JP2013036381A - Hermetic compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly-efficient hermetic compressor that reduces re-expansion loss by reducing dead volume and reduces loss in an ejection hole by improving a refrigerant gas flow in a compression chamber.SOLUTION: In the hermetic compressor, a protruding part 155, which makes the ejection hole 139 appear and disappear accompanied by the reciprocation of a piston 125, is provided on an end surface 153 of the piston 125, a sidewall 165a is provided in a side surface of the protruding part 155, and a gradient α of the sidewall 165a with respect to the end surface 153 of the piston 125 has less gradient than gradients β of the other sidewalls 165b, 165c, 165d that are provided in the protruding part 155 with respect to the end surface 153 of the piston 125. This reduces the dead volume formed in the ejection hole 139 and the loss in the compression chamber 135 and the ejection hole 139, thus providing the highly-efficient hermetic compressor.

Description

  The present invention relates to a hermetic compressor used in a refrigeration cycle such as an electric refrigerator, an air conditioner, and a refrigeration apparatus.

  In recent years, energy savings have been promoted in household refrigerators, and higher efficiency is being promoted in hermetic compressors installed in household refrigerators.

  Under such circumstances, this type of hermetic compressors that are conventionally installed in refrigerators for home use have a convex portion provided on the piston to reduce the dead volume of the discharge holes and improve the efficiency of the compressed gas. Some have reduced loss due to expansion and reduced refrigeration capacity (see, for example, Patent Document 1).

  7 is a longitudinal sectional view of a conventional hermetic compressor described in Patent Document 1, FIG. 8 is a perspective view of a piston of the conventional hermetic compressor, and FIG. 9 is a diagram of a conventional hermetic compressor. It is principal part sectional drawing by the AA of 8.

  As shown in FIGS. 7 to 9, the conventional hermetic compressor 1 accommodates a compression element 5 and an electric element 7 in a hermetic container 3, and the internal space is filled with a refrigerant gas 9.

  The compression element 5 has a configuration in which a piston 13 is inserted so as to freely reciprocate in a substantially cylindrical cylinder 11 and the piston 13 is connected to an eccentric shaft 19 of a crankshaft 17 by a connecting means 15.

  Further, a valve plate 25 having a suction hole 21 and a discharge hole 23 is disposed at the end of the cylinder 11, and a suction valve (not shown) that opens and closes the suction hole 21 and the discharge hole 23, respectively, and a discharge. A valve 27 is provided.

  A compression chamber 29 is formed by the cylinder 11, the valve plate 25, and the piston 13, and the piston 13 reciprocates in the cylinder 11 by the rotation of the crankshaft 17 that transmits the rotational force of the electric element 7. This is a compression mechanism that sucks, compresses, and discharges the refrigerant gas 9.

  Further, as shown in detail in FIGS. 8 and 9, the conventional hermetic compressor 1 has an end face (on the valve plate 25 side) of the piston 13 in order to reduce the dead volume (shaded portion) of the discharge hole 23. A convex portion 31 is provided at a position where it enters the discharge hole 23 on the front end surface.

  Further, the side surface of the convex portion 31 of the piston 13 continuously changes in the circumferential direction in order to reduce the change in the flow direction 39 of the refrigerant gas 9, and is minimized in the region of the side surface 33. It is set to be the maximum in the area.

  Further, the gradient is set so that the inner peripheral surface 37 of the discharge hole 23 is substantially parallel to the side surface 33 and the side surface 35 of the convex portion 31 of the piston 13.

  On the other hand, in the fluid technology, there is also known a book that discloses a technique for forming a bell mouth having a circular cross section at the inlet periphery of the discharge hole for discharging the fluid and reducing the loss at the inlet periphery due to the fluid flow. (For example, refer nonpatent literature 1).

US Pat. No. 5,980,223

Engineering Fundamental Fluid Mechanics 3rd Edition (Baifukan 1990 P.184-185)

  However, although the above-mentioned conventional configuration can reduce the dead volume (shaded portion) by the convex portion 31 provided on the valve plate 25 side of the piston 13 entering the discharge hole 23, as shown in FIG. Since the side surface 33 and the side surface 35 of 31 and the inner peripheral surface 37 of the discharge hole 23 are substantially parallel, the piston 13 gradually moves from the position indicated by the dotted line to the position indicated by the solid line (top dead center). There was a problem that the flow passage area of the refrigerant gas 9 decreased, overcompression occurred, and discharge loss increased.

