JP3958302B2 - Heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger used in an engine EGR system or the like.

  The heat exchanger is used as an exhaust gas cooling device in, for example, an EGR (exhaust gas recirculation) system. In this EGR system, a part of the exhaust gas discharged from the exhaust manifold of the engine exhaust system is cooled by a heat exchanger (EGR cooler), and this exhaust gas is added to the air-fuel mixture in the intake system.

  As shown in FIG. 11, the heat exchanger 1 is provided with headers 4 and 5 at both ends of a cylindrical shell 2, and a flow of a coolant 13 (cooling water) flows at one end of the shell 2. The inlet 6 is provided with a coolant outlet 7 on the other end side. The inlet 6 and the outlet 7 are connected to elbow pipes 14 and 15 that form a coolant flow path, respectively. These elbow pipes 14 and 15 are bent at 90 ° in the vicinity of the connecting portion with the shell 2, and the piping is formed along the vicinity of the shell 2 due to a problem in the space of the engine room.

  As shown in FIG. 12, a plurality of tubes 8 are arranged in the shell 2, and the end portions of these tubes 8 are fixed to end plates 10 and 11 that close the respective end portions of the shell 2, and are attached to the end plates. It is the state which protruded from the provided through-hole. The exhaust gas 12 flowing in from the header 4 passes through the tube 8, is cooled during that time, and flows out from the header 5. In the EGR system, the amount of oxygen contained in the intake air is controlled by adding the cooled exhaust gas 12 to the air-fuel mixture, and the amount of NOx in the exhaust gas is reduced.

  Here, if the cooling of the gas in the heat exchanger 1 is insufficient, the temperature of the exhaust gas returned to the intake system becomes high, so that the volume expands and the gas concentration becomes lean, and the amount of exhaust gas required. Cannot be secured. In general, the heat release amount (cooling amount) and the flow resistance (exhaust gas pressure loss) in the heat exchanger 1 are in a directly proportional relationship. As techniques for efficiently cooling the gas, the inventions described in Patent Documents 1 to 3 are disclosed. In the invention of Patent Document 1, the fluid supply path is arranged at a position corresponding to the tangent of the vertical cross section of the fluid path, and a vortex or swirl flow is formed in the shell to prevent stagnation of the cooling water, thereby efficiently cooling. This is what I did.

JP 2003-83174 A JP 2000-292089 A JP 2000-266494 A

  Now, the above-mentioned EGR cooler of high-temperature gas of the shell & tube type (in which the tube 8 is built in the shell 2) causes local boiling when there is little coolant, and because the gas temperature is high, damage of the tube, etc. There are concerns about the impact on durability. On the other hand, in the cooler for vehicles, it is necessary to ensure the circulation of the coolant by the differential pressure, and it is an important issue to reduce the flow resistance of the coolant of the EGR cooler.

  Further, as diesel exhaust gas regulations are strengthened, the EGR gas flow rate and the required heat dissipation amount also increase. For this reason, measures such as increasing the shell diameter and increasing the number of tubes in the shell have been attempted, but in this case, the tube density in the shell will increase, so it is a problem to suppress an increase in the resistance of the coolant. It becomes.

  Especially in the engine room, due to space problems, it is often the case that the elbow pipe bent at 90 ° is used for piping, so that the vicinity of the equipment is often used and the pipe diameter cannot be made large. As a result, there is a problem that a necessary flow rate of the coolant cannot be secured.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a heat exchanger that is excellent in cooling efficiency and space saving due to reduction in resistance of the coolant.

  In order to solve the above technical problem, as shown in FIGS. 1 and 2, the heat exchanger according to the present invention includes a cylindrical shell 22 in which heat is exchanged internally and each end side of the shell. Headers 24 and 25 having gas inlets or outlets formed therein, end plates 30 and 31 interposed between the shell and the headers, and end portions between the end plates. A plurality of tubes 28 provided through each end plate, and pipes 34 and 35 through which fluid liquid passes, and a fluid liquid inlet 26 provided on a surface portion of the shell between the end plates or The expansion chamber portions 32 and 33 having an inner diameter larger than that of the pipe are connected to the outlet 27, and the pipe is communicated with the expansion chamber portion.

  In addition, the heat exchanger according to the present invention has a configuration in which the middle of the pipe is bent, and the portion beyond the bent portion is disposed so as to maintain a substantially constant distance from the surface of the shell. In addition, the pipe communicates with the front end of the expansion chamber sideways, and the pipe is arranged in a state of maintaining a substantially constant distance from the surface of the shell.

