JP2012082782A - Hermetic compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hermetic compressor that prevents a race or a rolling element from being worn or peeled off during the high rotation of an inverter compressor using a thrust rolling bearing, and is improved in performance and reliability.SOLUTION: The hermetic compressor includes an upper-side thrust bearing 148 at an upper end of a main bearing 126 and a lower-side thrust bearing 170 at a lower end of the main bearing 126. The main bearing 126, the upper-side thrust bearing 148, the lower-side thrust bearing 170, and an elastic member 162 having a spring property in a vertical direction are piled up to be sandwiched between a flange 121 of a shaft 118 and a rotator 116, and thereafter applied with a proper axial load. As a result, the race or the rolling element is prevented from being worn or peeled off, and the compressor is improved in the performance and reliability.

Description

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

  In recent years, with regard to hermetic compressors used in electric refrigerator-freezers, high efficiency for reducing power consumption, low noise, and high reliability are desired.

  Conventionally, this type of hermetic compressor employs a rolling bearing as a thrust bearing to improve efficiency (for example, see Patent Document 1).

  Hereinafter, the conventional hermetic compressor will be described with reference to the drawings.

  FIG. 8 is a longitudinal sectional view of a conventional hermetic compressor described in Patent Document 1, and FIG. 9 is an exploded perspective view of a main bearing portion constituting the hermetic compressor.

  In FIG. 7, lubricating oil 4 is stored at the bottom of the sealed container 2, and the compressor main body 6 is elastically supported with respect to the sealed container 2 by a suspension spring (not shown).

  The compressor body 6 includes an electric element 10 and a compression element 12 disposed above the electric element 10. The electric element 10 includes a stator 14 and a rotor 16.

  The shaft 18 of the compression element 12 includes a main shaft portion 20, a flange portion 21 provided at the upper end of the main shaft portion 20, and an eccentric shaft portion 22 extending from the upper surface of the flange portion 21. While being rotatably supported by the main bearing 26 of the block 24, the rotor 16 is fixed. And it is the structure of the cantilever bearing supported with the main shaft part 20 and the main bearing 26 which are arrange | positioned only to the lower side of the eccentric shaft part 22 with respect to the eccentric shaft part 22 which receives a compressive load.

  Further, the shaft 18 includes an oil supply mechanism 28 including an inclined hole provided in the main shaft portion 20.

  The piston 30 is reciprocally inserted into a cylinder 34 having a substantially cylindrical inner surface formed in the cylinder block 24. Further, the connecting means 36 connects the eccentric shaft portion 22 and the piston 30 by fitting the hole portions provided at both ends into the piston pin 38 attached to the piston 30 and the eccentric shaft portion 22, respectively.

  The cylinder 34 and the piston 30 form a compression chamber 42 together with the valve plate 40 attached to the open end surface of the cylinder 34. Further, a cylinder head 44 is fixed so as to cover the valve plate 40 and cover it.

  The suction muffler 46 is molded from a resin such as PBT, forms a silencing space inside, and is attached to the cylinder head 44.

  Next, the thrust bearing 50 will be described.

  As shown in FIG. 9, the main bearing 26 has a thrust surface 52 that is a flat portion perpendicular to the axis on the upper end surface.

  A thrust bearing 50 including an upper race 54, a rolling element 56 that is a steel ball held by a holder portion 58, and a lower race 60 is disposed above the thrust surface 52.

  The upper race 54 and the lower race 60 are annular and metal flat plates, and the upper and lower surfaces are parallel. The holder portion 58 has an annular shape and accommodates the rolling elements 56 in a plurality of holes provided in the circumferential direction so as to be freely rollable.

  The lower race 60, the rolling elements 56, and the upper race 54 are stacked on the thrust surface 52 in the order of contact with each other, and the flange portion 21 of the shaft 18 is seated on the upper surface of the upper race 54.

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

  When the electric element 10 is energized, the rotor 16 rotates together with the main shaft portion 20 due to the rotating magnetic field generated in the stator 14. Due to the rotation of the main shaft portion 20, the eccentric shaft portion 22 moves eccentrically, and the eccentric movement of the eccentric shaft portion 22 is transmitted to the piston 30 via the connecting means 36, and the piston 30 reciprocates in the cylinder 34.