  In FIG. 9, although the change in the flow direction 39 of the refrigerant gas 9 can be reduced by the gentle side surface 33 of the convex portion 31, the convex portion 31 has a truncated cone shape. In the flow of the refrigerant gas 9 that flows toward the surface, the protrusion 31 wraps around the peripheral wall (side surface).

  Therefore, the refrigerant gas 9 flowing from the entire circumference of the side surface interferes with each other on the end surface (tip surface) of the convex portion 31, and turbulent flow is generated, so that the refrigerant gas 9 cannot flow out from the compression chamber 29 to the discharge hole 23. Then, the refrigerant gas 9 accumulated (remaining) in the compression chamber 29 is re-expanded with the suction operation of the piston 13. As a result, there has been a problem that the effects of reduction of dead volume and improvement of refrigerant gas flow in the hermetic compressor 1 cannot be sufficiently exhibited, such as suction loss.

  In addition, it is assumed that the configuration disclosed in Non-Patent Document 1 is applied to the discharge hole 23 of the conventional hermetic compressor 1, but the loss around the discharge hole 23 due to the protrusion 31 (complexity of refrigerant). It is predicted that sufficient effects cannot be expected due to

  The present invention solves the above-mentioned conventional problems, and by reducing dead volume, it reduces re-expansion loss, improves refrigerant gas flow, and reduces loss of discharge gas flow in the compression chamber and discharge holes. Thus, an object is to provide a highly efficient hermetic compressor.

  In order to solve the above conventional problems, a hermetic compressor according to the present invention is provided with at least one flat surface on a side surface of a convex portion provided on a front end surface of a piston, and the front end of the piston in one of the flat surfaces. The gradient α with respect to the surface is made gentler than the gradient β with respect to the piston on the other side surface of the convex portion.

Thus, the convex portion provided on the tip surface of the piston enters the discharge hole, thereby reducing the dead volume and reducing the reexpansion loss, thereby improving the efficiency of the compressor. Furthermore, in the flow of the refrigerant gas flowing from the suction hole toward the discharge hole, the flat surface blocks the wraparound to the peripheral wall extending in the axial direction of the convex portion, and efficiently guides the refrigerant gas blocked by the flat surface toward the discharge hole. Therefore, the accumulation (amount) of refrigerant gas in the compression chamber at the end of the compression stroke can be suppressed, and the intake loss associated with the re-expansion of the accumulated refrigerant gas can be reduced.

  The hermetic compressor of the present invention can reduce the loss of the discharge gas flow in the compression chamber and the discharge hole, and can reduce the suction loss accompanying re-expansion of the refrigerant gas accumulated in the compression chamber. The efficiency of the machine can be increased.

1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. The principal part perspective view of the piston of the hermetic compressor in Embodiment 1 Sectional drawing of the principal part by the BB line of FIG. 2 of the hermetic compressor in Embodiment 1 Explanatory drawing which shows the arrangement | positioning relationship with the suction | inhalation hole and discharge hole of a convex part seen from the compression surface of the piston of the hermetic compressor in Embodiment 1 The characteristic view which shows the relationship between the gradient (alpha) of the side surface of the convex part of the hermetic compressor in Embodiment 1, and a coefficient of performance COP The principal part perspective view of the piston which provided the convex part of a different structure in Embodiment 1 Vertical section of a conventional hermetic compressor A perspective view of a piston of a conventional hermetic compressor Sectional view of the main part of the conventional hermetic compressor taken along line AA in FIG.

  According to a first aspect of the present invention, an electric element and a compression element driven by the electric element are accommodated in a sealed container. The compression element reciprocates in the compression chamber space and a cylinder block having a compression chamber space. A piston that is disposed at an end of the compression chamber space and that forms a compression chamber with the piston, and a suction hole into which the refrigerant gas compressed in the compression chamber flows into the valve plate. A discharge hole for discharging the refrigerant gas compressed in the compression chamber is provided, and the discharge hole is projected and retracted at a position facing the discharge hole at the front end surface of the piston as the piston reciprocates. A convex portion is provided, and at least one flat surface is provided on a side surface of the convex portion, and a gradient α with respect to a tip surface of the piston in one of the flat surfaces is defined as the piston on the other side surface of the convex portion. Than the gradient β against the distal end surface is obtained by so becomes gentle.

  By adopting such a configuration, it is possible to reduce the dead volume formed in the discharge hole and reduce the suction loss due to re-expansion, so in addition to improving the efficiency of the compressor, the suction hole to the discharge hole In the flow of the refrigerant gas flowing toward, wraparound to the peripheral wall extending in the axial direction of the convex portion can be blocked by the flat surface.

