JP5556644B2 - Multi-tube heat exchanger - Google Patents

Description

  The present invention relates to a multi-tube heat exchanger that provides heat exchange between a medium in an inner tube and a medium between the inner tube and the outer tube.

  Conventionally, various multi-tube heat exchangers are known. For example, Patent Documents 1 to 4 propose using a multi-tube heat exchanger as an internal heat exchanger of a refrigeration cycle. Moreover, patent document 5 has proposed utilizing a multi-tube heat exchanger as a heat exchanger of a refrigerant | coolant and water.

  Further, Patent Document 6 to Patent Document 10 propose forming a dimple-like convex portion or concave portion in a heat exchanger tube.

Patent No. 4350058 Japanese Patent No. 4350079 Japanese Patent No. 4246189 JP 2007-327706 A JP 2009-243715 A JP 2004-190923 A JP 2008-261666 A JP 2008-139008 A JP 2009-270755 A JP 2007-326142 A

  In the techniques of Patent Document 1 to Patent Document 5, heat exchange is promoted by forming a plurality of grooves in the inner tube and / or the outer tube. However, the heat exchange performance may be insufficient with only the grooves. For this reason, the multi-tube heat exchanger which can exhibit higher heat exchange performance was calculated | required.

  In the technique of Patent Document 6, dimples that protrude toward the flow path between the inner tube and the outer tube are formed on the outer tube. However, in this configuration, since the dimples are formed on the outer tube, there is a problem that the dimples do not sufficiently contribute to heat exchange between the inner and outer sides of the inner tube.

  In the techniques of Patent Documents 7 to 9, a groove is provided in the inner tube, and a dimple is further provided at the bottom of the groove. However, these dimples provide a recess on the outside of the inner tube and a protrusion on the inside of the inner tube. However, such a shape has a problem in that heat exchange between the inner tube and the medium between the inner tube and the outer tube is not sufficiently promoted.

  Furthermore, the technique of Patent Document 10 also provides dimples on the pipe. However, the dimples provide a recess on the outside of the inner tube and a protrusion on the inside of the inner tube. For this reason, there has been a problem that heat exchange between the inner tube and the medium between the inner tube and the outer tube is not sufficiently promoted.

  The present invention has been made in view of the above problems, and an object thereof is to provide a multi-tube heat exchanger that can promote heat exchange between the inner tube and the medium between the inner tube and the outer tube. It is to be.

  Another object of the present invention is a multi-tube heat exchange capable of suppressing the pressure loss of the medium inside the inner pipe while promoting the heat exchange between the inner pipe and the medium between the inner pipe and the outer pipe. Is to provide a vessel.

  Still another object of the present invention is to provide a multiple tube capable of suppressing the volume between the inner tube and the outer tube while promoting heat exchange between the medium between the inner tube and the outer tube and the inner tube. It is to provide a heat exchanger.

  Still another object of the present invention is to provide a multi-tube heat exchanger suitable for an internal heat exchanger for a refrigeration cycle in which a high-pressure refrigerant flows between an inner tube and an outer tube, and a low-pressure refrigerant flows inside the inner tube. It is to be.

  The present invention employs the following technical means to achieve the above object.

  The invention described in claim 1 includes an outer tube (20) and an inner tube (30) disposed inside the outer tube, and defines an outer passage (12) between the outer tube and the inner tube. At the same time, in the multi-tube heat exchanger (10) that divides the inner passage (13) inside the inner tube, the wall of the inner tube protrudes toward the outer passage by projecting toward the outer passage (36). 236, 336) and concave portions (37, 337) toward the inner passage, and a plurality of bulging portions (35, 235, 335) arranged away from each other along the medium flow direction in the outer passage. ) Is formed. According to this configuration, the heat exchange between the medium flowing in the outer passage and the inner pipe is promoted by the convex portion. And since a recessed part is arrange | positioned facing an inner side channel | path, the increase in the pressure loss in an inner side channel | path is suppressed. Moreover, since the convex part protrudes toward the outer passage, the volume of the outer passage is suppressed.

According to the first aspect of the present invention, flow path grooves (238, 338) that spirally form a recess toward the outer passage are formed in the wall of the inner tube, and the bulging portion is formed by the flow path groove ( 238, 338). According to this configuration, the convex portion promotes heat exchange between the medium flowing in the spiral flow channel and the inner tube.

The invention according to claim 1 is characterized in that the height (DH) in the radial direction of the convex portion is smaller than the depth in the radial direction of the flow path groove. According to this configuration, heat exchange between the medium and the inner tube is promoted without excessively increasing the pressure loss of the medium flowing through the spiral flow channel.

According to the first aspect of the present invention, the length (DL) of the convex portion with respect to the flow direction of the medium in the outer passage and the width (DW) of the convex portion with respect to the direction perpendicular to the flow direction of the high-pressure refrigerant in the outer passage (12) . Is characterized by being larger than the height of the outer passage between the bottom surface of the channel groove and the inner surface of the outer tube and smaller than the inner diameter of the outer tube. According to this configuration, heat exchange between the medium and the inner tube is promoted without excessively increasing the pressure loss of the medium flowing through the spiral flow channel.

