Rotary machine and compressor

A rotary machine includes a rotor, a rotating shaft fixed to the rotor, and a balance weight fixed to the rotor. The balance weight has a balance part fixed to the rotor and not contacting the shaft, a locking part, a shaft abutting part, and a coupling part coupling the balance part and the shaft-abutting part, The locking part is disposed on a side of the shaft opposite from the balance part. The locking part is locked with the shaft to limit movement of the balance part along a direction of centrifugal force. The shaft-abutting part is positioned between the shaft and the balance part, is coupled with the locking part, and contacts the shaft. A length of the locking part along a rotor radial direction is shorter than a rotor radial distance between the shaft and the balance part. The shaft-abutting part is radially shorter than the locking part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. National stage application claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2012-168677, filed in Japan on Jul. 30, 2012, the entire contents of which are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a rotary machine and a compressor.

BACKGROUND ART

Conventionally, motors comprising a rotor, a rotating shaft coupled with the rotor, and a balance weight fixed to an end surface of the rotor have been used as rotary machines for driving compressors used in air conditioners and other apparatuses. The balance weight reduces unbalanced forces acting on the rotating rotor. When the rotor is rotating in such rotary machines, centrifugal forces acting on the balance weight may cause the rotor to deform. The balance weight disclosed in Japanese Laid-open Patent Application No. 2007-205282 is configured to be capable of locking with the rotating shaft in order to minimize deformation of the rotor.

SUMMARY

Technical Problem

However, the balance weight disclosed in Japanese Laid-open Patent Application No. 2007-205282 is configured from a balance part which maximally contributes to the generation of centrifugal force, a locking part for locking the balance weight with the rotating shaft, and a coupling part for coupling the balance part and the locking part. The locking part and the coupling part bring the center of gravity of the entire balance weight close to the axial center of the rotating shaft. Therefore, the mass of the balance part must be increased in order to generate sufficient centrifugal force to reduce unbalanced forces acting on the rotor. This results in an increase in the mass of the entire balance weight, leading to an increase in the size of the rotary machine that comprises the balance weight. When the mass of the entire balance weight is to be reduced, the mass of the locking part must be minimized; therefore, it may not be possible to ensure the locking part is of adequate strength. As a result, the rotor may deform due to the centrifugal force acting on the balance weight.

An object of the present invention is to provide a rotary machine in which a balance weight can be reduced in weight while ensuring the strength thereof, and a compressor comprising this rotary machine.

Solution To Problem

A rotary machine according to a first aspect of the present invention comprises a rotor, a rotating shaft fixed to the rotor, and a balance weight fixed to the rotor. The balance weight has a balance part, a locking part, a shaft-abutting part, and a coupling part. The balance part is fixed to the rotor and positioned so as not to contact the rotating shaft. The locking part is disposed on a side of the rotating shaft that is opposite from the balance part. The locking part is locked with the rotating shaft so as to limit movement of the balance part along a direction of centrifugal force generated by the rotation of the rotor. The shaft-abutting part is positioned between the rotating shaft and the balance part. The shaft-abutting part is coupled with the locking part. The shaft-abutting part comes into contact with the rotating shaft. The coupling part couples the balance part and the shaft-abutting part. The length of the locking part running along a radial direction of the rotor is shorter than the radial distance of the rotor between the rotating shaft and the balance part. The shaft-abutting part running along the radial direction of the rotor is shorter than the locking part running along the radial direction of the rotor.

The rotary machine according to the first aspect comprises a balance weight for reducing unbalanced forces acting on the rotor with which the rotating shaft is coupled. The balance weight is fixed to an end surface of the rotor, and is subjected to centrifugal force caused by rotation of the rotor. In the balance weight, the balance part which maximally contributes to the generation of centrifugal force and the locking part positioned on a side of the rotating shaft that is opposite from the balance part are coupled by the shaft-abutting part and the coupling part. The locking part locks the balance part, which stretches radially outward as centrifugal force is received, with the rotating shaft coupled with the rotor. The locking part thereby achieves the effect of minimizing deformation of the balance part caused by centrifugal force. In this rotary machine, the balance part and the shaft-abutting part are set apart from each other along the radial direction of the rotor, and are coupled with each other by the coupling part. The coupling part occupies part of a space between the balance part and the shaft-abutting part. The shaft-abutting part along the radial direction is shorter than the locking part along the radial direction. The length of the locking part in the radial direction is set so that deformation of the balance part caused by centrifugal force is sufficiently minimized. Therefore, the size of the shaft-abutting part and the coupling part is reduced while the strength of the locking part is ensured, whereby the mass of the entire balance weight can be minimized. Therefore, in the rotary machine according to the first aspect, the balance weight can be reduced in weight while ensuring the strength thereof.