  Furthermore, the flat surface gradient α makes the gradient gentler than the gradient β on the other side surface, thereby reducing the flow resistance of the flow along the plane in the refrigerant gas flow flowing from the compression chamber to the discharge hole. Can do.

  As a result, the refrigerant gas blocked by the plane can be efficiently guided toward the discharge hole, and the accumulation (remaining) of the refrigerant gas in the compression chamber at the end of the compression stroke is reduced. The suction loss accompanying re-expansion can be reduced, and the efficiency of the hermetic compressor can be improved.

  In the second invention, in particular, the flat surface having the gradient α in the convex portion of the first invention is arranged at a position facing the suction hole side.

  As a result, the flow of the refrigerant gas flowing from the suction hole and flowing toward the discharge hole is blocked by the plane, and the flow of the refrigerant gas toward the discharge hole along the plane is generated, and the refrigerant gas compression chamber particularly at the end of the compression stroke This further reduces the accumulation (remaining) at. As a result, it is possible to reduce the suction loss associated with the re-expansion of the accumulated refrigerant gas and improve the efficiency of the hermetic compressor.

  In the third invention, in particular, the discharge hole of the first or second invention is formed so that the cross-sectional area increases from the compression chamber side toward the opposite side of the compression chamber.

  As a result, the area of the flow path formed by the side surface of the convex portion and the inner peripheral surface of the discharge hole can be increased, and the flow path resistance of the refrigerant gas passing through the discharge hole can be minimized. As a result, it is expected that the compressed refrigerant gas can smoothly flow out from the discharge hole, reduce overcompression during the compression stroke, and reduce the input of the hermetic compressor.

  In the fourth invention, in particular, a bell whose cross-sectional area decreases from the compression chamber side to the opposite side of the compression chamber at the compression chamber side corner of the discharge hole of any one of the first to third inventions. A mouse part is provided.

  Thus, at the end of the compression stroke, the refrigerant gas guided toward the discharge hole by the convex portion of the piston can be more smoothly guided to the discharge hole. As a result, the accumulation (remaining) of the refrigerant gas in the compression chamber at the end of the compression stroke is reduced, and the suction loss accompanying the re-expansion of the accumulated refrigerant gas is reduced, thereby improving the efficiency of the hermetic compressor. be able to.

  In the fifth invention, in particular, the shape of the convex portion of any one of the first to fourth inventions is a polygonal shape in which a cross-sectional shape by a surface substantially parallel to the tip surface of the piston has a plurality of planes. Is.

  Thus, in the flow of the refrigerant gas flowing from the suction hole toward the discharge hole, the wraparound to the peripheral wall extending in the axial direction of the convex portion is blocked by a plurality of planes forming a polygon, and the refrigerant gas blocked by the planes Can be guided in the direction of the discharge hole, and the accumulation (remaining) of the refrigerant gas in the compression chamber at the end of the compression stroke can be further reduced. As a result, it is possible to reduce the suction loss due to the re-expansion of the accumulated refrigerant gas and further improve the efficiency of the hermetic compressor.

  In the sixth aspect of the invention, in particular, the shape of the convex portion of any one of the first to fifth aspects of the invention is such that the cross-sectional shape of the surface substantially parallel to the tip surface of the piston is substantially rectangular. is there.

  Accordingly, in the flow of the refrigerant gas flowing from the suction hole toward the discharge hole, the flow of the refrigerant gas toward the discharge hole can be made to flow along a plurality of planes surrounding the convex portion. Therefore, it is possible to smoothly guide the refrigerant gas in the direction of the discharge hole while suppressing the wraparound of the convex portion in the peripheral direction. Further, the accumulation (remaining) of refrigerant gas in the compression chamber at the end of the compression stroke is reduced, and the suction loss associated with the re-expansion of the accumulated refrigerant gas is reduced to improve the efficiency of the hermetic compressor. Can do.

  In the seventh invention, in particular, the gradient α at the convex portion of any one of the first to sixth inventions is set in a range of about 60 ° ≦ α ≦ about 85 °.

As a result, the flow toward the discharge hole of the refrigerant gas becomes smooth, and in particular, the accumulation (remaining) of the refrigerant gas in the compression chamber at the end of the compression stroke can be reduced, so that the accumulated refrigerant gas can be re-expanded. The accompanying suction loss can be reduced, and the efficiency of the hermetic compressor can be improved.

