Patent Description:
A rotary compressor applied to a refrigeration cycle such as an air conditioner previously has been known. In such a rotary compressor, a rotating shaft, a bearing for supporting the rotating shaft, a piston rotor eccentrically mounted on the rotating shaft, and a cylinder in which a piston rotor is disposed are mainly provided in a casing. In the rotary compressors, a fluid (refrigerant), which has flowed into the cylinder, is compressed by the rotation of the piston rotor.

In recent years, the demand for high efficiency has increased in the rotary compressor. For this reason, attempts have been made to reduce the size of a piston in order to increase the displacement of the piston. However, in this case, there is a problem in that a load acting on the piston increases and deflection easily occurs in the rotating shaft.

For example, in Patent Document <NUM> the deflection of a rotating shaft is suppressed using a technique, such as making the span between a main shaft part and a sub-shaft part of the rotating shaft. However, the technique of suppressing the deflection of a rotating shaft by optimizing the sectional shape of the rotating shaft is also considered.

The invention provides a rotating shaft of a rotary compressor and a rotary compressor capable of suppressing deflection of the rotating shaft to increase efficiency.

A rotating shaft of a rotary compressor according to an aspect of the invention is defined in claim <NUM>.

According to such the rotating shaft of a rotary compressor, each apex of the intermediate shaft part is disposed at a position shifted at an angle larger than <NUM> degrees and smaller than <NUM> degrees toward a backward side in a rotational direction with respect to an imaginary line passing through the axis orthogonally to the eccentric direction. That is, the apex is not disposed on the imaginary line passing through the axis orthogonally to the eccentric direction, and the diameter of the intermediate shaft part is maximized at the position shifted toward the backward side in the rotational direction with respect to the imaginary line. Therefore, the second moment of area of the intermediate shaft part can be increased at this position where the apex is provided, and the rigidity of the intermediate shaft part can be improved.

Here, the knowledge that the maximum load during compression acts in a range larger than <NUM> degrees and smaller than <NUM> degrees on the backward side in the rotational direction from the imaginary line with respect to the intermediate shaft part was obtained. In the present aspect, each apex is disposed at the position shifted at an angle larger than <NUM> degrees and smaller than <NUM> degrees toward the backward side in the rotational direction with respect to the imaginary line, and the rigidity is high at this position. Thus, even if the thickness of the intermediate shaft part on the forward side in the rotational direction from the apex is smaller than that of a columnar shape, the strength can be sufficiently secured. Therefore, it is possible to secure the strength while reducing the weight of the intermediate shaft part. Therefore, even when the load during compression from each piston rotor acts on the rotating shaft, it is possible to suppress deflection deformation of the rotating shaft.

Additionally, in the rotating shaft of the rotary compressor, the outer peripheral surface of the intermediate shaft part may be disposed within one region where an outer peripheral edge of the main shaft piston rotor and an outer peripheral edge of the sub-shaft piston rotor overlap each other as viewed in the cross section orthogonal to the axis.

According to such a configuration, each apex is formed such that the outer peripheral surface of the intermediate shaft part is cut off on the forward side in the rotational direction of the apex. Hence, when the rotating shaft rotates, the lubricating oil around the intermediate shaft part is smoothly guided toward the apex of the intermediate shaft part, and smoothly flows along the outer peripheral surface of the intermediate shaft part toward the backward side in the rotational direction. Therefore, the stirring loss of the lubricating oil can be reduced.

According to a further aspect of the invention set out in claim <NUM>, in the rotating shaft of the rotary compressor, each apex may be disposed at a position shifted at an angle larger than <NUM> degrees and smaller than <NUM> degrees toward the backward side in the rotational direction with respect to the imaginary line.

According to such a configuration, each apex is formed such that the outer peripheral surface of the intermediate shaft part is cut off on the forward side in the rotational direction of the apex. However, even in this case, the diameter of the intermediate shaft part does not extremely decrease on the forward side in the rotational direction of the apex, and the strength of the intermediate shaft part can be sufficiently secured.

Additionally, in the rotating shaft of the rotary compressor, the outer peripheral surface of the intermediate shaft part may have an apex-side curved surface that is disposed inside an outer edge of the one region and extends to be curved in a convex shape in a direction away from the axis from the apex toward a forward side in the rotational direction, and an eccentric-side curved surface that is smoothly continuous with the apex-side curved surface and is provided at a position including an intersection point between the imaginary line extending in the eccentric direction and the outer edge of the one region to extend along the outer edge of the one region.