A rotary machine according to a second aspect of the present invention is the rotary machine according to the first aspect of the present invention, wherein the rotor has a through-hole passing through along the axial direction of the rotating shaft. The coupling part couples the balance part and the shaft-abutting part so as not to overlap with the through-hole as viewed from the axial direction of the rotating shaft.

In the rotary machine according to the second aspect, the rotor has a through-hole. The through-hole is, e.g., a flow channel for refrigerant gas in a rotary machine used in a compressor of a refrigeration apparatus. The through-hole is formed along the rotating shaft, and opens onto the end surface of the rotor. The coupling part of the balance weight is positioned so as not to obstruct the opening of the through-hole.

A rotary machine according to a third aspect of the present invention is the rotary machine according to the first aspect of the present invention, wherein the balance part is fixed to the rotor by a fixing member. The coupling part couples the balance part and the shaft-abutting part so that a virtual extension extending from the shaft-abutting part toward the balance part does not overlap with the fixing member as viewed from the axial direction of the rotating shaft.

In the rotary machine according to the third aspect, the balance part is fixed to the end surface of the rotor by a bolt or other fixing member. The fixing member minimizes deformation of the balance part caused by centrifugal force. The coupling part of the balance weight is coupled with the balance part at a location that readily deforms due to centrifugal force, as with a portion between adjacent fixing members. This makes it possible to effectively suppress deformation of the balance weight caused by centrifugal force.

A rotary machine according to a fourth aspect of the present invention is the rotary machine according to any of the first through third aspects of the present invention, wherein the thickness of at least a part of the shaft-abutting part is zero.

In the rotary machine according to the fourth aspect, the shaft-abutting part is configured such as to be partially incomplete along a circumferential direction of the rotary shaft. This reduces the weight of the shaft-abutting part, making it possible to effectively minimize the mass of the balance weight.

A rotary machine according to a fifth aspect of the present invention is the rotary machine according to any of the first through fourth aspects of the present invention, wherein the balance weight is shaped such that there is substantially no distance between the center of gravity of a portion comprising the locking part, the shaft-abutting part, and the coupling part and the axial center of the rotating shaft.

In the rotary machine according to the fifth aspect, the balance weight is shaped such that the center of gravity of a portion excluding the balance part is as close as possible to the axial center of the rotating shaft. This makes it possible to minimize to mass of the balance part, which maximally contributes to the centrifugal force acting on the balance weight, and effectively minimizes the mass of the balance weight.

A rotary machine according to a sixth aspect of the present invention is the rotary machine according to any of the first through fifth aspects of the present invention, wherein the balance part is thicker than the locking part, the shaft-abutting part, and the coupling part.

In the rotary machine according to the sixth aspect, the portion excluding the balance part is made thinner than the balance part, whereby the mass of the portion excluding the balance part is minimized. This makes it possible to effectively minimize the mass of the balance weight.

A compressor according to a seventh aspect of the present invention comprises the rotary machine according to any of the first through sixth aspects of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

In the rotary machine according to the first through sixth aspects of the present invention, the balance weight can be reduced in weight while ensuring the strength thereof.

In the rotary machine according to the third aspect of the present invention, deformation of the balance weight caused by centrifugal force can be effectively suppressed.

In the rotary machine according to the fourth through sixth aspects of the present invention, the mass of the balance weight can be effectively minimized.

The compressor according to the seventh aspect of the present invention can be reduced in weight.

DESCRIPTION OF EMBODIMENTS

A compressor according to a first embodiment of the present invention will be described with reference to the annexed drawings. The compressor according to the present embodiment is a high-low pressure domed scroll compressor. A scroll compressor changes the volume of a space formed by two scroll members that mesh with each other, whereby the compressor compresses a refrigerant circulating in a refrigeration apparatus.

(1) Configuration of Compressor

FIG. 1is a vertical cross-sectional view of a scroll compressor101according to the present embodiment. The scroll compressor101is primarily configured from a casing10, a compression mechanism15, a housing23, a drive motor16, a crankshaft17, a lower bearing60, an intake pipe19, and a discharge pipe20.

