JP2015048778A - Hermetic compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hermetic compressor which is improved in the productivity of a piston and the processing accuracy of roundness or the like, and high in efficiency.SOLUTION: A piston 126 is manufactured in such a process that a seal part 130 is formed at a substantially-entire periphery on the top side, a guide part 131 which is substantially the same in radius as the seal part 130 is formed at a substantially-entire periphery on the skirt side, an external peripheral face is polished in that state, and after that, the guide part 131 is removed. By this configuration, even if polishing is applied to the external peripheral face of a piston 142, a polishing grindstone continuously abuts on the seal part 130 and the guide part 131, and thereby an attitude of the piston 142 is stabilized. Therefore, continuous processing by centerless polishing or the like becomes possible, productivity is improved, the roundness, surface roughness or the like of the piston 126 becomes favorable, thereby a slide loss of the piston 126 of a hermetic compressor is reduced, the leakage of a refrigerant is reduced, and efficiency is enhanced.

Description

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

  In recent years, this type of hermetic compressor is strongly desired to reduce power consumption while realizing cost reduction. The problem of cost reduction is improvement of productivity, and the problem of power consumption reduction is improvement of sliding characteristics. In order to solve these problems, conventional hermetic compressors have improved efficiency by reducing the sliding loss between the piston and the cylinder by improving the outer shape of the piston (for example, Patent Document 1). reference).

  Hereinafter, the conventional hermetic compressor will be described with reference to the drawings. FIG. 7 shows a perspective view of a piston used in the conventional hermetic compressor described in Patent Document 1. As shown in FIG. In FIG. 7, the piston 1 has a seal surface portion 3 formed on the outer peripheral surface 2 so as to be in close contact with the inner peripheral surface of the cylinder, and a movement direction of the piston 1 formed so as to be in close contact with a part of the inner peripheral surface of the cylinder. At least two guide surface portions 4 extending substantially parallel to the cylinder, and a removal portion 5 that does not adhere to the inner peripheral surface of the cylinder. The cylindrical central axis 6 of the piston 1 and the two boundary edges 4a, 4b of the guide surface portion 4 are connected to the piston. The angle formed by the lines connected in the radial direction is 40 ° or less, preferably 30 ° or less.

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

  During operation, the piston 1 reciprocates. In the vicinity of the bottom dead center, the piston 1 part of the skirt side comes out of the cylinder. When the piston 1 enters the cylinder, it is guided by the guide surface portion 4 and can enter the cylinder smoothly.

US Pat. No. 6,289,921

  However, in the above-described conventional configuration, since the removal portion 5 is provided, the skirt side is not cylindrical but has a step difference from the seal surface portion 3 on the outer periphery of the piston 1. As a result, the grinding wheel that rotates during processing is intermittently hit, and the posture of the piston is not stable.For example, a centerless polishing machine cannot be used, resulting in low productivity, or difficulty in securing component accuracy, and low efficiency. Had a problem that it could be.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a hermetic compressor with high productivity and high efficiency.

  In order to solve the above-described conventional problems, the piston of the hermetic compressor according to the present invention has a seal portion formed on substantially the entire circumference of the outer peripheral surface on the top side, and the seal portion on the substantially entire circumference of the outer peripheral surface on the skirt side. In this state, the outer peripheral surface including the seal part and the guide part is polished, and then the guide part is removed.

By this, when polishing the outer peripheral surface of the piston, for example, even if centerless polishing is performed, the polishing grindstone continuously hits the seal part and the guide part.
There is no shaking and the posture is stable. Therefore, continuous processing by centerless polishing is possible, and productivity can be improved. Also, since the piston posture during polishing is stabilized, the processing accuracy of polishing is improved, and the roundness and surface roughness of the piston outer peripheral surface are improved, so that the piston when incorporated in a hermetic compressor The sliding loss between the cylinders is reduced, and the refrigerant leakage between the piston and the cylinder is reduced, so that the efficiency is improved.

  In the hermetic compressor of the present invention, the end surface of the piston on the skirt side is a processed surface.

  As a result, when the piston is manufactured by removing the skirt side by machining, it is possible to manufacture pistons having different lengths only by changing the length to be removed. Therefore, even when producing pistons with different lengths, the same processing can be performed halfway, so that productivity is improved.

  The hermetic compressor of the present invention can be continuously processed by, for example, centerless grinding when the outer peripheral surface of the piston is polished. Therefore, the hermetic compressor can be made highly productive and highly efficient.