By providing the apex-side curved surface and the eccentric-side curved surface as the outer peripheral surface of the intermediate shaft part, a smooth curved surface in more forward side than the apex on the rotation direction is formed toward the outer peripheral surface of the intermediate shaft part. Therefore, when the lubricating oil is stirred by the rotating shaft, the lubricating oil is from the eccentric-side curved surface toward the apex-side curved surface by these surfaces and flows smoothly. Therefore, even in the intermediate shaft part having the apex, the stirring loss of the lubricating oil can be reduced.

In this way, by providing the apexes at the symmetrical positions, the lubricating oil can be smoothly guided while securing the strength of the intermediate shaft part, and the stirring loss of the lubricating oil during the rotation of the rotating shaft can be further reduced. Moreover, during rotation, centrifugal forces acting on the positions of the apexes of the intermediate shaft part can be canceled between the apexes, and the stability during the rotation of the rotating shaft can be improved.

According to a further aspect of the invention set out in claim <NUM>, in the rotating shaft of the rotary compressor, the pair of apexes may be different from each other in shift amount of an angle toward the backward side in the rotational direction with respect to a direction orthogonal to the eccentric direction.

Even in such a case, the lubricating oil can be smoothly guided while securing the strength of the intermediate shaft part, and the stirring loss of the lubricating oil during the rotation of the rotating shaft can be reduced.

Additionally, a rotary compressor according to one aspect of the invention includes the rotating shaft according to any of the above aspects, a drive unit that is configured to rotationally drive the rotating shaft, and a casing that accommodates the rotating shaft and the drive unit and has a first compression chamber and a second compression chamber therein.

According to such a rotary compressor, by including the above rotating shaft, when the rotating shaft rotates, the lubricating oil around the intermediate shaft part can be smoothly guided toward each apex of the intermediate shaft part, can smoothly flow along the outer peripheral surface of the intermediate shaft part toward the backward side in the rotational direction, and the stirring loss of the lubricating oil can be reduced. It is possible to increase the second moment of area of the intermediate shaft part compared to a case where no apex is provided, and it is possible to suppress the deflection deformation of the rotating shaft.

According to the rotating shaft of the rotary compressor, and the rotary compressor, by virtue of the above configuration, it is possible to suppress the deflection of the rotating shaft to increase efficiency.

Hereinafter, a rotary compressor <NUM> according to an embodiment of the invention will be described.

As shown in <FIG>, the rotary compressor <NUM> includes a drive unit <NUM>, a rotating shaft <NUM> rotationally driven by the drive unit <NUM>, and a casing <NUM> that accommodates the drive unit <NUM> and the rotating shaft <NUM>. The rotary compressor <NUM> is a so-called two-cylinder type rotary compressor <NUM> in which compression chambers S are provided in two upper and lower stages at an inner lower part of the casing <NUM>.

The casing <NUM> has a cylindrical shape centered on an axis O, and two disk-shaped cylinders 12A and 12B are provided at a distance in an upward-and-downward direction at an inner lower part of the casing <NUM>. An upper cylinder is referred to a main-shaft-side cylinder 12A, and a lower cylinder is referred to as a sub-shaft-side cylinder 12B.

Cylindrical cylinder inner wall surfaces 12S1 and 12S2 are formed inside the cylinders 12A and 12B, respectively. The first compression chamber S1 is defined by the cylinder inner wall surface 12S1 of the main-shaft-side cylinder 12A, and the second compression chamber S2 is defined by the cylinder inner wall surface 12S2 of the sub-shaft-side cylinder 12B. A disk-shaped partition plate <NUM> is provided between the upper and lower cylinders 12A and 12B. The first compression chamber S1 and the second compression chamber S2 are partitioned by the partition plate <NUM>.

Openings 22A and 22B are formed at the positions of a side surface, i.e., an outer peripheral surface of the casing <NUM>, which face outer peripheral surfaces of the main-shaft-side cylinder 12A and the sub-shaft-side cylinder 12B. Suction ports 23A and 23B communicating with the first compression chamber S1 and the second compression chamber S2 are respectively formed at the positions of the cylinders 12A and 12B facing the openings 22A and 22B.

