JP2013108375A - Rotary compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary compressor which can sufficiently maintain the minimum thickness of an oil film between the inner circumferential surface of a piston and the sliding surface of an eccentric part, and can reduce a viscosity loss caused by the oil film.SOLUTION: The rotary compressor includes: a shaft 4 where the eccentric part 41 having the cylindrical sliding surface 42 is provided; a piston fitted into the eccentric part 41; a cylinder housing the piston. A reduction part 43 for reducing the height of the sliding surface 42 in the axial direction of the shaft 4 is provided in the eccentric part 41. The reduction part 43 is formed so that at least part of it is overlapped within the range of 135-180° in the range of 115-225° when an eccentric direction of the eccentric part 41 is defined as 0° and the rotation direction of the shaft 4 is positive in an angle coordinate around the center of the eccentric part 41.

Description

  The present invention relates to a rotary compressor.

  Conventionally, for example, a rotary compressor is used in a refrigeration cycle apparatus or the like. For example, Patent Document 1 discloses a rotary compressor 100 as shown in FIG. In the rotary compressor 100, a working chamber is formed between a ring-shaped piston 112 and a cylinder 111 that houses the piston, and the working chamber is partitioned by a vane 113 into a low pressure chamber and a high pressure chamber. The piston 112 is fitted to the eccentric portion 122 of the shaft 121 and slides on a cylindrical sliding surface that is an end surface of the eccentric portion 122. An oil film is formed by lubricating oil between the inner peripheral surface of the piston 112 and the sliding surface of the eccentric portion 122.

  Further, in the rotary compressor 100, as shown in FIG. 8B, the eccentric portion 122 is provided with a reduction portion 123 that reduces the height of the sliding surface in the axial direction of the shaft 121. As shown in FIG. 8A, the eccentric portion 123 is 270 ° when the eccentric direction A of the eccentric portion 122 is 0 ° and the rotational direction of the shaft 121 is positive in the angular coordinates around the center of the eccentric portion 122. It is formed within a range of 90 ° on both sides with respect to the position.

Japanese Patent Laid-Open No. 5-164071

  When the shaft 121 rotates to suck, compress, and discharge the working fluid, a compression load is applied to the piston 112. The direction and magnitude of the compressive load varies depending on the rotation angle of the shaft 121. The thickness of the oil film between the inner peripheral surface of the piston 112 and the sliding surface of the eccentric portion 122 varies depending on the location, and the minimum thickness of the oil film depends on the compression load.

  However, when the reduction part 123 is provided in the range of 180 ° to 360 ° as shown in FIG. 8A, the viscosity loss (resistance to shaft rotation) caused by the oil film can be reduced. There is a risk that the minimum thickness of the oil film becomes very thin when the compressive load is small.

  In view of such circumstances, the present invention provides a rotary compressor that can reduce the viscosity loss caused by an oil film while sufficiently maintaining the minimum thickness of the oil film between the inner peripheral surface of the piston and the sliding surface of the eccentric portion. The purpose is to provide.

  In order to solve the above problems, a rotary compressor according to the present invention is fitted with a shaft provided with an eccentric portion having a cylindrical sliding surface and the eccentric portion, and slides on the sliding surface. A reduction part that reduces the height of the sliding surface in the axial direction of the shaft, the piston and a cylinder that accommodates the piston and forms a working chamber with the piston. The reducing portion has a range of 115 ° to 225 ° when the eccentric direction of the eccentric portion is 0 ° and the rotational direction of the shaft is positive in the angular coordinates around the center of the eccentric portion. It is formed so that at least one part may overlap in the range of 135 degrees-180 degrees.

  According to the above configuration, by not providing the reduced portion in the range of 0 ° to 115 ° and 225 ° to 360 ° where the minimum thickness of the oil film tends to be reduced, the inner peripheral surface of the piston and the eccentric portion The minimum thickness of the oil film between the sliding surfaces can be sufficiently maintained. Further, by providing the reduced portion so as to at least partially overlap the range of 135 ° to 180 ° in which the minimum thickness of the oil film tends to increase, viscosity loss due to the oil film can be reduced.