1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. Side view of the piston of the same embodiment Top view of the piston of the same embodiment (A) Side view before processing of the piston of the same embodiment (b) Side view before and after polishing of the piston of the same embodiment (c) Side view of a processed product of the piston of the same embodiment Schematic diagram showing the method of centerless polishing of the piston of the same embodiment Side view of the piston of the hermetic compressor according to the second embodiment of the present invention. A perspective view of a piston of a conventional hermetic compressor

  A first invention includes, in an airtight container, an electric element including a stator and a rotor, a compression element driven by the electric element, and a lubricating oil that lubricates the compression element. A shaft having a main shaft portion to which the rotor is fixed and an eccentric shaft portion; a block having a cylinder; a piston that reciprocates within the cylinder; and a connecting portion that connects the piston and the eccentric shaft portion. A main bearing provided on the block and pivotally supporting the main shaft portion, wherein the piston forms a seal portion on substantially the entire circumference of the outer peripheral surface on the top side, and on the entire circumference of the outer peripheral surface on the skirt side. A guide portion having substantially the same radius as the seal portion is formed, and in this state, the outer peripheral surface including the seal portion and the guide portion is polished, and then the guide portion is removed to manufacture.

  As a result, when polishing the outer peripheral surface of the piston, for example, even if centerless polishing is performed, the polishing grindstone continuously hits the seal portion and the guide portion, so that the piston does not rattle or shake during polishing. , The posture is stable. Therefore, continuous processing by centerless polishing or the like is possible, and productivity can be improved. Also, since the piston posture during polishing is stabilized, the processing accuracy of polishing is improved, and the roundness and surface roughness of the piston outer peripheral surface are improved, so that the piston when incorporated in a hermetic compressor The sliding loss between the cylinders is reduced, and the refrigerant leakage between the piston and the cylinder is reduced, so that the efficiency is improved.

  According to a second invention, in the first invention, before the piston outer peripheral surface is polished, a hollow portion having a smaller radius than the seal portion is formed over the entire circumference between the seal portion and the guide portion. It is characterized in that it is manufactured by cutting the recess after polishing and removing the guide.

  As a result, plastic deformation and burrs that occur in the vicinity of the cut portion when cutting are housed in the recessed portion, and deterioration of roundness and burrs due to plastic deformation do not occur on the polished outer peripheral surface. Therefore, sliding loss between the piston and the cylinder when the piston is incorporated in the hermetic compressor is reduced, and leakage of the refrigerant between the piston and the cylinder is reduced, thereby improving efficiency.

  According to a third invention, in the first or second invention, before polishing of the outer peripheral surface of the piston, an extension portion having substantially the same radius as the seal portion between the seal portion and the guide portion, and the seal portion A hollow portion having a small radius is formed. Therefore, the area of the outer peripheral part of the manufactured piston can be reduced, the sliding loss between the piston and the cylinder when incorporated in a hermetic compressor is reduced, and the efficiency is improved.

  According to a fourth invention, in any one of the first to third inventions, a protrusion is provided on an end surface on a top side of the piston. Due to the imbalance in weight due to the protrusions, the piston posture during polishing tends to become unstable under normal conditions. However, with the processing method of the present invention, the piston posture during polishing is stable, so the polishing processing accuracy The improvement effect is large, and the efficiency improvement effect is large.

  A fifth invention comprises, in an airtight container, an electric element including a stator and a rotor, a compression element driven by the electric element, and a lubricating oil that lubricates the compression element. A shaft having a main shaft portion to which the rotor is fixed and an eccentric shaft portion; a block having a cylinder; a piston that reciprocates within the cylinder; and a connecting portion that connects the piston and the eccentric shaft portion. A main bearing provided on the block and supporting the main shaft portion, and an end surface of the piston on the skirt side is a machining surface.

  That is, when the piston is manufactured by removing the skirt side by machining, it is possible to manufacture pistons having different lengths only by changing the length to be removed. Therefore, even when producing pistons with different lengths, the same processing can be performed halfway, so that productivity is 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 side view of the piston of the same embodiment, and FIG. 3 is a top view of the piston of the same embodiment. . FIG. 4A is a side view before processing the piston according to the embodiment, FIG. 4B is a side view before and after polishing the piston according to the embodiment, and FIG. It is a side view of the processing completion product of the piston of the form. FIG. 5 is a schematic view showing a centerless polishing method for the piston according to the embodiment.

  In FIGS. 1, 2, 3, 4, and 5, lubricating oil 102 is stored in a sealed container 101, and is driven by an electric element 105 including a stator 103 and a rotor 104, and the electric element 105. A compression element 106 is received. The shaft 110 includes a main shaft portion 111 to which the rotor 104 is fixed, and an eccentric shaft portion 112 that is disposed above the main shaft portion 111 and is formed eccentric to the main shaft portion 111.

  The block 114 includes a cylinder 115 and a main bearing 120 that supports the main shaft portion 111 is formed. The piston 126 is inserted into the cylinder 115 of the block 114 so as to be reciprocally slidable to form a compression chamber 116, and is connected to the eccentric shaft portion 112 by a connecting portion 128.