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

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. FIG. 2 is a perspective view of a main part of the piston of the hermetic compressor according to the first embodiment. 3 is a cross-sectional view of an essential part taken along line BB of FIG. 2 of the hermetic compressor according to the first embodiment. FIG. 4 is an explanatory diagram showing an arrangement relationship between the suction hole and the discharge hole of the convex portion as viewed from the compression surface of the piston of the hermetic compressor in the first embodiment. FIG. 5 is a characteristic diagram showing the relationship between the gradient α of the side surface of the convex portion of the hermetic compressor and the coefficient of performance COP in the first embodiment. FIG. 6 is a perspective view of a main part of a piston provided with a convex portion having a different configuration in the first embodiment.

  As shown in FIG. 1, a hermetic compressor (hereinafter referred to as a compressor) 100 has a hermetic container 101 filled with a refrigerant gas 103, an electric element 105, and a compression element driven by the electric element 105. 107 are elastically supported and accommodated in the sealed container 101 by the suspension spring 109.

  The compression element 107 is mainly composed of a crankshaft 111 that converts the rotational movement of the electric element 105 into a reciprocating movement, and a cylinder block 115 that includes a cylinder 113 having a substantially cylindrical compression chamber space.

  The crankshaft 111 includes a main shaft portion 119 to which the rotor 117 of the electric element 105 is fixed, and an eccentric portion 121 whose shaft center is eccentric with respect to the main shaft portion 119. The main shaft portion 119 is supported by the main bearing portion 123 of the cylinder block 115.

  A piston 125 is inserted into the cylinder 113 so as to freely reciprocate. The piston 125 is connected to the eccentric portion 121 of the crankshaft 111 via a connecting means 127. That is, one end of the connecting means 127 is rotatably connected to the eccentric part 121 of the crankshaft 111 and the other end is rotatably connected to a piston pin 129 attached to the piston 125. Thereby, the connecting means 127 converts the turning of the eccentric portion 121 accompanying the rotation of the crankshaft 111 into a reciprocating motion and transmits it to the piston 125.

  A valve plate 133 is disposed at the end 131 of the cylinder 113, and a compression chamber 135 is formed by the valve plate 133, the piston 125, and the cylinder 113.

  The valve plate 133 is provided with a suction hole 137 and a discharge hole 139 each formed in a circular shape, and a suction valve (not shown) that opens and closes the suction hole 137 and a discharge valve 145 that opens and closes the discharge hole 139 are well known. Is provided.

  The valve plate 133 is covered with a cylinder head 141, and a discharge chamber 147 communicating with the discharge hole 139 is provided inside the cylinder head 141.

  Further, the suction muffler 143 is sandwiched between the cylinder head 141 and the valve plate 133.

A discharge pipe 149 is connected to the discharge chamber 147, and the closed container 101 is connected to the discharge pipe 149.
An outlet pipe 151 extending to the outside is connected.

  The end face of the piston 125 on the valve plate 133 side, that is, the front end face 153 is integrally provided with a convex portion 155 at a position corresponding to the discharge hole 139 and protruding and retracting the discharge hole 139 as the piston 125 reciprocates. Yes.

  Further, as shown in FIG. 3, the discharge hole 139 provided in the valve plate 133 is provided with a bell mouth portion 173 having a circular cross section at the periphery on the inlet side (compression chamber 135 side), and the hole diameter thereof is the compression chamber 135. The cross-sectional area is increased from the side toward the opposite side of the compression chamber 135 (discharge chamber 147 side).

  The radius of the arc of the bell mouth portion 173 of the discharge hole 139 can be arbitrarily set.

  Further, the discharge hole 139 is formed in a size that allows the convex portion 155 of the piston 125 to easily enter, and is provided in the shaft center 159 at a position eccentric to the outer peripheral side of the shaft center 157 of the compression chamber 135. Yes.

  Accordingly, the position of the axial center 161 of the convex portion 155 is also substantially coincident with the axial center 159 of the discharge hole 139 because the discharge hole 139 appears and retreats when the piston 125 reciprocates. 157 and the axial center 157 of the piston 125 which is (substantially) coincident with the axial center 157 is provided at a position eccentric to the outer peripheral side of the axial center 163.

  Further, as shown in FIGS. 2 and 4, the convex portion 155 has a shape based on a rectangular parallelepiped, and is formed by four planes (hereinafter referred to as side walls) 165 a, 165 b, 165 c, 165 d and the top surface 167. Yes. The convex portion 155 has a substantially rectangular top surface 167 perpendicular to the axis 163 of the piston 125.

