JP2012041894A - Rotary compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary compressor preventing solid contact of a piston end surface and having high efficiency and high reliability.SOLUTION: In the rotary compressor, a rotary shaft is rotatably supported in a thrust direction by a pair of bearing surfaces opposed to each other. A rolling piston has first and second end surfaces opposed to the bearing surfaces and first and second groove parts generating first and second oil film surfaces between the bearing surfaces and the first and second end surfaces by using lubricating oils accompanying rotation of the rolling piston are respectively formed in the first and second end surfaces. The first and second groove parts give, to the first and second oil film surfaces, the pressure of first and second oil films having such pressure difference that one of the first and second end surfaces is pushed to corresponding one of the second and third bearing surfaces to generate a uniform gap.

Description

  Embodiments described herein relate generally to a rotary compressor.

  The rotary compressor includes a rotary compression mechanism that compresses the refrigerant in its sealed case, and the compressed refrigerant is supplied into the sealed case and supplied to the outside or directly supplied to the outside. This rotary compression mechanism usually includes a cylinder that defines a cylinder chamber and a rolling piston that rotates eccentrically in the cylinder chamber. The vane is brought into contact with the rolling piston so that the vane sucks the cylinder chamber and the compression chamber. It is divided into. Along with the eccentric rotation of the rolling piston, the refrigerant is introduced into the suction chamber via the suction pipe, the sucked refrigerant is compressed in the compression chamber, the compressed refrigerant is supplied and stored in the sealed case, and then the rotary The refrigerant supplied to the outside of the compressor or compressed is directly supplied to the outside.

  Further, in the rotary compressor, an eccentric crank is integrally formed on a rotating shaft in order to rotate the rolling piston eccentrically, and the rolling piston is rotatably fitted to the eccentric crank. The rotating shaft and rolling piston are supported by bearings. The rotating shaft is fixed to the motor / rotor, and a rotating force is generated in the motor / rotor by the magnetic force applied from the motor / stator to rotate the rotating shaft.

  In the rotary compressor having such a structure, a sealing oil film is formed on the end surface of the rolling piston to prevent the refrigerant from leaking when the lubricating oil is supplied. In particular, preferably, a groove is provided on the end surface of the rolling piston in order to improve the sealing performance and the pull-in performance of the lubricating oil.

Japanese Patent No. 2667226 JP 2006-258001 A Japanese Patent No. 2604814

  In the rotary compressor having the above-described structure, there is a possibility that the rotary shaft tilts as the eccentric crank rotates eccentrically, and the rotary piston tilts as the rotary shaft tilts. In particular, the conventional rotary compressor does not actively generate an oil film pressure on the piston end surface, so there is a possibility that the piston end surface may come into solid contact with the bearing surface, and there is a probability that the piston end surface will seize on the basis of this solid contact. There is.

  This embodiment has been made to solve the above-described problems, and an object thereof is to provide a highly efficient and highly reliable rotary compressor which prevents solid contact of the piston end face.

  The rotary compressor of this embodiment includes a rotary shaft, a motor drive unit that rotationally drives the rotary shaft, and a compression mechanism that compresses the refrigerant by the rotational force of the rotary shaft. The rotating shaft is rotatably supported in a radial direction by a bearing portion having at least one first bearing surface. Moreover, this bearing part has the 2nd and 3rd bearing surface which mutually opposes.

  The compression mechanism includes a cylinder having a cylinder chamber and a rolling piston that is fitted to a crank crank provided eccentrically on the rotating shaft and rotates eccentrically in the cylinder chamber.

  As the rolling piston rotates on the first and second end faces opposed to the second and third bearing surfaces, the first and second bearings are respectively provided between the second and third bearing surfaces by lubricating oil. First and second groove portions for forming the second oil film surface are respectively formed. Here, the first and second groove portions are formed so as to press one of the first and second end faces against the corresponding one of the second and third bearing faces to give a uniform gap. Yes.

1 is a cross-sectional view schematically showing a hermetic rotary compressor according to an embodiment. It is a top view which shows roughly the structure of the compression mechanism in the rotary compressor shown in FIG. FIG. 3 is a perspective view schematically showing a piston shown in FIG. 2. FIG. 4 is a plan view schematically showing one piston end face of the piston shown in FIG. 3. FIG. 3 is a plan view schematically showing the other piston end surface of the piston shown in FIG. 2. It is a top view which shows roughly the one piston end surface in the piston which concerns on the modification of the rotary compressor shown in FIG. It is a top view which shows roughly the other piston end surface in the piston which concerns on the modification of the rotary compressor shown in FIG.

