JP2008064399A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger capable of improving corrosion resistance of a fin while ensuring heat exchanging performance. <P>SOLUTION: The heat exchanger for exchanging heat between intake air pressurized by a supercharger 3 and cooling air is provided with an inner fin 44, which is brought into contact with the intake air pressurized by the supercharger 3 to promote heat exchange between the intake air pressurized by the supercharger 3 and the cooling air. The inner fin 44 is constructed of a pure copper core material 44a and a tin-plated layer 44b formed on the surface of the core material 44a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat exchanger, and is effective when applied to an intercooler that cools combustion air (intake air) sucked into an internal combustion engine.

  Conventionally, in a heat exchanger made of pure copper or a copper alloy, pure copper has been used as a fin material in order to ensure high heat exchange performance.

  However, when such a heat exchanger is used in a corrosive environment (for example, seawater, snowmelt salt, automobile exhaust gas, etc.), the fins corrode, causing a decrease in heat exchange performance and a decrease in strength. There's a problem.

  On the other hand, it is conceivable to employ a copper alloy having corrosion resistance for the fin material.

  However, in a heat exchanger that employs a copper alloy as the fin material, there is a problem that the heat exchange performance is lowered because the copper alloy often has a significantly lower thermal conductivity than pure copper.

  An object of this invention is to provide the heat exchanger which can improve the corrosion resistance of a fin, ensuring heat exchange performance in view of the said point.

  In order to achieve the above object, according to the present invention, there is provided a heat exchanger for exchanging heat between a first fluid and a second fluid, which is in contact with at least one of the first fluid and the second fluid. And fins (44) for promoting heat exchange between the first fluid and the second fluid, and the fins (44) are made of a pure copper core material (44a) and the surface of the core material (44a). The first feature is that it is made of a coating material (44b) made of a metal having corrosion resistance to coat the metal.

  Thus, in the fin (44), the heat resistance is ensured and the corrosion resistance of the fin (44) is improved by using pure copper having high thermal conductivity as a core material and covering the surface with a metal having corrosion resistance. It becomes possible to make it.

  In the above feature, a tube (41) through which the first fluid passes is provided, the second fluid is allowed to flow outside the tube (41), and the fin (44) is connected to the inside of the tube (41) and It can be arranged on at least one of the outer sides.

  In the present invention, the first fluid is mixed with the exhaust gas of the internal combustion engine (1), and the fin is an inner fin (44) disposed inside the tube (41). It has 2 features.

  Since the exhaust gas of the internal combustion engine (1) contains NOx and SOx, it is more effective to improve the corrosion resistance of the inner fin (44) in direct contact with the exhaust gas.

  In the present invention, the first fluid is the intake air of the internal combustion engine (1) pressurized by the supercharger (3) using the exhaust gas of the internal combustion engine (1), and the second fluid is A cooling fluid that cools the intake air pressurized by the supercharger (3), and the internal combustion engine (1) branches from the downstream side of the turbine (3b) of the supercharger (3) in the exhaust system. The third feature is that the exhaust gas is circulated upstream of the compressor (3a) of the supercharger (3).

  In such a system that recirculates a part of the exhaust gas to the upstream side of the compressor (3a) of the supercharger (3), the temperature becomes higher than the intake pressure of the conventional supercharging system, and the exhaust gas contains NOx or SOx in the intake air. Since gas is mixed, the inside of the heat exchanger that cools the intake air becomes a strong acid environment, and corrosion is a particular concern. Therefore, in such a case, it is particularly effective to improve the corrosion resistance of the inner fin (44).

  In the first to third features, the coating material may be a tin plating layer.

  The tube (41) may be made of pure copper or a copper alloy.

  Further, the fin (44) and the tube (41) can be joined with a brazing material having a melting point of 600 to 700 ° C. mainly composed of copper, tin, nickel and phosphorus.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In this embodiment, the heat exchanger according to the present invention is applied to an intercooler that cools combustion air (intake air) sucked into an internal combustion engine.

  FIG. 1 is a diagram showing an overall configuration of an internal combustion engine to which an intercooler according to an embodiment of the present invention is applied. An internal combustion engine (hereinafter also referred to as an engine) 1 shown in FIG. 1 is a water-cooled diesel internal combustion engine mounted on a vehicle, and the vehicle is driven by the internal combustion engine 1.

  The internal combustion engine 1 includes an intake pipe 11 and an intake manifold 12 that constitute an intake passage (intake system), an exhaust manifold 21 and an exhaust pipe 22 that constitute an exhaust passage (exhaust system), and a turbocharger 3 that pressurizes intake air. I have.

