US20060113069A1

US20060113069A1 - Heat exchanger

Info

Publication number: US20060113069A1
Application number: US11/287,712
Authority: US
Inventors: Toshihide Ninagawa; Tatsuo Ozaki; Yuuji Sako
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2004-11-29
Filing date: 2005-11-28
Publication date: 2006-06-01

Abstract

A heat exchanger has a tank communicated with tubes at longitudinal-direction ends of the tubes. A first plate member of the tank has a core plate portion connected with the tubes and two side wall portions facing each other, which are constructed of a metal plate material. The second plate member of the tank has an opposite wall portion facing the core plate portion and two cap portions facing each other, which are constructed of a metal plate material. The core plate portion has a protrusion-shaped cross section in the longitudinal direction of the tubes. The first plate member and the second plate member are integrated by brazing. An inner surface of one of the plate members contacts an end surface of other of the plate members, and a fillet is formed between an extension portion of the one plate member and a shear droop of the other plate member.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Applications No. 2004-344809 filed on Nov. 29, 2004 and No. 2004-363624 filed on Dec. 15, 2004, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger having a tank which is constructed of multiple metal plate members.

BACKGROUND OF THE INVENTION

Generally, referring to JP-2002-213895A, a tank of a heat exchanger is constructed of four metal plate members which are integrally joined to each other by brazing. Among the four plate members, the end plate member (core plate portion) and the tank plate member (which constructs side wall portions and opposite wall portion facing core plate portion) are respectively provided with plane-shaped junction parts, which are overlapped to be integrated by brazing.
However, the construction of the tank is complicated due to the overlapped junction parts of the end plate member and the tank plate member. In this case, it is difficult to maintain the capacity of the inner space of the tank, in which refrigerant flows.
If an end surface of the one plate member is arranged to contact an inner surface of the other plate member at the brazing junction therebetween in order to maintain the capacity of the inner space of the tank, a brazing defect will be readily caused at the brazing junction.
Referring to JP-2001-12891A, a tank of a heat exchanger includes a tank body (first member) constructed of a bent metal plate, and a tube plate (second member). The tank body has a bottom portion and a pair of side wall portions which face each other and spaced by the bottom portion. Each of two longitudinal-direction ends of the tube plate is bent at a right angle (90° C.), so that the tank having two seal ends is constructed.
The bottom portion of the tank body is provided with two bottom engagement portions, which are respectively disposed at two longitudinal-direction ends of the bottom portion and bent toward the inner surface side of the bottom portion. Moreover, each of the side wall portions has a side-wall engagement portion, which is disposed at the tip of the side wall portion and bent toward the inner surface side of the side wall portion.
Thus, the tips of the longitudinal-direction ends (which construct seal ends of tank) of the tube plate are respectively engaged with the bottom engagement portions, and the side edges of the tube plate are respectively engaged with the side-wall engagement portions. Then, the tank body is integrally joined to the tube plate by brazing.
The tube plate is provided with multiple tube insertion holes, into which the tubes are respectively inserted and integrated with the tube plate by brazing. Alternatively, the tube insertion holes can be also formed at the first member.
However, the tank of the heat exchanger is constructed of the metal plates by bending simply to have a slender rectangular-parallelepiped shape (having six plane surfaces). Moreover, in the case where the second member is used as the tube plate, the surface thereof where the tubes are integrated by brazing is limited to be simple plane because the longitudinal-direction ends of the second member are to be bent to construct the seal ends of the tank.
In the heat exchanger, there exist a thermal expansion difference between the tube and a side plate which is arranged at a stacking-direction outer side of the tube (which are stacked) to be used as a reinforce member, and a thermal expansion difference between the tubes due to a temperature difference (temperature variation) of inner fluid in the tubes. Thus, stress is caused at the tube (at brazing junction of tube and tube plate, for example).
Therefore, when the surface where the tubes are joined by brazing has a plane shape, stress is readily concentrated at longitudinal-direction ends of the flat-shaped tube. Thus, the breakage of the tube may be caused so that inner fluid in the tube is leaked.