  Hereinafter, a hermetic rotary compressor according to an embodiment will be described with reference to the drawings.

  FIG. 1 shows the overall structure of a rotary compressor (rotary compressor) 1 according to the embodiment. The hermetic rotary compressor according to this embodiment is described below as a high-pressure casing internal structure. However, this embodiment is obviously not limited to the high pressure type rotary compressor in the casing, but may be applied to the low pressure type rotary compressor in the casing.

  In the rotary compressor 1 shown in FIG. 1, a sealed casing 2 is formed by fitting an upper lid case 2-1 and a lower lid case 2-3 to both end openings of a cylindrical case 2-2. ing. The upper lid-shaped case 2-1 is provided with a discharge pipe 12 that communicates with the closed casing 1 in order to supply a compressed refrigerant to a condenser (not shown) of the refrigeration cycle apparatus. Further, a suction pipe 8 to which a low-pressure refrigerant evaporated by an evaporator (not shown) and having finished heat exchange is supplied is fixed to the lower lid case 2-3.

  In the refrigeration cycle apparatus, high-pressure refrigerant is discharged from the rotary compressor 1 to the condenser via the discharge pipe 12, condensed (liquefied) by the condenser, and condensed (liquefied) refrigerant is an expander (not shown). The refrigerant decompressed and decompressed by this expander is supplied to the evaporator, takes heat from the outside by the evaporator and becomes low-pressure gas refrigerant, and is returned to the rotary compressor 1 via the suction pipe 8. Yes.

  The suction pipe 8 extends into the rotary compressor, is connected to the cylinder 5 of the compression mechanism 4, and communicates with the cylinder chamber 10 in the cylinder 5. As shown in FIG. 2, a rolling piston 6 that is eccentrically rotated by an eccentric crank 11 is disposed in the cylinder chamber 10. A cylinder chamber 10 is formed between the outer peripheral surface of the rolling piston 6 and the inner peripheral surface of the cylinder 5, which is variable as the rolling piston 6 rotates eccentrically. A vane 13 is provided in the cylinder 5 so as to be able to advance and retreat, and its tip is in contact with the outer peripheral surface of the rolling piston 6. As an example, the vane 13 is slidably held in a vane groove formed in the cylinder 5 while being biased by a spring member 14 as shown in FIG. Therefore, the tip of the vane 13 is in contact with the film of the lubricating oil supplied to the rolling piston 6 in the cylinder chamber 10. The vane 13 that has entered the cylinder chamber 10 divides the inside of the cylinder chamber 10 into a suction chamber 10A and a compression chamber 10B that are variable as the rolling piston 6 rotates eccentrically.

  Since the center of the rolling piston 6 is eccentric with respect to the rotation center Oc of the eccentric crank 11, the rolling piston 6 is eccentrically rotated with the rotation of the eccentric crank 11, and the refrigerant flows into the suction chamber 10A from the suction port 10C. Then, the refrigerant in the compression chamber 10B is compressed into the sealed casing 1 through the discharge port 10D that is compressed and communicates with a discharge valve (not shown) as the rolling piston 6 rotates.

  The eccentric crank 11 is integrally formed with a rotating shaft 15 extending along the longitudinal direction of the hermetic casing 1, and the rotating shaft 15 is a pair of bearings (main bearing and auxiliary bearings) fixed to the upper surface and the lower surface of the cylinder 5. Bearings 7-1 and 7-2 are rotatably supported. The main bearing 7-1 and the sub bearing 7-2 have cylindrical bearing surfaces 17A and 17B on the inner surfaces thereof to support the rotary shaft 15 in the radial direction. The main bearing 7-1 and the sub-bearing 7-2 have bearing surfaces 17A and 17B, respectively, but at least one may have one of the bearing surfaces 17A and 17B.

