JP2016145662A - Heat exchanger and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger capable of improving brazing properties without causing deterioration of productivity.SOLUTION: A heat exchanger for cooling a first fluid by performing heat exchange between the first fluid, which is a gas, and a second fluid, which is a liquid whose temperature is lower than that of the first fluid, includes: a core part 3 in which the second fluid circulates inside and in which an outer part is constituted by laminating a plurality of tubes 1 in which the first fluid circulates and fins 2; a core plate 4a which is connected to at least one end part of the plurality of tubes 1; and a first fluid flow passage forming member 5 which is arranged so as to cover the core part 3 and the core plate 4a and which forms a first fluid flow passage in which the first fluid circulates. Between the tubes 1 and the fins 2, between the tubes 1 and the core plate 4a and between the core plate 4a and the first fluid flow passage forming member 5 are bonded by brazing respectively, and Si content of a brazing filler metal coated on the core plate 4a is 11.3% or greater.SELECTED DRAWING: Figure 5

Description

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

  Conventionally, a core portion including a core portion in which a plurality of tubes through which cooling water flows and a plurality of fins are laminated, a tank body portion and a core plate provided at an end portion of the plurality of tubes, An intercooler that is provided so as to cover and includes an intake flow path forming member through which intake air flows is known (see Patent Document 1). In this intercooler, the component parts are temporarily assembled and then brazed together by putting them into the heating furnace, and the tube and fin, tube and core plate, and core plate and intake channel forming member are joined by brazing. Is done.

JP 2014-214955 A

  By the way, in the intercooler described in Patent Document 1, brazing is performed in a brazing posture in which the core plate is disposed vertically inside the flow path forming member and the tubes inserted into the core plate are disposed horizontally. For this reason, brazing material is likely to be stored on the plate surface of the flow path forming member located below, and the flow path is formed rather than the fillet formed at the joint between the core plate and the tube or the joint between the tube and the fin. The fillet formed at the joint between the member and the core plate is larger.

  In this way, when joints having different fillets are connected via the brazing material, the brazing material moves from a joint having a large fillet to a joint having a small fillet according to the Young Laplace equation. That is, the brazing material at the joint between the flow path forming member and the core plate moves to the tube and the fin via the brazing material on the surface of the core plate. As a result, an excessive amount of brazing material is supplied to the joint between the core plate and the tube, and due to the action of Si contained in the brazing material, erosion (dissolution) and desolution (melting grooves) occur, resulting in a decrease in product strength. May be incurred.

  For such problems, it is conceivable to reduce the dispersion of fillet size by reducing the conveyor speed during brazing and soaking the core, thereby suppressing brazing material movement. Lowering the productivity will lead to deterioration of productivity.

  An object of this invention is to provide the heat exchanger which can improve brazing property, without causing the deterioration of productivity in view of the said point.

In order to achieve the above object, in the first aspect of the present invention, the first fluid is exchanged between the first fluid that is a gas and the second fluid that is a liquid lower in temperature than the first fluid. A heat exchanger for cooling,
A core portion (3) configured by laminating a plurality of tubes (1) and fins (2) through which the first fluid flows and the second fluid flows inside; and at least of the plurality of tubes (1) A core plate (4a) connected to one end, and a first fluid passage that is disposed so as to cover the core portion (3) and the core plate (4a) and that circulates the first fluid. 1 fluid flow path forming member (5),
The tube (1) and the fin (2), the tube (1) and the core plate (4a), and the core plate (4a) and the first fluid flow path forming member (5) are joined by brazing. The brazing filler metal applied to the core plate (4a) has a Si content of 11.3% or more.

  According to this, the brazing material stored on the first fluid flow path forming member (5) at the time of brazing becomes a brazing material film remaining on the surface of the core plate (4a) without deteriorating the productivity. It can suppress moving to a tube (1) or a fin (2) through, and generation | occurrence | production of erosion and a solution can be suppressed. As a result, the brazing performance can be improved without reducing the conveyor speed during brazing.

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

It is a perspective view which shows the intercooler which concerns on embodiment of this invention. It is a disassembled perspective view which shows an intercooler. It is sectional drawing which shows the intercooler seen from the tank side. It is explanatory drawing which shows the brazing attitude | position of an intercooler. It is VV sectional drawing of FIG. It is explanatory drawing which shows the junction part of the core plate and ducting plate after brazing. It is explanatory drawing which shows the junction part of the core plate and tube after brazing. It is explanatory drawing which shows the junction part of a core plate and a tube at the time of changing Si content rate of a brazing material.

