EP3557065A1

EP3557065A1 - Compressor provided with compression mechanism fixed to casing

Info

Publication number: EP3557065A1
Application number: EP17881953.8A
Authority: EP
Inventors: Naoto Tomioka; Kiyofumi SHIROUZU
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2016-12-13
Filing date: 2017-12-07
Publication date: 2019-10-23
Also published as: JP2018096272A; CN110073108A; AU2017375095B2; WO2018110426A1; EP3557065A4; AU2017375095A1

Abstract

A compressor (5) includes a casing (10), a motor (20), and a compression mechanism (40). The casing (10) includes a cylindrical portion (11) having an inner diameter of a first dimension (D1). The motor (20) includes a rotor (22) having an outer diameter of a second dimension (D2). The compression mechanism (40) compresses a low-pressure refrigerant to generate the high-pressure refrigerant. A ratio (D1/D2) of the first dimension (D1) to the second dimension (D2) is equal to or less than 1.8. The compression mechanism (40) includes a fixing portion (49) being in tight contact with an inner peripheral surface of the cylindrical portion (11) at a position where the compression mechanism (40) is disposed.

Description

TECHNICAL FIELD

The present invention relates to a compressor including a compression mechanism fixed to a casing.

BACKGROUND ART

A refrigeration apparatus such as an air conditioner and a refrigerator includes a compressor. As disclosed in Patent Literature 1 ( JP 2006-144731 A ), a reciprocating compressor undergoes a phenomenon in which significant torque fluctuations occur while a crank shaft rotates once. Such torque fluctuations cause vibrations, that is, noise. Other compressors such as a rotary compressor may have a similar problem. A solution to reduce vibrations owing to torque fluctuations is to upsize a rotor of a motor and to increase the weight of the rotor, thereby ensuring rotational inertia.

SUMMARY OF THE INVENTION

However, the increase in weight of the rotor may cause different vibrations. Such different vibrations may be vibrations owing to weight imbalance. The vibrations are generated when a leading end of a crank shaft slightly inclined due to subtle imbalance of weight distribution in a rotor produces motion such as reciprocation or rotation. The motion causes vibrations of a compression mechanism including a bearing supporting the crank shaft. The vibrations are transmitted to a casing, so that the entire compressor finally vibrates. The vibrations owing to the weight imbalance become particularly pronounced when a heavy rotor rotates at high speed.
An object of the present invention is to suppress vibrations of a compressor.