  In the heat exchanger according to the present invention, the inflow port and the outflow port are formed in a circular shape, and the diameter thereof is 1.3 times or more the inner diameter of the pipe formed in a circular tube shape. Furthermore, the said inlet and outlet are provided in the center part of the said tubes arrange | positioned on the outermost side of the said shell.

  Further, as shown in FIGS. 8 and 9, the heat exchanger according to the present invention has a cylindrical shell 23 in which heat is exchanged, and a gas inlet or outlet provided at each end of the shell. Headers 24 and 25 having portions formed therein, end plates 30 and 31 interposed between the shell and the headers, and a plurality of end plates provided between the end plates through the end plates. The pipe having the tube 28 and pipes 62 and 63 through which the fluid passes, and connected to the fluid liquid inlet 60 or outlet 61 provided on the surface of the shell between the end plates. The opening is formed in an oblique cross section, and this pipe is attached to be inclined with respect to the surface of the shell.

  The heat exchanger according to the present invention has a configuration in which the pipe is attached with an inclination angle of 45 ° to 75 ° with respect to the surface of the shell. Further, the middle of the pipe is bent at an angle larger than 90 °, and the portion ahead of the bent portion is arranged in a state maintaining a substantially constant distance from the surface of the shell.

  As described above, according to the heat exchanger according to the present invention, the expansion chamber portion whose inner diameter is larger than the pipe is provided at the fluid liquid inlet or outlet provided on the surface portion of the shell between the end plates. Since the pipe is connected to the expansion chamber, the flow resistance of the coolant passing through the inlet and the outlet is reduced, and the gas cooling effect is enhanced.

  Further, according to the heat exchanger according to the present invention, the pipe is bent in the middle, and the pipe communicates laterally with the distal end of the expansion chamber, so that the space can be saved around the heat exchanger. There is.

  Further, according to the heat exchanger according to the present invention, the inlet and outlet are formed in a circular shape, and the diameter thereof is set to 1.3 times or more of the inner diameter of the elbow pipe, so that the flow resistance of the coolant is efficiently reduced. There is an effect. Furthermore, since the inflow port and the outflow port are provided in the central portion between the outermost tubes, there is an effect that the flow resistance of the coolant is further reduced.

  Further, according to the heat exchanger according to the present invention, the fluid liquid inlet or outlet provided in the surface portion of the shell between the end plates is formed with an oblique opening in the pipe connected thereto. Since this pipe is configured to be inclined with respect to the surface of the shell, the flow resistance of the coolant passing through the inlet and outlet is reduced and the cooling effect is enhanced.

  Further, according to the heat exchanger according to the present invention, the pipe is attached with an inclination angle of 45 ° to 75 ° with respect to the surface of the shell, and the middle of the pipe is bent and formed at an angle larger than 90 °. Therefore, the space around the heat exchanger can be saved, and the flow resistance of the coolant passing through the pipe can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the heat exchanger is applied to an exhaust gas cooling device in an EGR system. As shown in FIGS. 1 and 2, the heat exchanger 20 is provided with headers 24 and 25 for inflow and outflow of the exhaust gas 12 at both ends of a cylindrical shell 22, respectively. A plurality of tubes 28 are arranged in the shell 22 at a predetermined interval in parallel with the axial direction of the shell 22, and both end portions of each tube are fixed to end plates 30 and 31, respectively.

  Further, an inlet 26 through which the coolant 13 (cooling water) flows is provided on one end side (inside between the end plates 30 and 31) of the shell 22, and a coolant outlet 27 is provided on the other end side. ing. An elbow pipe 34 is connected to the inflow port 26 through an expansion chamber portion 32, and an elbow pipe 35 is connected to the outflow port 27 through an expansion chamber portion 33.

  The elbow pipes 34 and 35 are circular pipes, and the vicinity of the connecting portion with the expansion chamber portions 32 and 33 is bent at 90 ° in order to secure a space. The tips of the elbow pipes 34 and 35 are arranged parallel to the surface of the shell 22 or maintained at a substantially constant interval. In this way, space is saved by arranging the elbow pipe along the surface of the shell 22. The bending direction of the elbow pipes 34 and 35 is free with respect to the shell 22 and is determined according to the layout or the like. Moreover, although the member which comprises a heat exchanger here consists of steel, and each was joined by brazing, this may be joined by general welding.

  The expansion chamber portion 32 has a cylindrical portion 36 having an inner diameter larger than the inner diameter of the elbow pipe 34 and a disk portion 37 formed at the upper portion and provided with a circular hole at the center. The configuration of the expansion chamber 33 is the same. The inner diameter of the cylindrical portion 36 is similar to the diameter of the inlet 26 and outlet 27 of the shell 22. The lower end portion of the cylindrical portion 36 of the expansion chamber portion 33 is connected to the peripheral surface portion of the inlet 26 of the shell 22, and the elbow pipe 34 is connected to the peripheral surface portion of the hole portion of the disc portion 37. Yes.