SUMMARY OF THE INVENTION

In view of the above-described disadvantages, it is an object of the present invention to provide a heat exchanger, in which stress in tubes is restricted and a satisfactory inner capacity and a stable brazing performance of a tank are maintained.
According to an aspect of the present invention, a heat exchanger is provided with a plurality of tubes which are stacked, and at least one tank which extends in a stacking direction of the tubes. The tank is connected with longitudinal-direction ends of the tubes so that an inner space of the tank is communicated with that of each of the tubes. The tank has a first plate member and a second plate member which are integrated by brazing. The first plate member includes a core plate portion which is connected with the tubes, and two side wall portions which are respectively disposed at two lateral-direction ends of the core plate portion and extend in a longitudinal direction of the core plate portion. The two side wall portions face each other and are spaced by the inner space of the tank. The core plate portion and the side wall portions are constructed of a metal plate material by bending. The second plate member includes an opposite wall portion which faces the core plate portion and is spaced from the core plate portion by the inner space of the tank, and two cap portions which are respectively arranged at two stacking-direction ends of the opposite wall portion and extend to sandwich the inner space of the tank therebetween. The two cap portions face each other. The opposite wall portion and the cap portions are constructed of a metal plate material by bending. The core plate portion has a cross section which is perpendicular to the stacking direction of the tubes and has a shape protruding to an outer side of the tank in the longitudinal direction of the tubes.
Therefore, the brazing area between the core plate portion and the tube can be increased, as compared with the case where the core plate portion has a plane shape. Moreover, stress concentration due to a force caused by the thermal expansion difference between the tubes can be ridded, so that stress caused in the tube is reduced.
In this case, the cross section (perpendicular to stacking direction of tubes) of the core plate portion has the shape protruding to the outer side of the tank in the longitudinal direction of the tubes. Thus, the cap portion which is to contact the core plate portion can be simply shaped (formed) to match the protrusion part of the core plate portion. Therefore, the manufacture of the tank is not complicated by the bending processes of the plate members.
According to another aspect of the present invention, a heat exchanger has a plurality of tubes which are stacked, and at least one tank which extends in a stacking direction of the tubes. The tank is connected with longitudinal-direction ends of the tubes so that an inner space of the tank is communicated with that of each of the tubes. The tank includes at least two metal plate members, which are respectively provided with brazing material layers at least at outer surfaces thereof to be integrated by brazing. The outer surface of the plate member constructs a part of an outer surface of the tank. At a brazing junction between the plate members, an inner surface of one of the plate members contacts an end surface of other of the plate members. The inner surface is at an inner side of the tank. At the brazing junction, the one of the plate members has an extension portion, which extends so that an end surface of the extension portion is positioned at an outer side of the tank with respect to a contact part between the plate members. At the brazing junction, the other of the plate members has a shear droop which is disposed at the outer surface thereof and formed by punching. A brazing material fillet is formed between the extension portion of the one of the plate members and the shear droop of the other of the plate members.
Because the inner surface of the one plate member contacts the end surface of the other plate member, the capacity of the inner space of the tank can be maintained. Moreover, the fillet is formed at the shear droop having a stable shape, so that a satisfactory brazing performance can be maintained.
Preferably, the tank of the heat exchanger is constructed of the first plate member having a core plate portion connected with the tubes, and the second plate member having an opposite wall portion which faces the core plate portion and is spaced from the core plate portion by the inner space of the tank.
Thus, the brazing parts of the tank can be reduced because the tank is constructed of the two plate members. Therefore, the further stable brazing performance can be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which:
FIG. 1 is a front view showing a whole construction of a heat exchanger according to a first embodiment of the present invention;
FIG. 2A is a plan view showing a first plate member of a tank according to the first embodiment, FIG. 2B is a front view of the first plate member, and FIG. 2C is a side view of the first plate member viewed in an arrow direction IIC in FIG. 2B;