1 is a longitudinal sectional view of a rotary compressor according to an embodiment of the present invention. Cross-sectional view along line II-II in FIG. Perspective view near the eccentric part of the shaft Cross section of shaft It is a numerical analysis result when using a shaft that is not provided with a reduction part in the eccentric part, and a graph showing at which angular coordinate the minimum thickness of the oil film occurs during one rotation of the shaft It is a numerical analysis result when using a shaft that is not provided with a reduction part in the eccentric part, and shows the pressure distribution of the oil film at every 30 degrees of rotation angle of the shaft in angular coordinates around the center of the eccentric part. It is a numerical analysis result when using a shaft that is not provided with a reduction part in the eccentric part, and shows the relationship between the rotation angle of the shaft and the compression load (A) is a cross-sectional view of a conventional rotary compressor, (b) is a perspective view of the vicinity of the eccentric portion of the shaft of the rotary compressor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

  1 and 2 show a rotary compressor 10 according to an embodiment of the present invention. The rotary compressor 10 includes a sealed container 1 that houses an electric motor 2 and a compression mechanism 3. The electric motor 2 and the compression mechanism 3 are connected by a shaft 4. In the present embodiment, the axial direction of the shaft 4 extends in the vertical direction and the electric motor 2 and the compression mechanism 3 are arranged vertically. However, the axial direction of the shaft 4 extends in the horizontal direction, and the electric motor 2 and the compression mechanism 3 are It may be arranged side by side.

  A discharge pipe 12 that penetrates the sealed container 10 and opens into the inner space of the sealed container 10 is provided at the upper part of the sealed container 10, and a compression mechanism that penetrates the sealed container 10 at the lower part of the sealed container 10. 3 is provided. The compression mechanism 3 discharges the working fluid (typically a refrigerant) sucked from the suction pipe 11 to the internal space of the sealed container 10.

  The electric motor 2 includes a stator 22 and a rotor 24. The stator 22 is provided with a notch that forms a flow path 26 along the inner peripheral surface of the sealed container 1. The working fluid discharged from the compression mechanism 3 is guided to the upper side of the electric motor 2 through the gap between the stator 22 and the rotor 24 of the electric motor 2 and the flow path 26, and is discharged to the outside from the discharge pipe 12.

  The shaft 4 is provided with a disc-shaped eccentric portion 41 having a center C2 at a position shifted from the axis C1 of the shaft 4. An end surface of the eccentric portion 41 constitutes a cylindrical sliding surface 42.

  The compression mechanism 3 includes a cylinder 30, a piston 32, a vane 33, an upper bearing 34 and a lower bearing 35.

  The piston 32 has a ring shape. The piston 32 is fitted with the eccentric portion 41 and slides on the sliding surface 42. An oil film is formed by lubricating oil between the inner peripheral surface of the piston 32 and the sliding surface 42 of the eccentric portion 41.

  The cylinder 30 houses a piston 32. A crescent-shaped working chamber 39 is formed between the inner peripheral surface of the cylinder 30 and the outer peripheral surface of the piston 32. A slot 30a is formed in the cylinder 30, and a vane 33 is inserted into the slot 30a so as to be able to reciprocate. A spring 38 that presses the vane 33 against the piston 32 is disposed in the slot 30a. The vane 33 partitions the working chamber 39 into a low pressure chamber in which the suction port 3a is opened and a high pressure chamber in which the discharge port 3b is opened. The vane 33 may be integrated with the piston 32.

  The upper bearing 34 and the lower bearing 35 close the working chamber 39 on both sides of the cylinder 30 and rotatably support the shaft 4.