The casing10is configured from a substantially cylindrical barrel casing part11, a bowl-shaped upper wall part12hermetically welded to an upper end part of the barrel casing part11, and a bowl-shaped bottom wall part13hermetically welded to a lower end part of the barrel casing part11. The casing10is disposed such that an axial direction of the substantially cylindrical shape of the barrel casing part11runs vertically.

Within the casing10is accommodated the compression mechanism15, the housing23disposed below the compression mechanism15, the drive motor16disposed below the housing23, the crankshaft17disposed so as to extend vertically, and other such parts. The intake pipe19and the discharge pipe20are hermetically welded to a wall part of the casing10. An oil reservoir space10ain which a lubricant accumulates is formed in the bottom part of the casing10. The lubricant is used during movement of the scroll compressor101in order to maintain proper lubrication of sliding parts in the compression mechanism15.

The compression mechanism15draws in low-temperature, low-pressure refrigerant gas, compresses the gas, and then discharges high-temperature, high-pressure refrigerant gas (referred to as “compressed refrigerant” below). The compression mechanism15is primarily configured from a fixed scroll component24and a movable scroll component26.

The fixed scroll24has a first mirror plate24a, and an involutely shaped first lap24bformed upright on the first mirror plate24a. Within the fixed scroll24is formed a main intake hole (not shown), and an auxiliary intake hole (not shown) adjacent to the main intake hole. The main intake hole interconnects the intake pipe19and a compression chamber40described below. The auxiliary intake hole interconnects a low-pressure space S2(described below) and the compression chamber40. A discharge hole41is formed in a central part of the first mirror plate24a. The discharge hole41interconnects a recessed space in an upper surface of the first mirror plate24awith a muffler space45covered by a lid body44. The muffler space45communicates with a first compressed refrigerant flow channel46which opens onto an outer peripheral part of a lower surface of the fixed scroll24.

The movable scroll26has a second mirror plate26a, and an involutely shaped second lap26bformed upright on the second mirror plate26a. An upper end bearing26cis formed in a central part of a lower surface of the second mirror plate26a. An oil supply hole63is formed in the second mirror plate26a. The oil supply hole63interconnects an outer peripheral part of an upper surface of the second mirror plate26aand a space inside the upper end bearing26c.

The first lap24band the second lap26bof the fixed scroll24and the movable scroll26mesh respectively with each other, whereby the compression chamber40configured in a space enclosed by the first mirror plate24a, the first lap24b, the second mirror plate26a, and the second lap26bis formed. The volume of the compression chamber40varies due to the revolving motion of the movable scroll26.

An outer side surface of the housing23is hermetically joined to an inner surface of the casing10, thereby partitioning a space inside the casing10into a high-pressure space S1below the housing23and a low-pressure space S2above the housing23. The fixed scroll24is mounted on the housing23, and the housing23and fixed scroll24are disposed on either side of the movable scroll26with an Oldham's coupling39interposed therebetween. The Oldham's coupling39is an annular member for preventing the movable scroll26from rotating in association. A second compressed refrigerant flow channel48is formed vertically through an outer peripheral part of the housing23. The second compressed refrigerant flow channel48communicates with the first compressed refrigerant flow channel46in the upper surface of the housing23, and with the high-pressure space S1in the lower surface of the housing23.

A crank chamber S3is recessed in a center part of the upper surface of the housing23. A housing through-hole31is also formed in the housing23. The housing through-hole31passes vertically through the housing23from a center part of the bottom surface of the crank chamber S3to a center part of the lower surface of the housing23. The portion of the housing23in which the housing through-hole31is formed is referred to below as an upper bearing32.

(1-4) Drive Motor

The drive motor16is a brushless DC motor disposed below the housing23. The drive motor16is primarily configured from a stator51fixed to the inner surface of the casing10, and a rotor52accommodated inside the stator51, an air gap being provided therein to allow rotation.

The stator51has a coil part (not shown) formed from a wound conductive wire, and a coil end53formed above and below the coil part. A plurality of notched core cut parts (not shown) are provided in an outside surface of the stator from the upper end surface thereof to the lower end surface thereof and at prescribed intervals along the circumferential direction. The core cut parts form a motor cooling passage55extending vertically between the barrel casing part11and the stator51.