FIG. 3A is a plan view showing a second plate member of the tank according to the first embodiment, FIG. 3B is a front view of the second plate member, and FIG. 3C is a side view of the second plate member viewed in an arrow direction IIIC in FIG. 3B;
FIG. 4 is a perspective view showing an assembling method of the first plate member and the second plate member according to the first embodiment;
FIG. 5 is a perspective view showing the first plate member and the second plate member which are assembled and joined to each other according to the first embodiment;
FIG. 6A is a cross-sectional view showing the tank according to the first embodiment, and FIG. 6B is an enlarged view of a part VIB in FIG. 6A;
FIG. 7A is a cross-sectional view showing a shear process surface according to the first embodiment, and FIG. 7B is cross-sectional view showing a shear process surface according to a comparison example;
FIG. 8A is a plan view showing a second plate member of a tank according to a second embodiment of the present invention, FIG. 8B is a front view of the second plate member, and FIG. 8C is a side view of the second plate member viewed in an arrow direction VIIIC in FIG. 8B;
FIG. 9 is a cross-sectional view showing an engagement method of a nail portion and a side wall portion according to the second embodiment;
FIG. 10 is a perspective view showing an assembling method of a first plate member and a second plate member according to a third embodiment of the present invention;
FIG. 11 is a plan view showing the first plate member and the second plate member viewed in an arrow direction XI in FIG. 10;
FIG. 12 is a perspective view showing an assembling method of a first plate member and a second plate member according to a fourth embodiment of the present invention;
FIG. 13 is a perspective view showing the first plate member and the second plate member which are assembled and joined to each other according to the fourth embodiment;
FIG. 14 is a plan view showing the first plate member and the second plate member viewed in an arrow direction XIV in FIG. 13;
FIG. 15 is a perspective view showing an assembling method of a first plate member and a second plate member according to a fifth embodiment of the present invention;
FIG. 16 is a perspective view showing the first plate member and the second plate member which are assembled and joined to each other according to the fifth embodiment;
FIG. 17 is a perspective view showing an assembling method of a first plate member and a second plate member according to a sixth embodiment of the present invention;
FIG. 18 is a perspective view showing a second plate member according to a modification of the sixth embodiment;
FIG. 19 is a perspective view showing an assembling method of a first plate member and a second plate member according to a seventh embodiment of the present invention;
FIG. 20 is a perspective view showing the first plate member and the second plate member which are assembled and joined to each other according to the seventh embodiment;
FIG. 21 is a perspective view showing an assembling method of a first plate member and a second plate member according to a modification of the seventh embodiment of the present invention;
FIG. 22 is a perspective view showing the first plate member and the second plate member which are assembled and joined to each other according to the modification of the seventh embodiment;
FIG. 23 is a cross-sectional view taken along a line XXIII-XXIII in FIG. 22;
FIG. 24 is a perspective view showing an assembling method of a first plate member and a second plate member according to an eighth embodiment of the present invention;
FIG. 25 is a partial side view of the first plate member and the second plate member viewed in an arrow direction XXV in FIG. 24;
FIG. 26 is a perspective view showing a first plate member and a second plate member which are assembled and joined to each other according to a ninth embodiment of the present invention;
FIG. 27A is a cross-sectional view showing a part of a tank according to the ninth embodiment, and FIG. 27B is an enlarged view of a part XXVIIB in FIG. 27A;
FIG. 28 is an enlarged cross-sectional view showing a junction of plate members according to other embodiments of the present invention;
FIG. 29 is a perspective view showing an assembling method of a first plate member and a second plate member according to the other embodiments; and
FIG. 30 is a cross-sectional view showing the first plate member and the second plate member which are assembled and joined to each other according to the other embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A heat exchanger 100 (e.g., radiator) according to a first embodiment of the present invention will be described with reference to FIGS. 1-7B. The radiator 100 can be suitably used to cool cooling water of an engine. Referring to FIG. 1, the radiator 100 has multiple tubes 110 (partially shown), multiple fins 120 (partially shown), two side plates 130, two tanks 140 and the like, which are made of, for example, aluminum (or aluminum alloy) and integrated by brazing or the like.
As shown in FIG. 1, the tubes 110 of the radiator 100 (e.g., cross flow type) can be arranged in a horizontal direction. The radiator 100 mainly includes a core unit 101 and the two tanks 140.