  The size of the inflow port 26 and the outflow port 27 is appropriate in a range in which the coolant 13 flowing from the elbow pipe 34 can diffuse without resistance, and in a range in which the coolant 13 flowing in the elbow pipe 35 can pass without resistance. is there. In this embodiment, the diameter of the circular inlet 26 provided in the shell 22 is 1.5 times larger than the inner diameter of the elbow pipe 34, but this is in the range of 1.3 times to 2 times (preferably 1.5 times to 2 times) is preferable. If the range is within 1.3 times, the influence of the resistance of the coolant at the inlet 26 and the outlet 27 is large. On the other hand, the effect of reducing the resistance of the coolant can be expected even if the above range is expanded more than twice. In addition, there are problems in strength and bonding.

  Further, as shown in FIG. 2, the inlet 26 and the outlet 27 are arranged such that the center of each mouth is located at the center between the outermost tubes 28 arranged in the shell 22. . A gap is provided between the tubes 28 for circulation of the cooling liquid. By positioning the inlet and the outlet at the central portion, the influence of the circulation resistance by the tubes 28 is reduced, and the cooling liquid As a heat exchanger, the exhaust gas cooling effect is improved.

  As described above, in the heat exchanger 20, the expansion chamber portions 32 and 33 having an inner diameter larger than the inner diameter of the elbow pipe are provided, and the cooling liquid is passed through the expansion chamber portion, thereby reducing the flow resistance of the cooling liquid. . As shown in FIG. 2, the flow of the cooling liquid that passes through the inlet and outlet of the shell is diffused by the above-described expansion chamber, so that the circulation is improved, and the resistance by the tube 28 at the end of the flow is also reduced. Because. On the other hand, when the expansion chamber is not provided, the influence of the resistance at the inlet and outlet of the shell and the resistance of the tube 28 at the end of the flow is large, and the flow resistance of the coolant is large.

  FIG. 3 shows an in-house test of the heat exchanger 20 having the pipe base expanded (φ22) and provided with the expansion chamber, and a conventional heat exchanger directly connected to the elbow pipe (φ16) not provided with the expansion portion. This shows the results. About the structure except this expansion chamber part, the conditions of each heat exchanger are the same. Here, the test was performed using an elbow pipe having an outer diameter of φ = 16 mm (inner diameter of 14 mm) and an expansion chamber having an outer diameter of φ = 22 mm (inner diameter of 20 mm). This test measures water resistance (ΔPw: pressure water) kPa against water flow rate (Vw: volumetric water) L / min. As a result, regardless of the water flow rate, it was possible to obtain a result that the water resistance was reduced by providing the expansion chamber portion in which the root of the pipe was expanded at a substantially constant rate, and the effect could be confirmed.

  4 and 5 show the exhaust gas inflow side of a heat exchanger provided with another embodiment of the expansion chamber (the same applies to the exhaust gas outflow side). The expansion chamber portion 40 of the heat exchanger of FIG. 4 is gradually enlarged in inner diameter from the tip portion connected to the elbow pipe 34, and the rear end portion is connected to the inlet 26 formed with a diameter substantially the same as this inner diameter. It is a form to be done.

  In addition, the expansion chamber portion 42 of the heat exchanger shown in FIG. 5 has a configuration in which the inner diameter is expanded in a cap shape from the tip portion connected to the elbow pipe 34 and the rear end portion is connected to the inlet 26 having substantially the same inner diameter. is there. In any of the above forms, the diameter of the inlet 26 can be increased by providing the expansion chamber portion, whereby the flow of the cooling liquid is diffused to improve the flow, and the tube 28 positioned ahead in the flow direction. The resistance due to is reduced.

  FIG. 6 shows the exhaust gas inflow side of the heat exchanger provided with the expansion chamber 44 of still another form (the same is true for the exhaust gas outflow side). The enlarged chamber portion 44 of this form is composed of a cylindrical tube member 48 of a predetermined length whose front end portion is closed in a flat shape, and the lower end portion is connected to the inlet 26 of the shell 22, while the tube member 48. A straight pipe 46 is communicated in a right angle direction with a hole 49 provided on the side surface of the upper portion. Therefore, the expansion chamber portion 44 has a form forming a part of the elbow pipe. In this form, the elbow pipe is not particularly necessary.