  In the present embodiment, a suction port 3 a that allows the working fluid to flow into the low pressure chamber of the working chamber 39 is provided in the cylinder 30, and a discharge port 3 b that allows the working fluid to flow out of the high pressure chamber of the working chamber 39 is provided in the upper bearing 35. Yes. A suction pipe 11 is connected to the upstream end of the suction port 3a, and a discharge valve 36 is provided at the downstream end of the discharge port 3b. The discharge valve 36 is elastically deformed to open the discharge port 3b when receiving a pressure of a predetermined magnitude or more. However, how to provide the suction port 3a and the discharge port 3b to which member can be appropriately selected.

  Further, a muffler 37 that covers the discharge valve 36 together with a space facing the upper bearing 34 is provided above the upper bearing 34. The muffler 37 is provided with an opening communicating with the internal space of the sealed container 1 at an appropriate position.

  As the shaft 4 rotates, the far point closest to the inner circumferential surface of the cylinder 30 in the piston 32 turns. The low pressure chamber of the working chamber 39 gradually increases in volume as the far point of the piston 32 moves away from the vane 33. As the volume increases, the working fluid flows from the suction port 3a into the low pressure chamber. When the far point of the piston 32 passes through the vane 33, the low pressure chamber is switched to the high pressure chamber. The high pressure chamber gradually decreases in volume as the far point of the piston 32 moves away from the vane 33. When the volume is reduced, the pressure in the high-pressure chamber increases, and when the working fluid is compressed to a predetermined pressure or higher, the discharge valve 36 opens and the working fluid flows out from the discharge port 3b.

  Next, the configuration of the eccentric portion 41 of the shaft 4 will be described in detail with reference to FIGS. 3 and 4.

  The eccentric portion 41 is provided with a reduction portion 43 that reduces the height of the sliding surface 42 in the axial direction of the shaft 4. The reduction part 43 is a continuous part extending in the circumferential direction.

  The reducing portion 43 is preferably located at the center of the eccentric portion 41 in the axial direction of the shaft 4. That is, it is preferable that, for example, arc-shaped notches are formed on both sides of the reduced portion 43 in the axial direction of the shaft 4. Note that the cutout does not necessarily have an arc shape, and may have a crescent shape.

  The reducing portion 43 is at least one in the range of 115 ° to 225 ° when the eccentric direction A of the eccentric portion 41 is 0 ° and the rotational direction of the shaft 4 is positive in the angular coordinates around the center C2 of the eccentric portion 41. The part is formed to overlap the range of 135 ° to 180 °.

  For example, the reduction unit 43 may be provided in the range of 115 ° to 150 ° in the angle coordinates, or may be provided in the range of 150 ° to 225 ° in the angle coordinates. However, the angular width of the reduction part 43 is preferably 45 ° or more. As a more preferable configuration, in the angle coordinates, the starting point (end point on the opposite side of the rotation direction of the shaft 4) of the reduction portion 43 is positioned at 135 ° or less, and the end point (end point in the rotation direction of the shaft 4) of the reduction portion 43 is. It is located at 180 ° or more.

  Next, in order to confirm the effect of the rotary compressor 10 of this embodiment, the numerical analysis performed with respect to the reference compressor containing the shaft in which the reduction part 43 is not provided in the eccentric part 41 is demonstrated.

  FIG. 5 is a graph showing at which angular coordinates the minimum thickness of the oil film occurs during one rotation of the shaft. FIG. 6 is a diagram illustrating the pressure distribution of the oil film at each rotation angle of the shaft of 30 degrees in angular coordinates around the center of the eccentric portion 41. FIG. 7 is a diagram showing the relationship between the rotation angle of the shaft and the compression load. In these figures, the shaft rotation angle of 0 ° is a state where the far point of the piston 32 is located on the vane 33 (the piston 32 moves the vane 33 most backward).