The rotor52is configured from a plurality of metal plates52dlayered vertically. The plurality of metal plates52dare jointly fastened by rivets52eand are integrally formed. The rotor52has a through-hole52cpassing vertically therethrough from the upper end surface52ato the lower end surface52b. The rotor52is interconnected with the crankshaft17, which passes vertically through the rotational center of the rotor52. The rotor52is connected with the compression mechanism15, with the crankshaft17interposed therebetween. A balance weight53is also attached to the lower end surface52bof the rotor52. The configuration of the balance weight53will be described in detail hereafter.

The crankshaft17is disposed so that the axial direction thereof runs vertically. The crankshaft17is shaped such that the axial center of an upper end part thereof is slightly eccentric in relation to the axial center of a portion excluding the upper end part. The crankshaft17has an eccentric weight18. The eccentric weight18is securely attached to the crankshaft17at a position below the housing23and above the drive motor16.

The crankshaft17is also interconnected with the rotor52vertically through the rotational center of the rotor52. The upper end part of the crankshaft17is inserted into the upper end bearing26cof the movable scroll26. The crankshaft17is supported by the upper part bearing32and the lower bearing60.

The crankshaft17also has therein a primary oil supply channel61funned so as to run along the axial direction of the crankshaft17. The upper end of the primary oil supply channel61communicates with an oil chamber83funned by the upper end surface of the crankshaft17and the lower surface of the second mirror plate26a. The oil chamber83communicates with a thrust bearing surface24c, which is a surface on which the first mirror plate24aand the second mirror plate26amake sliding contact with each other on an outer peripheral portion, with the oil supply hole63of the second mirror plate26ainterposed therebetween. The lower end of the primary oil supply channel61communicates with the oil reservoir space10ain the bottom part of the casing10.

(1-6) Lower Bearing

The lower bearing60is disposed below the drive motor16. An outside surface of the lower bearing60is hermetically joined to part of the inner surface of the casing10. The lower bearing60rotatably supports the crankshaft17. An oil separating plate73is attached to an upper surface of the lower bearing.

The intake pipe19is a pipe for guiding refrigerant from outside the casing10to the compression mechanism15. The intake pipe19is hermetically joined to the upper wall part12of the casing10. The intake pipe19passes vertically through the low-pressure space S2. An end part of the intake pipe19that is inside the casing10is inserted into the fixed scroll24.

The discharge pipe20is a pipe for discharging compressed refrigerant from the high-pressure space S1out of the casing10. The discharge pipe20is hermetically joined to the barrel casing part11of the casing10. An end part of the discharge pipe20that is inside the casing10is positioned in the high-pressure space S1at a position below the housing23and above the drive motor16.

(2) Operation of Compressor

First, the flow of the refrigerant inside the scroll compressor101will be described. Then, the flow of lubricating oil inside the scroll compressor101will be described.

(2-1) Flow of Refrigerant

First, the rotor52begins to rotate due to the start-up of the drive motor16, and the crankshaft17fixed to the rotor52begins an axial rotational movement. The axial rotation of the crankshaft17is transmitted to the movable scroll26of the compression mechanism15via the upper surface bearing26c. The movable scroll26revolves around the fixed scroll24, but, due to the Oldham's coupling39, does not rotate.

Uncompressed, low-temperature, low-pressure refrigerant is drawn into the compression chamber40of the compression mechanism15either from the intake pipe19via a primary intake hole or from the low-pressure space S2via an auxiliary intake hole. Due to the revolution of the movable scroll26, the compression chamber40moves from the outer peripheral part of the fixed scroll24toward the center part thereof while the volume of the compression chamber40is gradually reduced. As a result, the refrigerant in the compression chamber40is compressed and becomes compressed refrigerant. The compressed refrigerant is discharged from the discharge hole41to the muffler space45, and is supplied to the high-pressure space S1via the first compressed refrigerant flow channel46and the second compressed refrigerant flow channel48. The compressed refrigerant then flows down the motor cooling passage55and reaches the high-pressure space S1below the drive motor16. The direction of flow of the compressed refrigerant is then reversed, and the compressed refrigerant travels upward through the other motor cooling passage55, the through-hole52cof the rotor52, and the air gap of the drive motor16. The compressed refrigerant is then discharged from the discharge pipe20out of the scroll compressor101.