  The expansion chamber portion 50 of the heat exchanger shown in FIG. 7A is composed of a cylindrical tube member 52 having a tip formed in a spherical shape, and a lower end portion is connected to the inlet 26 of the shell 22, and the tube The pipe 46 is connected to the hole 53 provided on the side surface of the upper part of the member 52 at a right angle. The expansion chamber portion 54 of the heat exchanger shown in FIG. 7B is composed of a trumpet-shaped cylindrical member 56 whose front end portion is closed, and a lower end portion is connected to the inlet 26 of the shell 22, A pipe 46 is connected to a hole 57 provided on the upper side surface in a direction orthogonal to the axis of the cylindrical member 56.

  In any of the forms of the heat exchangers shown in FIGS. 6 and 7, the diameter of the inlet 26 of the shell 22 can be increased by providing the enlarged chamber portion, whereby the flow of the coolant is diffused and flows. And the resistance by the tube 28 located at the tip of the flow is reduced. Moreover, since these expansion chamber parts 44 and 50 have a larger inner diameter than the inner diameter of the pipe 46, they circulate from the pipe 46 to the expansion chamber part at a right angle (or from the expansion chamber part to the pipe 46). The circulation resistance of the coolant is small, and the flow of the coolant is good also in this respect.

  Thus, according to the above embodiment, there is an effect that the flow resistance of the cooling liquid at the inlet and outlet of the heat exchanger is reduced and the gas cooling effect is enhanced. Also, by aligning the position of the inlet and outlet of the coolant with the central part between adjacent tubes, and positioning the inlet and outlet at this part, the circulation of the coolant is improved and the passage resistance is increased. As a result, the cooling effect of the exhaust gas is improved and the EGR system functions well. Furthermore, since the pipe is configured as an elbow pipe in which the middle of the circular tube is bent at a right angle, there is an effect that the space around the heat exchanger (EGR cooler) in the engine room can be reduced.

  8 and 9 show a heat exchanger (EGR cooler) according to the second embodiment. As in the case of the heat exchanger 20, the heat exchanger 21 as a whole is provided with headers 24 and 25 at both ends of a cylindrical shell 23, and the shell 23 is parallel to the axial direction of the shell. A plurality of tubes 28 are arranged at predetermined intervals, and both end portions of each tube 28 are fixed to end plates 30 and 31, respectively.

  Further, the heat exchanger 21 has an inlet 60 through which the coolant 13 flows into one end side (the inner side between the end plates 30 and 31) of the shell 23, and an outlet through which the coolant flows out to the other end side. 61 are formed, and elbow pipes 62 and 63 each formed of a bent circular pipe are connected to the inlet 60 and the outlet 61, respectively. Further, as shown in FIG. 9, the coolant inlet 60 and outlet 61 are arranged so that the center of each port is located at the center between the outermost tubes 28 arranged in the shell 23. The flow resistance of the coolant is reduced.

  As shown in FIG. 10, the inflow port 60 has an elliptical shape. The reason why the inflow port 60 is thus elliptical is that the elbow pipe 62 is inclined and fixed from the upright position of 90 ° with respect to the surface of the shell 23 (tangential direction). By doing so, the area of the inflow port 60 can be increased, and the resistance of the coolant 13 can be reduced. The outflow port 61 is similarly elliptical.

  Further, the elbow pipe 62 is bent at an angle of 90 ° or more in the vicinity of the connecting portion with the shell 23 in order to save space. The bending angle (β °) is related to the inclination angle (α °) of the elbow pipe 62. Normally, the bending angle (β °) is an angle obtained by subtracting the inclination angle (α °) from 180 ° (β °). = 180 ° −α °). In this embodiment, the inclination angle α ° is about 50 °. In this case, the bending angle β ° is 130 °.

  Due to the relationship between the inclination angle (α °) and the bending angle (β °), the direction of the tip of the elbow pipe 62 after being bent is parallel to the surface of the shell 23. In this way, the elbow pipe is fixed to the shell with an inclination angle, and the elbow pipe is bent at an obtuse angle of 90 ° or more, whereby the resistance of the coolant passing through the elbow pipe is reduced.

  The inclination angle is about 50 ° here, but this is preferably in the range of 45 ° to 75 °. If the angle of inclination is less than 45 °, the inflow direction of the coolant flowing into the shell is too biased toward the surface of the shell, which hinders cooling, and if it is greater than 75 °, the elbow pipe has a large bending angle. Since this is not possible, the resistance of the coolant cannot be sufficiently reduced.

