JP2008038787A - Rotary compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary compressor capable of improving seizure resistance and abrasion resistance, even when an oil level of an oil reservoir lowers by refrigerant foaming in starting and after liquid return operation, by enhancing hardness by applying induction hardening to a main shaft part and a sub-shaft part of a shaft. <P>SOLUTION: This rotary compressor is constituted so that an electric motor 3 and compression parts 2A and 2B are arranged in a sealed vessel 1, and the compression parts have cylinders 8a and 8b, the shaft 4 having eccentric crank parts 4a and 4b, eccentrically rotating rollers 14a and 14b, a main bearing 9 holding the main shaft part of the shaft, and a sub-bearing 10 holding the sub-shaft part, and the main bearing and the sub-bearing are formed of a casting or a sintered product, and is constituted by imparting a hardness difference between the shaft, the main bearing and the sub-bearing, by performing quenching processing on any one or both surfaces of the main shaft part and the sub-shaft part, by forming the shaft of a cast material such as spherical graphite cast iron. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotary compressor used in an air conditioner, a refrigerator, and the like, and more particularly, to a configuration capable of improving seizure resistance and wear resistance of a shaft and a bearing member.

  In conventional rotary compressors, the main shaft bearing and sub-bearing of the motor shaft usually use gray cast iron or sintered product that is not heat-treated, and the shaft uses gray cast iron or spheroidal graphite cast iron. There is no difference in hardness between shafts, resulting in poor wear resistance. Therefore, seizure occurs when the lubricant is taken out from the compressor to the refrigeration cycle and the oil level of the oil sump drops due to starting after the compressor has been stopped for a long time or foaming of refrigerant after liquid back operation. And wear resistance may deteriorate.

  Therefore, as a technique corresponding to the above contents, for example, ones as shown in FIG. 4 and FIG.

  As shown in FIG. 4, a compression mechanism 3 'is built in the lower part of the sealed container 1', and an electric motor 2 'is built in the upper part. The electric motor 2 ′ is composed of a stator 4 ′ fixed in a sealed container 1 ′ by shrinkage and the like, and a rotor 5 ′ of a rotating body provided corresponding to the stator 4 ′. The compression mechanism 3 'has a cylinder 7' fixed by welding or the like in the hermetic container 1 ', and is decentered in the cylinder 7' by a shaft 6 'that is connected and fixed to the rotor 5' and rotates integrally therewith. A rotating eccentric crank portion 6a ′ is provided, and the roller 8 ′ is supported concentrically by the eccentric crank portion 6a ′. A vane (not shown) slides in contact with the roller 8 'in accordance with the rotation of the shaft 6', rotates eccentrically with the eccentric crank portion 6a ', repeatedly sucks and compresses the refrigerant into the cylinder 7', and discharges it.

  The shaft 6 has an upper bearing 11 ′ and a lower bearing 12 ′ bolted to a cylinder 7 ′ with a bolt 13 ′ across the eccentric crank portion 6a ′ and the roller 8 ′, and is close to the compression mechanism 3 ′. Only a simple bearing structure in which both the upper bearing 11 'and the lower bearing 12' are of the sliding bearing type. For this reason, it has a bearing structure that receives sliding friction.

  As shown in FIG. 5, the eccentric crank portion 6 a ′ separate from the shaft 6 ′ can be made of a material different from that of the shaft. The eccentric crank portion 6 a ′ is, for example, a steel forged product such as the shaft 6 ′ or this. The surface of the eccentric crank portion 6a ′ is subjected to a carburizing quenching process or a carbonitriding quenching process, and the surface layer 6b and the like have a structure of 70% or more of pearlite within a range not exceeding 3.0 mm.

  In this case, the eccentric crank portion 6a ′ is sintered iron, and the surface of the shaft 6 ′ or this and the eccentric crank portion 6a ′ is subjected to a carburizing quenching process or a carbonitriding quenching process, and does not exceed 3.0 mm. Thus, the surface layer has a pearlite structure of 70% or more.