(2-2) Flow of Lubricating Oil

When the compression mechanism15is started up by the axial rotational movement of the crankshaft17and the compressed refrigerant is initially supplied to the high-pressure space S1, the pressure in the high-pressure space S1, which includes the oil reservoir space10a, rises. The pressure in the compression chamber40of the compression mechanism15is brought below the pressure in the high-pressure space S1, the compression chamber40being communicated with the oil chamber83with the thrust bearing surface24cand the oil supply hole63interposed therebetween. Therefore, a pressure differential occurs in the oil reservoir space10aand the primary oil supply channel61of the crankshaft17communicated with the oil chamber83. The lubricating oil in the high-pressure-side oil reservoir space10athereby travels upward through the primary oil supply channel61toward the low-pressure-side oil chamber83.

Some of the lubricating oil traveling upward through the primary oil supply channel61is supplied, via a secondary oil supply channel horizontally diverging from the primary oil supply channel61to each of a sliding-contact surface between the crankshaft17and the lower bearing60, a sliding-contact surface between the crankshaft17and the upper bearing32of the housing23, and a sliding-contact surface between the crankshaft17and the upper end bearing26cof the movable scroll26, and is returned to the oil reservoir space10a. Lubricating oil that has traveled upward through the primary oil supply channel61and reached the oil chamber83is supplied to the thrust bearing surface24cof the compression mechanism15via the oil supply hole63, and flows into the compression chamber40. At this time, the high-temperature lubricating oil heats the uncompressed, low-temperature refrigerant present in the compression chamber40, and is mixed into the refrigerant as minute droplets. The lubricating oil mixed into the compressed refrigerant in the compression chamber40is supplied to the high-pressure space S1through the same passage as is the compressed refrigerant. The lubricating oil then flows down the motor cooling passage55together with the compressed refrigerant and strikes the oil separating plate73. The lubricating oil that adheres to the oil separating plate73travels downward toward the oil reservoir space10a.

(3) Configuration of Balance Weight

The configuration of the balance weight53will now be described in detail. FIG,2is a bottom view of the lower end surface52bof the rotor52as viewed from below along the vertical direction. For descriptive purposes,FIG. 2shows a horizontal cross-section of the crankshaft17at the height position of the lower end surface52bof the rotor52.FIG. 3is a perspective view of the balance weight53attached to the lower end surface52bof the rotor52. InFIG. 3, the crankshaft17is not redundantly shown. In the present embodiment, the rotor52has six rivets52eand six through-holes52c. The six rivets52eare disposed at positions in the outer peripheral part of the rotor52that have six-fold symmetry about the axial center of the crankshaft17. The six through-holes52care disposed in portions outward along the radial direction from the crankshaft17and inward along the radial direction from the balance weight53, the through-holes being positioned so as to have six-fold symmetry about the axial center of the crankshaft17. Here, “radial direction” refers to the radial direction of the rotor52. When the rotor52is viewed along the crankshaft17, “outward along the radial direction” refers to the outer-peripheral side of the end surface of the rotor52, and “inward along the radial direction” refers to the central side of the end surface of the rotor52.

Below, a member configured from the crankshaft17and the rotor52is referred to as a rotating body90. The balance weight53of the rotor52and the eccentric weight18of the crankshaft17are weights for counteracting unbalanced forces generated by the rotation of the rotating body90. The balance weight53is configured from a balance part53a, a locking part53b, a shaft-abutting part53c, and two coupling parts53d.

(3-1) Balance Part

As shown inFIG. 2, the balance part53ais C-shaped and is directly fixed by three rivets52eto the lower end surface52bof the rotor52at positions where no contact is made with the crankshaft17. Specifically, from among the six rivets52eintegrating the metal plates52dconstituting the rotor52, three rivets52ejointly fasten the metal plates52dand the balance part53a.

In the present embodiment, the balance weight53is configured such that the center of gravity of a portion comprising the locking part53b, the shaft-abutting part53c, and the coupling parts53dis as close as possible to the axial center of the rotating shaft17. Accordingly, the contribution made by the centrifugal force acting on the balance weight53due to the rotation of the rotating body90is greatest where the centrifugal force acts on the balance part53a.

(3-2) Locking Part

When the balance weight53is viewed along the crankshaft17, the locking part53bis positioned on a side of the crankshaft17opposite the balance part53a. The locking part53blocks the balance weight53with the rotating shaft17so as to prevent the balance part53afrom moving radially outward due to centrifugal force caused by the rotation of the rotating body90. The locking part53bis C-shaped, as shown inFIG. 2. The side surface of the locking part53bon the inward side in the radial direction is in contact with the outer peripheral surface of the crankshaft17. The length t1of the locking part53brunning along the radial direction is shorter than the radial distance t0between the rotating shaft17and the balance part53a. Specifically, the locking part53bis sized to prevent the locking part53bmaking contact with the balance part53a. The locking part53bis thinner than the balance part53a.