In the invention according to claim 2 , the bulging portion is left between the grooves (32, 34, 238, 338) formed by deforming the wall of the inner tube from the radially outer side toward the inner side. It is provided by an island-shaped part. According to this configuration, an inner tube having a complicated shape having a plurality of bulges is easily manufactured from the material tube.

According to the third aspect of the present invention, the length (DL) of the convex portion with respect to the flow direction of the medium in the outer passage and the width (DW) of the convex portion with respect to the direction perpendicular to the flow direction of the high-pressure refrigerant in the outer passage (12) . Is characterized by being approximately equal. According to this configuration, heat exchange between the medium and the inner tube is promoted without excessively increasing the pressure loss of the medium flowing through the spiral flow channel.

The invention according to claim 4 is characterized in that the convex portions (36, 236, 336) have a shape corresponding to a part of a sphere. According to this configuration, heat exchange between the medium and the inner tube is promoted without excessively increasing the pressure loss of the medium flowing through the spiral flow channel.

According to a fifth aspect of the invention, the outer passage is a passage for the high-pressure refrigerant of the refrigeration cycle (1), the inner passage is the passage for the low-pressure refrigerant of the refrigeration cycle, and provides an internal heat exchanger of the refrigeration cycle. Features. According to this configuration, the heat exchange between the high-pressure refrigerant and the inner pipe is promoted by the convex portion. Moreover, the concave portion suppresses an increase in pressure loss of the low-pressure refrigerant while promoting heat exchange between the low-pressure refrigerant and the inner pipe. Further, since the volume of the outer passage is suppressed by the convex portion, the amount of high-pressure refrigerant having a high refrigerant density can be suppressed, and the amount of refrigerant sealed in the refrigeration cycle can be suppressed.

  Note that the reference numerals in parentheses described in the claims and the above-described means indicate the correspondence with the specific means described in the embodiments described later as one aspect, and are technical terms of the present invention. It does not limit the range.

It is a block diagram which shows the refrigerating cycle which concerns on 1st Embodiment to which this invention is applied. It is a fragmentary sectional view showing the multiple tube heat exchanger of a 1st embodiment. It is a perspective view which shows the inner tube | pipe of the multiple tube heat exchanger of 1st Embodiment. It is a perspective view which shows the flow of the high pressure refrigerant | coolant of 1st Embodiment. It is a perspective view which shows the flow of the low pressure refrigerant | coolant of 1st Embodiment. It is a side view which shows the inner tube | pipe of the multiple tube heat exchanger of 2nd Embodiment to which this invention is applied. It is a side view which shows the inner tube | pipe of the multiple tube heat exchanger of 3rd Embodiment to which this invention is applied. It is sectional drawing which shows the flow of the high pressure refrigerant | coolant of 3rd Embodiment. It is sectional drawing which shows the flow of the low voltage | pressure refrigerant | coolant of 3rd Embodiment.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly show that combinations are possible in each embodiment, but also combinations of the embodiments even if they are not explicitly stated unless there is a problem with the combination. Is also possible.

(First embodiment)
FIG. 1 is a block diagram showing a refrigeration cycle according to a first embodiment to which the present invention is applied. The refrigeration cycle 1 is a refrigeration cycle for vehicles mounted on a vehicle as a part of a vehicle air conditioner. The refrigeration cycle 1 includes a compressor 2, a heat exchanger 3 for heat dissipation, a decompressor 4, a heat exchanger 5 for heat absorption, and a plurality of pipes connecting these as an annular cycle. The compressor 2 sucks and compresses the low-pressure refrigerant and discharges the high-pressure refrigerant. The heat exchanger 3 exchanges heat between the high-pressure refrigerant discharged from the compressor 2 and the cooling medium and radiates heat from the high-pressure refrigerant. The heat exchanger 3 is also called a heat radiator or a condenser. The high-pressure refrigerant that has exited the heat exchanger 3 is supplied to the decompressor 4. The decompressor 4 decompresses the high-pressure refrigerant and supplies it to the heat exchanger 5. The decompressor 4 is also called an expansion valve. The heat exchanger 5 provides heat exchange between the low-pressure refrigerant supplied from the decompressor 4 and a medium to be cooled, for example, conditioned air. As a result, for example, conditioned air is cooled and cooling is provided. The heat exchanger 5 is also called a cooler or an evaporator. The low-pressure refrigerant that has exited the heat exchanger 5 is again sucked into the compressor 2. The compressor 2 and the heat exchanger 3 are disposed outside the vehicle compartment of the vehicle, for example, in the engine room. The heat exchanger 5 is arrange | positioned in the vehicle air conditioner.

  The refrigeration cycle 1 includes a multi-tube heat exchanger 10. A high-pressure pipe for supplying low-pressure refrigerant from the heat exchanger 3 to the decompressor 4 and a low-pressure pipe for supplying low-pressure refrigerant from the heat exchanger 5 to the compressor 2 are provided by a multi-tube heat exchanger 10. The multi-tube heat exchanger 10 is also called an internal heat exchanger.