A first aspect of the present invention provides a compressor including a casing, a motor, and a compression mechanism. The casing includes a cylindrical portion having an inner diameter of a first dimension. The motor includes a rotor having an outer diameter of a second dimension. The compression mechanism is configured to compress a low-pressure refrigerant to generate the high-pressure refrigerant. A ratio of the first dimension to the second dimension is equal to or less than 1.8. The compression mechanism includes a fixing portion being in tight contact with an inner peripheral surface of the cylindrical portion at a position where the compression mechanism is disposed.
With this configuration, the fixing portion of the compression mechanism is in tight contact with the cylindrical portion of the casing. This configuration therefore enables firm fixation of the compression mechanism to the casing. This configuration thus suppresses vibrations of the compressor.
A second aspect of the present invention provides the compressor according to the first aspect, wherein the fixing portion extends over the compression mechanism so as to occupy 80% or more of an overall circumference of the inner peripheral surface.
With this configuration, the fixing portion of the compression mechanism occupies 80% or more of the overall circumference of the inner peripheral surface of the cylindrical portion. This configuration therefore enables tight contact of the compression mechanism with the casing over a wide range. This configuration thus further suppresses vibrations of the compressor.
A third aspect of the present invention provides the compressor according to the first or second aspect, wherein an average value of distances from the cylindrical portion to the compression mechanism falls within a range from 0.00 mm or more to 0.15 mm or less in the overall circumference of the cylindrical portion.
This configuration brings about the small average value of the distances from the inner peripheral surface of the cylindrical portion to the fixing portion of the compression mechanism. This configuration therefore further enhances the degree of tight contact of the fixing portion with the inner peripheral surface. This configuration thus further suppresses vibrations of the compressor.
A fourth aspect of the present invention provides the compressor according to any one of the first to third aspects, further including four or more weld portions at which the compression mechanism is fixed to the cylindrical portion.
With this configuration, the four or more weld portions contribute to stiffness to joints between the compression mechanism and the cylindrical portion. This configuration thus further suppresses vibrations of the compressor.
A fifth aspect of the present invention provides the compressor according to the fourth aspect, including the weld portions the number of which is six or more.
With this configuration, the six or more weld portions impart additional stiffness to the joints between the compression mechanism and the cylindrical portion. This configuration thus further suppresses vibrations of the compressor.
A sixth aspect of the present invention provides the compressor according to the fourth or fifth aspect, further including a crank shaft. The crank shaft is fixed to the rotor to rotate about an axis of rotation. The compression mechanism includes a cylinder, a piston movable inside the cylinder, and a shaft support portion supporting the crank shaft in a rotatable manner. The shaft support portion is fixed to the cylindrical portion at the weld portions.
This configuration shortens a difference in height from each joint between the compression mechanism and the cylindrical portion to the center of gravity of the rotor. This configuration thus further suppresses vibrations of the compressor.
A seventh aspect of the present invention provides the compressor according any one of the first to sixth aspects, wherein the cylindrical portion is a multi-segment expanded tube including eight or more inner diameter increased portions and eight or more inner diameter decreased portions.
With this configuration, the inner diameter increased portions are brought into contact with the compression mechanism, and the inner diameter decreased portions are firmly pressed against the compression mechanism while being elastically deformed. This configuration thus further suppresses vibrations of the compressor.
An eighth aspect of the present invention provides a method for manufacturing a compressor. The manufacturing method includes a step of preparing a cylindrical portion having an inner diameter of a first dimension, a motor including a rotor having an outer diameter of a second dimension, and a compression mechanism configured to compress a low-pressure refrigerant to generate the high-pressure refrigerant. The manufacturing method also includes a step of fixing the compression mechanism to the cylindrical portion so as to bring a fixing portion of the compression mechanism into tight contact with an inner peripheral surface of the cylindrical portion. A ratio of the first dimension to the second dimension is equal to or less than 1.8.
This method enables tight contact of the compression mechanism with the cylindrical portion. This configuration therefore enables firm fixation of the compression mechanism to the casing. This configuration thus suppresses vibrations of the compressor.
A ninth aspect of the present invention provides the manufacturing method according to the eighth aspect, wherein the fixing portion extends over the compression mechanism so as to occupy 80% or more of an overall circumference of the inner peripheral surface.
With this method, the fixing portion of the compression mechanism occupies 80% or more of the overall circumference of the inner peripheral surface of the cylindrical portion. This configuration therefore enables tight contact of the compression mechanism with the casing over a wide range. This configuration thus further suppresses vibrations of the compressor.
A tenth aspect of the present invention provides the manufacturing method according to the eighth or ninth aspect, wherein the fixing step includes a step of welding the compression mechanism to the cylindrical portion at four or more positions.
With this method, the four or more weld portions contribute to stiffness to joints between the compression mechanism and the cylindrical portion. This configuration thus further suppresses vibrations of the compressor.
An eleventh aspect of the present invention provides the manufacturing method according to the tenth aspect, wherein in the fixing step, an average value of distances from the fixing portion to the inner peripheral surface falls within a range from 0.00 mm or more to 0.15 mm or less in the entire fixing portion.
This method brings about the small average value of the distances from the fixing portion of the compression mechanism to the inner peripheral surface of the cylindrical portion. This configuration therefore further enhances the degree of tight contact of the fixing portion with the inner peripheral surface. This configuration thus further suppresses vibrations of the compressor.
A twelfth aspect of the present invention provides the manufacturing method according to the eighth or ninth aspect, wherein the fixing step includes: a step of increasing the first dimension by heat application to the cylindrical portion; a step of inserting the compression mechanism into the cylindrical portion; and a step of decreasing the first dimension by heat radiation from the cylindrical portion.
With this method, the compression mechanism is fixed by shrink fitting to the cylindrical portion. This configuration therefore enables contact of the compression mechanism with the substantially overall circumference of the cylindrical portion. This configuration thus further suppresses vibrations of the compressor.
A thirteenth aspect of the present invention provides the manufacturing method according to the eighth or ninth aspect, wherein the fixing step includes a step of applying a strong force to the compression mechanism to insert the compressor into the cylindrical portion while elastically deforming the cylindrical portion.
With this method, the compression mechanism is fixed by press fitting to the cylindrical portion. This configuration therefore enables contact of the compression mechanism with the substantially overall circumference of the cylindrical portion. This configuration thus further suppresses vibrations of the compressor.
A fourteenth aspect of the present invention provides the manufacturing method according to any one of the eighth to thirteenth aspects, further including a motor fixing step of fixing the motor to the cylindrical portion. The motor fixing step includes: a step of increasing the first dimension by heat application to the cylindrical portion; a step of inserting the motor into the cylindrical portion; and a step of decreasing the first dimension by heat radiation from the cylindrical portion.
With this method, the motor is firmly fixed by shrink fitting to the cylindrical portion. This configuration therefore suppresses wobbles of the motor relative to the casing. This configuration thus further suppresses vibrations of the compressor.

