Abstract:
An oil separator includes a cylindrical first separating section having a first inner space where the refrigerant can swirl; a cylindrical second separating section disposed below the first separating section and having a second inner space where the refrigerant can swirl; an introduction tube sending the refrigerant toward an inner wall of the first separating section so that a swirl flow occurs; a delivery tube delivering the separated refrigerant; and an exhaust pipe discharging the separated refrigerant oil, the second separating section having a surface connecting the inner wall of the first separating section and an upper end of an inner wall of the second separating section and forming a step, and an angle between the surface and the inner wall of the first separating section and an angle between the surface and the inner wall of the second separating section being 90 degrees or smaller.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an oil separator that separates refrigerant oil from a refrigerant containing the refrigerant oil and a method for producing the oil separator. 
     2. Description of the Related Art 
     In general, refrigerant oil is used to lubricate a compressor for use in an air-conditioning device or the like. This refrigerant oil circulates through a refrigerant circulatory system together with a refrigerant. The refrigerant oil taken in from the intake side of the compressor is supplied to each slide member provided in the compressor and is used for lubrication of each slide member. In addition, the refrigerant oil is also supplied to a working chamber. The refrigerant oil seals a gap in the working chamber, thereby preventing leak of vaporized refrigerant. 
     In the circulatory system, in a case where the refrigerant ejected from the compressor contains a large amount of refrigerant oil, the refrigerant oil is likely to adhere to an inner wall surface of a heat-transfer tube of a heat exchanger. The refrigerant oil adhering to the inner wall surface of the heat-transfer tube inhibits heat transfer of the heat-transfer tube and thereby deteriorates the heat-transfer efficiency of the heat exchanger. In order to avoid such a situation, an oil separator is provided in the circulatory system. The oil separator separates the refrigerant oil from the refrigerant ejected from the compressor and brings this refrigerant oil back to the intake side of the compressor. 
     The high-temperature and high-pressure refrigerant containing refrigerant oil ejected from the compressor is introduced into a cylindrical oil separator so that a swirl flow occurs. A centrifugal force produced by this swirl flow causes the refrigerant oil to adhere to an inner wall surface of the oil separator. This refrigerant oil moves to a lower portion of the oil separator due to gravity and forms an oil pool. In this way, the refrigerant oil is separated from the refrigerant. 
     However, the aforementioned oil separator has a problem that the refrigerant brings up the refrigerant oil in the oil pool together with the refrigerant and carries the refrigerant oil to the ejection path for the refrigerant. In view of the problem, Japanese Unexamined Patent Application Publication No. 2005-180808 proposes an oil separator that is configured so that an inner diameter of a lower portion of the oil separator is larger than that of an upper portion of the oil separator. This reduces the swirl speed of the swirl flow in the lower portion of the oil separator, thereby keeping the refrigerant from bringing up the refrigerant oil together with the refrigerant. 
     Furthermore, Japanese Unexamined Patent Application Publication No. 2005-180808 mentions that the inner diameter gradually decreases from the upper portion of the oil separator to the central portion of the oil separator, and the inner diameter gradually increases from the central portion of the oil separator to the lower portion of the oil separator. According to Japanese Unexamined Patent Application Publication No. 2005-180808, this increases the swirl speed of the swirl flow in the central portion of the oil separator and rectifies the flow, thereby achieving a good separating property. 
     SUMMARY 
     However, the separating property of the conventional oil separator is not sufficient. 
     One non-limiting and exemplary embodiment provides an oil separator that has an improved refrigerant oil separating property and a method for producing the oil separator. 
     In one general aspect, the techniques disclosed here feature an oil separator that separates refrigerant oil from a refrigerant containing the refrigerant oil, including: a first separating section that has a cylindrical shape and that has a first inner space in which the refrigerant is capable of swirling by which refrigerant oil is at least partially separated from refrigerant; a second separating section that is disposed below the first separating section, the second separating section having a cylindrical shape and having a second inner space in which the refrigerant that has flowed out from the first separating section is capable of swirling by which refrigerant oil is at least partially separated from refrigerant; an introduction tube that causes a swirl flow of the refrigerant to occur in the first inner space by causing the refrigerant to flow out toward an inner wall surface of the first separating section; a delivery tube that delivers the refrigerant from which the refrigerant oil has been separated; and an exhaust pipe that discharges, from the second inner space, the refrigerant oil separated from the refrigerant, the second separating section having a surface that connects the inner wall surface of the first separating section and an upper end of an inner wall surface of the second separating section and that forms a step, and an angle between the surface and the inner wall surface of the first separating section being 90 degrees or smaller and an angle between the surface and the inner wall surface of the second separating section being 90 degrees or smaller. 
     The oil separator according to the present disclosure has an improved refrigerant oil separating property. 
     It should be noted that general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. 
     Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and/or advantages may be individually obtained by the various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and/or advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating an example of a configuration of an oil separating device according to an embodiment of the present disclosure; 
         FIG. 2A  is a view for explaining angles of a surface of a step; 
         FIG. 2B  is a view for explaining angles of a surface of a step; 
         FIG. 3  is a view for explaining an example of the way in which an introduction tube is disposed; 
         FIG. 4A  is a view for explaining parameters used for property analysis of the oil separator; 
         FIG. 4B  is a view for explaining parameters used for property analysis of the oil separator; 
         FIG. 5  is a view illustrating a relationship between a pressure loss ΔPS and a ratio (D 1 −D 2 )/D 1 ; 
         FIG. 6  is a view illustrating a relationship between an oil separation rate and a ratio D 1 /(D 1 −D 2 ); 
         FIG. 7  is a view illustrating an example of a pressure distribution of an oil separator having a step; 
         FIG. 8  is a view illustrating a flow line of an oil droplet of refrigerant oil under the pressure distribution illustrated in  FIG. 7 ; 
         FIG. 9  is a view illustrating a relationship between a pressure loss ratio and an inner diameter D 1  of a first separating section; and 
         FIG. 10  is a view illustrating a relationship between a ratio between oil separation rates and the inner diameter D 1  of the first separating section. 
     