The core unit 101 (heat radiating unit), in which cooling water is cooled, includes the flat-shaped tubes 110, the corrugated fins 120 and the side plates 130. The tubes 110 and the fins 120 are alternately stacked (laminated). That is, each of the tubes 110 is arranged between the adjacent fins 120. The stacking direction (e.g., up-down direction in FIG. 1) of the tubes 110 and the fins 120 is substantially perpendicular to the longitudinal direction of the tube 110 (or fin 120). The side plates 130 having a ⊃-shaped cross section are disposed at further outer sides (upper side and lower side in FIG. 1) of the stacking-direction outmost fins 120, to be used as reinforce members.
The tank 140, being a slender container, has a longitudinal direction corresponding to the stacking direction of the tubes 110. The two tanks 140 are respectively connected with two longitudinal-direction ends of the each tube 110 and those of the each side plate 130. Thus, an inner space 145 of the tank 140 is communicated with those of the tubes 110.
The two tanks 140 are respectively provided with an inlet pipe 146 through which cooling water flows into the inner space 145 of the tank 140, and an outlet pipe 147 through which cooling water is discharged from the inner space 145. For example, referring to FIG. 1, the inlet pipe 146 is arranged at the upper portion of the tank 140 of the left side, and the outlet pipe 147 is arranged at the lower portion of the tank 140 of the right side.
Each of the tanks 140 is constructed of a first plate member 140A and a second plate member 140B.
Referring to FIGS. 2A-2C, the first plate member 140A is constructed by a single metal plate by bending or the like, to have a core plate portion 141 and a pair of side wall portions 142. The side wall portions 142 are erected (i.e., substantially perpendicular) with respect to the core plate portion 141, and disposed respectively at two lateral-direction (i.e., up-down direction in FIG. 2A) ends of the core plate portion 141. The side wall portion 142 extends in the longitudinal direction thereof (perpendicular to lateral direction of side wall portion 142), which corresponds to the longitudinal direction of the core plate portion 141 and the up-down direction in FIG. 1. The core plate portion 141 is provided with multiple holes 141 a, through which the tubes 110 and the side plates 130 are inserted to be connected with the tank 140.
FIG. 2C is a side view of the first plate member 140A viewed in the arrow direction IIC (corresponding to longitudinal direction of core plate portion 141) in FIG. 2B. As shown in FIG. 2C, the core plate portion 141 protrudes toward an opposite side to the opposite wall portion 143, to have a substantially trapezoidal-shaped cross section which projects to the outer side of the tank 140 in the longitudinal direction of the tube 110. The cross section is perpendicular to the longitudinal direction of the core plate portion 141 and parallel to the longitudinal direction of the tube 110. In this case, the hole 141 a formed at the core plate portion 141 extends to three edges of the core plate portion 141 when viewed in the trapezoidal-shaped cross section thereof.
As shown in FIG. 2B, multiple engagement notches (i.e., openings) 148 are formed at an erection-direction end (i.e., lateral-direction end) of the each side wall portion 142. The erection-direction end is disposed at the opposite side (i.e., upper side in FIG. 2B) to the core plate portion 141. Moreover, two engagement notches 148 are respectively formed at the two longitudinal-direction ends of the core plate portion 141. The notches 148 will be engaged with engagement nail portions 149 of the second member 140B.
As shown in FIG. 3, the second plate member 140B is constructed of a single metal plate by bending or the like, to have an opposite wall portion 143 and a pair of cap portions 144. The opposite wall portion 143 faces the core plate portion 141 and is spaced from it by the inner space 145, in the tank assembly. The cap portions 144 are erected (i.e., substantially perpendicular) with respect to the opposite wall portion 143. The cap portions 144 respectively disposed at two longitudinal-direction (left-right direction in FIGS. 3A and 3B) ends of the opposite wall portion 143, and extend in the erection direction (i.e., lateral direction) of the side wall portion 142.
The cap portions 144 construct sealing members (i.e., end caps) for sealing longitudinal-direction ends of the slender container body that is defined by the core plate portion 141, the two side wall portions 142 and the opposite wall portion 143.
The multiple engagement nail portions 149 (protrusion portions) are arranged at each of two lateral-direction ends of the opposite wall portion 143. Each of the nail portions 149 of the opposite wall portion 143 protrudes outward from the opposite wall portion 143, to be engaged with the notch 148 (which is formed at erection-direction end of side wall portions 142) in the tank assembly.
Moreover, an erection-direction end of the each cap portion 144 is provided with an engagement nail portion 149. The erection-direction end is disposed at an opposite side (i.e., lower side in FIG. 3B) to the opposite wall portion 143. The nail portion 149 of the cap portion 144 protrudes outward from the cap portion 144, to be engaged with the notch 148 (which is formed at longitudinal-direction end of core plate portion 141) in the tank assembly.