The compressor according to any one of the first to seventh aspects of the present invention suppresses vibrations thereof.
The manufacturing method according to any one of the eighth to fourteenth aspects of the present invention suppresses vibrations of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a compressor 5 according to an embodiment of the present invention.
FIG. 2 is a plan view of a cylindrical portion 11 and a motor 20 in the compressor 5.
FIG. 3 is a sectional view of a stator 21 in the compressor 5.
FIG. 4 is a sectional view of a rotor 22 in the compressor 5.
FIG. 5 is a partial sectional view of the compressor 5.
FIG. 6 is a plan view of the cylindrical portion 11 and a compression mechanism 40 in the compressor 5.
FIG. 7A is a plan view of the compression mechanism 40.
FIG. 7B is a plan view of an alternative compression mechanism 40.
FIG. 8 is a sectional view of a cylindrical portion 11 including a multi-segment expanded tube according to a modification of the present invention.

DESCRIPTION OF EMBODIMENTS

With reference to the drawings, a description will be given of an air conditioning apparatus according to an embodiment of the present invention. It should be noted that a specific configuration of the air conditioning apparatus according to the present invention is not limited to the following embodiment, and may be appropriately modified without departing from the gist of the present invention.

(1) General Configuration

(1-1) Outline

FIG. 1 illustrates a compressor 5 according to an embodiment of the present invention. In air conditioning apparatuses and refrigeration apparatuses such as a refrigerator, the compressor 5 is configured to compress a gaseous refrigerant. The compressor 5 includes a casing 10, a motor 20, a crank shaft 30, and a compression mechanism 40.

(1-2) Casing 10

The casing 10 is configured to house the constituents of the compressor 5, and is resistant to high pressure of the refrigerant. The casing 10 includes a cylindrical portion 11, an upper portion 12, and a lower portion 13. The cylindrical portion 11 is the largest one of the constituents of the casing 10, and has a cylindrical shape. Each of the upper portion 12 and the lower portion 13 is joined to the cylindrical portion 11. The casing 10 has on its lower side an oil reservoir 14 where a refrigerating machine oil 141 is retained.
The cylindrical portion 11 has a suction pipe 15 mounted thereto. The upper portion 12 has a discharge pipe 16 and a terminal 17 each mounted thereto. The suction pipe 15 is disposed for sucking the low-pressure refrigerant. The discharge pipe 16 is disposed for discharging the high-pressure refrigerant. The terminal 17 is configured to receive external power supply.

(1-3) Motor 20

The motor 20 is configured to generate mechanical power from electric power supplied from the terminal 17 via a lead wire (not illustrated). The motor 20 includes a stator 21 and a rotor 22. As illustrated in FIG. 2, the stator 21 has a cylindrical shape, and is fixed to the cylindrical portion 11 of the casing 10. A clearance 23 is defined between the stator 21 and the rotor 22. The clearance 23 functions as a refrigerant passage.
As illustrated in FIG. 3, the stator 21 includes a stator core 21a, insulators 21b, and a winding wire 21c. The stator core 21a includes a stack of steel plates. The stator core 21a has a space 213 where the rotor 22 is disposed. Each of the insulators 21b is made of resin. The insulators 21b are respectively disposed on a stator core upper surface 211 and a stator core lower surface 212. The winding wire 21c is used for generating an alternating-current magnetic field, and is wound around a stack of the stator core 21a and insulators 21b.
As illustrated in FIG. 4, the rotor 22 includes a rotor core 22a, a permanent magnet 22b, end plates 22c, a balance weight 22d, and bolts 22e. The rotor core 22a includes a stack of steel plates. The rotor core 22a has a space 223 where the crank shaft 30 is fixed. The permanent magnet 22b is used for rotating the entire rotor 22 by interacting with the alternating-current magnetic field generated by the winding wire 21c. The permanent magnet 22b is disposed in a cavity 224 of the rotor core 22a. The end plates 22c are respectively disposed on a rotor core upper surface 221 and a rotor core lower surface 222 to prevent the permanent magnet 22b from slipping out of the cavity 224. The balance weight 22d is used for adjusting the center of gravity of a rotatable body including the rotor 22 and the components rotatable in conjunction with the rotor 22. The balance weight 22d is disposed on one of the end plates 22c. Each bolt 22e secures the end plates 22c or the balance weight 22d to the rotor core 22a.