When the balance weight53is viewed along the crankshaft17, the shaft-abutting part53cis positioned between the crankshaft17and the balance part53a. The shaft-abutting part53cis coupled with the locking part53b. The side surface of the shaft-abutting part53con the inward side in the radial direction is in contact with the outer peripheral surface of the crankshaft17. As shown inFIG. 2, the length t2of the shaft-abutting part53crunning along the radial direction is shorter than the length t1of the locking part53brunning along the radial direction. The shaft-abutting part53cis of the same thickness as the locking part53b, and is thinner than the balance part53a.

(3-4) Coupling Parts

The two coupling parts53dcouple the balance part53aand the shaft-abutting part53capproximately along the radial direction, When the balance weight53is viewed along the crankshaft17, the coupling parts53dcouple the balance part53aand the shaft-abutting part53con a portion between two through-holes52cthat are adjacent to each other. Specifically, the coupling parts53dare positioned so as not to obstruct the through-holes52copening in the lower end surface52bof the rotor52

In the present embodiment, as shown inFIG. 2, two of the six through-holes52care positioned radially outward from each of the boundaries of the locking part53band the shaft-abutting part53c. Each of the six rivets52eis positioned radially outward from the midpoints of two through-holes52cthat are adjacent to each other. The two coupling parts53dcouple the balance part53aand the shaft-abutting part53cbetween a through-hole52cpositioned radially outward from the boundaries of the locking part53band the shaft-abutting part53cand a through-hole52cadjacent to the first through-hole52con the balance part53a-side thereof. The coupling parts53dare of the same thickness as the locking part53band the shaft-abutting part53c, and are thinner than the balance part53a.

(4) Features of Compressor

In the present embodiment, the drive motor16comprises a balance weight53for reducing unbalanced forces caused by rotation of the rotating body90. The centrifugal force acting on the balance weight53due to rotation of the rotor52, together with the centrifugal force acting on the eccentric weight18of the crankshaft17, act as unbalanced forces counteracting the unbalanced forces of the rotating body90. Any unbalanced force remaining in the rotating body90during rotation will cause the rotating body90to vibrate when rotating, thus producing noise in the drive motor16. Specifically, the unbalanced forces in the rotating body90are reduced by the balance weight53and the eccentric weight18, and noise in the drive motor16is minimized.

In the present embodiment, when the balance weight53is viewed along the crankshaft17, the shaft-abutting part53cand the coupling parts53dcoupling the balance part53aand the locking part53boccupy part of a portion between the balance part53aand the crankshaft17, as shown inFIG. 2. The locking part53b, the shaft-abutting part53c, and the coupling parts53dare thinner than the balance part53a. Therefore, the balance part53ais shaped such that the mass of a portion excluding the balance part53ais minimized. Because the mass of the entire balance weight53is thereby minimized, the drive motor16can be reduced in weight. Therefore, the scroll compressor101can be reduced in weight.

In the present embodiment, there is substantially no distance between the center of gravity of a portion comprising the locking part53b, the shaft-abutting part53c, and the coupling parts53dand the axial center of the crankshaft17. Therefore, the centrifugal force acting on the balance part53ais not reduced by the centrifugal force acting on the portion excluding the balance part53ato the same extent as when the center of gravity of the portion excluding the balance part53ais positioned opposite the balance part53aacross the axial center of the crankshaft17. Therefore, the mass of the balance part53a, which maximally contributes to the centrifugal force acting on the balance weight53, can be minimized. Because the mass of the entire balance weight53is thereby minimized, the drive motor16can be reduced in weight. Additionally, because the size of the balance weight53is minimized, the drive motor16can be made compact.

In the present embodiment, as shown inFIG. 2, the length t2of the shaft-abutting part53crunning along the radial direction is shorter than the length t1of the locking part53brunning along the radial direction. Therefore, the locking part53bcan be given the minimum strength necessary for locking the balance weight53, and the shaft-abutting part53ccan be given the minimum strength necessary for molding and machining. Because the mass of the entire balance weight53is thereby minimized, the drive motor16can be reduced in weight.