  The turbocharger 3 includes a compressor 3a disposed in the intake pipe 11 and a turbine 3b disposed in the exhaust pipe 22, and the compressor 3a and the turbine 3b are connected via a turbine shaft. As a result, the turbine 3b is driven using the thermal energy of the exhaust gas, and the compressor 3a is driven via the turbine shaft, and the intake air introduced into the intake pipe 11 is pressurized by the compressor 3a.

  The intake pipe 11 on the downstream side of the compressor 3a of the turbocharger 3 is provided with an intercooler 4 for cooling the air compressed by the compressor 3a. In the present embodiment, a precooler 5 is provided between the compressor 3 a and the intercooler 4 in the intake pipe 11, and the air compressed by the compressor 3 a is precooled by the precooler 5 and then sent to the intercooler 4. .

  An air cleaner 6 is provided in the intake pipe 11 on the upstream side of the compressor 3 a of the turbocharger 3 to remove foreign matter from the intake air. An exhaust gas purification device 7 that purifies exhaust gas or supplements exhaust particulates (PM) in the exhaust gas is provided in the exhaust pipe 22 on the downstream side of the turbine 3b of the turbocharger 3.

  In addition, the engine 1 in the present embodiment employs an EGR (Exhaust Gas Recirculation) system as a countermeasure for exhaust emission. The EGR system includes an exhaust gas recirculation passage 8 and an EGR cooler 9 that is provided in the middle of the exhaust gas recirculation passage 8 and cools the exhaust gas that is recirculated. The inlet side of the exhaust gas recirculation passage 8 is connected to the exhaust pipe 22 on the downstream side of the exhaust gas purification device 7, and the outlet side is the intake pipe 11 upstream of the compressor 3 a of the turbocharger 3, that is, the compressor 3 a in the intake pipe 11. And the air cleaner 6. Thereby, a part of the exhaust gas can be recirculated to the intake pipe 11. Such an arrangement of the EGR system is called a so-called low pressure loop (LPL). In this case, since the exhaust energy supplied to the turbine 3b of the turbocharger 3 does not decrease, deterioration of the supercharging efficiency of the turbocharger 3 can be suppressed.

  Next, the configuration of the intercooler 4 according to the present embodiment will be described. FIG. 2 is a front view of the intercooler 4 according to the present embodiment.

  As shown in FIG. 2, the intercooler 4 is a fin tube type heat exchanger, and includes a plurality of tubes 41 arranged in parallel and outer fins 42 arranged between adjacent tubes 41. ing. In addition, the intercooler 4 includes header tanks 43 disposed on both ends in the longitudinal direction of the tube 41.

  The tube 41 constitutes a flow path through which intake air flows, and has a flat shape. And each tube 41 is arrange | positioned so that a major axis direction may correspond with the cooling wind flow which is a paper surface perpendicular | vertical direction in FIG. The intake air pressurized by the turbocharger 3 corresponds to the first fluid of the present invention, and the cooling air corresponds to the second fluid.

  The outer fins 42 are formed in a wave shape and are joined to the tubes 41, and promote heat exchange between the cooling air flowing between the tubes 41 and the intake air flowing inside the tubes 41. The outer fin 42 is provided with a louver 42a which is partly cut and raised into an armor window shape to prevent the temperature boundary layer from growing by disturbing the air flow (see FIG. 3).

  One of the header tanks 43 distributes and supplies intake air pressure-fed from the turbocharger 3 (see FIG. 1) to each tube 41, and the other collects and collects intake air flowing out from the tube 41 to collect the intake manifold 12 of the engine 1. (See FIG. 1). The header tank 43 includes a header plate 43a having an opening, and a tank body 43b that constitutes a tank internal space together with the header plate 43a. And the tube 41 is inserted in the opening part of the header plate 43a, and the header plate 43a and the tube 41 are fitting. In addition, the tube 41, the outer fin 42, and the header tank 43 are comprised by the pure copper or the copper alloy, for example. In the present specification, “pure copper” refers to copper having a purity of 99% or more.

  3 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 3, inner fins 44 are arranged inside the tube 41. The inner fin 44 is formed in a wave shape and joined to the tube 41 to promote heat exchange between the cooling air and the intake air.

  FIG. 4 is an enlarged schematic view of a portion B in FIG. As shown in FIG. 4, the inner fin 44 is composed of a core material 44a made of pure copper and a tin plating layer 44b formed on the surface of the core material 44a. That is, the inner fin 44 is formed of a plate material in which tin plating is applied to the surface of the core material 44a. The tin plating layer corresponds to the coating material made of a metal having corrosion resistance according to the present invention.