  The refrigerant returned from the refrigeration cycle (not shown) outside the hermetic container 2 is introduced into the compression chamber 42 via the suction muffler 46, compressed by the piston 30 in the compression chamber 42, and the compressed refrigerant is It is sent from the sealed container 2 to the refrigeration cycle.

  Further, the lower end of the shaft 18 is immersed in the lubricating oil 4, and when the shaft 18 rotates, the lubricating oil 4 is supplied to each part of the compression element 12 by the oil supply mechanism 28 to lubricate the sliding portion.

  The thrust bearing 50 is a rolling bearing that rolls in contact with the rolling elements 56, the upper race 54, and the lower race 60, and can rotate while supporting a vertical axial load such as the weight of the shaft 18 and the rotor 16. It is. Rolling bearings have less friction than commonly used thrust bearings in the form of sliding bearings, and can reduce input and improve efficiency.

JP 2005-127305 A

  However, in the conventional configuration described above, when the same thrust bearing 50 is employed in an inverter compressor that rotates at a frequency exceeding the power frequency, the upper race 54 and the lower race 60 are peeled or worn during high-speed rotation exceeding the power frequency. Signs were seen.

  This sign becomes more noticeable as the number of revolutions increases, and in recent years it has become the mainstream of electric elements for inverter compressors. It turned out to be more prominent.

In general, when a bearing is used, it is necessary to apply a contact load so that the rolling elements 56, the upper race 54, and the lower race 60 maintain a rolling state and no slipping occurs. This contact load is generally determined by the bearing specifications such as the diameter of the rolling elements and the rotational speed used, and is generally considered to be proportional to the square of the rotational speed of the bearing. Based on this concept, an axial load that is 1.7 times that of 60 r / s and 2.6 times that of 50 r / s is required at a rotational speed of 80 r / s, as compared with the case of driving at a commercial power supply frequency. become.

  However, in an inverter compressor using concentrated winding type electric elements, the weight of the rotor and shaft is lighter and the axial load tends to be smaller than the constant speed compressor using an induction motor. The cause of peeling and wear occurring in the upper race 54 and the lower race 60 at the time of high rotation of the inverter compressor is predicted to be due to a shortage of the axial load.

  Therefore, in the conventional configuration, when the thrust bearing 50 is employed in the inverter compressor, there is a problem in that the thrust bearing is peeled off or worn due to insufficient axial load during high-speed operation.

  The present invention solves the above-mentioned conventional problems, and even when a lightweight rotor is used and a high speed operation is performed, the rolling element can be divided into an upper race and a lower race by applying an appropriate axial load to the thrust bearing. An object of the present invention is to realize a hermetic compressor that prevents slippage during rolling and suppresses thrust bearing separation and wear.

  In order to solve the above conventional problems, a hermetic compressor according to the present invention includes an upper thrust bearing, which is a rolling bearing disposed between a thrust surface and a flange portion, and a lower end of a main bearing and a rotor. Lower thrust bearing, which is an installed rolling bearing, between the flange and upper thrust bearing, between upper thrust bearing and thrust surface, between lower end of main bearing and lower thrust bearing, and lower thrust bearing and rotation Elastic members that are arranged in at least one place between the rotors and have spring properties in the vertical direction are stacked in the vertical direction and are sandwiched between the flange portion of the shaft and the rotor, reducing the weight of the rotor, etc. Even when high-speed operation is performed, by applying an appropriate axial load to the thrust bearing by the spring force of the elastic member in addition to the weight of the rotor, Since it remain rolling without rolling elements slipping between the over scan and lower race, has the effect of preventing occurrence of peeling and wear of the thrust bearing.

  The hermetic compressor of the present invention uses a lightweight rotor, and even when high speed operation is performed, the rolling element reliably rolls between the upper race and the lower race and prevents the occurrence of slipping. It is possible to prevent occurrence of bearing peeling and wear and improve reliability.