  An embodiment of the present invention will be described with reference to the drawings. In this embodiment, the heat exchanger of the present invention is applied to an intercooler that cools intake air by exchanging heat between the intake air of the internal combustion engine and a cooling fluid (for example, water). Here, the intake air that is a gas corresponds to the first fluid of the present invention, and the cooling fluid that is a liquid lower in temperature than the intake air corresponds to the second fluid of the present invention. In FIG. 2, illustration of fins 2 described later is omitted.

  As shown in FIGS. 1 to 3, the intercooler of the present embodiment has a plurality of tubes 1 for circulating a cooling fluid therein, and is arranged on both ends of the plurality of tubes 1 to circulate each tube 1. It is configured as a so-called tank-and-tube heat exchanger having a tank portion 4 and the like for collecting or distributing the cooling fluid.

  Specifically, the intercooler includes a plurality of tubes 1 through which the cooling fluid flows and the intake air flows to the outside. The tube 1 is formed in an oblong shape (flat shape) whose vertical cross section in the longitudinal direction is flat so that the flow direction of intake air (hereinafter referred to as the intake flow direction) coincides with the major axis direction. 1 to 3, the direction from the left side to the right side in the drawing is the intake air flow direction.

  The plurality of tubes 1 are arranged in a row in a direction orthogonal to the intake flow direction. Further, the plurality of tubes 1 are arranged in two rows along the direction of intake air flow. That is, the plurality of tubes 1 are arranged so as to form an upstream row located upstream in the intake flow direction and a downstream row located downstream from the upstream row.

  The tube 1 is a tubular member that forms a fluid passage through which a cooling fluid flows, and has two flat surfaces that face each other across the fluid passage. Fins 2 as heat transfer members formed in a wave shape are joined to flat surfaces on both sides of the tube 1, and a plurality of tubes 1 and a plurality of fins 2 are alternately stacked. The fin 2 increases the heat transfer area with the air to promote heat exchange between the cooling water and the air. Hereinafter, the substantially rectangular heat exchanging portion including the tube 1 and the fin 2 is referred to as a core portion 3.

  The tube 1 of the present embodiment is formed by bending a single metal (for example, aluminum) plate-like member and joining the ends thereof. A sacrificial material is provided on the inner and outer surfaces of the tube 1.

  The tank portion 4 extends in a direction orthogonal to the tube longitudinal direction at both ends in the longitudinal direction of the tube 1 (hereinafter referred to as tube longitudinal direction) and communicates with the plurality of tubes 1. The tank unit 4 includes a core plate 4a in which a plurality of tubes 1 are inserted and joined, and a tank body 4b that forms a space in the tank together with the core plate 4a.

  Here, of the two tank portions 4 provided at both ends of the tube 1, the one disposed on the upper side in the vertical direction is referred to as a first tank portion 41, and the one disposed on the lower side in the vertical direction is the second tank portion. 42.

  Inside the first tank portion 41 (between the core plate 4a and the tank main body portion 4b), a separator 4c that divides the space in the tank into two in the intake flow direction is provided. Here, of the two tank spaces partitioned by the separator 4c, a space located on the downstream side of the intake flow is referred to as a first space, and a space located on the downstream side of the intake flow is referred to as a second space.

  The first space communicates with the tubes 1 belonging to the downstream row among the plurality of tubes 1 and diverts the cooling water to the tubes 1 belonging to the downstream row. The second space communicates with the tubes 1 belonging to the upstream row among the plurality of tubes 1 and collects the cooling fluid flowing out from the tubes 1 belonging to the upstream row side.

  The tank body portion 4b of the first tank portion 41 is provided with an inlet pipe 4d that allows the cooling fluid to flow into the first space, and an outlet pipe 4e that causes the cooling fluid heated by heat exchange with the intake air to flow out. ing.

  The second tank unit 42 collects the cooling fluid that has flowed out of the tubes 1 belonging to the downstream row, and diverts the collected cooling water to the tubes 1 belonging to the upstream row. Further, the second tank portion 42 extends between the core plate 4a and the tank main body portion 4b in a direction substantially orthogonal to the stacking direction of the tubes 1 (hereinafter referred to as the tube stacking direction). A plurality (two in the present embodiment) of reinforcing plates 4f that reinforce the tank portion 42 are provided.