  The multiple tube heat exchanger 10 is a double tube heat exchanger having an outer tube 20 and an inner tube 30. The outer tube 20 is manufactured from a straight tubular material tube having a round cross section. The inner tube 30 is manufactured from a straight tubular material tube having a round cross section. The inner tube 30 is inserted into the outer tube 20. The inner tube 30 is longer than the outer tube 20. Both end portions of the inner tube 30 further extend from both ends of the outer tube 20. The outer tube 20 and the inner tube 30 are joined by joint portions 51 and 52. The joint portions 51 and 52 are provided at both end portions of the outer tube 20. The joint portions 51 and 52 are a reduced diameter portion formed by slightly reducing the diameter of the end portion of the outer tube 20, and a brazing material that is disposed between the outer tube 20 and the inner tube 30 and joins the two. Is formed by. Branch pipes 61 and 62 are connected to both ends of the outer pipe 20.

  The multi-tube heat exchanger 10 is laid on the vehicle as piping for the refrigeration cycle 1. The multi-tube heat exchanger 10 has a plurality of bent portions 11 for laying on a vehicle. In the plurality of bent portions 11, due to the difference in deformation amount between the outer tube 20 and the inner tube 30, the inner surface of the outer tube 20 is strongly pressed against the outer surface of the inner tube 30, and the outer tube 20 pushes the inner tube 30. Tightened. Thereby, the inner tube 30 is fixed inside the outer tube 20.

  FIG. 2 is a partial cross-sectional view showing the multi-tube heat exchanger 10 of the first embodiment. In the drawing, the middle portion of the multiple tube heat exchanger 10 is omitted, and a partially broken cross section is shown with the outer tubes at both ends removed.

  The inner diameter of the outer tube 20 is larger than the maximum outer diameter of the inner tube 30. As a result, a gap is formed between the outer tube 20 and the inner tube 30. The gap and grooves 32 and 34 described later form the outer passage 12 between the outer tube 20 and the inner tube 30. The outer passage 12 is a passage through which the medium flows along the outer surface of the inner tube 30. The outer passage 12 provides a high-pressure passage through which high-pressure refrigerant flows. The joint portions 51 and 52 close the gap between the outer tube 20 and the inner tube 30 and close both ends of the outer passage 12. The internal passages of the branch pipes 61 and 62 communicate with the outer passage 12. The branch pipes 61 and 62 provide an inlet and an outlet of the outer passage 12.

  The inner tube 30 forms an inner passage 13 along the inner surface of the inner tube 30. The inner passage 13 provides a low pressure passage through which the low pressure refrigerant flows. The inner tube 30 has end portions 31a and 31b that leave the shape of the material tube at both ends thereof. The end portions 31 a and 31 b of the inner pipe 30 provide an inlet and an outlet of the inner passage 13.

  The inner tube 30 has a groove 32 formed by plastically deforming the wall of the material tube toward the inside in the radial direction. The groove 32 is formed from the position of the branch pipe 61 to the position of the branch pipe 62. The groove 32 forms an annular groove 33 a surrounding the entire circumference of the inner tube 30 corresponding to the position of the branch tube 61. The groove 32 forms an annular groove 33 b that surrounds the entire circumference of the inner pipe 30 corresponding to the position of the branch pipe 62. The annular groove 33 a functions as a distribution groove that distributes the high-pressure refrigerant to the entire circumference of the outer passage 12. The annular groove 33 b functions as a collecting groove for collecting high-pressure refrigerant from the entire circumference of the outer passage 12.

  The groove 32 forms a reticulated channel groove 34 between the annular groove 33a and the annular groove 33b. The net-like flow channel grooves 34 define bulging portions 35 for promoting heat exchange at portions corresponding to the meshes between the flow channel grooves 34. The bulging portion 35 protrudes from the outer surface of the inner tube 30 into the outer passage 12. The bulging portion 35 can also be referred to as a deformation portion formed on the wall of the inner tube 30. The bulging portion 35 can also be called a wart-like protruding portion, a dimple portion, or an embossed portion.

  FIG. 3 is a perspective view showing the inner tube 30 of the multiple tube heat exchanger 10 of the first embodiment. In the drawing, the outer tube 20 is cut and the inner tube 30 is exposed.

  The bulging portion 35 forms a convex portion 36 on the outer surface of the inner tube 30. The convex portion 36 protrudes from the surface of the inner tube 30 toward the outer tube 20. In other words, the convex portion 36 protrudes from the surface of the inner tube 30 toward the outer passage 12. The shape of the convex portion 36 is a hemispherical shape or a part of a sphere. The bulging portion 35 forms a concave portion 37 on the inner surface of the inner tube 30. The concave portion 37 is formed at a position corresponding to the convex portion 36. The shape of the recess 37 is hemispherical or a part of a sphere.