Next, the assembling of the tank 140 will be described.
At first, referring to FIG. 4, the longitudinal-direction ends of the tubes 110 and the side plates 130 are inserted into the holes 141 a of the first plate member 140A. In this case, the tubes 110 and the side plates 130 are temporarily fixed to each other. Then, the second plate member 140B is attached to the first plate member 140A from the upper side in FIG. 4, so that the nail portions 149 of the second plate member 140B are engaged with the notches 148 of the first plate member 140A. In this case, the periphery end surface, at which the nail portions 149 are disposed, of the second plate member 140B contacts the inner surface of the first plate member 140A. This periphery end surface of the opposite wall portion 143 and that of the cap portion 144 are respectively parallel to the thickness directions thereof.
Before the second plate member 140B is assembled to the first plate member 140A, the longitudinal-direction ends of the tubes 110 can be also provided with a diameter-enlarging process to closely contact the core plate portion 141.
Referring to FIG. 5, after the first plate member 140A is mounted at the second plate member plate 140B, tips of the nail portions 149 of the second plate portion 140B are bent to be engaged with the outer surface of the first plate member 140A so that the two plate members 140A and 140B are temporarily integrally fixed.
Then, the assembly of the components of the core unit 101 and the plate members 140A and 140B of the tanks 140 are heated to be integrated by brazing through brazing material, which is beforehand provided (e.g., by cladding) to the surfaces (at positions where brazing is required) of the components of the core unit 101 and the plate members 140A and 140B. Thus, the radiator 100 having the tank 140 is manufactured.
In this embodiment, the brazing material is beforehand provided for the outer surface of the tube 110, the surface (i.e., inner side surface) of the side plate 130 of the side of the fin 120, outer surfaces 150 a and 160 a of the plate members 140A and 140B, by cladding. Flux is applied to the above-described components before the brazing, to improve the brazing performance.
FIG. 6A shows a cross section (which is perpendicular to longitudinal direction of tank 140) of the tank 140. FIG. 6B is an enlarged view of the part VIB in FIG. 6A.
Referring to FIG. 6B, brazing material layers 151 and 161 are respectively arranged at the outer surface 150 a of the first plate member 140A and the outer surface 160 a of the second plate member 140B. An end surface 162 of the second plate member 140B contacts an inner surface 150 b of the first plate member 140A.
The second plate member 140B is formed by punching or the like, and have a shear droop 162A which is disposed at the end surface 162 of the side of the outer surface 160 a.
As shown in FIG. 6B, the side wall portion 142 includes an extension portion 153 having an end surface 152 (being surface of longitudinal-direction end of first plate member 140A), which is disposed at an outer side of the tank 140 with respect to a contact part 163 between the plate members 140A and 140B. That is, the first plate member 140A extends to the outer side of the tank 140 with respect to the second plate member 140B.
Thus, a brazing material fillet 161A can be formed between an inner surface (which is disposed at same side with inner space 145 with respect to side wall portion 142) of the extension portion 153 of the first plate member 140A and the shear droop 162A of the second plate member 140B.
In this embodiment, the plate member 140A, 140B is constructed of an aluminum alloy plate having a thickness of 1.2 mm-1.6 mm or so wherein 10% is the thickness of the brazing material. The second plate member 140B is provided with the shear droop 162A, which is disposed at the arrangement side (side of outer surface 160 a) of the brazing material layer 161 and has a radius of 0.2 mm-0.3 mm or so.
The length (being dimension in longitudinal direction of first plate member 140A) of the extension portion 153 is set based on the difference between the depth (being dimension in longitudinal direction of first plate member 140A) of the notch 148 of the first plate member 140A and the thickness of the second plate member 140B (nail portion 149). In this case, the length of the extension portion 153 is set to be 0.5 mm-1.0 mm or so. The first plate member 140A also has a shear droop which is formed due to the punching process and is not shown in FIG. 6B.
The junctions between the plate members 140A and 140B have the same construction with the junction between the side wall portion 142 of the first plate member 140A and the opposite wall portion 143 of the second plate member 140A, as shown in FIG. 6B.
According to this embodiment, the end surface 162 of the second plate member 140B (opposite wall portion 143) contacts the inner surface 150 b of the first plate member 140A (side wall portion 142). The fillet 161A of the brazing material is formed between the inner surface of the extension portion 153 of the first plate member 140A and the shear droop 162A of the second plate member 140B.