1 is a longitudinal sectional view of a hermetic compressor according to Embodiment 1 of the present invention. The principal part enlarged view of the upper side thrust bearing employ | adopted for the hermetic compression in Embodiment 1 The principal part enlarged view of the lower side thrust bearing employ | adopted for the hermetic type compression in Embodiment 1 The top view of the holder part of the upper side thrust bearing employ | adopted for the hermetic compression in Embodiment 1 The top view of the holder part of the lower side thrust bearing employ | adopted for the hermetic compression in Embodiment 1 (A) is a top view of the elastic member adopted in the closed compression in the first embodiment, (b) is a side view of the elastic member adopted in the closed compression in the first embodiment. The perspective view of the aligning washer employable for the hermetic compression in the first embodiment Vertical section of a conventional hermetic compressor An exploded perspective view of a cylinder block part constituting a conventional hermetic compressor

  1st invention accommodates the electric element provided with the stator and the rotor, and the compression element arrange | positioned above the said electric element in the airtight container which stored lubricating oil, Furthermore, the said compression element, A shaft having an eccentric shaft portion formed through a main shaft portion and a flange portion to which the rotor is fixed, a cylinder block having a cylinder, and a piston inserted in the cylinder so as to be able to reciprocate; A connecting means for connecting the piston and the eccentric shaft portion; a main bearing formed on the cylinder block and supporting the main shaft portion of the shaft; and a thrust surface provided on an upper portion of the main bearing. An upper thrust bearing configured by a rolling bearing disposed between the thrust surface and the flange portion and having rolling elements sandwiched between an upper race and a lower race, and the main bearing. A lower thrust bearing comprising a rolling bearing disposed between an end and the rotor and having rolling elements sandwiched between an upper race and a lower race, and having a spring property in the vertical direction, and the main shaft portion Is provided between the flange portion and the upper thrust bearing, and / or between the upper thrust bearing and the thrust surface, and / or the lower end of the main bearing. It is a hermetic compressor disposed at least at one location between the lower thrust bearing and / or between the lower thrust bearing and the rotor.

  With this configuration, the upper thrust bearing, the lower thrust bearing, and the elastic member are stacked in the vertical direction, and a configuration in which the flange portion and the rotor are sandwiched is obtained. Therefore, even when a high-speed operation is performed using a lightweight rotor, an appropriate axial load can be applied to the thrust bearing, preventing slippage when the rolling element rolls between the upper race and the lower race. can do. As a result, it is possible to improve the reliability by suppressing the separation and wear of the thrust bearing.

  In the second invention, the electric element of the first invention is driven at a plurality of frequencies including a frequency equal to or higher than a commercial frequency.

  With this configuration, particularly when a high-speed operation is performed using a salient pole concentrated winding DC brushless motor having a lightweight rotor, the axial load applied to the thrust bearing decreases as the weight of the rotor decreases. Since the rotational speed is high, the rolling elements and the race are very slippery, but an appropriate axial load acts on the thrust bearing by the spring force of the elastic member. As a result, in addition to the effects described in the first invention, the rolling element and the race can be prevented from slipping, the thrust bearing can be prevented from being peeled off and the wear can be suppressed, and the reliability of the hermetic compressor is improved. can do.

  A third invention is the counterbore according to the first or second invention, wherein the rotor of the electric element is formed with a concave portion having a predetermined diameter centered on the main shaft portion and houses the lower portion of the main bearing. Further, the diameter of the rolling element of the lower thrust bearing is made smaller than the diameter of the rolling element of the upper thrust bearing.

  By adopting such a configuration, it is possible to prevent slipping when the rolling element rolls between the upper race and the lower race in the lower thrust bearing having a smaller axial load than the upper thrust bearing. As a result, separation of the thrust bearing and wear can be suppressed, reliability can be improved, and the inner diameter and depth of the counterbore provided in the rotor can be reduced, and the efficiency of the electric element can be reduced. It can prevent that it falls more than necessary.

  According to a fourth invention, in any one of the first to third inventions, the number of rolling elements of the lower thrust bearing is smaller than the number of rolling elements of the upper thrust bearing.

  By adopting such a configuration, in the lower thrust bearing having a smaller axial load than the upper thrust bearing, it is possible to prevent the rolling element from slipping when rolling between the upper race and the lower race. The reliability of the sliding part can be improved by suppressing the peeling of the bearing and the occurrence of wear. In addition, by reducing the number of rolling elements, the number of holes provided in the holder part can be reduced, and the rigidity of the holder part can be improved. As a result, even when the lower thrust bearing is disposed in the vicinity of the rotor that becomes high temperature when fixed to the shaft, it is possible to suppress the deformation of the holder portion due to heat, and to prevent the occurrence of problems due to such deformation. can do.