    
    
     DETAILED DESCRIPTION 
     As a result of diligent studies, the inventors of the present disclosure found that, in an oil separator utilizing a centrifugal force produced by a swirl flow, it is important for a refrigerant containing refrigerant oil to swirl for as long a time as possible in the oil separator. According to the oil separator disclosed in Japanese Unexamined Patent Application Publication No. 2005-180808, it is difficult to improve a swirling time in an upper space of the oil separator that contributes to oil separation. 
     An embodiment of the present disclosure is described below in detail with reference to the drawings. Note that the embodiment described below is merely an example, and the present disclosure is not limited by this embodiment. 
       FIG. 1  is a view illustrating an example of a configuration of an oil separator  10  according to the embodiment of the present disclosure. The oil separator  10  is a device that separates refrigerant oil from a refrigerant containing the refrigerant oil. The oil separator  10  includes a first separating section  11 , a second separating section  12 , an introduction tube  13 , a delivery tube  14 , and an exhaust pipe  15 .  FIG. 1  illustrates a cross section of the oil separator  10  taken along a plane that passes through the center of the oil separator  10  and that is parallel with a tube axis  13   a  of the introduction tube  13 . 
     The first separating section  11  and the second separating section  12  are cylindrical containers each having an inner space in which the refrigerant is capable of swirling. The second separating section  12  is provided below the first separating section  11 . An inner diameter D 2  of the second separating section  12  is smaller than an inner diameter D 1  of the first separating section  11 . This allows the swirling speed that has decreased during swirling in the first separating section  11  to be increased in the second separating section  12 , thereby improving the efficiency of oil separation. 
     The introduction tube  13  and the delivery tube  14  are provided so as to penetrate the first separating section  11 . The introduction tube  13  allows the refrigerant containing refrigerant oil to flow out towards the inner wall surface of the first separating section  11 , thereby producing a swirl flow of the refrigerant. The delivery tube  14  delivers, from the oil separator  10 , the refrigerant from which the refrigerant oil has been separated. 
     The refrigerant oil contained in the refrigerant adheres to the inner wall surface of the oil separator  10  due to the action of a centrifugal force produced by the swirl flow of the refrigerant. Thus, the refrigerant oil is separated from the refrigerant. Then, the refrigerant oil separated from the refrigerant moves to the bottom of the second separating section  12  due to gravity. 
     An net of the delivery tube  14  is desirably placed inside the second separating section  12 . This makes it possible to narrow an inner space of the second separating section  12  on the first separating section  11  side, thereby further increasing the swirling speed of the refrigerant flow in the second separating section  12 . 
     The exhaust pipe  15  is provided so as to penetrate the second separating section  12 . The exhaust pipe  15  allows the refrigerant oil that has moved to the bottom of the second separating section  12  to exit from the oil separator  10 . The refrigerant oil that has exited from the oil separator  10  is brought back again to the intake side of the compressor. 
     Since the refrigerant ejected from the compressor has a high temperature, the refrigerant oil that has moved to the bottom of the second separating section  12  can be brought back to an oil pool of a high temperature in a hermetically-sealed container of the compressor if the refrigerant oil that has moved to the bottom of the second separating section  12  has a high temperature. According to this arrangement, efficient operation of the compressor is possible. 
     The second separating section  12  is provided so as to face the inner space of the first separating section  11 . The second separating section  12  has a surface  16  that connects the inner wall surface of the first separating section  11  and an upper end of the inner wall surface of the second separating section  12 . The angle between the surface  16  and the inner wall surface of the first separating section  11  is set to 90 degrees or less, and the angle between the surface  16  and the inner wall surface of the second separating section  12  is also set to 90 degrees or less. 