  The convex portion 36 has a height DH with respect to the radial direction of the inner tube 30. The height DH is smaller than the height of the outer passage 12 between the bottom surface of the flow channel 34 and the inner surface of the outer tube 20. The height DH is slightly smaller than the depth of the flow channel 34. In other words, the diameter of the virtual circle in which the apexes of the plurality of convex portions 36 are inscribed is slightly smaller than the outer diameter of the end portions 31a and 31b that leave the outer diameter of the material pipe. The height DH is slightly smaller than the radial height of the outer passage 12. It can be said that the height DH is substantially equal to the radial height of the outer passage 12. A part of the plurality of convex portions 36 comes into contact with the inner surface of the outer tube 20 through the apex thereof. As a result, contact between the bottom of the flow channel 34 and the outer tube 20 is avoided by the plurality of convex portions 36, and the outer passage 12 is maintained. Moreover, in the bending part 11, a part of some convex part 36 contacts the inner surface of the outer tube | pipe 20 strongly by the vertex. As a result, also in the bent portion 11, contact between the bottom portion of the flow channel 34 and the outer tube 20 is avoided by the plurality of convex portions 36, and the outer passage 12 is maintained.

  The convex portion 36 has a length DL with respect to the flow direction of the high-pressure refrigerant in the outer passage 12. The convex portion 36 has a width DW with respect to a direction perpendicular to the flow direction of the high-pressure refrigerant in the outer passage 12. In this embodiment, the length DL is slightly larger than the width DW. The length DL and the width DW can be set substantially equal. The length DL is sufficiently smaller than the inner diameter of the outer tube 20. The width DW is sufficiently smaller than the inner diameter of the outer tube 20. The width DW is sufficiently smaller than the length of the outer peripheral surface of the inner tube 30. In this embodiment, eight convex portions 36 are arranged in a row on the outer peripheral surface of the inner tube 30. A channel groove 34 is formed between the eight convex portions 36. Therefore, the width DW is shorter than 1/8 of the length of the outer peripheral surface of the inner tube 30. The width DW can be set shorter than 1/16 of the length of the outer peripheral surface of the inner tube 30. The length DL is formed between the annular groove 33a and the annular groove 33a so that ten or more convex portions 36 can be arranged apart from each other in the axial direction of the inner tube 30. It is sufficiently shorter than the length of the inner tube 30 between the groove 33b. The length DL and the width DW are larger than the height of the outer passage 12 between the bottom surface of the flow channel 34 and the inner surface of the outer tube 20. The width DW is set to be equal to or greater than the processing limit at which the convex portion 36 can be formed.

  The depth, length, and width of the concave portion 37 are smaller than the height DH, length DL, and width DW of the convex portion 36. The depth of the recess 37 is sufficiently smaller than the diameter of the inner passage 13 formed in the inner tube 30.

  The plurality of convex portions 36 are arranged on the outer surface of the inner tube 30 so as to be separated from each other. The plurality of convex portions 36 are arranged separately from each other along the circumferential direction of the inner tube 30. The plurality of convex portions 36 are arranged separately from each other even in the axial direction of the inner tube 30. The plurality of bulging portions 35 are arranged away from each other along the medium flow direction in the outer passage 12. The plurality of convex portions 36 are arranged in the outer passage 12 so as not to form a straight passage that continues straight along the axial direction of the inner tube 30. In other words, the plurality of convex portions 36 are arranged so that the high-pressure refrigerant flowing in the axial direction of the inner tube 30 along the outer surface of the inner tube 30 always collides with the convex portions 36. In the drawing, the flow of the high-pressure refrigerant is shown by arrows. The flow of the high-pressure refrigerant collides with the convex portion 36 and flows so as to bypass the convex portion 36.

  The plurality of convex portions 36 form a line arranged along the circumferential direction of the inner tube 30. A plurality of convex portions 36 are arranged in one row. In the example shown in the figure, eight convex portions form one row. As a result, with respect to the circumferential direction of the inner tube 30, the other two convex portions 36 are arranged close to both sides of the one convex portion 36. The plurality of convex portions 36 are arranged in a plurality of rows with respect to the axial direction of the inner tube 30. Further, when viewed along the axial direction of the inner tube 30, a plurality of convex portions are arranged such that one convex portion 36 in the downstream row is positioned between the two convex portions 36 belonging to the upstream row. A part 36 is arranged. In other words, the plurality of convex portions 36 are arranged so that the high-pressure refrigerant flowing in the axial direction of the inner tube 30 along the outer surface of the inner tube 30 repeats the collision with the plurality of convex portions 36. Thus, the height and arrangement of the plurality of convex portions 36 are set so as to greatly influence the flow of the high-pressure refrigerant in the outer passage 12 and greatly disturb the flow of the high-pressure refrigerant.

  Moreover, since the convex part 36 protrudes toward the outer side channel | path 12, the flow-path cross-sectional area of the outer side channel | path 12 is decreased. Further, the convex portion 36 reduces the volume of the outer passage 12. The high-pressure refrigerant that fills the outer passage 12 has a higher refrigerant density than the low-pressure refrigerant that fills the inner passage 13. For this reason, the convex part 36 contributes greatly in order to reduce the refrigerant | coolant amount enclosed in the refrigerating cycle 1. FIG.