  As shown in FIG. 3, the four side walls 165a, 165b, 165c, and 165d of the convex portion 155 have a slightly tapered cross section, and the top portion (top surface 167) at a position away from the front end surface 153 of the piston 125. The side walls 165a, 165b, 165c, and 165d are closer to each other so that the cross-sectional area of the horizontal section becomes smaller. And this convex part 155 is arrange | positioned in the position in which the axial center 161 corresponds with the axial center 159 of the discharge hole 139. FIG.

  The positional relationship between the projection 155 (discharge hole 139) and the suction hole 137 provided in the valve plate 133 extends from the extension line X of the side wall 165a to the region beyond the axis 163 of the piston 125 as shown in FIG. A suction hole 137 is located in the projection plane (hatched area).

  Further, the gradient α (FIG. 3) formed by the side wall 165a and the tip surface 153 of the piston 125 is set to 70 °. The gradient α can be arbitrarily set in the range of about 60 ° ≦ α ≦ about 85 ° based on the experimental results described later. In addition, the gradient α includes some tolerance because the piston 125 and the convex portion 155 are molded.

  Next, the gradient β (FIG. 3) formed by the other side walls 165b, 165c, 165d and the tip surface 153 of the piston 125 is set to about 85 °. Note that the gradient β is an angle excluding the draft (about 5 °) at the time of molding the above-described mold, and can be arbitrarily set.

  Here, the gradient α is set so as to be gentler than the gradient β.

  Further, as shown in FIG. 4, the direction of the side wall 165a is such that the axis 163 of the piston 125 and the line Y passing through the axis (center) 169 of the suction hole 137 and the axis (center) 163 of the piston 125 are An angle θ (hereinafter referred to as an arrangement angle) θ formed by the extension line X of the side walls 165a extending in the intersecting direction is set to be about 45 °.

  This arrangement angle θ is perpendicular to the side wall 165a, and a straight line Z passing through the center of the side wall 165a intersects a line Y passing through the axis 169 of the suction hole 137 and the axis 163 of the piston 125 within a predetermined angle range. In particular, in the first embodiment, the straight line Z is set to an angle that intersects between the axis 169 of the suction hole 137 and the axis 163 of the piston 125.

  Therefore, depending on the position of the suction hole 137, the arrangement angle θ (about 45) where the extension line X of the side wall 165a intersects the line Y passing through the axis 169 of the suction hole 137 and the axis 163 of the piston 125 described above. °) may vary.

  Further, a curved surface 171 (FIG. 3) having a predetermined diameter is formed at a portion where the side wall 165 a of the convex portion 155 intersects (a protruding portion of the convex portion 155) on the tip surface 153 of the piston 125. In other words, the side wall 165a of the convex portion 155 has a shape partially including the curved surface 171.

  About the compressor 100 comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. Here, the compressor 100 has a refrigerant circuit in which a condenser, a decompressor, and an evaporator (all not shown) are connected between a suction pipe (not shown) and an outlet pipe 151 as is well known, It constitutes a well-known refrigeration cycle. Note that R600a is adopted as the refrigerant gas 103 to be compressed.

  When the electric element 105 is energized, the rotor 117 rotates to rotate the crankshaft 111, and the rotation (turning) motion of the eccentric portion 121 of the crankshaft 111 is transmitted to the piston 125 through the connecting means 127. Accordingly, the piston 125 reciprocates in the cylinder 113.

  During the suction stroke of the piston 125 from the top dead center to the bottom dead center, the volume of the compression chamber 135 increases as the piston 125 moves toward the crankshaft 111, and the pressure in the compression chamber 135 decreases. The suction valve (not shown) is opened by the pressure difference between the suction muffler 143 and the inside of the compression chamber 135, and the compression chamber 135 and the suction muffler 143 communicate with each other through the suction hole 137.

  Therefore, the refrigerant gas 103 is guided from the refrigerant circuit into the sealed container 101, and sequentially passes through the suction muffler 143 and the suction hole 137 and is sucked into the compression chamber 135.

  Next, in the compression stroke of the piston 125 from the bottom dead center to the top dead center, the volume of the compression chamber 135 decreases as the piston 125 moves to the valve plate 133 side. The pressure rises, and the suction valve (not shown) is closed by the pressure difference between the suction muffler 143 and the compression chamber 135. Thereafter, the refrigerant gas 103 in the compression chamber 135 is compressed, and the pressure in the compression chamber 135 further increases.

  When the pressure in the compression chamber 135 rises to the pressure in the discharge chamber 147, the discharge valve 145 opens due to the pressure difference between the discharge chamber 147 and the compression chamber 135, and the piston 125 reaches the top dead center. The compressed refrigerant gas 103 is discharged from the discharge hole 139 to the discharge chamber 147 in the cylinder head 141.