     Accordingly, the first separating section  11  and the second separating section  12  form a step. That is, the inner diameter of the oil separator  10  rapidly changes at a boundary between the first separating section  11  and the second separating section  12 . 
       FIG. 2  is a view for explaining angles of the surface  16  of the step. In  FIG. 2 , the angle between the surface  16  of the step and the inner wall surface of the first separating section  11  is indicated by a and the angle between the surface  16  of the step and the inner wall surface of the second separating section  12  is indicated by β.  FIG. 2A  illustrates a case where both of the angles α and β are 90 degrees, and  FIG. 2B  illustrates a case where both of the angles α and β are smaller than 90 degrees. 
     By setting the angles of the surface  16  of the step to these angles, the direction of flow of the refrigerant in the vicinity of the wall of the container can be changed from a downward direction to a horizontal direction or to a direction pointing upward away from the horizontal direction. This makes it possible to prolong the duration of swirling of the refrigerant in the first separating section  11 , thereby promoting separation of the refrigerant oil from the refrigerant. Note that the following describes a case where both of the angles α and β are 90 degrees. 
       FIG. 3  is a view for explaining an example of the way in which the introduction tube  13  is disposed.  FIG. 3  is a cross-sectional view of the oil separator  10  taken along a horizontal plane that passes the tube axis  13   a  of the introduction tube  13 . As illustrated in  FIG. 3 , the direction of the tube axis  13   a  of the introduction tube  13  is deviated from the center direction of the first separating section  11 . 
     Accordingly, the refrigerant that has flowed out from the introduction tube  13  collides with the inner wall surface of the first separating section  11  from an oblique direction. This produces a swirl flow of the refrigerant. Then, the refrigerant oil contained in the refrigerant is separated from the refrigerant due to the action of the centrifugal force produced by this swirl flow. The refrigerant oil separated from the refrigerant adheres to the inner wall surface of the oil separator. 
     The oil separator  10  described above can be very easily produced. Specifically, it is only necessary to insert the second separating section  12  into the first separating section  11  and to use, as the surface  16  of the step, an upper end of the wall surface of the second separating section  12 . It is possible to achieve a reduction in cost of the device by employing such a production method. 
     In  FIGS. 1 and 3 , the introduction tube  13  is disposed laterally. Note, however, that the introduction tube  13  may be disposed longitudinally. In this case, in order to produce a swirl flow of the refrigerant, it is only necessary to bend a front end of the introduction tube  13  in a substantially horizontal direction in the first separating section  11 . 
     Next, a relationship between the inner diameter of the first separating section  11  and the inner diameter of the second separating section  12  is described on the basis of a result of the property analysis of the oil separator  10 .  FIG. 4  is a view for explaining parameters used for the property analysis of the oil separator  10 . 
     As illustrated in  FIG. 4A , it is assumed that the inner diameter of the first separating section  11  is D 1  (m), the inner diameter of the second separating section  12  is D 2  (m), and the inner diameter of the delivery tube  14  is D 3  (m). Furthermore, it is assumed that the average descent speed of the refrigerant in the space of the first separating section  11  from the height of the central axis of the introduction tube  13  to the height of the surface  16  of the step is V 1  (m/s) and that the average descent speed of the refrigerant in the space of the second separating section  12  from the height of the surface  16  of the step to the height of the inlet of the delivery tube  14  is V 2  (m/s). 
     As illustrated in  FIG. 4B , it is assumed that the area obtained by subtracting the area occupied by the delivery tube  14  from the area of the inner region of the first separating section  11  in a horizontal cross section of the oil separator  10  is A 1 , the area obtained by subtracting the area occupied by the delivery tube  14  from the area of the inner region of the second separating section  12  is A 2 , and the area occupied by the delivery tube  14  is A 3 . 
     In this case, the areas A 1  through A 3  are expressed as follows:
 