  By configuring the two tank parts 4 (the first tank part 41 and the second tank part 42) as described above, the flow of the cooling fluid makes a U-turn in the intercooler of this embodiment.

  Side plates 30 that extend substantially parallel to the tube 11 and reinforce the core portion 3 are provided at both ends of the core portion 3 in the tube stacking direction. Of the side plate 30, the surface on the core portion 3 side is brazed to the fins 2, both end portions in the longitudinal direction are brazed to the core plate 4 a of the tank portion 4, and the surface opposite to the core portion 3 is the intake air described later. It is brazed to the flow path forming member 5.

  An intake passage forming member 5 is provided outside the core portion 3 so as to cover the core portion 3 and forms an intake passage through which intake air flows. The intake flow path forming member 5 is configured by combining and bonding a first ducting plate 51 as a first member and a second ducting plate 52 as a second member.

  The first ducting plate 51 and the second ducting plate 52 are made of the same material (aluminum in this example) as other components such as the tube 1, the fins 2, and the tank part 4. The first ducting plate 51 and the second ducting plate 52 constituting the intake flow path forming member 5 are brazed and joined to the core plate 4a of the tank unit 4 at both ends in the tube longitudinal direction.

  In the present embodiment, the first ducting plate 51 and the second ducting plate 52 are formed in substantially the same shape. Specifically, each of the first ducting plate 51 and the second ducting plate 52 includes a first plate surface 5a substantially orthogonal to the intake flow direction and both ends of the first plate surface 5a in the tube stacking direction. It is formed in a substantially U-shaped cross section having a pair of second plate surfaces 5b that protrude from the portion in a direction substantially orthogonal to the first plate surface 5a and extend substantially parallel to the intake flow direction. By joining the second plate surfaces 5b of the first ducting plate 51 and the second ducting plate 52, the intake flow path forming member 5 having a rectangular cross section is formed. The second plate surface 5 b is brazed to the side plate 30.

  The first plate surface 5 a of each of the first ducting plate 51 and the second ducting plate 52 is formed with an opening 5 c that allows the intake air to flow into and out of the intake flow path in the intake flow path forming member 5. In the present embodiment, the opening 5c is formed over substantially the entire first plate surface 5a. Further, a wall portion 5d extending toward the opposite side to the core portion 3 is provided at the outer peripheral edge portion of the opening portion 5c.

  The inner surface of the wall 5d (the surface on the opening 5c side) is disposed on substantially the same plane as the inner surface of the core plate 4a in the tube longitudinal direction. As a result, no step is generated between the opening 5 c and the core portion 3, so that foreign matter can be prevented from accumulating between the opening 5 c and the core portion 3.

  A connection plate 7 for connecting the intake air flow path of the intercooler and the intake duct 6 is joined to the openings 5 c of the first ducting plate 51 and the second ducting plate 52. That is, the intake duct 6 is connected to the opening 5 c of each of the first ducting plate 51 and the second ducting plate 52 via the connection plate 7.

  The intercooler having the above configuration is integrally brazed by putting each component into a heating furnace in a temporarily assembled state. In the present embodiment, a brazing material made of an Al—Si eutectic alloy containing Si is used. Further, as a constituent material of the tube 1, the core plate 4a, and the ducting plates 51 and 52, a clad material in which a brazing material is clad on at least one surface of an aluminum core material is employed. In the present embodiment, the thickness of the core plate 4a is 1.25 mm, and the clad rate of the brazing material applied to the core plate 4a is 10% of the thickness of the core plate 4a.

  In the present embodiment, the intercooler is brazed in the brazing posture shown in FIG. FIG. 4 shows a state where the tank body 4b is not attached and the core plate 4a is visible. In the brazing posture shown in FIG. 4, the first plate surface 5a of the ducting plates 51 and 52 is arranged in the vertical direction, the second plate surface 5b is arranged in the horizontal direction, and the second plate surface 5b is arranged on the upper side and the lower side. Is located. The core plate 4a is disposed vertically on the second plate surface 5b of the ducting plates 51 and 52 located below, and the tube 1 is disposed horizontally while being inserted into the core plate 4a.

  The brazing is performed in a state where the brazing material is applied to the surfaces of the tube 1, the core plate 4 a, and the ducting plates 51 and 52. When brazing is performed in the brazing posture shown in FIG. 4, the brazing material is likely to be stored on the second plate surface 5 b located below. In particular, at the left and right ends surrounded by broken lines in FIG. 4, the tube 1 does not exist in the vertical direction, so that the brazing material tends to be stored downward. In such a case, the brazing material stored on the ducting plates 51 and 52 at the time of brazing becomes easy to move to the tube 1 and the fin 2.