In the present embodiment, the coupling parts53dof the balance weight53couple the balance part53aand the shaft-abutting part53cso as not to obstruct the through-holes52copening onto the lower end surface52bof the rotor52. This makes it possible for the compressed refrigerant in the high-pressure space S1to travel upward and pass through the through-holes52cin the rotor52after flowing down the motor cooling passage55without being inhibited by the coupling parts53d.Therefore, the rotor52is effectively cooled by the compressed refrigerant passing through the through-holes52c. Additionally, because the cross-sectional area of the flow channel of the compressed refrigerant is ensured by the through-holes52c, the flow velocity of the compressed refrigerant traveling upward through the high-pressure space S1inside the casing10can be suppressed. Therefore, the lubricating oil mixed into the compressed refrigerant can be prevented from being discharged together with the compressed refrigerant out of the scroll compressor101via the discharge pipe20. Because oil loss is reduced, the reliability of he scroll compressor101is thereby enhanced.

A scroll compressor according to a second embodiment of the present invention will now be described. Because the basic configuration, operation, and features of the present embodiment are the same as those of the scroll compressor according to the first embodiment, the points of difference from the first embodiment will mainly be described. Elements having the same structure and function as in the first embodiment are given the same symbols.

(1) Configuration of Balance Weight

FIG. 4is a bottom view of a rotor152to which a balance weight153of the present embodiment is attached. The balance weight153is attached to a lower end surface152bof the rotor152. The balance weight153is configured from a balance part153a, a locking part153b, a shaft-abutting part153c, and two coupling parts153d. The rotor152has six rivets152e, similarly to the first embodiment. The rotor152does not have through-holes corresponding to the through-holes52cof the rotor52in the first embodiment.

In the present embodiment, when the balance weight153is viewed along a crankshaft17, the two coupling parts153dcouple the balance part153aand the shaft-abutting part153cso that a virtual extension153d1extending the coupling parts153dfrom the shaft-abutting part153ctoward the balance part153adoes not overlap with the rivets152e.

(2) Features of Compressor

In the present embodiment, the coupling parts153dare coupled with the balance part153aon a portion between two rivets152ethat are adjacent to each other. The portion between two rivets152ethat are adjacent to each other is a location at which the balance part153areadily deforms due to centrifugal force caused by the rotation of a rotating body90. Therefore, the coupling parts153dcouple with a portion at which the balance part153areadily deforms, whereby the strength of the balance part153acan be increased and deformation of the balance weight153caused by centrifugal force can be effectively suppressed.

A scroll compressor according to a third embodiment of the present invention will now be described. Because the basic configuration, operation, and features of the present embodiment are the same as those of the scroll compressor according to the first embodiment, the points of difference from the first embodiment will mainly be described. Elements having the same structure and function as in the first embodiment are given the same symbols.

(1) Configuration of Balance Weight

FIG. 5is a bottom view of a rotor52to a balance weight253of the present embodiment is attached. The balance weight253is configured from a balance part253a, a locking part253b, a shaft-abutting part253c, and two coupling parts253d. The shaft-abutting part253chas a portion having a thickness of zero. Specifically, the shaft-abutting part253cdiffers from the shaft-abutting part53cof the first embodiment in being configured such that the shaft-abutting part253cis partially incomplete along a circumferential direction of the crankshaft17. Therefore, as shown inFIG. 5, the shaft-abutting part253cis configured from two portions coupled with two circumferential end parts of the locking part253b, respectively.

(2) Features of Compressor

In the present embodiment, because the shaft-abutting part253cis configured such as to be partially incomplete along the circumferential direction of the crankshaft17, the shaft-abutting part253cweighs less than the shaft-abutting parts of the first and second embodiments. Therefore, the mass of the balance weight253can be effectively minimized.

The basic configuration of the first through third embodiments of the present invention can be modified without departing from the main point of the present invention. Modifications applicable to the embodiments of the present invention are described below.

(1) Modification A

FIG. 6is a bottom view of a rotor52to which a balance weight353according to a first modification of the balance weight53of the first embodiment is attached. The balance weight353is configured from a balance part353a, a locking part353b, a shaft-abutting part353c, and one coupling part353d.

In the present modification, the number and position of the coupling part353dof the balance weight353differ from those of the coupling parts53dof the balance weight53of the first embodiment. As shown inFIG. 6, the one coupling part353dcouples a circumferential center part of the balance part353aand a circumferential center part of the shaft-abutting part353cbetween two through-holes52cthat are adjacent to each other.