  Since the rolling piston 6 is fitted to the eccentric crank 11 so that the rotation shaft 15 and the rotation center axis Oc of the eccentric crank 11 are eccentric (offset) with respect to the center axis Op of the rolling piston 6, When the shaft 15 is rotated in the direction of the arrow shown in FIG. 2, the central axis Op is rotated around the central axis Oc, and the rolling piston 6 is rotated while being eccentric in the cylinder chamber 10. With the suction chamber 10A having the minimum volume, the volume in the compression chamber 10B is maximized, and as the volume of the suction chamber 10A increases, the volume in the compression chamber 10B decreases, and the refrigerant is sucked into the suction chamber 10A. The refrigerant in the compression chamber 10B is compressed. When the refrigerant is compressed to a pressure equal to or higher than a predetermined pressure, a discharge valve (not shown) is opened and the compressed refrigerant is discharged into the sealed casing 1. Therefore, the sealed casing 1 is filled with the compressed refrigerant.

  The rolling piston 6 and the eccentric crank 11 constitute a compression mechanism 4 that compresses and discharges the refrigerant sucked together with the cylinder 5. Further, the rotating shaft 15 is supported so that an oil film surface with a minute gap is formed between the inner surfaces of the main bearing 7-1 and the sub bearing 7-2 so that the radial direction can rotate. Further, the end surfaces 6A and 6B (see FIG. 3) of the rolling piston 6 have a minute gap between the disk-shaped flat surfaces 18A and 18B of the main bearing 7-1 and the sub-bearing 7-2, respectively. As will be described in more detail later, grooves 9A and 9B for forming an oil film of lubricating oil are formed on the end faces 6A and 6B as shown in FIGS. 4A and 4B, and rolling that is rotated by the oil film The piston 6 is supported in the thrust direction. A motor / rotor 3B is fixed to the rotary shaft 15 in order to give a rotational force to the rotary shaft 15, and the motor / stator 3A is placed around the motor / rotor 3B through a small gap in the hermetic casing 1. It is fixed and provided. The motor / stator 3A and the motor / rotor 3B constitute a motor drive unit 3. The motor / rotor 3B is rotated by applying magnetic flux from the motor / stator 3A to the motor / rotor 3B.

  A lubricating oil 25 is stored in the hermetic casing 1, and the stored lubricating oil 25 is circulated to the compression mechanism 4 by a supply mechanism (not shown) to form a groove 9A formed on the end face of the rolling piston 6. , 9B and the lubricating oil 25 is supplied to the contact surface between the vane 13 and the rolling piston 6.

  In the embodiment, as shown in FIG. 3, the rolling piston 6 shown in FIG. 1 is formed in a ring shape, and the end faces 6A and 6B of the rolling piston 6 are formed on the end faces 6A and 6B. As shown in FIG. 5, grooves 9A and 9B for generating oil film pressure on the end faces 6A and 6B are formed rotationally symmetrical around the center Op of the rolling piston 6. Here, the grooves 9A and 9B are formed in a step shape with respect to the flat surfaces of the end faces 6A and 6B by cutting or etching. Each of the grooves 9A and 9B preferably has the same shape, for example, a fan-shaped base portion (a triangular portion of the fan) is removed, and the base portion is open to the inner peripheral portion 28 of the rolling piston 6. Has been. Further, the grooves 9A and 9B are not opened to the outer peripheral surface of the rolling piston 6, but are formed to have an outer peripheral wall 26 between the outer peripheral surface of the rolling piston 6 and the outer periphery of the fan. Then, the lubricating oil is supplied from the inner peripheral portion 28 to the respective fan-shaped grooves 9A and 9B by the centrifugal force accompanying the rotation. The oil film in the grooves 9A and 9B reaches the outer peripheral wall 26, and the sealing performance between the piston end surfaces 6A and 6B and the disk-like flat surfaces 18A and 18B of the main bearing 7-1 and the sub-bearing 7-2 is further improved. Enhanced.

  Further, one end face 6A (upper end face) of the rolling piston 6 is provided with four (NA) grooves 9A, whereas the other end face 6B (lower end face) of the rolling piston 6 is provided on the other end face 6A (upper end face). 6 (NB) grooves 9B are provided, and one end face 6A (upper end face) and the other end face 6B (lower end face) have different numbers (NA <NB) of grooves or different groove areas (NA). The end surfaces 6A and 6B of the rolling piston 6 are formed so as to satisfy (× LA <NB × LB).