(1-4) Crank Shaft 30

Referring back to FIG. 1, the crank shaft 30 is configured to transmit to the compression mechanism 40 power generated by the motor 20. The crank shaft 30 rotates about an axis of rotation RA. The crank shaft 30 includes a main shaft portion 31 and an eccentric portion 32. A part of the main shaft portion 31 is fixed to the rotor 22. The eccentric portion 32 is eccentric relative to the axis of rotation RA.

(1-5) Compression Mechanism 40

The compression mechanism 40 is configured to compress the low-pressure refrigerant to generate the high-pressure refrigerant. The compression mechanism 40 includes a cylinder 41, a piston 42, a shaft support portion 61, an auxiliary shaft support portion 62, and a muffler 45.
The cylinder 41 is a metal member, and has an internal space communicating with the outside of the casing 10 through the suction pipe 15. The piston 42 is a cylindrical metal member, and is smaller than the cylinder 41. The piston 42 is mounted to the eccentric portion 32. The eccentric portion 32 and the piston 42 are disposed in the internal space of the cylinder 41. When the crank shaft 30 rotates, the piston 42 revolves. The shaft support portion 61 supports the main shaft portion 31 located above the eccentric portion 32, in a rotatable manner. The shaft support portion 61 has a function of closing an upper side of the internal space in the cylinder 41. The shaft support portion 61 is fixed to the cylindrical portion 11 at weld portions 50. The auxiliary shaft support portion 62 supports the main shaft portion 31 located below the eccentric portion 32, in a rotatable manner. The auxiliary shaft support portion 62 has a function of closing a lower side of the internal space in the cylinder 41. The cylinder 41, the piston 42, the shaft support portion 61, and the auxiliary shaft support portion 62 define a compression chamber 43. The muffler 45 is mounted to the shaft support portion 61. The shaft support portion 61 and the muffler 45 define a muffler chamber.
The compression chamber 43 has a volumetric capacity that increases or decreases by the revolution of the piston 42. The compression mechanism 40 consequently compresses the low-pressure refrigerant to generate the high-pressure refrigerant. The high-pressure refrigerant is discharged from the compression chamber 43 toward the muffler chamber through a passage 44 formed in the shaft support portion 61. A discharge valve (not illustrated) is disposed on the passage 44. The discharge valve suppresses a backflow of the high-pressure refrigerant from the muffler chamber toward the compression chamber 43. The high-pressure refrigerant passes through the passage 44 each time the piston 42 revolves once. The high-pressure refrigerant intermittently passing through the passage 44 may cause noise. In the muffler chamber, the muffler 45 smooths variations in pressure of the gas refrigerant, thereby reducing noise. The high-pressure refrigerant is discharged from the compression mechanism 40 through a discharge hole 46 formed in the muffler 45.
The foregoing configuration in which the shaft support portion 61 is fixed to the cylindrical portion 11 at the weld portions 50 may be replaced with a configuration in which a component, such as the cylinder 41, of the compression mechanism 40 rather than the shaft support portion 61 is fixed to the cylindrical portion 11 at the weld portions 50.

(2) Basic Operation

In FIG. 1, arrows each indicate a flow of the refrigerant. The low-pressure refrigerant is sucked into the compression chamber 43 of the compression mechanism 40 through the suction pipe 15. The compression mechanism 40 compresses the low-pressure refrigerant to generate the high-pressure refrigerant. The high-pressure refrigerant passes through the passage 44 and the discharge hole 46. The high-pressure refrigerant is then discharged from the compression mechanism 40. Thereafter, the high-pressure refrigerant is blown toward the rotor 22, and then flows toward the clearance 23. The high-pressure refrigerant flows upward through the clearance 23, and then is discharged from the casing 10 through the discharge pipe 16.