 A   1 =π( D   1 /2) 2 −π( D   3 /2) 2   equation 1
 
 A   2 =π( D   2 /2) 2 −π( D   3 /2) 2   equation 2
 
 A   3 =π( D   3 /2) 2   equation 3
 
     Moreover, assuming that the amount of refrigerant introduced from the introduction tube  13  is Q (m 3 /s) and that the refrigerant flows only in a downward direction in the space from the height of the central axis of the introduction tube  13  to the height of the net of the delivery tube  14 , the following equation is established:
 
 Q=A   1   V   1   =A   2   V   2   equation 4
 
     A pressure loss ΔPs that occurs due to the step as illustrated in  FIG. 4  can be estimated by the following equation:
 
Δ Ps= 0.5ζ ρV   2   2   equation 5
 
     Since the area A 3  is smaller than the areas A 1  and A 2  and does not have a large influence on the flow of the refrigerant, the presence of the delivery tube  14  is ignored in equation 5. 
     In equation 5, ζ is a loss coefficient that changes in accordance with the area ratio A 2 /A 1  and is obtained by way of experiment. Specifically, in a case where A 2 /A 1  is 0, 0.01, 0.1, 0.2, 0.4, 0.6, 0.8, or 1.0, values of ζ that correspond to these values of A 2 /A 1  are 0.5, 0.449, 0.372, 0.372, 0.292, 0.185, 0.09, and 0. 
       FIG. 5  is a view illustrating a relationship between the pressure loss ΔPs derived by using equations 1 through 5 and a ratio (D 1 −D 2 )/D 1 . In calculating the pressure loss ΔPs, the density ρ of the refrigerant was set to 90.6 kg/m 3 . This density is a density of a refrigerant R410A at 88.5 degrees C. The amount Q of introduced refrigerant was set to 0.0015 m 3 /s. The calculation was performed by setting the inner diameter D 2  of the second separating section  12  to 0.067 m, fixing the diameter D 3  of the delivery tube  14  to 0.019 m, and changing the inner diameter D 1  of the first separating section  11 . 
     The pressure loss that occurs in the oil separator  10  is several tens of kPa. Meanwhile, a pressure loss ΔPs that occurs due to the step is several Pa, which is a value that can be ignored as compared with the pressure loss that occurs in the oil separator  10 . However, this slight increase in the pressure loss suppresses descent of the refrigerant and works to maintain the swirl flow of the refrigerant in the space of the first separating section  11 . 
     This will be described. The refrigerant that is introduced into the inner space of the first separating section  11  through the introduction tube  13  collides with the inner wall surface of the first separating section  11  and flows in all directions along the inner wall surface. Then, the refrigerant that flows in a downward direction collides with the surface  16  of the step. This increases the pressure in the vicinity of the surface  16 , which in turn, inhibits flow of the refrigerant in the downward direction, thereby allowing the refrigerant to swirl for a long time in the first separating section  11 . As a result, separation of the refrigerant oil from the refrigerant is promoted. 
     As is clear from  FIG. 5 , when the ratio (D 1 −D 2 )/D 1  exceeds approximately 0.5, the inclination of the tangent to the graph of ΔPs rapidly decreases. That is, even if the ratio (D 1 −D 2 )/D 1  becomes larger than this value, a large increase in the pressure loss cannot be expected. 
     To increase the ratio (D 1 −D 2 )/D 1 , the inner diameter D 1  of the first separating section  11  is further increased or the inner diameter D 2  of the second separating section  12  is further reduced. However, from the perspective of a reduction of the width of the oil separator  10 , it is desirable that the inner diameter D 1  of the first separating section  11  be small. Furthermore, from the perspective of suppression of the pressure loss that occurs in the second separating section  12 , it is desirable that the inner diameter D 2  of the second separating section  12  be not so small. 
     Therefore, it is desirable that the relationship between the inner diameter D 1  of the first separating section  11  and the inner diameter D 2  of the second separating section  12  be
 