An accumulator <NUM>, which performs gas-liquid separation of the refrigerant taken in from the upper suction inlet 24a before the refrigerant (fluid) is introduced into the casing <NUM>, is fixed to the casing <NUM> via a stay <NUM>. The accumulator <NUM> is provided with suction pipes 26A and 26B for introducing a gaseous phase of the refrigerant separated into gas and liquid in the accumulator <NUM> into the first compression chamber S1 and the second compression chamber S2 in the casing <NUM>. Distal end parts of the suction pipes 26A and 26B are connected to the suction ports 23A and 23B through the openings 22A and 22B.

Additionally, an upper part of the casing <NUM> is provided with discharge port <NUM> through which the refrigerant compressed in the first compression chamber S1 and the second compression chamber S2 is discharged.

The drive unit <NUM> is an electric motor and has a stator <NUM> fixed to an inner surface of the casing <NUM> above the main-shaft-side cylinder 12A, and a rotor <NUM> disposed so as to face the stator <NUM> inside the stator <NUM>.

As shown in <FIG>, the rotating shaft <NUM> includes a shaft main body <NUM> having a rod shape that extends in the direction of the axis O around the axis O, a main shaft piston rotor 14A and a sub-shaft piston rotor 14B that are provided in the shaft main body <NUM>, and an intermediate shaft part <NUM> that is disposed at the position sandwiched between the main shaft piston rotor 14A and the sub-shaft piston rotor 14B in the direction of the axis O.

The shaft main body <NUM> is provided so as to be fitted into the rotor <NUM> of the drive unit <NUM> and is rotated around the axis O together with the rotor <NUM> by supplying electric power to the drive unit <NUM>. The shaft main body <NUM> is rotatably supported on the casing <NUM> by an upper bearing 17A provided at an upper part of the main-shaft-side cylinder 12A, and a lower bearing 17B provided at a lower part of the sub-shaft-side cylinder 12B.

The main shaft piston rotor 14A is provided in the shaft main body <NUM>, is accommodated in the first compression chamber S1, and is rotated around the axis O together with the shaft main body <NUM>. The main shaft piston rotor 14A is formed integrally with the shaft main body <NUM>, is externally fitted to a main-shaft-side shaft part 13A having a columnar shape centered on an eccentric axis O1 parallel to the axis O, and has an annular shape. Accordingly, the main shaft piston rotor 14A rotates eccentrically with respect to the shaft main body <NUM> if the shaft main body <NUM> rotates.

The sub-shaft piston rotor 14B is provided in the shaft main body <NUM>, is accommodated in the second compression chamber S2, and is rotated around the axis O together with the shaft main body <NUM>. The sub-shaft piston rotor 14B is formed integrally with the shaft main body <NUM>, is externally fitted to a sub-shaft-side eccentric shaft part 13B having a columnar shape centered on an eccentric axis O2 parallel to the axis O and the eccentric axis O1, and has an annular shape. The eccentric axis O2 is disposed at a position symmetrical to the eccentric axis O1 with respect to the axis O.

That is, the main shaft piston rotor 14A and the sub-shaft piston rotor 14B are rotated in a state where <NUM> degrees phases are eccentric in different directions with respect to the shaft main body <NUM>.

Here, the rotating shaft <NUM> may be formed such that a main shaft portion provided with the main shaft piston rotor 14A and a sub-shaft portion provided with the sub-shaft piston rotor 14B are separately manufactured and these portions are joined together, or may be integrally formed. The main shaft portion and the sub-shaft portion may have mutually different external diameters.

Next, the intermediate shaft part <NUM> will be described.

As shown in <FIG>, the intermediate shaft part <NUM> is provided at the position sandwiched between the main shaft piston rotor 14A and the sub-shaft piston rotor 14B in the direction of the axis O. That is, the intermediate shaft part <NUM> is disposed between the main-shaft-side cylinder 12A and the sub-shaft-side cylinder 12B within the casing <NUM>.