(3) Specific Configuration

The rotor 22 of the compressor 5 according to the present invention is configured to rotate at 100 to 150 rps (revolutions per second), preferably 120 to 130 rps. This rotational speed is faster than the rotational speed (e.g., 15 to 75 rps) of a rotor of a conventional compressor.
FIG. 5 illustrates dimensions of the respective components in the compressor 5. A first dimension D1 refers to an inner diameter of the cylindrical portion 11 of the casing 10. A second dimension D2 refers to an outer diameter of the rotor core 22a of the rotor 22. A ratio D1/D2 of the first dimension D1 to the second dimension D2 is designed to be equal to or less than 1.8. For example, the first dimension D1 is 90 mm, and the second dimension is 50 mm. The ratio D1/D2 may be designed to be less than 1.8.
The shaft support portion 61 of the compression mechanism 40 is fixed to the cylindrical portion 11 of the casing 10 at four or more weld portions 50. As illustrated in FIG. 6, preferably, the shaft support portion 61 is fixed to the cylindrical portion 11 at six weld portions 50. Alternatively, the fixation may be made using seven or more weld portions 50. Preferably, the weld portions 50 are evenly spaced away from one another.
FIG. 7A illustrates the compression mechanism 40. The compression mechanism 40 includes a fixing portion 49. The fixing portion 49 extends over an outer periphery of the compression mechanism 40. The outer periphery of the compression mechanism 40 corresponds to an overall circumference of the cylindrical portion 11. The fixing portion 49 is brought into tight contact with the inner peripheral surface of the cylindrical portion 11 of the casing 10, at a position where the compression mechanism 40 is disposed, that is, a height position of the compression mechanism 40. In order to enhance the degree of tight contact, each of the compression mechanism 40 and the cylindrical portion 11 is formed with accurate roundness. Specifically, an average value of distances from the fixing portion 49 to the inner peripheral surface of the cylindrical portion 11 falls within a range from 0.00 mm or more to 0.15 mm or less in the entire fixing portion 49.
The compression mechanism 40 may have a configuration illustrated in FIG. 7B in place of the configuration illustrated in FIG. 7A. In this configuration, the compression mechanism 40 has a cutout 48. The cutout 48 is formed in a part of the outer periphery of the compression mechanism 40, and is out of contact with the inner peripheral surface of the cylindrical portion 11. The fixing portion 49 extends over the outer periphery of the compression mechanism 40 so as to occupy 80% or more of the overall circumference of the cylindrical portion 11, rather than the overall circumference of the cylindrical portion 11. Also in this configuration, an average value of distances from the fixing portion 49 to the inner peripheral surface of the cylindrical portion 11 falls within a range from 0.00 mm or more to 0.15 mm or less in the entire fixing portion 49.

(4) Manufacturing Method

A method for manufacturing the compressor 5 according to the present invention includes the following steps.

(4-1) First Step: Preparation of constituents

The manufacturing method includes preparing the cylindrical portion 11 having the inner diameter of the first dimension D1, the motor 20 including the rotor 22 having the outer diameter of the second dimension D2, and the compression mechanism 40. In this step, the ratio D1/D2 of the first dimension D1 to the second dimension D2 is equal to or less than 1.8.

(4-2) Second Step: Fixation of compression mechanism 40

The manufacturing method also includes fixing the compression mechanism 40 to the cylindrical portion 11 by welding. Specifically, the manufacturing method includes forming four or more, preferably six or more weld portions 50. The fixing portion 49 of the compression mechanism 40 is thus brought into tight contact with the inner peripheral surface of the cylindrical portion 11 at the position where the compression mechanism 40 is disposed, that is, the height position of the compression mechanism 40. Specifically, the average value of the distances from the fixing portion 49 to the inner peripheral surface of the cylindrical portion 11 falls within the range from 0.00 mm or more to 0.15 mm or less in the entire fixing portion 49.

(4-3) Third Step: Fixation of motor 20

The manufacturing method also includes fixing the motor 20 to the cylindrical portion 11 by shrink fitting. Specifically, first, the cylindrical portion 11 is heated, so that the first dimension D1 slightly increases. Next, the motor 20 is inserted into the cylindrical portion 11. Finally, the cylindrical portion 11 is cooled by radiating heat, so that the first dimension D1 decreases. The cylindrical portion 11 thus firmly holds the stator 21 of the motor 20.

