center of the compression space.
  • This structure reduces the sliding resistance, that is, the sliding loss between the piston and the cylindrical hole.
  • This structure also reduces the load when the region of the outer surface of the piston that did not slide with the tapered portion before the reversal comes into contact with the tapered portion.
  • the load reduction can be achieved because in the initial stage of the compression stroke, the end face on the compression space of the piston is subjected to only a small compressive load. This reduces the contact between the piston and the tapered portion at the time of the reversal, as compared with the case in which the piston is reversed in its inclination direction in the middle or later stage of the compression stroke.
  • this reduces the contact when the piston is reversed in its inclination direction with respect to the axial center of the cylindrical hole, thereby achieving efficiency improvement and noise reduction. Furthermore, the offset arrangement of the bearing and the compression space reduces the sliding loss between the cylinder block and the piston.
  • the axial length of the straight portion is L 1
  • the minimum inner diameter of the compression space is D 1
  • the outer diameter of the piston is D 2
  • the eccentricity of the eccentric shaft portion with respect to the main shaft portion is “e”
  • the distance from the connection center of the connection mechanism and the piston to the compression-space-side end face of the piston is L 2
  • the rotation angle of the main shaft portion whose rotation angle is 0 (zero) degrees when the piston is in the top dead center position is “ ⁇ ”
  • the offset distance (the distance between the first and third center lines) is “s”
  • the angle formed by the axial center of the compression space and the tapered portion is “ ⁇ ”.
  • the angle “ ⁇ ” is defined by Mathematical Formula 2 which is based on the dimension value “ ⁇ ” expressed by Mathematical Formula 3 based on the design dimensions: the inner diameter D 1 of the cylindrical hole, the outer diameter D 2 of the piston, the length L 1 of the straight portion, the main sliding surface length L 2 , the eccentricity “e”, the rotation angle “ ⁇ ”, and the offset distance “s”.
  • the design dimensions of the hermetic compressor that are involved in the behaviors of the piston can be determined in such a manner as to reduce the contact between the outer surface of the piston and the tapered portion when the piston is reversed in its inclination direction with respect to the axial center of the cylindrical hole.
  • the angle “ ⁇ ” formed by the axial center of the compression space and the tapered portion can be determined by setting the rotation angle “ ⁇ ” of the main shaft portion with respect to which the piston is reversed in its inclination direction, and also by setting the following design values: the inner diameter D 1 of the cylindrical hole, the outer diameter D 2 of the piston, the length L 1 of the straight portion, the main sliding surface length (the distance from the center of the piston pin to the compression-space-side end face of the piston) L 2 , the eccentricity “e”, and the offset distance “s”.
  • the rotation angle “0” of the main shaft portion is in the range of ⁇ to 4 ⁇ /3 (rad).
  • the hermetic compressor of the present invention which has low sliding loss of the piston, low input, high efficiency, and low collision impact with low noise, is applicable to any device having a refrigeration cycle such as domestic refrigerators, dehumidifiers, showcases, and vending machines.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressor (AREA)
US13/119,494 2008-10-29 2009-10-19 Sealed compressor Abandoned US20110176942A1 (en)

Applications Claiming Priority (3)

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JP2008277973 2008-10-29
JP2008277972 2008-10-29
PCT/JP2009/005449 WO2010050141A1 (ja) 2008-10-29 2009-10-19 密閉型圧縮機

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US (1) US20110176942A1 (ja)
EP (1) EP2256344A4 (ja)
JP (1) JP5136639B2 (ja)
CN (1) CN101970879B (ja)
WO (1) WO2010050141A1 (ja)

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US20120090461A1 (en) * 2010-10-14 2012-04-19 Panasonic Corporation Compressor
US10295233B2 (en) * 2015-12-25 2019-05-21 Panasonic Appliances Refrigeration Devices Singapore Closed compressor and refrigeration device using the same

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JP5810273B2 (ja) * 2010-10-21 2015-11-11 パナソニックＩｐマネジメント株式会社 密閉型圧縮機および冷凍装置
JP5579676B2 (ja) * 2011-08-23 2014-08-27 日立アプライアンス株式会社 密閉型圧縮機及びこれを用いた冷蔵庫

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Publication number Publication date
EP2256344A4 (en) 2018-03-07
WO2010050141A1 (ja) 2010-05-06
CN101970879B (zh) 2013-08-07
JP5136639B2 (ja) 2013-02-06
CN101970879A (zh) 2011-02-09
JPWO2010050141A1 (ja) 2012-03-29
EP2256344A1 (en) 2010-12-01

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