  The thrust ball bearing 132 is provided between the shaft 110 and the block 114, and supports the shaft 110 in the vertical direction.

  The shaft 110 is provided with an oil supply passage 134, and a lower end portion of the main shaft portion 111 is immersed in the lubricating oil 102, and the oil supply passage 134 is opened in the lubricating oil 102.

  The piston 126 has a seal portion 130 formed on substantially the entire circumference of the outer peripheral surface on the top side, and a guide portion 131 having substantially the same radius as that of the seal portion 130 formed on the substantially entire circumference of the outer peripheral surface on the skirt side. The outer peripheral surface including the portion 130 and the guide portion 131 is polished, and then the guide portion 131 is removed to manufacture.

  Further, before the piston outer peripheral surface is polished, a hollow portion 135 having a smaller radius than the seal portion 130 is formed between the seal portion 130 and the guide portion 131, and after the piston outer peripheral surface is polished, the hollow portion 135 is formed. The guide part 131 is removed by cutting.

  Further, before the outer peripheral surface of the piston 126 is polished, an extension portion 136 having a radius substantially the same as that of the seal portion 130 and a hollow portion 137 having a radius smaller than that of the seal portion 130 are provided between the seal portion 130 and the guide portion 131. Forming.

  In the present embodiment, the refrigerant used in the hermetic compressor is a hydrocarbon refrigerant or the like, which is a natural refrigerant having a low global warming coefficient represented by R134a or R600a having an ozone depletion coefficient of zero, and is compatible with each other. In combination with a high lubricating oil 102 having a high viscosity. The viscosity of the lubricating oil 102 is a low viscosity VG5 grade.

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

  The rotor 104 of the electric element 105 rotates the shaft 110, and the rotational movement of the eccentric shaft portion 112 is transmitted to the piston 126 via the connecting portion 128, so that the piston 126 reciprocates in the cylinder 115. Thus, the refrigerant is sucked into the compression chamber 116 from the cooling system (not shown), compressed, and then discharged to the cooling system again.

  The weight of the shaft 110 and the rotor 104 is supported by the thrust ball bearing 132, and when the shaft 110 rotates, the thrust ball bearing 132 makes the rotation smooth, and the loss in the thrust bearing can be reduced.

  The lubricating oil 102 stored in the sealed container 101 is supplied to the main shaft portion 111, the eccentric shaft portion 112, and the piston 126 through the oil supply passage 134 along with the rotation of the shaft 110, and lubricates each portion.

  Next, a manufacturing method of the piston 126 will be described. The piston material 140 before processing has a cylindrical shape as shown in FIG. 4A, and is usually formed of sintered metal or cast iron.

  Next, as shown in FIG. 4B, a seal portion 130 is formed on substantially the entire circumference of the outer peripheral surface on the top side, and a guide portion having substantially the same radius as the seal portion 130 on the entire circumference of the outer peripheral surface on the skirt side. 131, a recess 135 having a smaller radius than the seal portion 130 is formed between the seal portion 130 and the guide portion 131, and the seal portion 130 and the guide portion 131 have substantially the same radius as the seal portion 130. Processing is performed so as to form an extension portion 136 having a gap and a hollow portion 137 having a smaller radius than the seal portion 130.

Therefore, in the piston 142 in the middle of processing in this state, the seal portion 130 and the guide portion 1
31 and the extension part 136 have substantially the same radius, and the recessed part 135 and the hollow part 137 have a smaller radius and a step.

  Next, centerless polishing is performed in order to improve the surface roughness of the outer peripheral surface of the seal portion 130, the guide portion 131, and the extension portion 136 of the piston 142 in this state and finely adjust the target diameter. In the centerless polishing, as shown in FIG. 5, the piston 142 is placed on the support blade 146, sandwiched between the rotating polishing grindstone 144 and the adjusting grindstone 145, and the outer peripheral surface is polished while rotating the piston 142. Is the method. Centerless polishing does not require the piston 142 to be attached to a grinding machine such as cylindrical polishing, and the piston 142 can be continuously polished, so that productivity is good.

  When performing this centerless polishing, since the polishing wheel 144 continuously hits the seal portion 130 and the guide portion 131, the piston 142 does not rattle or shake during polishing, and the posture is stabilized. . Therefore, the processing accuracy of polishing is improved, and the roundness and surface roughness of the outer peripheral surface of the piston are improved.

  After the polishing process, the piston 142 is cut to form the piston 126 having a final shape shown in FIG. 4C. Plastic deformation and burrs generated in the vicinity of the cut portion when the dent portion 135 is cut are contained in the dent portion 135, and the roundness and burrs are not deteriorated due to plastic deformation in the polished seal portion 130 and the extension portion 136.