  The refrigerant gas 103 discharged into the discharge chamber 147 passes through the discharge pipe 149 and is sent out from the outlet pipe 151 to the refrigerant circuit outside the sealed container 101 to form a refrigeration cycle.

  The suction, compression, and discharge processes as described above are repeated for each rotation of the crankshaft 111, and the refrigerant gas 103 circulates in the refrigeration cycle.

  The flow of the refrigerant gas 103 discharged from the discharge hole 139 in the discharge stroke described above will be described in detail with reference to FIG. Here, for convenience, the discharge stroke is included in the compression stroke based on the moving direction of the piston 125.

  In the latter half of the compression stroke, when the volume of the compression chamber 135 decreases, as shown in FIG. 3, the tip surface 153 of the piston 125 approaches the valve plate 133, and at the same time, the convex portion 155 approaches the opposed discharge hole 139. . Then, the discharge valve 145 opens as the pressure in the compression chamber 135 increases.

  As soon as the discharge valve 145 is opened, the refrigerant gas 103 compressed in the compression chamber 135 is discharged at once into the discharge chamber 147 in the cylinder head 141 through the discharge hole 139 as indicated by an arrow in the figure. .

  As the compression process further proceeds, the convex portion 155 of the piston 125 enters the opposing discharge hole 139 and is compressed into a dead volume (shaded portion) formed by the convex portion 155 and the discharge hole 139. The compression process is terminated with a part of the gas 103 remaining.

  The flow of the refrigerant gas 103 in the compression chamber 135 in the compression stroke is a three-dimensional flow in which both the speed and the flow direction change greatly, and exhibits a complicated behavior.

  In the first embodiment, the convex portion 155 provided on the front end surface 153 of the piston 125 has a shape based on a rectangular parallelepiped having four side walls 165a, 165b, 165c, and 165d. The shape is difficult to go around 155.

  Therefore, particularly at the end of the compression stroke, as shown in FIG. 3, the flow path of the refrigerant gas 103 formed by the discharge holes 139 and the projections 155 is narrowed, and the flow rate of the refrigerant gas 103 is increased. The refrigerant gas 103 flowing into the discharge holes 139 is considered to flow in a direction toward the discharge holes 139 along the surfaces of the side walls 165a, 165b, 165c, and 165d.

  That is, the refrigerant gas 103 flowing along the inner wall of the cylinder 113 is blocked from flowing in the direction by the side walls 165b and 165d mainly of the convex portion 155, and at the corners of the 165a and 165c adjacent to the side walls 165b and 165d, Although turbulent flow is assumed, it is considered that the flow component guided to the discharge hole 139 increases.

  In addition, it is considered that the refrigerant gas 103 that has flowed toward the side wall 165c of the convex portion 155 collides with the flow from both sides, and a part thereof is guided to the discharge hole 139 along the surface of the side wall 165c.

  Further, the refrigerant gas 103 flowing from the suction hole 137 toward the discharge hole 139 is similarly blocked in that direction by the side wall 165a, and the flow component guided to the discharge hole 139 along the side wall 165a increases. Consider.

In addition, the base of the protruding portion 155 of the tip surface 153 of the piston 125 is a curved surface 171, and each side wall 165 a, 165 b, 165 c, 1, 1 of the refrigerant gas 103 is formed.
The effect of smoothing the flow along the surface of 65d can be expected.

  Here, although it is well known that the volume of the dead volume formed by the convex portion 155 and the discharge hole 139 greatly affects the efficiency of the hermetic compressor 100, the present invention is equivalent to the volume of the dead volume. It has been experimentally found that the shape of the convex portion 155 of the piston 125 influences the above.

  Hereinafter, the operational effects associated with the shape of the convex portion 155 of the piston 125 will be described.

  FIG. 5 is a characteristic diagram showing the results of measuring the relationship between the gradient α of the side wall 165a and the efficiency of the compressor 100 having the above configuration. Here, the horizontal axis is the gradient α formed by the side wall 165a of the convex portion 155 and the tip surface 153 of the piston 125, and the vertical axis is the coefficient of performance COP.

  The measurement results shown in FIG. 5 are based on the compressor 100 having a cylinder volume of 6.0 cc and an operating frequency of 50 Hz.

  As shown in FIG. 5, it has been experimentally confirmed that the efficiency increases when the gradient α of the side wall 165a of the convex portion 155 is in the range of about 60 ° ≦ α ≦ about 85 °.

  Next, the experimental result of the gradient α shown in FIG. 5 is inferred.