  The movement of the brazing material that occurs during brazing will be described with reference to FIGS. As shown in FIG. 5, when brazing material is stored on the ducting plates 51, 52, the fillet of the joint 100 (hereinafter referred to as “lower joint 100”) between the ducting plate 51 and the core plate 4 a. Becomes larger than the fillet of the joint portion 101 (hereinafter referred to as “upper joint portion 101”) between the tube 1 and the core plate 4a.

  When the joints 100 and 101 having different fillet sizes are connected via a brazing filler metal, the brazing filler metal fills the fillet from the lower joint part 100 having a large fillet according to the Young Laplace formula shown in the following formula 1. Moves to the lower upper joint 101 and tries to be the same size fillet.

(Equation 1)
P = −γ / R (P: pulling force of brazing material, γ: surface tension, R: fillet radius)
The lower joint 100 of the fillet radius R1 is “P1 = −γ / R1”, and the upper joint 101 of the fillet radius R2 is “P2 = −γ / R2”. When “the fillet radius R1 of the lower joint 100”> “the fillet radius R2 of the upper joint 101”, “the pulling force P1 of the brazing material of the lower joint 100” <“the pull of the brazing material of the upper joint 101” Force P2 ". For this reason, as shown by the arrow A in FIG. 5, the brazing material moves from the lower joint portion 100 having a large fillet to the upper joint portion 101 having a small fillet. Further, the brazing material that has moved to the joint portion 101 between the tube 1 and the core plate 4a also moves to the joint portion between the tube 1 and the fin 2 as indicated by an arrow B in FIG.

  As shown in FIG. 6, a brazing material film 100 remains on the surface of the core plate 4a after brazing. The brazing material moves from the lower joint portion 100 to the upper joint portion 101 through the brazing material film 100 existing on the surface of the core plate 4a as a path.

  As described above in the section “Problems to be Solved by the Invention”, when the brazing material is excessively supplied to the upper joint portion 101 due to the movement of the brazing material from the lower joint portion 100, Si contained in the brazing material. Due to the above action, there is a possibility that erosion (dissolution) shown in FIG. 7A and desolution (dissolution groove) shown in FIG.

  In order to suppress the occurrence of erosion or the like in the upper joint portion 101, the present inventors have different amounts of movement of the brazing material depending on the thickness D of the brazing material connecting the joint portions 100 and 101 having different fillet sizes. Focused on that.

  The film thickness D of the brazing material remaining on the surface of the core plate 4a is determined mainly based on the Si content of the brazing material. The higher the Si content of the brazing material, the more the brazing material remaining on the surface of the core plate 4a. The film thickness D becomes thin. That is, when the Si content of the brazing material is increased, the flow coefficient of the brazing material is increased, so that the film thickness D of the brazing material remaining on the surface of the core plate 4a is reduced. For example, the film thickness D of the brazing material remaining on the core plate 4a after brazing is about 47 μm when a brazing material having a Si content of 10% is used, and when a brazing material having a Si content of 12% is used. About 15 μm.

  Here, the result of brazing by changing the Si content of the brazing material applied to the core plate 4a will be described with reference to FIG. FIG. 8 shows the case where brazing was performed by changing the Si content of the brazing material applied to the core plate 4a to 10.0%, 11.3%, 12.0%, and 12.6%, respectively. The result of having investigated the presence or absence of generation | occurrence | production of the erosion in the upper side junction part 101 (joint part of the core plate 4a and the tube 1) is shown.

  As shown in FIG. 8, erosion occurred at the upper joint portion 101 when a brazing filler metal having a Si content of 10.0% was used. On the other hand, when the brazing filler metal having a Si content of 11.3%, 12.0%, and 12.6% was used, no erosion occurred in the upper joint portion 101. That is, by increasing the Si content of the brazing material, the film thickness of the brazing material remaining on the surface of the core plate 4a is reduced, and the movement of the brazing material from the lower joint portion 100 to the upper joint portion A2 is suppressed. It is considered that the erosion can be suppressed at the upper joint portion 101. Specifically, when the Si content of the brazing material applied to the core plate 4a is 11.3% or more, the occurrence of erosion at the upper joint portion 101 can be prevented.