  Therefore, since the piston 126 manufactured by this method has good roundness and surface roughness of the outer peripheral surface of the seal portion 130 and the extension portion 136, the space between the piston 126 and the cylinder 115 when incorporated in a hermetic compressor. , And the refrigerant leakage between the piston 126 and the cylinder 115 is reduced, and the efficiency is improved.

  Further, since the piston 126 is formed with the hollow portion 137, the area of the outer peripheral portion can be reduced, the sliding loss between the piston 126 and the cylinder 115 is reduced, and the efficiency is improved.

  The end face 150 on the skirt side of the piston 126 is a machining surface. That is, when the piston 126 is manufactured by removing the skirt side by machining, it is possible to manufacture pistons having different lengths only by changing the length to be removed. Therefore, even when producing pistons with different lengths, the same processing can be performed halfway, so that productivity is improved.

  The effect that the refrigerant leakage between the piston 126 and the cylinder 115 is reduced and the efficiency is improved is that the low-viscosity lubricating oil 102 of VG5 grade or less that is likely to leak is used, or 30 r / This is remarkable during operation at a low rotational speed of s or less, and the effects of the present invention can be effectively utilized.

(Embodiment 2)
FIG. 6 is a side view of the piston of the hermetic compressor according to the second embodiment of the present invention. In addition, about the same structure as Embodiment 1, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In FIG. 6, a protrusion 227 is provided on the end surface on the top side of the piston 226. The operation of the hermetic compressor configured as described above will be described below.

  The protrusion 227 is formed so as to enter the discharge hole at the top dead center of the piston 226, and has been conventionally used for the purpose of reducing the dead volume of the discharge hole.

  Due to the imbalance of the weight due to the protrusions 227, the posture of the piston at the time of polishing is likely to be unstable normally, but the posture of the piston at the time of polishing is stable in the processing method of Embodiment 1, Greatly improves the polishing accuracy. That is, since the effect of improving the roundness and surface roughness of the outer peripheral surface of the seal portion 130 and the extension portion 136 is great, the sliding loss between the piston 226 and the cylinder 115 when incorporated in a hermetic compressor is reduced. In addition, the refrigerant leakage between the piston 226 and the cylinder 115 is reduced, and the efficiency improvement effect is great.

  As described above, since the hermetic compressor according to the present invention is highly productive and can improve efficiency, it can be applied to vending machines and air-conditioning equipment in addition to refrigerators.

DESCRIPTION OF SYMBOLS 101 Airtight container 102 Lubricating oil 103 Stator 104 Rotor 105 Electric element 106 Compression element 110 Shaft 111 Main shaft part 112 Eccentric shaft part 114 Block 115 Cylinder 120 Main bearing 126, 142, 226 Piston 128 Connection part 130 Seal part 131 Guide part 135 Recessed part 136 Extension part 137 Hollow part 150 End face 227 Projection part

Claims (5)

An airtight container includes an electric element including a stator and a rotor, a compression element driven by the electric element, and lubricating oil for lubricating the compression element, and the compression element has the rotor fixed thereto. A shaft having a main shaft portion and an eccentric shaft portion, a block having a cylinder, a piston that reciprocates within the cylinder, a connecting portion that connects the piston and the eccentric shaft portion, and a block. A main bearing that pivotally supports the main shaft portion;
The piston forms a seal portion on substantially the entire circumference of the outer peripheral surface on the top side, forms a guide portion having substantially the same radius as the seal portion on the substantially entire circumference of the outer peripheral surface on the skirt side, and the seal portion and the guide A hermetic compressor characterized in that it is formed by polishing an outer peripheral surface including a portion and then removing the guide portion. Before polishing the outer peripheral surface of the piston, a hollow portion having a smaller radius than the seal portion is formed between the seal portion and the guide portion, and the hollow portion is cut after polishing the outer peripheral surface of the piston. The hermetic compressor according to claim 1, wherein the guide part is removed and formed. An extension portion having substantially the same radius as the seal portion and a hollow portion having a smaller radius than the seal portion are formed between the seal portion and the guide portion before polishing of the outer peripheral surface of the piston. The hermetic compressor according to 1 or 2. The hermetic compressor according to any one of claims 1 to 3, wherein a protrusion is provided on an end surface on a top side of the piston. An airtight container includes an electric element including a stator and a rotor, a compression element driven by the electric element, and lubricating oil for lubricating the compression element, and the compression element has the rotor fixed thereto. A shaft having a main shaft portion and an eccentric shaft portion, a block having a cylinder, a piston that reciprocates within the cylinder, a connecting portion that connects the piston and the eccentric shaft portion, and a block. A hermetic compressor including a main bearing that pivotally supports the main shaft portion, wherein an end surface of the piston on a skirt side is a processing surface.