  According to a fifth invention, in any one of the first to fourth inventions, the raceway diameter of the rolling element of the lower thrust bearing is made smaller than the raceway diameter of the rolling element of the upper thrust bearing.

  By adopting such a configuration, in the lower thrust bearing having a smaller axial load than the upper thrust bearing, it is possible to prevent the rolling element from slipping when rolling between the upper race and the lower race. The reliability of the sliding part can be improved by suppressing the peeling of the bearing and the occurrence of wear. In addition, since the track diameter of the lower thrust bearing is reduced, the rolling distance of the rolling elements is shortened, and the durability of the lower thrust bearing can be improved.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the upper thrust bearing is disposed on the outer diameter side of a bearing extension provided at an upper portion of the main bearing.

  By setting it as this structure, the length of the said main bearing can be lengthened. As a result, the main bearing receives a compressive load in the vicinity of the compression mechanism, and the load received by the main bearing can be reduced. As a result, the friction acting on the main bearing can be reduced and the durability 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 a first embodiment of the present invention. FIG. 2 is an enlarged view of a main part of an upper thrust bearing employed for hermetic compression in the first embodiment. FIG. 3 is an enlarged view of a main part of a lower thrust bearing employed for hermetic compression in the first embodiment. FIG. 4 is a top view of the holder portion of the upper thrust bearing employed for hermetic compression in the first embodiment. FIG. 5 is a top view of the holder portion of the lower thrust bearing employed for hermetic compression in the first embodiment. 6A is a top view of the elastic member employed in the hermetic compressor in the first embodiment, and FIG. 6B is an elastic member employed in the hermetic compressor in the first embodiment. FIG. FIG. 7 is a perspective view of a centering washer that can be used for hermetic compression in the first embodiment. In FIGS. 1, 2, and 3, lubricating oil 104 is stored at the bottom inside the hermetic container 102. Further, the compressor main body 106 is suspended in the hermetic container 102 via a suspension spring 108. The sealed container 102 is filled with R600a (isobutane), which is a refrigerant with a low warming potential.

  The compressor body 106 includes an electric element 110 and a compression element 112 driven by the electric element 110, and a power supply terminal 113 for supplying power to the electric element 110 is attached to the sealed container 102.

  First, the electric element 110 will be described.

  The electric element 110 includes a stator 114 in which a winding is directly wound around a plurality of magnetic pole teeth of an iron core in which steel plates are laminated via an insulating material, and a rotor incorporating a permanent magnet disposed on the inner diameter side of the stator 114. A DC brushless motor of a salient pole concentrated winding type provided with 116, and the winding of the stator 114 is connected to a power supply (not shown) outside the hermetic compressor via a power supply terminal 113 by a conductive wire.

  Next, the compression element 112 will be described.

  The compression element 112 is disposed above the electric element 110. The shaft 118 constituting the compression element 112 includes a main shaft portion 120, a flange portion 121 at the upper end of the main shaft portion 120, and an eccentric shaft portion 122 extending from the upper surface of the flange portion 121 and parallel to the main shaft portion 120. Yes. A rotor 116 is fixed to the main shaft portion 120.

  The cylinder block 124 includes a main bearing 126 having a cylindrical inner surface, and the main shaft portion 120 is inserted into and supported by the main bearing 126 in a rotatable state. The compression element 112 has a configuration of a cantilever bearing that supports the load acting on the eccentric shaft portion 122 by the main shaft portion 120 and the main bearing 126 arranged below the eccentric shaft portion 122.

  Further, the shaft 118 includes an oil supply mechanism 128 including a spiral groove provided on the surface of the main shaft portion 120.

  Furthermore, the cylinder block 124 includes a cylinder 134 that is a cylindrical hole, and a piston 130 is reciprocally inserted into the cylinder 134.

  Further, the connecting means 136 is connected to the eccentric shaft portion 122 and the piston 130 by inserting holes (not shown) provided at both ends into the piston pin 138 and the eccentric shaft portion 122 attached to the piston 130, respectively. is doing.