(5) Features

(5-1)

The fixing portion 49 of the compression mechanism 40 is in tight contact with the cylindrical portion 11 of the casing 10. This configuration therefore enables firm fixation of the compression mechanism 40 to the casing 10. This configuration thus suppresses vibrations of the compressor 5.

(5-2)

The fixing portion 49 of the compression mechanism 40 occupies 80% or more of the overall circumference of the inner peripheral surface of the cylindrical portion 11. This configuration therefore enables tight contact of the compression mechanism 40 with the casing 10 over a wide range. This configuration thus further suppresses vibrations of the compressor 5.

(5-3)

The average value of the distances from the fixing portion 49 of the compression mechanism 40 to the inner peripheral surface of the cylindrical portion 11 is small. This configuration therefore further enhances the degree of tight contact of the fixing portion 49 with the inner peripheral surface. This configuration thus further suppresses vibrations of the compressor 5.

(5-4)

The four or more, preferably six or more weld portions 50 contribute to stiffness to the joints between the compression mechanism 40 and the cylindrical portion 11. This configuration thus further suppresses vibrations of the compressor 5.

(5-5)

The shaft support portion 61 is fixed to the cylindrical portion 11 at the weld portions 50. This configuration therefore shortens the difference in height from each weld portion 50 corresponding to the joint between the compression mechanism 40 and the cylindrical portion 11 to the center of gravity of the rotor 22. This configuration thus further suppresses vibrations of the compressor 5.

(5-6)

The motor 20 is firmly fixed by shrink fitting to the cylindrical portion 11. This configuration therefore suppresses wobbles of the motor 20 relative to the casing 10. This configuration thus further suppresses vibrations of the compressor 5.

(6) Modifications

(6-1) Fixation by Shrink Fitting

In the foregoing embodiment, the compression mechanism 40 is fixed by welding to the cylindrical portion 11. Alternatively, the compression mechanism 40 may be fixed by shrink fitting to the cylindrical portion 11. Specifically, first, the cylindrical portion 11 is heated, so that the first dimension D1 slightly increases. Next, the compression mechanism 40 is inserted into the cylindrical portion 11. Finally, the cylindrical portion 11 is cooled by radiating heat, so that the first dimension D1 decreases. The cylindrical portion 11 thus firmly holds the shaft support portion 61 of the compression mechanism 40. With this configuration, the compression mechanism 40 is brought into contact with 80% or more of the overall circumference of the cylindrical portion 11 at the position where the compression mechanism 40 is disposed, that is, the height position of the compression mechanism 40. An average value of distances from the cylindrical portion 11 to the compression mechanism 40 falls within a range from 0.00 mm or more to 0.15 mm or less in the overall circumference of the cylindrical portion 11.
This method enables contact of the compression mechanism 40 with the substantially overall circumference of the cylindrical portion 11. This method thus further suppresses vibrations of the compressor 5.

(6-2) Fixation by Press Fitting

In the foregoing embodiment, the compression mechanism 40 is fixed by welding to the cylindrical portion 11. Alternatively, the compression mechanism 40 may be fixed by press fitting to the cylindrical portion 11. Specifically, a strong force is applied to the compression mechanism 40, so that the compression mechanism 40 is inserted into the cylindrical portion 11 while the cylindrical portion 11 becomes elastically deformed. With this configuration, the compression mechanism 40 is brought into contact with 80% or more of the overall circumference of the cylindrical portion 11 at the position where the compression mechanism 40 is disposed, that is, the height position of the compression mechanism 40. An average value of distances from the cylindrical portion 11 to the compression mechanism 40 falls within a range from 0.00 mm or more to 0.15 mm or less in the overall circumference of the cylindrical portion 11.
This method enables contact of the compression mechanism 40 with the substantially overall circumference of the cylindrical portion 11. This method thus further suppresses vibrations of the compressor 5.

(6-3) Use of Multi-segment Expanded Tube

FIG. 8 illustrates a cylindrical portion 11 of a casing 10 for use in a compressor 5 according to a modification of the foregoing embodiment. In this modification, the cylindrical portion 11 is a multi-segment expanded tube. Specifically, the cylindrical portion 11 is produced with a tube expander. The cylindrical portion 11 thus includes eight or more inner diameter increased portions 121 and eight or more inner diameter decreased portions 122.
With this configuration, the inner diameter increased portions 121 are brought into contact with a compression mechanism 40, and the inner diameter decreased portions 122 are firmly pressed against the compression mechanism 40 while being elastically deformed. This configuration thus further suppresses vibrations of the compressor 5.