In this case, the tank 140 is not provided with the overlap construction at the brazing junction in the inner space 145. The brazing material can be accumulated at the shear droop 162A so that the brazing area of the fillet 161A is enlarged, while the capacity of the inner space 145 is maintained. Thus, the stable brazing performance can be maintained.
FIG. 7A shows a shear part of the metal plate member (e.g., second plate member 140B) by the punching process according to this embodiment. In this case, the shear droop 162A, a shear surface 162B, a rupture surface 162C and a burr portion 162D are formed at the second plate member 140B. The shear droop 162A is a plastic deformation portion due to shear stress, and has a relatively stable size when the process is repeated.
The shear droop 162A of the second plate member 140B is beforehand formed at the arrangement side of the brazing material layer 161, so that the brazing material layer 161 can be disposed contiguously to the contact part 163 between the first plate member 140A and the end surface 162 (specifically, shear surface 162B) of the second plate member 140B.
Accordingly, the brazing material can be accumulated at the shear droop 162A (which is relatively stably formed) to be substantially supplied. Thus, the satisfactory fillet 161A can be formed.
As compared with the shear droop 162A, the shapes (length, angle and the like) of the rupture surface 162C and the burr portion 162D are readily changed corresponding to the punching process. FIG. 7B shows a shear part of the metal plate member (e.g., second plate member 140B) by a punching process according to a comparison example. In this case, the shear droop 162A is formed at the opposite side to the arrangement side of the brazing material layer 161. Thus, it is difficult to for the brazing material of the brazing material layer 161 to flow to be contiguous to the contact part 163 through the rupture surface 162 c and the burr portion 162D.
According to this embodiment, the shear droop 162A is formed at the arrangement side of the brazing material layer 161, so that the stable brazing performance can be substantially maintained.
When the plate members 140A and 140B are temporarily fixed to each other, the nail portions 149 are to be bent to be engaged with the outer surface 150 a of the first plate member 140A. The nail portion 149 is spaced from the tube 110 and the fin 120, which are readily deformed if stress therein is biased. The side wall portion 142 is arranged between the nail portion 149 and the tube 110 (fin 120). Therefore, the bend process can be readily performed.
According to this embodiment, the heat exchanger 100 is made of the aluminum alloy, so that the weight thereof can be reduced and the cladding of the brazing material can be readily formed at the surfaces of the components.
The heat exchanger 100, for example, the radiator, can be used to cool engine cooling water, which flows through the core unit 101 (tubes 110) to be heat-exchanged with cooling air at the exterior of the core unit 101.
In the operation of the radiator 100, the thermal expansion difference between the tube 110 and the side plate 130, and that between the tubes 110 due to the temperature difference of inner fluid (e.g., water) will cause stress at a brazing portion 150 of the tube 110 (joined to core plate portion 141 at brazing portion 150). Therefore, if the core plate portion 141 which is bonded to the tubes 110 by brazing has a plane shape, stress concentration is readily caused at the longitudinal-direction ends of the flat tubes 110.
According to this embodiment, the core plate portion 141 protrudes to the outer side of the tank 140 to have the cross section (parallel to longitudinal direction of tube 110 and perpendicular to that of core plate portion 141) with the trapezoid shape, for example. In this case, the hole 141 a where the tube 101 is inserted extends to the three edges of the trapezoid. Therefore, as compared with the case where the core plate portion 141 is plane-shaped, the brazing range (area) of the brazing portion 150 of the tube 110 according to this embodiment can be enlarged and the stress concentration caused by the force F due to the thermal expansion difference between the tubes 110 can be removed, referring to FIG. 6A. Therefore, the stress caused at the tubes 110 can be reduced.
According to the first embodiment, the core plate portion 141 is provided with the convex shape. The tank 140 can be constructed by only matching the outline of the cap portion 144 with the convex shape of the core plate portion 141, which is to be engaged with the cap portion 144. Therefore, the bending process of the plate members 140A and 140B is not complicated.
In the brazing, the gap at the brazing portion between the two plate members 140A and 140B can be reduced through the engagement of the nail portions 149 with the notches 148. Therefore, the brazing performance can be increased.
Alternatively, the notches 148 can also be formed at the second plate member 140B and the nail portions 149 can be also formed at the first plate member 140A, at the corresponding positions which are described above.