  As described above, the recess 37 faces the inner passage 13. Further, as described above, the depth and diameter of the concave portion 37 are smaller than the height and diameter of the convex portion 36. Furthermore, the low-pressure refrigerant that fills the inner passage 13 has a lower refrigerant density than the high-pressure refrigerant that fills the outer passage 12. For this reason, the influence which the recessed part 37 has on the flow of a low pressure refrigerant | coolant is clearly smaller than the influence which the convex part 36 has on the flow of a high pressure refrigerant | coolant. Specifically, the depth and shape of the recess 37 are set so as to hardly increase the pressure loss of the low-pressure refrigerant.

  FIG. 4 is a perspective view showing the flow of the high-pressure refrigerant of the first embodiment. In the drawing, the flow of the high-pressure refrigerant is shown by arrows. The flow of the high-pressure refrigerant in the outer passage 12 depends on the shape and arrangement of the protrusions 36. When the flow of the high-pressure refrigerant collides with the convex portion 36, the flow direction is changed so as to bypass the convex portion 36. The flow of the high-pressure refrigerant flows so as to bypass the left and right sides of the convex part 36 or so as to bypass the convex part 36. Since the convex portion 36 is substantially equal to the height of the outer passage 12 in the radial direction, the flow of the high-pressure refrigerant flows along the convex portion 36 without being far away from the convex portion 36. Also, since the plurality of convex portions 36 are arranged in the circumferential direction of the inner tube 30, the flow of the high-pressure refrigerant flows along the convex portions 36 without being far from the convex portions 36. Therefore, the flow of the high-pressure refrigerant strongly collides with the convex portion 36. Further, the flow of the high-pressure refrigerant flows along the surface of the convex portion 36. Further, the flow of the high-pressure refrigerant generates many vortices on the downstream side of the convex portion 36. Such a flow of the high-pressure refrigerant reduces the temperature boundary layer between the high-pressure refrigerant and the inner pipe 30 and promotes heat exchange between the high-pressure refrigerant and the inner pipe 30.

  FIG. 5 is a perspective view showing the flow of the low-pressure refrigerant of the first embodiment. In the drawing, the flow of the high-pressure refrigerant is shown by arrows. The flow of the low-pressure refrigerant in the inner passage 13 changes the flow direction so as to flow into the recess 37 when it encounters the recess 37. A part of the flow of the low-pressure refrigerant generates a large and slow vortex in the upstream portion of the recess 36. Further, a part of the flow of the low-pressure refrigerant generates a vortex on the downstream side of the recess 36. These vortices reduce the temperature boundary layer between the low pressure refrigerant and the inner pipe 30 and promote heat exchange between the low pressure refrigerant and the inner pipe 30. However, the depth of the recess 37 is sufficiently smaller than the inner diameter of the inner tube 30. For this reason, the vortex generated by the recess 37 is small and the speed is low. On the other hand, since the concave portion 37 has little influence on the flow of the low-pressure refrigerant, the concave portion 37 hardly increases the pressure loss of the low-pressure refrigerant.

  The multi-tube heat exchanger 10 of this embodiment can be manufactured by the following manufacturing method. First, in the preparation step, a material tube as a material for the outer tube 20 and a material tube as a material for the inner tube 30 are prepared. Next, in the inner pipe processing step, the flow path groove 34 is formed by deforming the wall of the material pipe of the inner pipe 30 from the radially outer side to the inner side. At this time, the channel groove 34 is formed so as to leave a plurality of island-shaped portions between the channel grooves 34. In addition, the flow channel groove 34 is formed so that the island-like portion has the shape of the bulging portion 35. The bulging portion 35 is a portion left in the shape of an island when the flow channel 34 is formed by deforming the material pipe from the radially outer side toward the radially inner side. It can be said that the bulging portion 35 is formed by leaving a portion having a small amount of deformation from the material pipe in a mesh shape. As a result, a plurality of bulging portions 35 are provided. Next, in the insertion step, the inner tube 30 is inserted into the outer tube 20. Next, in the joining step, joining portions 51 and 52 are formed between the outer tube 20 and the inner tube 30. Furthermore, branch pipes 61 and 62 are joined to the outer pipe 20 in a subsequent process.

  In this embodiment, when the compressor 2 is operated, the refrigerant circulates in the refrigeration cycle 1. The refrigerant after having been radiated by the heat exchanger 3 and before being decompressed by the decompressor 4 flows through the outer passage 12 of the multi-tube heat exchanger 10. The refrigerant that has been absorbed by the heat exchanger 5 and before being pressurized by the compressor 2 flows through the inner passage 13 of the multi-tube heat exchanger 10. Therefore, the refrigerant flowing in the outer passage 12 has a higher pressure than the refrigerant flowing in the inner passage 13. Further, the refrigerant flowing in the outer passage 12 is at a higher temperature than the refrigerant flowing in the inner passage 13. The multi-tube heat exchanger 10 provides heat exchange between the high-pressure refrigerant before being supplied to the decompressor 4 and the low-pressure refrigerant after flowing out of the heat exchanger 5. The multi-tube heat exchanger 10 provides a function as an internal heat exchanger of the refrigeration cycle 1.