  Further, the shaft 6 'is made of a steel pipe, and at least the surface of the sliding portion such as a sliding bearing is subjected to induction hardening treatment or carbonitriding hardening treatment, and the surface layer is pearlite 70 within a range not exceeding 3.0 mm. %, And such surface treatment does not particularly impair the toughness of the shaft 6 ′, and the wear resistance with other sliding parts such as the sliding bearings of the upper bearing 11 ′ and the lower bearing 12 ′. Can be improved.

However, the shaft 6 'is composed of a shaft body made of another material and an eccentric crank portion 6a', and the hardness difference of the shaft body is improved with respect to the upper bearing 11 'and the lower bearing 12', so that assembly is difficult. This increases costs.
Japanese Unexamined Patent Publication No. 2000-227083 (pages 8-9, FIGS. 1 and 3)

  In view of the above-mentioned problems, the present invention performs induction hardening on the main shaft portion and the sub shaft portion of the shaft to increase the hardness and make a hardness difference between each bearing, so that at the time of starting or after the liquid back operation An object of the present invention is to provide a rotary compressor capable of improving seizure resistance and wear resistance even when the oil level of the oil reservoir is reduced due to foaming of the refrigerant.

In order to solve the above-described problems, the present invention arranges an electric motor and a compression portion in a sealed container, and the compression portion includes a cylinder, a shaft having an eccentric crank portion, a roller that moves eccentrically, and a main shaft of the shaft. In a rotary compressor comprising a main bearing holding a portion and a sub-bearing holding a sub-shaft portion, wherein the main bearing and the sub-bearing are formed of a cast or sintered product,
A material of the shaft is a casting material, and a surface of one or both of the main shaft portion and the sub shaft portion is subjected to a quenching process, and the surface of the shaft and the surface of the main bearing and / or the surface of the sub bearing It has a configuration with a hardness difference between them.

  Further, the shaft is made of spheroidal graphite cast iron.

  Further, the thrust surface of the eccentric crank portion on the auxiliary bearing side is subjected to a quenching process simultaneously with the surface of the auxiliary shaft portion of the shaft, and the thrust receiving surface of the auxiliary bearing and the auxiliary bearing side of the eccentric crank portion on the auxiliary bearing side. It has a configuration in which a hardness difference is provided between the thrust surface and the thrust surface.

  A thrust bearing for supporting the bottom surface of the shaft is provided at a lower portion of the auxiliary bearing, and the thrust surface of the bottom surface of the shaft is subjected to quenching treatment simultaneously with the surface of the auxiliary shaft portion of the shaft. A hardness difference is provided between the bearing and the thrust surface on the bottom surface of the shaft.

  Further, the quenching portion on the main shaft side is extended to the vicinity of the rotor shrinkage fitting portion of the electric motor.

  According to the present invention, the shaft is made of a cast material having good hardenability such as spheroidal graphite cast iron, and the surface of either one or both of the main shaft portion and the sub shaft portion is partially subjected to high-frequency partial hardening treatment, Even if the oil level of the oil reservoir is lowered due to the foaming of the refrigerant after the start-up or the liquid back operation, by adopting a configuration in which a hardness difference is provided between the shaft and the main bearing and the sub-bearing, Seizure resistance and wear resistance can be improved. Further, by adopting a configuration in which the quenching portion on the main shaft side is extended to the vicinity of the rotor shrinkage fitting portion of the electric motor, the rigidity of the shaft 4 itself is improved, the swinging of the rotor 6 is reduced, and each portion of the bearing is Abnormal contact sliding can be reduced, and a rotary compressor capable of extending the operation range by increasing reliability and increasing rotation can be obtained.

  Embodiments of a hermetic compressor according to the present invention will be described in detail with reference to the accompanying drawings based on examples of a twin rotary compressor. FIG. 1 is a sectional side view of a rotary compressor according to the present invention, and FIG.

  In FIG. 1, reference numeral 1 denotes an airtight container. In the lower part of the airtight container 1, two first compression parts 2A and a second compression part 2B are accommodated, and an electric motor 3 is accommodated in the upper part. . The electric motor 3 includes a stator 5 fixed to the inner surface of the hermetic container 1 and a rotor 6 that is disposed inside the stator 5 with a predetermined gap and is fitted to the shaft 4. The electric motor 3 and the first and second compression parts 2A and 2B are formed on the shaft 4 and are connected via eccentric crank parts 4a and 4b that are eccentrically rotated with the compression process shifted by 180 degrees. ing. The shaft 4 is composed of a main shaft portion 4c at the upper portion of the eccentric crank portion 4a and a countershaft portion 4d at the lower portion of the eccentric crank portion 4b.