  Therefore, the rotational movement of the eccentric shaft portion 122 accompanying the rotation of the shaft 118 is converted into the reciprocating movement by the connecting means 136, and the piston 130 performs the reciprocating movement.

  A valve plate 140 is attached to the end face of the cylinder 134 and forms a compression chamber 142 together with the cylinder 134 and the piston 130. Further, a cylinder head 144 is fixed so as to cover the valve plate 140 and cover it. The suction muffler 146 is molded from a resin such as PBT, forms a silencing space inside, and is attached to the cylinder head 144.

  Next, the configuration of the upper thrust bearing 148 will be described with reference to FIG.

  The main bearing 126 has a thrust surface 152 that is a flat portion perpendicular to the shaft center, and a bearing extension 153 that extends further upward than the thrust surface 152 and has an inner surface facing the main shaft portion 120.

An upper race 154 is disposed above the bearing extension 153, and is a ball bearing steel ball held by a holder 158 on the outer diameter side of the bearing extension 153 and below the upper race 154. A moving body 156 and a lower race 160 are disposed, and an upper thrust bearing 148 is configured.

  An elastic member 162 that is elastically deformable in the vertical direction is disposed between the lower side of the lower race 160 and the thrust surface 152.

  Specifically, as shown in FIG. 6, the shape of the elastic member 162 is a shape in which an annular thin plate is provided with projections and depressions, and three locations 162a, 162b, and 162c are convex upward, and 162d, 162e, and 162f are three. The portion has a downwardly convex shape.

  Next, the configuration of the lower thrust bearing 170 will be described.

  The lower thrust bearing 170 is arranged below the main bearing 126 in the order of an upper race 172, a rolling element 174 which is a ball bearing steel ball held by a holder portion 176, and a lower race 178. Yes. The lower race 178 is in contact with a thrust portion 180 (FIG. 3) provided inside the rotor 116.

  A series of components of the upper thrust bearing 148, the elastic member 162, the main bearing 126, and the lower thrust bearing 170 are stacked in the vertical direction, and the flange constituting the shaft 118 is in a state where the elastic member 162 is compressed from its natural length. The thrust surface 121a of the portion 121 and the thrust portion 180 of the rotor 116 fixed to the shaft 118 are assembled.

  Further, in the upper thrust bearing 148 and the lower thrust bearing 170, the upper race 154, the upper race 172, the lower race 160, and the lower race 178 are annular metal plates, preferably formed of heat-treated spring steel or the like. The upper and lower surfaces are parallel and the surface is smooth.

  The holder portion 158 and the holder portion 176 are formed of a resin material such as polyamide and have an annular shape, and a plurality of holes (not shown) in which the rolling element 156 and the rolling element 174 are respectively housed so as to be freely rollable. have.

  As shown in FIG. 4, rolling elements 156 are arranged in 12 holes (not shown) arranged in the circumferential direction of the holder portion 158 of the upper thrust bearing 148. In addition, as shown in FIG. 5, rolling elements 174 are arranged in six holes (not shown) arranged in the circumferential direction of the holder portion 176 of the lower thrust bearing 170. Further, the locus of the contact point when each rolling element 156, 174 rolls with the upper and lower races is indicated by a one-dot chain line, and the diameter of each locus, which is the diameter of the locus, is du at the upper thrust bearing 148, and In the side thrust bearing 170, dl.

  As shown in FIG. 4, the track diameter du of the rolling element 156 of the upper thrust bearing 148 is larger than the track diameter dl of the rolling element 174 of the lower thrust bearing 170. Further, the number of rolling elements 156 of the upper thrust bearing 148 is twelve, which is larger than the number of rolling elements 174 of the lower thrust bearing 170. Furthermore, the diameter tu of the rolling element 156 of the upper thrust bearing 148 is larger than the diameter tl of the rolling element 174 of the lower thrust bearing 170.

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

When the electric element 110 is energized from the power supply terminal 113, the rotor 116 rotates together with the shaft 118 due to the magnetic field generated in the stator 114. The eccentric rotation of the eccentric shaft portion 122 accompanying the rotation of the main shaft portion 120 is converted into a reciprocating motion by the connecting means 136, and the piston 130 is reciprocated in the cylinder 134. Then, when the volume of the compression chamber 142 changes, a compression operation is performed in which the refrigerant in the sealed container 102 is sucked into the compression chamber 142 and compressed.