  According to this embodiment, heat exchange between the high-pressure refrigerant flowing in the outer passage 12 and the inner pipe 30 is promoted by the convex portion 36. Further, the heat exchange between the low-pressure refrigerant flowing through the inner passage 13 and the inner pipe 30 is promoted by the recess 37. As a result, heat exchange between the high-pressure refrigerant and the low-pressure refrigerant is also promoted. Here, the heat exchange promotion effect provided by the convex portion 37 is greater than the heat exchange promotion effect provided by the concave portion 37. In this embodiment, since the convex part 36 is formed so as to protrude into the outer passage 12, heat exchange between the high-pressure refrigerant having a high refrigerant density and the inner pipe 30 is greatly promoted. On the other hand, since the recess 37 faces the inner passage 13, an increase in pressure loss in the flow of the low-pressure refrigerant is suppressed. Further, the convex portion 36 presses the flow of the high-pressure refrigerant against the inner surface of the outer tube 20. For this reason, heat exchange between the outer tube 20 and the high-pressure refrigerant is also promoted. As a result, heat radiation from the high-pressure refrigerant to the outside of the outer tube 20 can be promoted.

  Moreover, since the convex part 36 protrudes toward the outer side channel | path 12 with which the refrigerant density was filled with the high pressure refrigerant | coolant, the volume of the outer side channel | path 12 is decreased. As a result, the amount of high-pressure refrigerant is reduced, and the amount of refrigerant enclosed in the refrigeration cycle 1 is also reduced. In addition, by forming the plurality of convex portions 36 by the island-shaped portions left between the flow channel grooves 34, the inner tube 30 having the plurality of convex portions 36 can be easily manufactured.

(Second Embodiment)
FIG. 6 is a side view showing the inner tube 230 of the multiple tube heat exchanger 10 of the second embodiment to which the present invention is applied. In the drawing, the outer tube 20 is cut and the inner tube 230 is exposed.

  In the first embodiment, the inner tube 30 has a net-like flow channel groove 34 formed by a groove 32. Instead, in this embodiment, the inner tube 30 has a plurality of spiral flow channel grooves 238 formed by the grooves 32. The channel groove 238 is formed in the wall of the inner tube and extends in a spiral shape. The channel groove 238 forms a recess toward the outer passage 12. The channel groove 238 is formed to communicate with the annular groove 33a at one end and to communicate with the annular groove 33b at the other end. The channel groove 238 provides the outer passage 12. Further, the inner tube 230 has a plurality of bulging portions 235 only in the flow channel groove 238. The bulging portion 235 forms a convex portion 236 on the outer surface of the inner tube 230. In one channel groove 338, a plurality of bulging portions 235, that is, a plurality of convex portions 236, are provided in a section where the channel groove 338 makes a round around the inner tube 30. The plurality of bulging portions 235 are arranged away from each other along the spiral flow direction of the high-pressure refrigerant in the outer passage 12. The convex portion 236 forms a constricted portion that partially narrows the channel cross-sectional area provided by the channel groove 238 in the channel groove 238. The convex part 236 has the same shape as the convex part 36 of the first embodiment.

  Between the plurality of flow channel grooves 238, a ridge-like bulge 239 that is convex toward the outer passage 12 and extends spirally is formed. The bulge 239 is a portion where the outer surface of the material pipe of the inner pipe 230 is left as it is. The bulge 239 has a width sufficiently larger than the bulging portion 235. The bulge 239 can partially contact the inner surface of the outer tube 20. The bulge 239 prevents strong contact between the bulging portion 235 and the outer tube 20 by contacting the inner surface of the outer tube 20, and protects the bulging portion 235.

  The flow channel groove 238 and the convex portion 236 can be formed by a manufacturing method in which the material pipe is deformed radially inward by a roller. The roller used in this manufacturing method is provided with a recess for forming the protrusion 236.

  In this embodiment, the high-pressure refrigerant in the outer passage 12 mainly flows in the flow channel 238. A part of the high-pressure refrigerant flows along the axial direction of the inner pipe 230 from one channel groove 238 toward the downstream channel groove 238 and over the ridge between them. Such a complicated flow facilitates heat exchange between the high-pressure refrigerant and the inner pipe 230. Furthermore, since the convex portion 236 is provided only in the flow channel groove 238 through which the high-pressure refrigerant flows, the flow of the high-pressure refrigerant concentrated in the flow channel groove 238 can be strongly disturbed. Further, the constricted portion provided by the convex portion 236 increases the flow of the high-pressure refrigerant over the peak portion between the flow channel groove 238 and the flow channel groove 238. As a result, heat exchange between the high-pressure refrigerant and the inner pipe 230 is further promoted.

(Third embodiment)
FIG. 7 is a side view showing the inner tube 330 of the multiple tube heat exchanger 10 of the third embodiment to which the present invention is applied. In the drawing, the outer tube 20 is cut and the inner tube 330 is exposed.