As shown in <FIG>, when the intermediate shaft part <NUM> is viewed in a cross section orthogonal to the axis O, an outer peripheral surface of the intermediate shaft part <NUM> is disposed within one region AR where an outer peripheral edge 14Aa of the main shaft piston rotor 14A and an outer peripheral edge 14Ba of the sub-shaft piston rotor 14B overlap each other. More specifically, in the present embodiment, the outer peripheral surface of the intermediate shaft part <NUM> is disposed within a region where an outer peripheral edge 13Aa of the main-shaft-side shaft part 13A and an outer peripheral edge 13Ba of the sub-shaft-side eccentric shaft part 13B overlap each other.

That is, the sectional shape of the intermediate shaft part <NUM> is a substantially elliptical shape, rugby ball shape, or almond shape. Accordingly, the intermediate shaft part <NUM> has a pair of apexes 17a that protrudes toward both sides in a direction intersecting an eccentric direction that is a direction in which an imaginary line X connecting the eccentric axes O1 and O2 and the axis O over the entire area in the direction of the axis O extend.

The pair of apexes 17a is provided at positions symmetrical to each other with respect to the axis O. Each apex 17a is disposed at a position by an angle α toward a backward side in a rotational direction R of the rotating shaft <NUM> with respect to an imaginary line Y that extends in the direction orthogonal to the eccentric direction, and thereby, the external diameter dimension of the intermediate shaft part <NUM> is the largest at the position of the angle α. Additionally, the external diameter dimension of the intermediate shaft part <NUM> is the smallest in the eccentric direction.

An outer peripheral surface of the apex 17a has an arcuate apex-side curved surface 17b that is disposed at a position apart from the outer peripheral edge 13Aa or 13Ba that is an outer edge of the one region AR, that is, radially inward of the outer edge and is curved in a convex shape from the apex 17a in a direction away from the axis O toward a forward side in the rotational direction R, and the arcuate eccentric-side curved surface 17c continuous with the apex 17a.

Since the pair of apexes 17a is provided in the present embodiment, a pair of apex-side curved surfaces 17b is provided at positions symmetrical to each other with respect to the axis O.

Here, the curvature radius of the apex-side curved surface 17b is preferably as large as possible in order to keep the second moment of area of the intermediate shaft part <NUM>.

The eccentric-side curved surface 17c is smoothly continuous with the apex-side curved surface 17b in a state where there is no angle on the forward side in the rotational direction of the apex 17a. Also, the eccentric-side curved surface 17c is provided at a position including an intersection point P between the imaginary line X extending in the above eccentric direction, and an outer edge of the one region AR, and extends on the outer edge along the outer edge.

Since the pair of apexes 17a is provided in the present embodiment, a pair of the eccentric-side curved surfaces 17c of the positions symmetrical to each other with respect to the axis O is provided. Accordingly, one eccentric-side curved surface 17c extends along the outer edges of one region AR continuously on the forward side in the rotational direction R with one apex-side curved surface 17b extending toward the forward side in the rotational direction from one apex 17a, and is connected to the other apex 17a. Additionally, the other eccentric-side curved surface 17c is continuous on the forward side in the rotational direction R with the other apex-side curved surface 17b extending toward the forward side in the rotational direction R from the other apex 17a, extends along the outer edge of the one region AR, and is connected to the one apex 17a.

In other words, the intermediate shaft part <NUM> has a shape in which a portion of a forward portion in the rotational direction of the apex 17a is cut off radially inward from the substantially elliptical shape, rugby ball shape, or almond shape by the apex-side curved surface 17b.

Here, when the apex-side curved surface 17b is machined, in order to machine the apex-side curved surface while suppressing the amount of cutting, for example, it is possible to dispose the center of a machining circle on the backward side in the rotational direction R of the rotating shaft <NUM> with respect to the imaginary line Y to shave the intermediate shaft part <NUM> in an arcuate shape. Moreover, although an angle δ from the imaginary line Y to a connection point between the apex-side curved surface 17b and the eccentric-side curved surface 17c continuous toward the forward side in the rotational direction with the apex-side curved surface 17b is a value larger than the angle α (α < δ), δ may be a value that is as close to α as possible.

Here, the value of the above angle α is, for example, a value larger than <NUM> degrees and smaller than <NUM> degrees in the present embodiment.