  Further, as shown in FIG. 10C, the cooling liquid 13 discharged from the elbow pipe 62 is directed toward the end plate 30 by arranging the direction of the inclination angle of the elbow pipe 62 toward the end plate 30 of the shell 23. After a while, the direction is changed by the end plate 30 and flows toward the outlet 61. For this reason, the coolant 13 spreads over the entire shell 23 relatively, and the cooling efficiency is also improved in this respect.

  Therefore, according to the second embodiment described above, the elbow pipe is inclined with respect to the shell and the shell is provided with an elliptical opening so as to form a large liquid passage range. The flow resistance of the coolant at the outlet is reduced, and the gas cooling effect is enhanced. In addition, the position of the inlet and outlet of the coolant is aligned with the central portion between the adjacent tubes, and the inlet and outlet are positioned at this location, so that the coolant can flow and resistance to flow is reduced. Reduced. Further, by forming the elbow pipe at a bending angle larger than 90 °, the flow resistance of the coolant passing through the elbow pipe is reduced, the exhaust gas cooling effect is improved, and the heat exchanger (EGR cooler in the engine room) is also improved. ) Has the effect of requiring less space around.

It is a figure which shows the heat exchanger which concerns on 1st embodiment of this invention. It is a figure which concerns on 1st embodiment and shows the cross section of a shell. It is a figure which concerns on 1st embodiment and shows the result of an in-house test. It is a figure which shows the expansion chamber part of another form in connection with embodiment, (a) is a partial plane, (b) is a side view, (c) is a figure which shows a partial front. It is a partial front view of the further another form of the expansion chamber part of another form in connection with embodiment. It is a figure which shows one expanded chamber part concerning embodiment, (a) is a partial plane, (b) is a side view, (c) is a figure which shows a partial front. It is a figure which concerns on embodiment, and is a figure which shows the other expansion chamber part of another form, (a) (b) is a figure which shows a partial front, respectively. It is a figure which shows the heat exchanger which concerns on 2nd embodiment of this invention. It is a figure which concerns on 2nd embodiment and shows the cross section of a shell. It is related with embodiment, (a) is a figure which shows a partial plane, (b) is a side surface, (c) is a figure which shows a partial front. It is a figure which shows the heat exchanger which concerns on a prior art example. It is a figure which concerns on a prior art example and is a figure which shows the cross section of a shell.

Explanation of symbols

22, 23 Shell 24, 25 Header 26, 60 Inlet 27, 61 Outlet 28 Tube 30, 31 End plate 32, 33, 40, 42, 44, 50, 54 Expansion chamber 34, 35, 46, 62, 63 Pipe (elbow pipe)

Claims (4)

A cylindrical shell with heat exchange inside;
A header provided on each end side of the shell, and formed with a gas inlet or outlet;
An end plate interposed between the shell and each header;
Between these end plates, a plurality of tubes provided with end portions penetrating each end plate;
A pipe through which the coolant passes,
The coolant inlet and outlet provided on the surface of the shell between the end plates are formed in a circular shape, and the diameter thereof is in the range of 1.5 to 2 times the inner diameter of the pipe formed in a circular tube shape. In addition, an expansion chamber portion having an inner diameter similar to that of the inflow port and the outflow port is connected, the pipe is connected to the expansion chamber portion , and the tip portion of the pipe is the surface of the shell. disposed in a state to maintain a substantially constant spacing, the heat exchanger, wherein the inlet and outlet, and this was provided in the central portion of the tube between which is disposed on the outermost side of the shell.   2. The heat exchanger according to claim 1, wherein the pipe is bent in the middle, and a portion ahead of the bent portion is disposed so as to maintain a substantially constant distance from the surface of the shell.   2. The heat exchanger according to claim 1, wherein the pipe communicates laterally with the tip of the expansion chamber, and the pipe is disposed in a state of maintaining a substantially constant distance from the surface of the shell. A cylindrical shell with heat exchange inside;
A header provided on each end side of the shell, in which a gas inlet or outlet is formed;
An end plate interposed between the shell and each header;
Between these end plates, a plurality of tubes provided with end portions penetrating each end plate;
A circular pipe through which the coolant passes,
The coolant inlet and outlet provided on the surface of the shell between the end plates are formed in an elliptical shape, and the opening of the pipe to be connected thereto is formed in an oblique cross-section, and the pipe is connected to the shell. An inclination angle of 45 ° to 75 ° is provided with respect to the surface of the pipe, and the direction of the pipe is attached toward the end plate of the shell to discharge the coolant from the pipe toward the end plate,
A heat exchanger characterized in that an intermediate portion of the pipe is bent at an angle larger than 90 °, and a portion ahead of the bent portion is disposed in parallel with the longitudinal direction of the shell .

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