  Also in this embodiment, the inner tube 30 has a plurality of spiral flow channel grooves 338 formed by the grooves 32. The spiral channel groove 338 is formed so as to communicate with the annular groove 33a at one end and communicate with the annular groove 33b at the other end. The flow channel 338 provides the outer passage 12. Furthermore, the inner tube 330 has a plurality of bulging portions 335 only inside the flow channel groove 338. The bulging portion 335 forms a convex portion 336 on the outer surface of the inner tube 330. The convex part 336 has a shape similar to the convex part 36 of the first embodiment. The convex part 336 is formed in the flow path groove 338 having an arcuate concave cross section. For this reason, the outer edge of the convex part 336 is not clear, and the curved surface which changes gently from the concave surface of the flow-path groove 338 to the convex surface of the convex part 336 is formed.

  Between the plurality of flow channel grooves 338, a ridge-like bulge 339 that is convex toward the outer passage 12 and extends spirally is formed. The bulge 339 is a portion where the outer surface of the material pipe of the inner pipe 330 is left as it is. The bulge 339 has a width sufficiently larger than the bulging portion 335. The ridge 339 can partially contact the inner surface of the outer tube 20. The bulge 339 prevents direct contact between the bulging portion 335 and the outer tube 20 by making contact with the inner surface of the outer tube 20, and secures a flow path of high-pressure refrigerant radially outward from the bulging portion 335. .

  The convex portion 336 has a height DH with respect to the radial direction of the inner tube 30. The height DH is smaller than the radial depth of the flow channel 338. The height DH is smaller than the height of the outer passage 12 between the bottom surface of the flow channel 338 and the inner surface of the outer tube 20. The convex portion 336 has a length DL with respect to the flow direction of the high-pressure refrigerant in the outer passage 12. The convex portion 336 has a width DW with respect to a direction perpendicular to the flow direction of the high-pressure refrigerant in the outer passage 12. The length DL and the width DW are substantially equal. The length DL and the width DW are smaller than the width of the flow channel 338. The length DL and the width DW are larger than the height of the outer passage 12 between the bottom surface of the flow channel 338 and the inner surface of the outer tube 20 and smaller than the inner diameter of the outer tube 20. Further, the height DH and the width DW of the convex portion 336 can be set so that the cross-sectional area of the outer passage 12 mainly formed by one flow channel 338 is at least halved.

  Moreover, the number per unit area of the convex part 336 which the inner pipe | tube 330 has is smaller than the number per unit area of the convex part 236 which the inner pipe 230 of 2nd Embodiment has. The number of the convex portions 336 is set so as to adjust the pressure loss in the outer passage 12 to an appropriate value. In the illustrated example, the number of convex portions 336 provided in one flow channel groove 338 is three in a section in which one flow channel groove 338 goes around the inner tube 30. For this reason, the improvement of the performance by promotion of the heat exchange resulting from the convex part 336 and the increase in the pressure loss resulting from the convex part 336 are achieved.

  FIG. 8 is a cross-sectional view showing the flow of the high-pressure refrigerant of the third embodiment. In the drawing, a VIII-VIII cross section in FIG. 7 is shown. That is, in the drawing, a cross section along the extending direction of the flow path groove 338 is shown. In this embodiment, the flow component of the high-pressure refrigerant that flows along the bottom of the groove 338 is greatly disturbed by the convex portion 336. Further, since the high-pressure refrigerant flows in the groove 338 in a concentrated manner, the flow component of the high-pressure refrigerant flowing in the upper part of the groove 338 can be disturbed. As a result, heat exchange between the high-pressure refrigerant and the inner pipe 330 is promoted.

  FIG. 9 is a cross-sectional view showing the flow of the low-pressure refrigerant of the third embodiment. In the drawing, a IX-IX cross section in FIG. 7 is shown. That is, in the drawing, a cross section along the axial direction of the inner tube 330 is shown. Formed on the inner surface of the inner tube 330 is a pulse-like ridge 340 that is positioned corresponding to the groove 338 and protrudes toward the inner passage 13. The ridge 340 extends in a spiral shape. Of the flow components of the low-pressure refrigerant flowing through the inner passage 13, the flow component flowing along the inner surface of the inner pipe 330 collides with the ridge 340, changes the flow direction, and moves over the ridge 340. A recess 337 is formed only at a position corresponding to the protrusion 336 in the bulge 340. The flow component that collided with the ridge 340 and changed the flow direction then encounters the recess 337. However, since the flow component is after the flow direction is changed inward in the radial direction by the bumps 340, it is difficult for the flow component to flow into the recess 337. For this reason, the disturbance of the low-pressure refrigerant caused by the recess 337 is small in the upstream portion of the recess 337. In addition, the flow component flowing out from the recess 337 is small even at the downstream side of the recess 337. For this reason, also in the site | part of the downstream of the recessed part 337, disorder of the low voltage | pressure refrigerant | coolant resulting from the recessed part 337 is small. As a result, the influence of the concave portion 337 on the flow of the low-pressure refrigerant in the inner passage 13 is suppressed to be small.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. The structure of the said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  For example, the multi-tube heat exchanger 10 may be configured as a multi-tube that is more than a double tube such as a triple or quadruple. In such a configuration, of the two adjacent tubes, the tube located outside is the outer tube, and the tube located inside is the inner tube.