  In the suction stroke accompanying this compression operation, the refrigerant in the sealed container 102 is intermittently sucked into the compression chamber 142 via the suction muffler 146 and compressed in the compression chamber 142, and then the high-temperature and high-pressure refrigerant is discharged. It is sent from the sealed container 102 to a refrigeration cycle (not shown) via a pipe (not shown).

  Further, the lower end of the shaft 118 is immersed in the lubricating oil 104. When the shaft 118 rotates, the lubricating oil 104 supplies the main shaft portion 120 and the main bearing 126 by the oil supply mechanism 128, and then the flange portion 121 and the eccentricity. The lubricating oil 104 is also supplied to the upper thrust bearing 148 and the lower thrust bearing 170 in this process.

  In the upper thrust bearing 148, twelve rolling elements 156 having the same diameter tu are arranged between the flat upper race 154 and the lower race 160. Similarly, the lower thrust bearing 170 is also a rolling element 174 having a diameter tl. Are arranged between the upper race 172 and the lower race 178 so that each rolls in a point contact state. As a result, the friction can be made extremely small, the input of the electric element 110 can be reduced along with the reduction of the sliding loss, and the efficiency of the hermetic compressor can be improved.

  In the upper thrust bearing 148, the vertical axial load acting on the rolling elements 156, the upper race 154, and the lower race 160 is in addition to the load due to gravity accompanying the mass of the shaft 118 and the rotor 116, and the spring force of the elastic member 162. Therefore, the optimum load can be selected regardless of the mass of the shaft 118 and the rotor 116, and the sliding between the rolling element 156 and the upper race 154 and the lower race 160 can be prevented, and the rolling state can be maintained. It is possible to prevent the occurrence of abrasion and peeling, and to ensure (improve) reliability.

  Moreover, since it is not necessary to extremely reduce the number of the rolling elements 156 in order to ensure the axial load necessary for preventing the rolling elements 156 from slipping, the compression load acts on the shaft 118, and the upper thrust bearing 148. Even when an unbalanced load is applied, the occurrence of damage due to the concentration of the load on some of the rolling elements 156 can be prevented, and the reliability can be maintained.

  Further, when the closed compressor is transported, for example, when the compressor collides with the floor surface, the upper thrust bearing 148 includes an upper thrust bearing 148 in order to receive the inertial force accompanying the mass of the rotor 116 and the like. A very large axial load is temporarily applied. As a result, plastic deformation such as depression occurs at the contact point between the upper race 154 and the lower race 160 and the rolling element 156, which may adversely affect reliability.

  However, in the case of the first embodiment, an appropriate axial load is secured by the spring force of the elastic member 162 while using the lightweight rotor 116, so that the axial load generated at the time of dropping is reduced, and transportation, etc. In this case, it is possible to provide a hermetic compressor that is less likely to be damaged and maintains reliability.

  The first embodiment is an inverter-driven hermetic compressor using a salient pole concentrated winding type DC brushless motor as the electric element 110, and is driven at a plurality of frequencies including frequencies higher than the commercial frequency. Is.

In general, when a thrust bearing is used, it is necessary for the rolling elements 156 to maintain a rolling state between the upper race 154 and the lower race 160 and to apply a contact load that does not cause slippage. The load is generally determined by the specifications of the thrust bearing such as the diameter of the rolling element and the number of rotations used, and is generally considered to be proportional to the square of the number of rotations of the bearing.

  That is, as compared with the case of driving at a commercial power supply frequency, an axial load that is 1.7 times that of 60 r / s and 2.6 times that of 50 r / s is required at a rotational speed of 80 r / s.

  Therefore, when a DC brushless motor having a light weight of the rotor 116 is used and a high speed operation of 80 r / s is performed, the axial load due to the weight of the rotor 116 is small, and the rolling elements 156 are formed between the upper race 154 and the lower race 160. It is considered that it is in a harsh state from the viewpoint of reliability.

  However, in the first embodiment, an appropriate axial load can be applied to the rolling element 156 by using the spring force by the elastic member 162 in addition to the axial load due to its own weight.