  The slope α of the wide side wall 165a facing the suction hole 137 in the four side walls 165a, 165b, 165c, 165d of the convex portion 155 and the tip surface 153 of the piston 125 is about 60 ° ≦ α ≦ about 85 °. By doing so, the flow passage area of the refrigerant gas 103 formed by the side wall 165a and the inner peripheral surface of the discharge hole 139 is formed by the other side walls 165b, 165c, 165d and the inner peripheral surface of the discharge hole 139. Since the flow area of the refrigerant gas 103 is larger, the refrigerant gas 103 guided in the direction of the discharge hole 139 by the side wall 165a of the convex portion 155 closest to the suction hole 137 considered to have a high flow velocity of the refrigerant gas 103 increases. Conceivable.

  Further, since the gradient α of the side wall 165a of the convex portion 155 becomes gentle, in the refrigerant flow flowing from the compression chamber 135 into the discharge hole 139, the flow path resistance of the flow along the side wall 165a is reduced, and more refrigerant is obtained. It is considered that the gas 103 was guided to the discharge hole 139.

  That is, the flow resistance of the refrigerant gas 103 generated by the close proximity of the convex portion 155 and the inner peripheral surface of the discharge hole 139 is reduced, and the flow of the refrigerant gas 103 is further rectified accordingly. As a result, the amount of the refrigerant gas 103 accumulated in the refrigerant gas decreases, and the intake loss due to the re-expansion of the refrigerant gas 103 accumulated immediately before the intake stroke starts is reduced. As a result, the electric input of the compressor 100 is reduced (coefficient of performance COP). It is speculated that the effect was improved.

  On the other hand, when the gradient α is gentler than about 60 °, the amount of the refrigerant gas 103 guided toward the discharge hole 139 by the side wall 165a increases, but the refrigerant gas 103 guided toward the discharge hole 139 by the side wall 165c mutually increases. Due to the interference and turbulent flow, the refrigerant gas 103 cannot flow out of the compression chamber 135, and the refrigerant gas 103 collected (remaining) in the compression chamber 135 is re-expanded with the suction operation of the piston 125. As a result, it is presumed that the effect of reducing the dead volume and improving the refrigerant gas flow in the hermetic compressor 100 cannot be sufficiently exhibited, such as suction loss.

This experimental result shows that, in addition to the volume of the dead volume, the shape of the discharge hole 139, and the shape of the convex portion 155 of the piston 125, the shaft of the suction hole 137 in the four side walls 165a, 165b, 165c, 165d of the convex portion 155. This confirms that the gradient α formed by the side wall 165a closest to the center 169 and the tip surface 153 of the piston 125 affects the efficiency.

  Moreover, although the convex part 155 of this Embodiment 1 has a difference in an efficiency improvement effect with an operating frequency, in addition to the operating frequency 50Hz confirmed in FIG. It has been confirmed experimentally that it improves.

  Therefore, even when the setting of the gradient α of the side wall 165a of the convex portion 155 and the inverter drive control using a plurality of operating frequencies including 50 Hz are adopted, the compressor 100 of the first embodiment can further save energy. I can expect.

  Further, in the first embodiment, the refrigerant gas 103 is smoothly guided toward the discharge hole 139 by providing the bell mouth portion 173 having a circular cross section at the inlet side periphery of the discharge hole 139. Therefore, the loss at the inlet portion of the discharge hole 139 can be improved.

  That is, the refrigerant gas 103 rectified in the axial direction of the discharge hole 139 by the side walls (planes) 165a, 165b, 165c, and 165d of the convex portion 155 is easy to flow along the arc of the bell mouth portion 173, and smoothly discharge holes. Pass 139.

  In other words, since the flow of the refrigerant gas 103 is smoothed by the synergistic action of the convex portion 155 and the bell mouth portion 173, accumulation of the refrigerant gas 103 in the compression chamber 135 at the end of the compression stroke is reduced.

  Therefore, in addition to the effect of reducing the dead volume in the discharge hole 139 by the convex portion 155, the re-expansion loss due to the accumulation of the refrigerant gas 103 is reduced, and the input of the compressor 100 can be reduced.

  Furthermore, in the first embodiment, by forming the hole diameter of the discharge hole 139 so that the cross-sectional area increases from the compression chamber 135 side to the opposite side of the compression chamber 135 (discharge chamber 147 side), the convex portion 155 and the flow path area formed by the inner wall of the discharge hole 139 can be expanded, and the passage resistance of the refrigerant gas 103 passing through the discharge hole 139 can be minimized.