  Further, in order to supply the brazing material to the lower joint portion 100 and the upper joint portion 101 provided on the core plate 4a, it is necessary to ensure a certain amount of thickness for the brazing material applied to the core plate 4a. For this reason, when Si content rate of the brazing material applied to the core plate 4a is made too high, the film thickness of the brazing material becomes thin, and the joining properties of the joint portions 100 and 101 provided on the core plate 4a deteriorate. For this reason, it is desirable that the Si content of the brazing material applied to the core plate 4a does not exceed 13%.

  According to the present embodiment described above, the brazing material stored on the ducting plates 51 and 52 during brazing can be obtained by setting the Si content of the brazing material applied to the core plate 4a to 11.3% or more. Further, it is possible to suppress the movement to the tube 1 or the fin 2 through the brazing material film remaining on the surface of the core plate 4a. Thereby, it can suppress that an excessive brazing material is supplied to the tube 1 and the fin 2 at the time of brazing, and can suppress generation | occurrence | production of the erosion and desolution resulting from Si contained in a brazing material. Moreover, according to this embodiment, it is not necessary to reduce the conveyor speed at the time of brazing, and the intercooler productivity is not deteriorated.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In the above embodiment, the thickness of the core plate 4a is 1.25 mm. However, the thinner the core plate 4a, the thinner the brazing material remaining on the surface of the core plate 4a after brazing. can do. For this reason, it is desirable that the thickness of the core plate 4a be 1.25 mm or less.

  (2) In the above embodiment, the clad rate of the brazing material applied to the core plate 4a is 10% of the thickness of the core plate 4a, but the lower the clad rate, the remaining on the surface of the core plate 4a after brazing. The film thickness of the brazing filler metal can be reduced. For this reason, it is desirable that the clad rate of the brazing material applied to the core plate 4a is 10% or less of the thickness of the core plate 4a.

  (3) In the above-described embodiment, an example in which the flow of the cooling fluid is configured to make a U-turn in the intercooler has been described. However, the present invention is not limited thereto, and the configuration may be such that the flow of the cooling fluid does not turn. The cooling fluid flow may be W-turned (three U-turns).

DESCRIPTION OF SYMBOLS 1 Tube 2 Fin 3 Core part 4 Tank part 4a Core plate 5 Intake flow path formation member 51 1st ducting plate 52 2nd ducting plate 100 Lower side joint part 101 Upper side joint part

Claims (4)

A heat exchanger that cools the first fluid by performing heat exchange between a first fluid that is a gas and a second fluid that is a liquid lower in temperature than the first fluid,
A core portion (3) configured by laminating a plurality of tubes (1) and fins (2) through which the first fluid flows and the second fluid flows inside;
A core plate (4a) connected to at least one end of the plurality of tubes (1);
A first fluid flow path forming member (5) which is disposed so as to cover the core portion (3) and the core plate (4a) and forms a first fluid flow path through which the first fluid flows. ,
Between the tube (1) and the fin (2), between the tube (1) and the core plate (4a), between the core plate (4a) and the first fluid flow path forming member (5). Are joined by brazing,
The heat exchanger characterized in that the Si content of the brazing material applied to the core plate (4a) is 11.3% or more.   The heat exchanger according to claim 1, wherein the core plate (4a) has a plate thickness of 1.25 mm or less.   The heat exchanger according to claim 1 or 2, wherein a clad rate of the brazing material applied to the core plate (4a) is 10% or less of a plate thickness of the core plate (4a). A core portion formed by laminating a plurality of tubes (1) and fins (2) through which a first fluid which is a gas flows and a second fluid which is a liquid lower in temperature than the first fluid flows. (3), a core plate (4a) connected to at least one end of the plurality of tubes (1), and disposed so as to cover the core portion (3) and the core plate (4a) A heat exchanger manufacturing method comprising a first fluid flow path forming member (5) that forms a first fluid flow path through which the first fluid flows,
An assembly step of temporarily assembling at least the tube (1), the fin (2), the core plate (4a), and the first fluid flow path forming member (5);
Between the tube (1) and the fin (2), between the tube (1) and the core plate (4a), between the core plate (4a) and the first fluid flow path forming member (5). And a joining step for joining by brazing,
In the joining step, the core plate (4a) is arranged vertically on the plate surface (5b) of the first fluid flow path forming member (5) arranged horizontally, and the tube (1) is arranged horizontally. The method for manufacturing a heat exchanger is characterized in that brazing is performed in a state of being applied and the Si content of the brazing material applied to the core plate (4a) is 11.3% or more.