  As a result, slipping between the rolling elements 156 and the upper race 154 and the lower race 160 can be prevented even during high-speed driving driven at a frequency higher than the power supply frequency, and the rolling state can be maintained. The effect of suppressing the decrease in reliability is remarkable.

  On the other hand, in FIG. 3, the axial load acting on the lower thrust bearing 170 (between the upper race 172 and the lower race 178) is smaller than that of the upper thrust bearing 148 because only the spring force of the elastic member 162 acts. Therefore, when a thrust bearing having the same specifications as the upper thrust bearing 148 is used, the axial load is insufficient and slipping easily occurs. However, in the first embodiment, the diameter of the rolling element 174 of the lower thrust bearing 170 is increased. The rolling element 156 of the upper thrust bearing 148 is made smaller.

  Hereinafter, the relationship between the diameter of the rolling elements and the axial load will be described.

  The rolling element that is a steel ball and the race that is a flat plate are in point contact, and microscopically, elastic deformation occurs at the contact point. And the area is proportional to the 1/3 power of the radius of a rolling element. In addition, the average surface pressure at this contact point is proportional to the -2/3 power of the radius of the sphere.

  In order to prevent slipping, the contact pressure at the contact point must be a certain value or more, and the contact surface pressure increases as the radius of the sphere decreases, so for the same axial load, the diameter of the rolling element The smaller the is, the less likely it is to slip.

  Therefore, by making the diameter of the rolling element 174 of the lower thrust bearing 170 smaller than that of the rolling element 156 of the upper thrust bearing 148, even when the axial load is small, the rolling element 174 is less likely to slip when rolling. Since the rolling state can be maintained, it is possible to prevent wear and peeling.

  In addition, by reducing the diameter of the rolling element 174, the lower thrust bearing 170 can be reduced in height in the vertical direction and width in the radial direction, and the lower thrust bearing 170 can be reduced in size. Therefore, the inner diameter dm and the depth hm of the counterbore 116a, which is a recess provided in the rotor 116 for accommodating the lower end of the main bearing 126, can be reduced, and the efficiency of the electric element 110 can be prevented from being lowered. Can do.

In Embodiment 1, the contact load per rolling element 174 is reduced by reducing the number of rolling elements 174 of the lower thrust bearing 170 to six compared to twelve rolling elements 156 of the upper thrust bearing 148. Increased to prevent slipping during rolling. Therefore, the reliability of the lower thrust bearing 170 can be improved.

  Moreover, since the rotor 116 is fixed to the shaft 118 by shrink fitting, the temperature becomes high during shrink fitting, and the temperature of the lower thrust bearing 170 disposed in the vicinity of the rotor 116 also rises. However, since the holder portion 176 of the lower thrust bearing 170 has a small number of holes for accommodating the rolling elements 174 and has high rigidity, deformation of the holder portion 176 itself due to heat can be reduced. As a result, with the deformation of the holder portion 176, it is possible to prevent the occurrence of chipping and cracking caused by the holder portion 176 coming into contact with other components.

  Further, by making the raceway diameter dl of the rolling element 174 of the lower thrust bearing 170 smaller than the raceway diameter du of the rolling element 156 of the upper thrust bearing 148, the rolling speed of the rolling element is reduced to prevent the occurrence of slipping. Thus, the reliability of the lower thrust bearing 170 can be improved, and the lower thrust bearing 170 can be reduced in the radial direction, so that the inner diameter dm of the counter bore 116a provided in the rotor 116 can be reduced. Therefore, a reduction in efficiency of the electric element 110 can be prevented.

  In addition, by arranging the upper thrust bearing 148 outside the bearing extension 153, the length of the main bearing 126 is not shortened, and the load acting on the shaft 118 near the compression mechanism such as the piston 130 is supported. Therefore, the load supported by the main bearing 126 can be reduced, and the sliding loss can be reduced.

  In the first embodiment of the present invention, the elastic member 162 is provided between the lower side of the upper thrust bearing 148 and the thrust surface 152 formed on the main bearing 126. However, the flange 121 and the upper thrust bearing 148 are provided. Or between the lower end tip of the main bearing 126 and the lower thrust bearing 170, and further, the horizontal surface portion of the counter bore 116a provided on the lower thrust bearing 170 and the rotor 116 (the lower race 178 is placed). The same effect can be obtained even if it is provided anywhere between the two surfaces.