  That is, the flow path formed by the convex portion 155 and the inner wall of the discharge hole 139 increases in cross-sectional area toward the outlet side (discharge chamber 147 side) of the discharge hole 139, and the refrigerant gas 103 flows out to the discharge chamber 147. Therefore, the accumulation in the compression chamber 135 at the end of the compression stroke is reduced, the re-expansion loss due to the accumulation of the refrigerant gas 103 can be reduced, and the input of the compressor 100 can be reduced.

  The discharge hole 139 of the first embodiment is formed so that the cross-sectional area increases from the compression chamber 135 side toward the opposite side of the compression chamber 135, but the cylindrical discharge hole 139 has a uniform cross-sectional area. However, although there is a difference in the efficiency improvement effect, the efficiency improvement effect can be expected as compared with the conventional hermetic compressor 1, and the same can be implemented.

  In the description so far, the convex portion 155 has been described as having a rectangular parallelepiped, but as shown in FIG. 6, the convex portion 175 has a shape in which the truncated cone is cut in the axial direction to form a flat surface 177a. Even in the configuration based on the above, by setting the relationship between the flat surface 177a and the side surface 177b to the same condition, a similar effect can be expected although there is a difference in efficiency improvement effect.

That is, the convex portions 155 and 175 preferably have a shape having flat surfaces 165a and 177a that suppress the wraparound of the refrigerant gas 103 around the convex portions 155 and 175 (side surfaces) just before the end of the compression stroke by the piston 125 and the cylinder 113. The configuration of the convex portions 155 and 175 shown in FIGS. 2 and 6 can be expected to have the same effect as a configuration that suppresses the wraparound (side surface) of the refrigerant gas 103.

  As described above, the hermetic compressor according to the present invention is a highly efficient and inexpensive hermetic compressor while ensuring high productivity, and can be applied to a hermetic compressor used in a refrigeration cycle, Can be widely installed in refrigeration equipment. In addition, an article storage device equipped with such a hermetic compressor can be expanded to various devices such as a dehumidifier, a showcase, and a vending machine, including a household refrigerator, and is widely used as a storage device with reduced power consumption. Can be applied.

DESCRIPTION OF SYMBOLS 100 Sealed compressor 101 Sealed container 103 Refrigerant gas 105 Electric element 107 Compression element 115 Cylinder block 125 Piston 133 Valve plate 135 Compression chamber 137 Suction hole 139 Discharge hole 153 Tip surface 155 Protruding part 165a Side wall (plane)
165b Side wall (plane)
165c Side wall (plane)
165d side wall (plane)
173 Bellmouth part 175 Convex part 177a Plane 177b Side surface α gradient β gradient

Claims (7)

An electric element and a compression element driven by the electric element are accommodated in a sealed container, and the compression element includes a cylinder block having a compression chamber space, a piston that reciprocates in the compression chamber space, and the compression A valve plate which is disposed at an end of the chamber space and forms a compression chamber with the piston, and is compressed in the compression chamber with a suction hole into which the refrigerant gas compressed in the compression chamber flows. Provided with a discharge hole through which the refrigerant gas is discharged, and further, at a position facing the discharge hole on the front end surface of the piston, and a convex part that protrudes and protrudes with the reciprocation of the piston, At least one flat surface is provided on the side surface of the convex portion, and a gradient α with respect to the front end surface of the piston in one of the flat surfaces is set against the front end surface of the piston on the other side surface of the convex portion. Hermetic compressor to be gentler than the gradient beta. 2. The hermetic compressor according to claim 1, wherein the flat surface having a slope α provided in the convex portion is disposed at a position facing the suction hole side. The hermetic compressor according to claim 1 or 2, wherein the discharge hole is formed so that a cross-sectional area increases from the compression chamber side toward the opposite side of the compression chamber. The hermetic mold according to any one of claims 1 to 3, wherein a bell mouth portion having a cross-sectional area that decreases from the compression chamber side toward the opposite side of the compression chamber is provided at a corner portion of the discharge hole on the compression chamber side. Compressor. The hermetic compressor according to any one of claims 1 to 4, wherein a shape of the convex portion is a polygonal shape in which a cross-sectional shape by a surface substantially parallel to the tip surface of the piston has a plurality of planes. The hermetic compressor according to any one of claims 1 to 5, wherein a shape of the convex portion is such that a cross-sectional shape of a surface substantially parallel to a tip surface of the piston is substantially rectangular. The hermetic compressor according to any one of claims 1 to 6, wherein the gradient α is in a range of about 60 ° ≤ α ≤ about 85 °.