  Here, the numbers NA and NB are set to arbitrary integers, preferably even numbers to maintain rotational symmetry with respect to the center, and the grooves 9A and 9B have center groove lengths LA and LB. The central groove lengths LA and LB are proportional to the respective groove areas SA and SB of the grooves 9A and 9B, and the groove areas SA and SB can be obtained by multiplying the constants in the central groove lengths LA and LB. Further, as the rolling piston 6 rotates, the oil film forming ability PA generated on one end surface 6A (upper end surface) of the rolling piston 6 is proportional to the total area (NA × SA) of the grooves 9A and 9B. The oil film forming ability PB generated on the other end face 6B (lower end face) of the rolling piston 6 is also generated in proportion to the groove area (NB × SB). In terms of the central groove lengths LA and LB, the oil film forming ability PA and PB is proportional to the total of the central groove length LA (NA × LA) and the total of the central groove length LA (NB × LB).

  Since the oil film forming ability PB of the other end face 6B (lower end face) of the rolling piston 6 is higher than the oil film forming ability PA of one end face 6A of the rolling piston 6, a larger thrust force is applied to the other end face 6B ( Is generated on the lower end face). Therefore, the end surface 6A (upper end surface) of the rolling piston 6 is uniformly pressed against the disk-shaped surface 18A of the main bearing 7-1 so that the rolling piston 6 is lifted up by a larger thrust force. As a result, even if the rolling piston 6 is eccentrically rotated, the end surface 6A of the rolling piston 6 is prevented from being shaken, and a situation in which the disk-shaped surface 18A of the main bearing 7-1 is partially contacted. Therefore, solid contact between the piston end surfaces 6A and 6B and the bearing end surface can be prevented.

  As described above, in the compression mechanism 4 of the rotary compressor 1 in the first embodiment, the grooves 9A and 9B for generating the oil film pressure are provided on the end surfaces 6A and 6B of the rolling piston 6, and the oil film on the one end surface 6B is provided. Since the forming ability PB is higher than the oil film forming ability PA of the other end face 6A, between the end faces 6A and 6B of the rolling piston 6 and the disk-like faces 18A and 18B of the bearings 7-1 and 7-2, A uniform oil film pressure can be positively generated. As a result, the rolling piston 6 is excessively inclined with the eccentric rotation of the crank 11, and the piston end surfaces 6A and 6B can be prevented from coming into contact with the disk-shaped surfaces of the bearings 7-1 and 7-2. Further, by pressing one end surface of the rolling piston 6 against the bearing end surfaces of the bearings 7-1 and 7-2, the motion of the rolling piston 6 follows the bearing end surface. As a result, it is possible to prevent the rolling piston 6 from being excessively inclined with respect to the bearing end surface, and to prevent solid contact between the piston end surfaces 6A and 6B and the bearing end surface.

  In the first embodiment in which the upper end surface 6A of the rolling piston 6 is pressed against the bearing end surface 18A of the main bearing 7-1, the gap between the lower end surface 6B of the rolling piston 6 and the bearing end surface 18B can be increased uniformly. It is possible to assist the discharge of the wear powder generated at the sliding part of the inner peripheral surface of the rolling piston and the outer peripheral surface of the crank, and the accumulation of the wear powder can be prevented.

  In the structure of the first embodiment, the friction loss at the end face is reduced and the possibility of seizure is also reduced, and a highly efficient and reliable compressor can be realized.

  As described in the embodiments described below, instead of increasing the oil film forming ability PB of one end face 6B compared to the oil film forming ability PA of the other end face 6A, the oil film forming of one end face 6A The capability PA may be set higher than the oil film forming capability PB of the other end face 6B. As shown in FIGS. 5A and 5B, one end face 6A (upper end face) of the rolling piston 6 is provided with six (= NA) grooves 9A, and the other end face 6B of the piston 6 (lower face) The end face is provided with four (= NB) grooves 9B, and the oil film forming ability PA of one end face 6A can be set higher than the oil film forming ability PB of the other end face 6B.

  Further, the depth DB of the groove 9B of the lower piston end surface 6B and the depth DA of the groove 9A of the upper piston end surface 6A are set to be different from each other. With this setting, the oil film forming capability PA of one end surface 6A and the other The oil film forming ability PB of the end face 6B may be different.

That is, in general, in the step-like groove, the oil film forming ability is maximized.
(Groove depth + oil film thickness) / oil film thickness = 1.87. Here, the oil film thickness is a gap between the piston end face on one side and the cylinder end face, and this is defined as a representative gap C.

From now on, the optimum value of the groove depth between the piston and cylinder is
The optimum groove depth = 0.87 × oil film thickness (representative gap C). When approximated roughly, the optimum groove depth value≈representative gap C.