Each of the first and second compression parts 2A and 2B includes a first cylinder 8a and a second cylinder 8b that are disposed below the shaft 4 with a partition plate 7 therebetween.
A main bearing 9 is superimposed on the upper surface of the first cylinder 8a, and is fixed to the first cylinder 8a via bolts or the like.

  Further, the auxiliary bearing 10 is superimposed on the lower surface portion of the second cylinder 8b, and is attached and fixed to the second cylinder 8b via a bolt or the like.

  Inner diameter portions of the first cylinder 8a and the second cylinder 8b are vertically divided by the partition plate 7, and a first cylinder chamber 15a and a second cylinder chamber 15b having the same diameter are formed. In each of the cylinder chambers, a first roller 14 a and a second roller 14 b that are eccentrically rotated by the eccentric crank portions 4 c and 4 d provided on the outer peripheral portion of the shaft 4 are disposed.

  The interiors of the first cylinder chamber 15a and the second cylinder chamber 15b are each divided into a discharge chamber and a suction chamber by vanes (not shown) so that the discharge pressure does not leak into the suction chamber. The portion is in pressure contact with the first roller 14a and the second roller 14b, which rotate eccentrically, and reciprocates in vane groove portions (not shown) provided in the first cylinder 8a and the second cylinder 8b, respectively.

  In the above configuration, the refrigerant gas enters the first cylinder chamber 15a and the second cylinder chamber 15b from a suction pipe (not shown) through a flow path (not shown) provided in the first cylinder 8a and the second cylinder 8b. Led. When the electric motor 3 is energized and the shaft 4 integral with the rotor 6 of the electric motor 3 is rotated, the first roller 14a and the second roller 14b perform eccentric rotational movement, and the volumes of the compression chamber and the suction chamber change. As a result, the refrigerant gas is sucked and compressed. The compressed refrigerant gas is discharged from the discharge pipe T to the outside of the sealed container 1 through the inside of the sealed container 1 when a discharge valve (not shown) of a discharge hole (not shown) is opened.

  The main bearing 9 and the sub-bearing 10 shown in FIG. 1 usually use gray cast iron (for example, tensile strength equivalent to FC250) or a sintered product that is not heat-treated, and the shaft 4 uses gray cast iron or spheroidal graphite cast iron. Since there is no difference in hardness, wear resistance is poor.

  In addition, the eccentric crank portions 4a and 4b are hardened and tempered by monichro cast iron, and slide with a roller with increased hardness. Therefore, when heat treatment is performed, the hardness difference is reduced and wear resistance is reduced. There is. Therefore, only the main shaft portion 4c and the sub shaft portion 4d, which are required to have wear resistance, are partially hardened to give a hardness difference.

  After the shaft 4 is finished by cutting, the surfaces of the main shaft portion 4c and the sub-shaft portion 4d are subjected to induction hardening to be ground (polished). Further, as the material of the shaft 4, spheroidal graphite cast iron of FCD500 or higher with good hardenability may be used.

  Further, as shown in FIG. 2, induction hardening treatment is performed simultaneously with the surface of the sub-shaft portion 10 of the shaft on the thrust surface 4e of the eccentric crank portion 4b on the sub-bearing 10 side (also serving as the thrust surface of the shaft 4 main body). Thus, a difference in hardness is provided between the thrust receiving surface 10a of the auxiliary bearing 10 and the thrust surface 4e of the eccentric crank portion 4b on the auxiliary bearing 10 side.

  As a result, seizure resistance and wear resistance can be improved even when the oil level of the oil reservoir is reduced due to foaming of the refrigerant after the start-up or after the liquid back operation.