As shown in <FIG>, and Table <NUM>, under any condition (HP (discharge-side pressure)/LP (suction-side pressure)), it could be confirmed from experimental results that the maximum gas load acts in a range larger than <NUM> degrees and smaller than <NUM> degrees toward the backward side in the rotational direction R with reference to the imaginary line Y that extends in the direction orthogonal to the eccentric direction in the intermediate shaft part <NUM>. That is, the range where the maximum gas load acts is a range of α= <NUM> degrees to <NUM> degrees.

Additionally, the value of HP/LP in Table <NUM> was set assuming HP/LP in general air conditioners.

According to the rotary compressor <NUM> of the present embodiment described above, the apex 17a of the intermediate shaft part <NUM> is disposed at a position shifted at an angle larger than <NUM> degrees and smaller than <NUM> degrees toward the backward side in the rotational direction R with respect to the direction orthogonal to the eccentric direction. That is, the apex 17a is not disposed on the imaginary line Y that extends in the direction orthogonal to the eccentric direction.

Therefore, since the diameter of the intermediate shaft part <NUM> is maximized at a position where the apex 17a is provided, the second moment of area of the intermediate shaft part <NUM> can be increased at this position, and the rigidity of the intermediate shaft part <NUM> can be improved. Therefore, even when the load during compression acts on each of the piston rotors 14A and 14B, it is possible to suppress deflection deformation of the rotating shaft <NUM>.

Particularly, as shown in the above <FIG>, and Table <NUM>, the knowledge that the maximum load during compression acts in a range of <NUM> degrees or more and <NUM> degrees or less toward the backward side in the rotational direction R with respect to the intermediate shaft part <NUM> was obtained. Therefore, the maximum load during compression does not act on the forward side in the rotational direction R from the apex 17a.

In this regard, in the present embodiment, the apex 17a is disposed at the position shifted by the angle α larger than <NUM> degrees and smaller than <NUM> times toward the backward side in the rotational direction R with respect to the direction orthogonal to the eccentric direction. Thus, the thickness of the intermediate shaft part <NUM> on the forward side in the rotational direction R from the apex 17a is smaller than that of a columnar shape.

However, in the portion in which the thickness of this intermediate shaft part <NUM> is smaller, as described above, the load acting during compression is smaller than the maximum load. Therefore, even if the apex 17a is provided at the above position, the strength of the intermediate shaft part <NUM> can be sufficiently secured. Also, the weight of the intermediate shaft part <NUM> can also be reduced.

Additionally, in the present embodiment, the outer peripheral surface of the intermediate shaft part <NUM> is disposed within the one region AR where the outer peripheral edge of the main shaft piston rotor 14A and the outer peripheral edge of the sub-shaft piston rotor 14B overlap each other, and the apex 17a is formed such that the outer peripheral surface of the intermediate shaft part <NUM> is cut off on the forward side in the rotational direction R of the apex 17a. For this reason, when the rotating shaft <NUM> rotates, the lubricating oil present around the intermediate shaft part <NUM> is smoothly guided toward the apex 17a of the intermediate shaft part <NUM>, and smoothly flows along the outer peripheral surface of the intermediate shaft part <NUM> toward the backward side in the rotational direction R. Therefore, the stirring loss when the lubricating oil is stirred by the intermediate shaft part <NUM> during rotation can be reduced.

Particularly, in the present embodiment, by providing the apex-side curved surface 17b and the eccentric-side curved surface 17c as the outer peripheral surfaces of the intermediate shaft part <NUM>, a smooth curved surface having no angle from the above intersection point P toward the apex 17a is formed on the outer peripheral surface of the intermediate shaft part <NUM> on the forward side in the rotational direction R from the apex 17a. Hence, when the lubricating oil is stirred by the rotating shaft <NUM>, the lubricating oil is guided from the eccentric-side curved surface 17c toward the apex-side curved surface 17b by these surfaces and flows smoothly. Therefore, even in the intermediate shaft part <NUM> having the apex 17a, the stirring loss of the lubricating oil can be reduced.

Moreover, by providing a pair of apexes 17a at the positions symmetrical to each other with respect to the axis O, the lubricating oil can be smoothly guided on the outer peripheral surface of the intermediate shaft part <NUM> while securing the strength of the intermediate shaft part <NUM>, and the stirring loss of the lubricating oil can be further reduced. Moreover, during rotation, centrifugal forces acting on the positions of the apexes 17a of the intermediate shaft part <NUM> can be canceled between the apexes 17a, and the stability during the rotation of the rotating shaft <NUM> can be improved.