  Moreover, in the said embodiment, the shape of the convex parts 36, 236, and 336 was made into a part of sphere. It can replace with this and can adopt convex parts of various shapes, such as a truncated cone, a truncated pyramid, a triangular pyramid, a cylinder, a rectangular parallelepiped. Further, the shape of the convex portions 36, 236, and 336 may be formed into an elongated oval shape or a rectangular shape along the medium flow direction in the outer passage 12. In the above embodiment, the heights of the convex portions 36, 236, and 336 are made smaller than the depth of the flow channel groove 34. Alternatively, the height of the convex portion may be equal to the depth of the groove. That is, you may leave a part of raw material pipe | tube at the vertex of a convex part.

  Further, in place of the above embodiment, the number of convex portions 336 provided in one flow channel groove 338 is two or more or 15 in a section where one flow channel groove 338 goes around the inner tube 30. It can be as follows.

  Further, in the above embodiment, the flow channel groove 338 is still left even at the portion where the convex portion 336 is formed. Instead of this, the height DH and the width DW of the convex portion 336 may be set so as to completely fill one flow channel 338.

  Moreover, in the said embodiment, the bulging part was formed by the site | part left in the shape of an island between the groove | channels formed by deform | transforming the raw material pipe | tube of the inner pipe | tube 30 from radial direction outer side toward inner side. Instead of this, the bulging portion may be formed by deforming the wall from the inside of the material tube of the inner tube 30 toward the radially outer side. For example, hydroforming can be used.

  In the above embodiment, the outer tube 20 and the inner tube 30 are directly bonded at the bonding portions 51 and 52. Instead, a configuration in which a passage block that separates the outer passage 12 and the inner passage 13 is employed and the outer tube 20 and the inner tube 30 are connected to the passage block may be employed.

  DESCRIPTION OF SYMBOLS 1 Refrigeration cycle, 2 Compressor, 3 Heat exchanger, 4 Pressure reducer, 5 Heat exchanger, 10 Multi-tube heat exchanger, 11 Bending part, 12 Outer passage, 13 Inner passage, 20 Outer tube, 30 Inner tube, 31a End portion, 31b End portion, 32 groove, 33a annular groove, 33b annular groove, 34 mesh flow channel groove, 238 spiral flow channel groove, 338 spiral flow channel groove, 35 bulge portion, 235 bulge portion 335 bulge part, 36 convex part, 236 convex part, 336 convex part, 37 concave part, 337 concave part, 339 vein-like ridge, 340 vein-like ridge, 51 joint part, 52 joint part, 61 branch pipe, 62 branch tube.

Claims (5)

An outer tube (20);
An inner pipe (30) disposed inside the outer pipe,
In the multi-tube heat exchanger (10) which partitions an outer passage (12) between the outer tube and the inner tube and partitions an inner passage (13) inside the inner tube,
On the wall of the inner tube, a convex portion (36, 236, 336) is formed toward the outer passage by projecting toward the outer passage, and a concave portion (37, 337) is formed toward the inner passage. None, a plurality of bulges (35, 235, 335) disposed apart from each other in the flow direction of the medium in the outer passage are formed,
On the wall of the inner tube, flow channel grooves (238, 338) extending spirally toward the outer passage are formed,
The bulging portion is formed in the flow channel groove (238, 338),
The radial height (DH) of the convex portion is smaller than the radial depth of the flow channel groove,
The length (DL) of the convex portion with respect to the flow direction of the medium in the outer passage and the width (DW) of the convex portion with respect to the direction perpendicular to the flow direction of the high-pressure refrigerant in the outer passage (12) are A multi-tube heat exchanger characterized by being larger than a height of the outer passage between a bottom surface of a groove and an inner surface of the outer tube and smaller than an inner diameter of the outer tube. The bulging portion is provided by an island-like portion left between grooves (32, 34, 238, 338) formed by deforming the wall of the inner tube from the radially outer side toward the inner side. The multi-tube heat exchanger according to claim 1 , wherein The length (DL) of the convex part in the flow direction of the medium in the outer passage and the width (DW) of the convex part in the direction perpendicular to the flow direction of the high-pressure refrigerant in the outer passage (12) are substantially equal. The multi-tube heat exchanger according to claim 1 or 2 , characterized in that The multi-tube heat exchanger according to claim 3 , wherein the convex portion (36, 236, 336) has a shape corresponding to a part of a sphere. The outer passage is a passage for high-pressure refrigerant in the refrigeration cycle (1), the inner passage is a passage for low-pressure refrigerant in the refrigeration cycle, and provides an internal heat exchanger for the refrigeration cycle. The multi-tube heat exchanger according to any one of claims 1 to 4 .

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