  Further, a plurality of elastic members 162 may be disposed adjacent to the upper thrust bearing 148 and the lower thrust bearing 170, respectively. In this case, in addition to the effect of adding the axial load described above, even when the shaft 118 is slightly inclined, the load can be evenly applied to the rolling elements 156 and 174 of the upper and lower thrust bearings 148 and 170. A so-called alignment effect can be obtained, and damage to the rolling elements 156, 174 and the upper and lower races 154, 160, 172, 178 can be prevented.

  In addition, the elastic member 162 may be provided adjacent to the upper thrust bearing 148 and a member that absorbs inclination may be provided adjacent to the lower thrust bearing 170. As a specific example of the member that absorbs the inclination, as shown in FIG. 7, two convex portions 201 and 202 are formed on the upper and lower surfaces, respectively, and can roll in the directions of two orthogonal axes X and Y. A centering washer 200 or the like can be used. Also in this case, even when the shaft 118 is slightly inclined, the axial load can be equally applied to the rolling elements 156 and 174 of the upper and lower thrust bearings 148 and 170, and the occurrence of damage can be prevented.

  In the first embodiment of the present invention, the steel ball is used as the rolling element of the rolling bearing, but the same effect can be obtained by using a substantially cylindrical roller instead.

As described above, since the hermetic compressor according to the present invention can suppress deterioration in performance and reliability over a long period using a thrust bearing, it is not limited to an electric refrigerator-freezer for home use, an air conditioner, and a vending machine. And widely applicable to other refrigeration apparatuses.

DESCRIPTION OF SYMBOLS 102 Sealing container 104 Lubricating oil 110 Electric element 112 Compression element 114 Stator 116 Rotor 118 Shaft 120 Main shaft part 121 Flange part 122 Eccentric shaft part 124 Cylinder block 126 Main bearing 130 Piston 134 Cylinder 136 Connecting means 148 Upper thrust bearing 152 Thrust surface 153 Bearing extension 156 Rolling element 162 Elastic member 170 Lower thrust bearing 174 Rolling element

Claims (6)

An electric element having a stator and a rotor and a compression element disposed above the electric element are accommodated in a sealed container storing lubricating oil, and the rotor is fixed to the compression element. A shaft having an eccentric shaft portion formed through the main shaft portion and the flange portion, a cylinder block having a cylinder, a piston inserted in the cylinder so as to be able to reciprocate, the piston and the eccentric shaft A connecting means for connecting portions, a main bearing formed on the cylinder block and supporting the main shaft portion of the shaft, and a thrust surface provided on an upper portion of the main bearing, An upper thrust bearing comprising a rolling bearing disposed between a thrust surface and the flange portion, and a rolling element sandwiched between an upper race and a lower race; and a lower end of the main bearing and the rotation A lower thrust bearing composed of a rolling bearing in which a rolling element is sandwiched between an upper race and a lower race, and an annular shape having springiness in the vertical direction and through which the main shaft portion passes. The elastic member is provided between the flange portion and the upper thrust bearing and / or between the upper thrust bearing and the thrust surface and / or the lower end of the main bearing and the lower thrust bearing. And / or at least one location between the lower thrust bearing and the rotor. The hermetic compressor according to claim 1, wherein the electric element is driven at a plurality of frequencies including a frequency equal to or higher than a commercial frequency. The rotor of the electric element is provided with a counter bore that is formed of a concave portion having a predetermined diameter centered on the main shaft portion and accommodates the lower portion of the main bearing, and further, the diameter of the rolling element of the lower thrust bearing The hermetic compressor according to claim 1, wherein is smaller than a diameter of a rolling element of the upper thrust bearing. The hermetic compressor according to any one of claims 1 to 3, wherein the number of rolling elements of the lower thrust bearing is smaller than the number of rolling elements of the upper thrust bearing. The hermetic compressor according to any one of claims 1 to 4, wherein a raceway diameter of the rolling element of the lower thrust bearing is smaller than a raceway diameter of the rolling element of the upper thrust bearing. The hermetic compressor according to any one of claims 1 to 5, wherein the upper thrust bearing is disposed on an outer diameter side of a bearing extension provided at an upper portion of the main bearing.