  FIG. 3 shows another embodiment of the present invention. As shown in FIG. 3, a thrust bearing 10 b that supports the bottom surface of the shaft 4 is provided below the auxiliary bearing 10, and the surface of the auxiliary shaft portion 4 d of the shaft 4 is provided on the thrust surface 4 f of the bottom surface of the shaft 4. At the same time, induction hardening is performed so that a hardness difference is provided between the thrust bearing 10 b of the sub-bearing 10 and the thrust surface 4 f of the bottom surface of the shaft 4.

  Thus, as in the case of FIG. 2, the seizure resistance and the wear resistance can be improved even when the oil level of the oil sump is lowered due to foaming of the refrigerant after the start-up or the liquid back operation. .

  Further, the thrust receiving surface 10a of the auxiliary bearing 10 is also a cast or sintered material that is not subjected to heat treatment, and therefore has poor wear resistance. Therefore, a plate material with increased hardness such as a thrust plate may be combined between the thrust surface 4e and the thrust receiving surface 10a.

  Further, the quenching part on the main shaft part 4 c side is extended to the vicinity of the quenching part of the rotor 6 of the electric motor 3. As a result, the rigidity of the shaft 4 itself can be improved, the swinging of the rotor 6 can be reduced, abnormal contact sliding at each part of the bearing can be reduced, and the operating range can be expanded due to high reliability and high rotation. .

  As described above, in the rotary compressor in which the main bearing 9 and the auxiliary bearing 10 are formed of a cast or sintered product, the shaft 4 is made of a cast material having good hardenability such as spheroidal graphite cast iron, and the main shaft portion 4c. In addition, induction hardening is partially performed on one or both surfaces of the auxiliary shaft portion 4d, and a hardness difference is provided between the shaft 4, the main bearing 9, and the auxiliary bearing 10. Thus, even when the oil level of the oil sump is lowered due to the foaming of the refrigerant after the start-up or the liquid back operation, the rotary compressor can improve the seizure resistance and the wear resistance.

It is a sectional side view of the twin rotary compressor in the present invention. It is a principal part expanded sectional view which shows the relationship between the shaft and the thrust surface of a subbearing in this invention. It is a principal part expanded sectional view which shows the relationship between the thrust surface of the other shaft and sub bearing in this invention. It is a sectional side view of the rotary compressor in a prior art example. It is principal part sectional drawing of the shaft in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airtight container 2A 1st compression part 2B 2nd compression part 3 Electric motor 4 Shaft 4a, 4b Eccentric crank part 5 Stator 6 Rotor part 7 Partition plate 8a 1st cylinder 8b 2nd cylinder 9 Upper bearing 10 Lower bearing 14a 1st Roller 14b Second roller 15a First cylinder chamber 15b Second cylinder chamber T Discharge pipe

Claims (5)

An electric motor and a compression part are disposed in a sealed container, and the compression part includes a cylinder, a shaft having an eccentric crank part, a roller that moves eccentrically, a main bearing that holds the main shaft part of the shaft, and a countershaft part. A rotary compressor in which the main bearing and the sub-bearing are formed of a cast or sintered product.
A material of the shaft is a casting material, and a surface of one or both of the main shaft portion and the sub shaft portion is subjected to a quenching process, and the surface of the shaft and the surface of the main bearing and / or the surface of the sub bearing A rotary compressor characterized by having a hardness difference between them.   2. The rotary compressor according to claim 1, wherein spheroidal graphite cast iron is used for the shaft.   The thrust surface on the auxiliary bearing side of the eccentric crank portion is subjected to quenching treatment simultaneously with the surface of the auxiliary shaft portion of the shaft, and the thrust receiving surface of the auxiliary bearing and the thrust surface on the auxiliary bearing side of the eccentric crank portion The rotary compressor according to claim 1, wherein a hardness difference is provided between the rotary compressor and the rotary compressor.   A thrust bearing for supporting the bottom surface of the shaft is provided at a lower portion of the auxiliary bearing, and the thrust surface of the bottom surface of the shaft is subjected to quenching treatment simultaneously with the surface of the auxiliary shaft portion of the shaft, The rotary compressor according to claim 1, wherein a hardness difference is provided between a thrust surface on a bottom surface of the shaft.   3. The rotary compressor according to claim 1, wherein a quenching portion on the main shaft side is extended to the vicinity of a rotor shrinkage fitting portion of the electric motor.

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