( D   1   −D   2 )/ D   1 ≦0.5  equation 6
 
     In other words, it is desirable that the relationship between the inner diameter D 1  of the first separating section  11  and the inner diameter D 2  of the second separating section  12  be
 
2 ≦D   1 /( D   1   −D   2 )  equation 7
 
     Next, a relationship between an oil separation rate obtained by modeling a motion equation by which an oil droplet of the refrigerant oil moves in a radial direction by the centrifugal force produced by the swirl flow and the ratio D 1 /(D 1 −D 2 ) is described.  FIG. 6  is a view illustrating a relationship between the oil separation rate and the ratio D 1 /(D 1 −D 2 ). The oil separation rate is one obtained by numerical experiments by using a prediction method proposed by Murakami et al. (Murakami, Wakamoto, Morimoto, “Performance Prediction of a Cyclone Oil Separator”, Transactions of Japan Society of Refrigerating and Air Conditioning Engineers, Vol. 22 (3), pp. 315-324, Sep. 30, 2005). 
     Specifically, the diameter of the oil droplet of the refrigerant oil was determined by using the Monte Carlo method so as to be within several tens of μm. Furthermore, it was determined from which position of the outlet of the introduction tube  13  the droplet was introduced. Then, the change in oil separation rate was examined while changing the ratio D 1 /(D 1 −D 2 ). The density ρ of the refrigerant was set to 90.6 kg/m 3 , the amount of introduced refrigerant was set to 0.0015 m 3 /s, the height of the first separating section  11  was set to 0.12 m, and the height of the second separating section  12  was set to 0.22 m. 
     As is clear from  FIG. 6 , when the ratio D 1 /(D 1 −D 2 ) becomes 18 or smaller, the oil separation rate rapidly increases. That is, it is desirable that the ratio D 1 /(D 1 −D 2 ) satisfy the following relationship:
 
 D   1 /( D   1   −D   2 )≦18  equation 8
 
     Next, an example of a pressure distribution of the oil separator  10  having a step is described.  FIG. 7  is a view illustrating an example of a pressure distribution of the oil separator  10  having a step.  FIG. 7  illustrates a result obtained by computational fluid dynamics (CFD). 
     In  FIG. 7 , each of the values surrounded by the rectangles is a pressure (Pa) of a line of equal pressure. A pressure specifying condition is set on an upper end surface of the delivery tube  14  in  FIG. 7  as an outlet boundary condition of an analysis region, and the pressure on this upper end surface is set to 0 (standard pressure). In the example of  FIG. 7 , the introduction tube  13  is disposed laterally, but the front end portion of the introduction tube  13  is bent in a substantially horizontal direction in the first separating section  11 . 
     As is clear from  FIG. 7 , the pressure in the vicinity of the surface  16  of the step is higher than that in a peripheral region around the surface  16  of the step. Accordingly, the direction of flow of the refrigerant changes from the downward direction to the horizontal direction. Thus, the flow of the refrigerant in the downward direction is inhibited. 
       FIG. 8  is a view illustrating a flow line of an oil droplet of the refrigerant oil under the pressure distribution illustrated in  FIG. 7 .  FIG. 8  illustrates a result obtained by DPM (Discrete Phase Model) analysis.  FIG. 8  illustrates how the direction of flow of the refrigerant changes due to the presence of a high-pressure region in the vicinity of the surface  16  of the step. 
     In a case where the volume Vol of the oil separator  10  is set constant, it is desirable that the inner diameter D 1  of the first separating section  11  satisfy the following relationship:
 