(2) Modification B

FIG. 7is a bottom view of a rotor52to which a balance weight453according to a second modification of the balance weight53of the first embodiment is attached. The balance weight453is configured from a balance part453a, a locking part453b, a shaft-abutting part453c, and three coupling parts453d.

In the present modification, the number and position of the coupling parts453dof the balance weight453differ from those of the coupling parts53dof the balance weight53of the first embodiment. As shown inFIG. 7, the three coupling parts453dcouple the balance part453aand the shaft-abutting part453cfrom between two through-holes52cthat are adjacent to each other. Specifically, the balance weight453has the two coupling parts53dof the balance weight53of the first embodiment, and the one coupling part353dof the balance weight353of modification A.

(3) Modification C

FIG. 8is a bottom view of a rotor552to which a balance weight553according to a third modification of the balance weight53of the first embodiment is attached. The balance weight553is attached to a lower end surface552bof the rotor552. The balance weight553is configured from a balance part553a, a locking part553b, a shaft-abutting part553c, and two coupling parts553d.The rotor552has four rivets552eand four through-holes552c. The four rivets552eand the four through-holes552care disposed at positions so as to have four-fold symmetry about the axial center of the crankshaft17.

In the present modification, as shown inFIG. 8, two of the four through-holes552care positioned radially outward from each of the boundaries of the locking part553band the shaft-abutting part553c. Each of the four rivets552eis positioned radially outward from the midpoints of two through-holes552cthat are adjacent to each other. The two coupling parts553dcouple the balance part553aand the shaft-abutting part553cbetween a through-hole552cpositioned radially outward from the boundaries of the locking part553band the shaft-abutting part553cand a through-hole552cadjacent to the first through-hole552con the balance part553a-side thereof.

(4) Modification D

FIG. 9is a bottom view of a rotor652to which a balance weight653according to a first modification of the balance weight153of the second embodiment is attached. The balance weight653is attached to a lower end surface652bof the rotor652. The balance weight653is configured from a balance part653a, a locking part653b, a shaft-abutting part653c, and three coupling parts653d. The rotor652has four rivets652e. The four rivets652eare disposed in the same positions as are the four rivets552eof modification C.

In the present modification, as shown inFIG. 9, when the balance weight653is viewed along the crankshaft17, the three coupling parts653dcouple the balance part653aand the shaft-abutting part653cso that a virtual extension653d1extending the coupling parts653dfrom the shaft-abutting part653ctoward the balance part653adoes not overlap with the rivets652e.

(5) Modification E

FIG. 10is a bottom view of a rotor152to which a balance weight753according to a second modification of the balance weight153of the second embodiment is attached. The balance weight653is configured from a balance part753a, a locking part753b, a shaft-abutting part753c, and two coupling parts753d. The shaft-abutting part753chas a portion having a thickness of zero. Specifically, the shaft-abutting part753cis similar to the shaft-abutting part253cof the third embodiment in that the shaft-abutting part253cis configured such as to be partially incomplete along a circumferential direction of the crankshaft17. Therefore, as shown inFIG. 10, the shaft-abutting part753cis configured from two portions coupled with two circumferential end parts of the locking part753b, respectively.

In the present embodiment, because the shaft-abutting part753cis configured such as to be partially incomplete along the circumferential direction of the crankshaft17, the shaft-abutting part753cweighs less than the shaft-abutting parts of the first and second embodiments. Therefore, the mass of the balance weight753can be effectively minimized.

(6) Modification F

In the first embodiment, the balance weight53is attached to the lower end surface52bof the rotor52; however, the balance weight53may be attached to the upper end surface52aof the rotor52, or may be attached to both the upper end surface52aand the lower end surface52bof the rotor52. The present modification can also he applied to the second embodiment, the third embodiment, and the previous modifications.

(7) Modification G

In the first through third embodiments, a scroll compressor101comprising a compression mechanism15configured from a fixed scroll component24and a movable scroll component26is used as a compressor; however, a compressor comprising another type of compression mechanism may be used. For example, a rotary-type compressor and/or a reciprocating compressor may be used. In the present modification as well, the balance weight of the first through third embodiments and the previous modifications is attached to an end surface of a rotor of a drive motor used in the compressor.

INDUSTRIAL APPLICABILITY

In the rotary machine according to the present invention, a balance weight can be reduced in weight while ensuring the strength thereof.