  Here, for example, by setting the depth DA of the groove 9A as the representative gap C which is the optimum value of the groove gap, the depth DB of the groove 9B as 0.5C, and the groove depths different from each other, the oil film forming capability PA (9A) becomes larger than the oil film forming ability PB (9B), and the piston is pressed against the 6B end face.

  In the structure of the first embodiment, for example, the grooves 9A and 9B in the end surfaces 6A and 6B have the same depth D0, and this depth D0 is a gap between the piston end surfaces (uppermost surfaces) 6A and 6B and the bearing end surface. It is set to about half of G (≈G / 2). Here, the piston end surfaces 6A and 6B correspond to the uppermost surfaces of the end surfaces defining the grooves 9A and 9B, not the bottom surfaces in the grooves 9A and 9B.

  Also, the total length (LB × NB) of the circumferential length LB of the groove 9B on the piston end surface 6B and the number 9 of the grooves 9B (LB × NB) is set to about ½ of the total circumferential length CL of the center line 20. The total groove length (LA × NA) of the circumferential length LB of the groove 9A on the piston end surface 6A and the number NA of the grooves 9A (LA × NA) is about ¼ to ３ of the total circumferential length CL of the center line 20. Is set to In such a setting, the oil film forming ability PB of the piston end face 6B is higher than the oil film forming ability PA of the piston end face 6A, the piston 6 is pushed upward, that is, against gravity, and the upper piston end face 6A is Pressed against the end face.

  In the structure of the second embodiment, for example, the total groove length (LA × NA) and (LB × NB) are set to the same value having about half of the total circumferential length CL of the center line 20. Further, the depth DB of the groove 9B of the lower piston end surface 6B is set to about ½ of the total gap G between the piston end surface and the bearing end surface, whereas the depth DA of the groove 9A of the piston end surface 6A is the piston end surface. And about 1/4 to 1/3 of the total gap G between the bearing end faces. With this setting, the oil film forming ability PB of the piston end face 6B can be set higher than the oil film forming ability PA of the piston end face 6A, and the piston 6 is pushed upward (in a direction against gravity) to move the upper piston end face 6A to the bearing. It can be pressed against the end face.

  In Example 3 as a modified example of the first embodiment, one end face 6A (upper end face) of the piston 6 is provided with six (= NA) grooves 9A instead of the four grooves 9A. The other end face 6B (lower end face) of the piston 6 may be provided with four (= NB) grooves 9B instead of the six grooves 9B. When one end face 6A (upper end face) and the other end face 6B (lower end face) are formed on end faces having different numbers of grooves or different groove areas, one end face 6A (upper face) of the piston 6 is formed. The other end face 6B (lower end face) of the piston 6 having a larger number of grooves or a larger groove area than the end face) has a higher oil film forming ability PB and generates a larger thrust force. Therefore, the end surface 6B (lower end surface) of the rolling piston 6 is uniformly pressed against the disk-shaped surface of the secondary bearing 7-2 so that the rolling piston 6 is lifted down by a larger thrust force. Therefore, even if the rolling piston 6 is eccentrically rotated, it is possible to prevent a situation in which the end surface 6B of the rolling piston 6 slips and partially contacts the disk-shaped surface of the auxiliary bearing 7-2. Solid contact between the end faces 6A and 6B and the bearing end face can be prevented.

  In Example 3 in which the piston lower end surface 6B is pressed against the bearing end surface, when the weight of the piston 6 is large, the piston upper end surface 6A is not pressed against the bearing end surface against gravity but according to gravity (in the direction of gravity) ) The piston lower end surface 6B is pressed against the bearing end surface. According to such a structure, it is possible to make the piston 6 have a rotational motion that more reliably follows the end face.

  In the third embodiment, for example, the groove depths DA and DB in the piston end surfaces 6A and 6B are set to substantially the same value (about half of the total gap G between the piston end surface and the bearing end surface). In addition, the sum (LA × NA) of the circumferential length LA of the groove 9A and the number of grooves NA (LA × NA) in the piston end surface 6A is determined to be approximately ½ of the total circumferential length CL of the center line 20, and the piston end surface 6B. The total length (LB × NB) of the circumferential length LB of the groove 9B and the number of grooves NB (LB × NB) is determined to be about ¼ to ３ of the total circumferential length CL of the center line 20. By this setting, the oil film forming ability PA of the piston end face 6A becomes higher than the oil film forming ability PB of the piston end face 6B, the piston 6 is pushed down, and the lower piston end face 6B is pressed against the bearing end face.