REFERENCE SIGNS LIST

5: compressor
10: casing
11: cylindrical portion
12: upper portion
13: lower portion
20: motor
21: stator
22: rotor
30: crank shaft
40: compression mechanism
41: cylinder
42: piston
43: compression chamber
44: passage
45: muffler
46: discharge hole
49: fixing portion
50: weld portion
61: shaft support portion
62: auxiliary shaft support portion
RA: axis of rotation

CITATION LIST

PATENT LITERATURE

Patent Literature 1: JP 2006-144731 A

Claims

A compressor (5) comprising:
a casing (10) including a cylindrical portion (11) having an inner diameter of a first dimension (D1);

a motor (20) including a rotor (22) having an outer diameter of a second dimension (D2); and

a compression mechanism (40) configured to compress a low-pressure refrigerant to generate the high-pressure refrigerant,

wherein

a ratio (D1/D2) of the first dimension to the second dimension is equal to or less than 1.8, and

the compression mechanism includes a fixing portion (49) being in tight contact with an inner peripheral surface of the cylindrical portion at a position where the compression mechanism is disposed.
The compressor according to claim 1, wherein
the fixing portion extends over the compression mechanism so as to occupy 80% or more of an overall circumference of the inner peripheral surface.
The compressor according to claim 1 or 2, wherein
an average value of distances from the fixing portion to the inner peripheral surface falls within a range from 0.00 mm or more to 0.15 mm or less in the entire fixing portion.
The compressor according to any one of claims 1 to 3, further comprising:
four or more weld portions (50) at which the compression mechanism is fixed to the cylindrical portion.
The compressor according to claim 4, comprising:
the weld portions the number of which is six or more.
The compressor according to claim 4 or 5, further comprising:
a crank shaft (30) fixed to the rotor and configured to rotate about an axis of rotation (RA),

wherein

the compression mechanism (40) includes:
a cylinder (41);

a piston (42) movable inside the cylinder; and

a shaft support portion (61) supporting the crank shaft in a rotatable manner, and the shaft support portion is fixed to the cylindrical portion at the weld portions.
The compressor according to any one of claims 1 to 6, wherein
the cylindrical portion is a multi-segment expanded tube including:
eight or more inner diameter increased portions (121); and

eight or more inner diameter decreased portions (122).
A method for manufacturing a compressor (5),
the manufacturing method comprising:
a step of preparing a cylindrical portion (11) having an inner diameter of a first dimension (D1), a motor (20) including a rotor (22) having an outer diameter of a second dimension (D2), and a compression mechanism (40) configured to compress a low-pressure refrigerant to generate the high-pressure refrigerant; and

a step of fixing the compression mechanism to the cylindrical portion such that a fixing portion (49) of the compression mechanism is brought into tight contact with an inner peripheral surface of the cylindrical portion,

wherein

a ratio (D1/D2) of the first dimension to the second dimension is equal to or less than 1.8.
The manufacturing method according to claim 8, wherein
the fixing portion extends over the compression mechanism so as to occupy 80% or more of an overall circumference of the inner peripheral surface.
The manufacturing method according to claim 8 or 9, wherein
the fixing step includes a step of welding the compression mechanism to the cylindrical portion at four or more positions.
The manufacturing method according to claim 10, wherein
in the fixing step, an average value of distances from the fixing portion to the inner peripheral surface falls within a range from 0.00 mm or more to 0.15 mm or less in the entire fixing portion.
The manufacturing method according to claim 8 or 9, wherein
the fixing step includes:
a step of increasing the first dimension by heat application to the cylindrical portion;

a step of inserting the compression mechanism into the cylindrical portion; and

a step of decreasing the first dimension by heat radiation from the cylindrical portion.
The manufacturing method according to claim 8 or 9, wherein
the fixing step includes a step of applying a strong force to the compression mechanism to insert the compression mechanism into the cylindrical portion while elastically deforming the cylindrical portion.
The manufacturing method according to any one of claims 8 to 13, further comprising:
a motor fixing step of fixing the motor to the cylindrical portion,

wherein

the motor fixing step includes:
a step of increasing the first dimension by heat application to the cylindrical portion;

a step of inserting the motor into the cylindrical portion; and

a step of decreasing the first dimension by heat radiation from the cylindrical portion.