  From FIG. 5, it can be seen that as the shaft rotation angle increases, the oil film minimum thickness generation position shifts in the direction opposite to the shaft rotation direction. In the range of 115 ° to 225 ° in the angular coordinates around the center of the eccentric portion 41, the minimum thickness of the oil film, that is, the clearance between the inner peripheral surface of the piston 32 and the sliding surface 42 should be kept large. Can be confirmed. It can also be confirmed from the figure that the minimum thickness of the oil film when the rotation angle is 120 ° is smaller than the minimum thickness of the oil film when the rotation angle is 150 °. Further, from FIG. 5, the minimum thickness of the oil film tends to increase in the range of 135 ° to 180 ° in the angle coordinate, and the minimum of the oil film in the range of 0 ° to 115 ° and 225 ° to 360 ° in the angle coordinate. It can be confirmed that the thickness tends to decrease.

  From FIG. 6, when the oil film pressure is generated in the range of 135 ° to 180 ° in the angle coordinates, the rotation angle of the shaft is 150 ° and around that, and the oil film pressure is in the range of 180 ° to 225 ° in the angle coordinates. When it occurs, it can be confirmed that the rotation angle of the shaft is 120 ° and before and after. Further, from FIG. 6, when the oil film pressure is generated in the range of 135 ° to 180 ° in the angle coordinate, the oil film pressure is compared with when the oil film pressure is generated in the range of 180 ° to 225 ° in the angle coordinate. Can be confirmed.

  Considering the results of FIG. 5 and FIG. 6 described above, when the oil film pressure is generated in the range of 135 ° to 180 ° in the angle coordinate, the thickness of the oil film increases, and in the angle coordinate in the range of 180 ° to 225 °. When oil film pressure is generated, the thickness of the oil film decreases. That is, it can be said that it is easy to generate the load bearing force due to the oil film pressure in the angle coordinate range of 135 ° to 180 °. This is because the compression load at the rotation angle of 150 ° shown in FIG. 7 is larger than the compression load at the rotation angle of 120 °. When the oil film pressure is generated, the oil film is kept thick even though the compression load is large. In the angle coordinate range of 135 ° to 180 °, it is easy to generate the load bearing force by the oil film pressure. I support that.

  As described above, the clearance between the inner peripheral surface of the piston 32 and the sliding surface 42 is kept large in the range of 135 ° to 225 ° in the angle coordinates, and the oil film pressure is further in the range of 135 ° to 180 ° in the angle coordinates. When the load supporting force due to the oil pressure is generated, it is easier to generate the load supporting force than when the load supporting force due to the oil film pressure is generated in the range of 180 ° to 225 ° in the angle coordinates. Therefore, the load supporting force is over-spec in the range of 135 ° to 180 ° in angular coordinates. Therefore, by providing the reducing portion 43 so that at least a part thereof overlaps the range of 135 ° to 180 ° in the angle coordinate, the viscosity loss due to the oil film can be reduced. Further, by not providing the eccentric portion 43 in the range of 0 ° to 115 ° and 225 ° to 360 ° in the angle coordinates, the minimum thickness of the oil film between the inner peripheral surface of the piston 32 and the sliding surface 42 is sufficient. Can be kept in.

  For example, when the reduction unit 43 is provided in the range of 135 ° to 180 ° in angular coordinates (angle width 45 °), the viscosity loss due to the oil film can be reduced by 11.6%.

DESCRIPTION OF SYMBOLS 10 Rotary compressor 30 Cylinder 32 Piston 39 Working chamber 4 Shaft 41 Eccentric part 42 Sliding surface 43 Reduced part

Claims (2)

A shaft provided with an eccentric portion having a cylindrical sliding surface;
A piston that fits with the eccentric part and slides on the sliding surface;
A cylinder that accommodates the piston and forms a working chamber with the piston;
The eccentric portion is provided with a reduced portion that reduces the height of the sliding surface in the axial direction of the shaft,
The reduced portion has at least a part within a range of 115 ° to 225 ° when the eccentric direction of the eccentric portion is 0 ° and the rotational direction of the shaft is positive in angle coordinates around the center of the eccentric portion. A rotary compressor formed so as to overlap a range of 135 ° to 180 °.   The rotary compressor according to claim 1, wherein an angle width of the reduced portion is 45 ° or more.