  In the structure of the fourth embodiment, for example, the total groove length (LA × NA) and (LB × NB) are set to the same value having about half of the total circumferential length CL of the center line 20. The groove depth DA of the upper piston end face 6A is set to about ½ of the total gap G between the piston end face and the bearing end face, whereas the groove depth DB of the piston end face 6B is set between the piston end face and the bearing end face. It is set to about ¼ to の of the total gap G. With this setting, the oil film forming ability PA of the piston end face 6A can be set higher than the oil film forming ability PB of the piston end face 6B, and the piston 6 is pushed downward (in the direction of gravity) to lower the lower piston end face 6B to the bearing end face. Can be pressed.

  As described above, the above-described embodiments and examples are not limited to the high pressure type rotary compressor in the casing, but may be applied to the low pressure type rotary compressor in the casing as long as the rotary compressor (rotary compressor) 1 is provided. Can do.

  As described above, in the rotary compressor according to the embodiment, the oil film pressure is positively generated on the end surface of the rolling piston. When the oil film pressure exerts a force that inclines the rolling piston, the oil film on the end surface of the rolling piston acts like a spring against this force to suppress an excessive inclination of the rolling piston. Moreover, the oil film forming ability of one piston end face is set larger than that of the other piston end face so that the rolling movement that follows the rotation of the eccentric crank is regulated by the bearing end face (horizontal direction), and the bearing The other piston end face is pressed against the end face. Accordingly, the inclination of the rolling piston due to the inclination of the eccentric crank is suppressed, and the piston end face and the bearing end face are prevented from being touched or seized.

  On the rolling piston end face, which is the sliding part of the rotary compressor, solid contact between the piston end face and the bearing end face due to the tilting of the rolling piston is prevented, improving reliability and reducing friction loss and improving the compressor efficiency. .

  According to the structure of this embodiment, solid contact of the piston end surface can be prevented, and a highly efficient and highly reliable compressor can be realized.

  Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Rotary compressor, 2 ... Casing, 3 ... Motor drive part, 3B ... Motor rotor, 3A ... Motor stator, 4 ... Compression mechanism, 5 ... Cylinder, 6 ... Rolling piston, 6A ... Piston upper end surface, 6B ... Piston Lower end surface, 7-1, 7-2 ... bearing, 8 ... suction pipe, 9A, 9B ... groove on piston end face, 10 ... cylinder chamber, 10C ... suction port, 10D ... discharge port, 11 ... crank, 12 ... discharge pipe 15 ... rotating shaft, 20 ... center line, 25 ... lubricating oil

Claims (5)

A rotating shaft;
A motor drive unit for rotationally driving the rotary shaft;
A bearing portion having second and third bearing surfaces facing each other and at least one first bearing surface that rotatably supports the rotating shaft in a radial direction;
A cylinder having a cylinder chamber, a compression mechanism that is fitted to a crank crank provided eccentrically on the rotating shaft, has a rolling piston that rotates eccentrically in the cylinder chamber, and compresses the refrigerant;
In a rotary compressor comprising:
As the rolling piston rotates on the first and second end faces opposed to the second and third bearing surfaces, the first and second bearings are respectively provided between the second and third bearing surfaces by lubricating oil. First and second groove portions for generating a second oil film surface are formed, respectively.
The first and second groove portions are formed so as to press one of the first and second end surfaces against a corresponding one of the second and third bearing surfaces to provide a uniform gap. The featured rotary compressor.   The rolling piston is formed in an annular shape having an inner peripheral portion, and the groove is opened to the inner peripheral portion of the rolling piston and is not opened to the outer peripheral surface, and the lubricating oil is drawn from the inner peripheral portion. The rotary compressor according to claim 1.   2. The rotary compressor according to claim 1, wherein the first and second grooves are rotationally symmetrical with respect to the center of the rolling piston, and are composed of an even number of different grooves.   Each of the first and second groove portions is composed of an even number of first and second grooves arranged rotationally symmetrically with respect to the center of the rolling piston, and the first and second grooves are different first ones. The rotary compressor according to claim 1, wherein the rotary compressor is formed at a second depth.   2. The rotary compressor according to claim 1, wherein the first and second groove portions apply first and second oil film pressures that push down the rolling piston in a gravity direction to the first and second oil film surfaces.

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