Although the embodiments of the invention have been described in detail with reference to the drawings, the respective configurations and combinations thereof in the respective embodiments are examples, additions, omissions, substitutions, and other modifications of components can be made without departing from the concept of the invention. Additionally, the invention is not limited by the embodiment, and is limited only by the claims.

For example, as shown in <FIG>, the apex 17a may be provided only at one point. The apex 17a is disposed at a position shifted by an angle β larger than <NUM> degrees and smaller than <NUM> degrees toward the backward side in the rotational direction R with respect to the imaginary line Y orthogonal to the eccentric direction.

Moreover, as shown in <FIG>, the pair of apexes 17a is provided, and the positions at which the respective apexes 17a are disposed are disposed at positions shifted by θ1 and θ2 toward the backward side in the rotational direction R with respect to the imaginary line Y orthogonal to the eccentric direction. θ1 and θ2 are mutually different angles, and both are angles larger than <NUM> degrees and smaller than <NUM> toward the backward side in the rotational direction R with respect to the imaginary line Y orthogonal to the eccentric direction.

Additionally, the apex-side curved surface 17b of the intermediate shaft part <NUM> may be formed, for example, in a planar shape without being limited to the arcuate curved surface.

Additionally, the apex 17a may be disposed outside the one region AR.

Additionally, although the above angles α, β, θ1, and θ2 are, for example, values larger than <NUM> degrees and smaller than <NUM> degrees, the angles are not limited to this. That is, since the apex 17a to where the distance from the axis O is maximized may be located at the position where the maximum load acts on the intermediate shaft part <NUM>, the values of α, β, θ1, and θ2 may be larger than <NUM> degrees and smaller than <NUM> degrees. Particularly, in a case where the apex 17a is disposed outside the one region AR, the diameter of the intermediate shaft part <NUM> does not extremely decreases on the backward side in the rotational direction R of the apex 17a. Thus, in consideration of this point, α, β, θ1, and θ2 may not be limited to the value larger than <NUM> degrees and smaller than <NUM> degrees as described above.

Claim 1:
A rotating shaft (<NUM>) of a rotary compressor (<NUM>) that is rotatably supported with respect to a casing (<NUM>) having a compression chamber (S) therein and is rotationally driven around an axis (O) to allow a fluid to be compressed with lubricating oil, the rotating shaft comprising:
a shaft main body (<NUM>) that extends in a rod shape around the axis;
a main shaft piston rotor (14A) that is eccentrically provided at the shaft main body and is accommodated in a first compression chamber (S1) in the compression chamber;
a sub-shaft piston rotor (14B) that is disposed apart in a direction of the axis from the main shaft piston rotor, is provided eccentrically with respect to the shaft main body in a direction different in phase by <NUM> degrees from the main shaft piston rotor, and is accommodated in a second compression chamber (S2) in the compression chamber; and
an intermediate shaft part (<NUM>) around which the lubricating oil is present and which is provided at a position sandwiched between the main shaft piston rotor and the sub-shaft piston rotor in the shaft main body,
wherein the intermediate shaft part (<NUM>) protrudes in a direction intersecting an eccentric direction (X) of the main shaft piston rotor (14A) and the sub-shaft piston rotor (14B) as viewed in a cross section orthogonal to the axis (O), and has a pair of apexes (17a) where a distance between the outer peripheral surface and the axis (O) is maximized on an outer peripheral surface of the intermediate shaft part, characterised in that
the pair of the apexes is provided at positions symmetrical to each other with respect to the axis (O), and
wherein the intermediate shaft part (<NUM>) has a shape in which only a portion of the outer peripheral surface of the intermediate shaft part (<NUM>) on a forward side of the rotational direction (R) with respect to each apex (17a) is partially cut off radially inward from one region (AR) where an outer peripheral edge of the main shaft piston rotor (14A) and an outer peripheral edge of the sub-shaft piston rotor (14B) overlap each other, when the intermediate shaft part is viewed in a cross section orthogonal to the axis such that each apex (17a) is disposed at a position shifted at an angle larger than <NUM> degrees and smaller than <NUM> degrees toward a backward side in a rotational direction (R) with respect to an imaginary line (Y) passing through the axis (O) orthogonally to the eccentric direction (X).