0.060 (m)≦ D 1≦0.095 (m)  equation 9
 
     Making the volume Vol constant means that the cost of materials for the oil separator  10  becomes almost constant. The following describes the derivation of this relationship. 
     It is assumed here that the volume Vol of the oil separator  10  is 0.0016 m 3  and that the inner diameter D 2  of the second separating section  12  is smaller than the inner diameter D 1  of the first separating section  11  by 0.006 m. Furthermore, it is assumed that the height of the first separating section  11  is 0.100 m and that the inner diameter D 3  of the delivery tube  14  is 0.019 m. 
       FIG. 9  is a view illustrating a relationship between a pressure loss ratio and the inner diameter D 1  of the first separating section  11 . The pressure loss ratio is a ratio ΔPt/ΔPt′, which is a ratio of the pressure loss ΔPt to a pressure loss ΔPt′ obtained in a case where D 1  is 0.067 m. 
     The pressure loss ΔPt and the pressure loss ΔPt′ are calculated by adding the pressure loss that occurs in cylindrical tube flow in the first separating section  11  and the pressure loss that occurs in cylindrical tube flow in the second separating section  12 . Note that evaluation of the pressure loss ΔPt and the pressure loss ΔPt′ except for the pressure loss that occurs due to a step or the like is conducted. 
     In this case, the pressure loss ΔPt can be approximated by the following equation:
 
Δ Pt =(λ h   1   /D   1 ×0.5ρ V   1   2   +λh   2   /D   2 ×0.5ρ V   2   2 )  equation 10
 
     where h 1  and h 2  are the height from the central axis of the introduction tube  13  in the first separating section  11  to the surface  16  of the step and the height of the second separating section  12 , respectively, and λ is a coefficient of pipe friction. 
     The pressure loss ΔPt/ΔPt′ can be calculated by using equation 10 and equation 4 as follows:
 
Δ Pt/ΔPt′={h   1   /D   1 ×(1 /A   1 ) 2   +h   2   /D   2 ×(1 /A   2 ) 2   }/{h   1   /D   1 ×(1 /A   1 ) 2   +h   2   /D   2 ×(1 /A   2 ) 2 }′  equation 11
 
     In equation 11, {h 1 /D 1 ×(1/A 1 ) 2 +h 2 /D 2 ×(1/A 2 ) 2 }′ is a value of {h 1 /D 1 ×(1/A 1 ) 2 +h 2 /D 2 ×(1/A 2 ) 2 } obtained in a case where D 1  is 0.067 m. A 1  and A 2  are calculated by using equations 1 and 2. Since the volume Vol of the oil separator  10  is constant, the following relationship is satisfied:
 
Vol= h   1   A   1   +h   2   A   2 =constant  equation 12
 
     A result of calculation of the pressure loss ratio ΔPt/ΔPt′ using the above relationship is illustrated in  FIG. 9 . As is clear from  FIG. 9 , when D 1  becomes approximately 0.060 (m) or smaller, the pressure loss ratio rapidly increases. A large pressure loss ratio is not preferable since a compressor that has higher ejection capability is needed to circulate the refrigerant. 
     It is therefore desirable that the inner diameter D 1  of the first separating section  11  satisfy the following relationship:
 
0.060 (m)≦ D 1  equation 13
 
       FIG. 10  is a view illustrating a relationship between a ratio of oil separation rates and the inner diameter D 1  of the first separating section  11 . The ratio of the oil separation rates is a ratio SO/SO′, which is a ratio of an oil separation rate SO to an oil separation rate SO′ obtained in a case where D 1  is 0.067 m. The model of the oil separator  10  is identical to that in the case of  FIG. 9 . The oil separation rates were obtained by numerical experiments by using the same method as that in the case of  FIG. 6 . 
     As is clear from  FIG. 10 , when D 1  becomes approximately 0.095 (m) or larger, the ratio of the oil separation rates rapidly decreases. It is therefore desirable that the inner diameter D 1  of the first separating section  11  satisfy the following relationship:
 
 D   1 ≦0.095 (m)  equation 14
 
     The relationship of equation 9 is obtained by using equations 13 and 14. 
     As described above, according to the present embodiment, it is possible to prolong a swirling time of a refrigerant containing refrigerant oil in the first separating section  11 , thereby improving a separation property of the refrigerant oil. 
     INDUSTRIAL APPLICABILITY 
     An oil separator according to the present disclosure is suitably used as an oil separator that separates refrigerant oil from a refrigerant containing the refrigerant oil for lubricating a compressor used in an air-conditioning device or the like, and a method for producing an oil separator according to the present disclosure is suitably used for production of the above oil separator.