  In the present embodiment, tin plating is applied to the core material 44a made of pure copper before the inner fin 44 is formed into a wave shape. The tin plating method may be any of electroplating, chemical plating, displacement plating, hot dipping, etc., and is not particularly limited. Then, after the tin fin-plated inner fin 44 is formed into a wave shape, the inner fin 44 and the tube 41 are integrally joined by brazing. In this embodiment, a brazing material having a melting point of 600 to 700 ° C. containing copper, tin, nickel and phosphorus as main components is used. It should be noted that a fillet (a mass of brazing material) as shown in part C of FIG. 4 is formed at the joint between the inner fin 44 and the tube 41, and the inner fin 44 and the tube 41 are firmly brazed.

  As explained above, the inner fin 44 is made of pure copper having high thermal conductivity and tin plating with high corrosion resistance is applied to both sides thereof, thereby improving the corrosion resistance of the inner fin 44 while ensuring heat exchange performance. It becomes possible to make it.

  In addition, the low pressure loop (LPL) system that recirculates a part of the exhaust gas to the intake pipe 11 is higher in temperature and pressure than the intake air by the conventional supercharging system, and further, exhaust gas containing NOx and SOx is mixed in the intake air. The interior of the intercooler 4 becomes a strong acid environment, and corrosion is a particular concern. Therefore, in such a case, it is particularly effective to employ the inner fin 44 according to the present embodiment.

(Other embodiments)
In the above embodiment, the heat exchanger of the present invention is applied to the intercooler 4, but the application of the present invention is not limited to this. For example, a radiator of a vehicle air conditioner, a vehicle air conditioner The present invention can also be applied to a heat exchanger such as a heater core, an evaporator or a condenser of a vapor compression refrigerator, or a radiator that cools the cooling water of the engine 1. In particular, the present invention is preferably applied to a heat exchanger used in a corrosive environment such as exhaust gas.

  Moreover, in the said embodiment, although the fin of this invention was applied to the inner fin 44 arrange | positioned inside the tube 41, application of this invention is not limited to this, For example, it arrange | positions on the outer side of the tube 41. The present invention can also be applied to fins such as the outer fin 42.

  Moreover, in the said embodiment, although tin plating was performed to the core material 44a before shape | molding the inner fin 44 in a waveform, it is not restricted to this, You may apply a tin plating after shape | molding the inner fin 44 in a waveform.

  Moreover, in the said embodiment, tin was used as a metal which has corrosion resistance. In addition, although it is expensive, corrosion resistance can be obtained by coating with gold or platinum.

  Moreover, in the said embodiment, although the inner fin 44 was made into the wave shape, this invention is not limited to this, For example, it is good also as a plate fin formed in flat form, a pin fin formed in needle shape, etc.

  Moreover, in the said embodiment, although the tube 41, the outer fin 42, and the header tank 43 were comprised by the pure copper or the copper alloy, you may comprise not only this but other metals, such as aluminum, for example.

It is a figure showing the whole internal-combustion engine composition to which intercooler 4 concerning an embodiment of the present invention is applied. It is a front view of the intercooler 4 which concerns on embodiment of this invention. It is AA sectional drawing of FIG. It is the schematic diagram which expanded the B section in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 3 ... Supercharger, 3a ... Compressor, 3b ... Turbine, 41 ... Tube, 44 ... Inner fin, 44a ... Core material, 44b ... Tin plating layer (coating material).

Claims (7)

A heat exchanger for exchanging heat between a first fluid and a second fluid,
A fin (44) that contacts at least one of the first fluid and the second fluid and facilitates heat exchange between the first fluid and the second fluid;
The fin (44) includes a pure copper core material (44a) and a coating material (44b) made of a metal having corrosion resistance that covers the surface of the core material (44a). . A tube (41) through which the first fluid passes;
The second fluid flows outside the tube (41);
The heat exchanger according to claim 1, wherein the fin (44) is arranged on at least one of the inside and the outside of the tube (41). The exhaust gas of the internal combustion engine (1) is mixed in the first fluid,
The heat exchanger according to claim 2, wherein the fin is an inner fin (44) disposed inside the tube (41). The first fluid is intake air of the internal combustion engine (1) pressurized by a supercharger (3) that uses exhaust gas of the internal combustion engine (1),
The second fluid is a cooling fluid that cools the intake air pressurized by the supercharger (3),
The internal combustion engine (1) branches downstream from the turbine (3b) of the supercharger (3) in the exhaust system and exhausts upstream from the compressor (3a) of the supercharger (3) in the intake system. The heat exchanger according to claim 3, wherein gas is circulated. The heat exchanger according to any one of claims 1 to 4, wherein the covering material is a tin plating layer. The heat exchanger according to any one of claims 2 to 5, wherein the tube (41) is made of pure copper or a copper alloy. The said fin (44) and the said tube (41) are joined by the brazing material whose melting | fusing point which has copper, tin, nickel, and phosphorus as a main component is 600-700 degreeC. Heat exchanger.

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