Second Embodiment

A second embodiment will be described with reference to FIGS. 8A-9. In this case, the second plate member 140B is further provided with ribs (e.g., recesses) 143 a and 143 b, as compared with the above-described first embodiment.
As shown in FIGS. 8A-8C, the opposite wall portion 143 of the second plate member 140B is provided with the recess 143 a extending in the longitudinal direction of the opposite wall portion 143. The cap portion 144 is provided with the recess 143 b extending in the erection direction of the cap portion 144. The recess 143 a, 143 b has a concave shape (when being viewed from outer side of tank 140) to protrude into the inner space 145 of the tank 140.
According to the second embodiment, the stiffness of the second plate member 140B can be increased by the ribs (recesses) 143 a and 143 b. Therefore, the deformation of the second plate member 140B when being mounted at the first plate member 140A to construct the tank 140 can be restricted. Accordingly, the gap caused between the plate members 140A and 140B can be reduced, thus improving the stability of the brazing.
Moreover, after the tank 140 is manufactured, the recesses 143 a and 143 b function to reinforce the second plate member 140B. Thus, the pressure-resistant strength of the tank 140 can be increased.
The recess 143 a, 143 b is arranged to protrude into the inner space 145 of the tank 140, without enlarging the size of the tank 140. Thus, the vehicle mounting performance of the radiator 100 having the tank 140 will not be worsened.
Moreover, referring to FIG. 9, the recess 143 a formed at the opposite wall portion 143 can be used as a positioning portion for a pinchers or a pliers, which is used to engage the nail portions 149 of the opposite wall portion 143 with the side wall portions 142 of the first plate member 140A.
Alternatively, the rib 143 b of the cap portion 144 can be also omitted responding to the gap between the two plate members 140A and 140B in the construction of the tank 140, while the recess 143 a is arranged at the slender opposite wall portion 143 to reinforce it.
More alternatively, the ribs 143 a and 143 b can also protrude to the outer side of the tank 140 to have a convex shape when being viewed from the outer side of the tank 140, conditioning that the mounting space in the vehicle is sufficient.

Third Embodiment

A third embodiment of the present invention will be described with reference to FIGS. 10 and 11. In this case, the junction of the side wall portions 142 and the cap portion 144 is changed as a first modification of the first embodiment.
As shown in FIG. 10, each of the side wall portions 142 of the first plate member 140A is provided with two junction grooves 142 a (being concave portion when being viewed from inner side of tank 140), which are respectively arranged at the two longitudinal-direction ends of the side wall portion 142 and respectively disposed at the positions corresponding to the mounting positions of the cap portions 144. The junction groove 142 a convexes toward the outer side of the tank 140.
In this case, the width (dimension perpendicular to longitudinal directions of second plate member 140B and tube 110) of the cap portion 144 is set larger than that of the opposite wall portion 143. The width of the opposite wall portion 143 is substantially equal to the distance between the two side wall portions 142 of the first plate member 140A. Thus, the cap portion 144 can slide along the junction grooves 142 a of the side wall portions 142. In this case, two width-direction (i.e., lateral-direction) ends 144 a of the cap portion 144 respectively contact the junction grooves 142 a.
In the mounting of the second plate member 140B at the first plate member 140A, the ends 144 a of the cap portion 144 are slid along the junction grooves 142 a, so that the nail portion 149 of the cap portion 144 is inserted into the notch 148 of the first plate member 140A.
Because the second plate member 140B (cap portion 144) can be guided along the junction groove 142 a to be mounted at the first plate member 140A, the mounting performance of the two plate members 140A and 140B can be improved.
Moreover, in the brazing of the plate members 140A and 140B, the brazing material can accumulate in the junction grooves 142 a. Therefore, the brazing performance of the side wall portion 142 with respect to the cap portion 144 can be improved.

Fourth Embodiment

A fourth embodiment of the present invention will be described with reference to FIGS. 12-14. In this case, the junction of the side wall portions 142 and the cap portion 144 is changed, as a second modification of the first embodiment.
According to the fourth embodiment, each of the side wall portions 142 of the first plate member 140A is provided with two slit 142 b (first slit), which are respectively arranged at the longitudinal-direction end of the side wall portion 142 and respectively disposed at the positions corresponding to the mounting positions of the cap portions 144. The width (being dimension parallel to longitudinal direction of side wall portion 142) of the slit 142 b is substantially equal to the thickness of the cap portion 144.
In this case, the width (being dimension perpendicular to longitudinal directions of second plate member 140B and tube 110) of the cap portion 144 is larger than that of the opposite wall portion 143. Thus, the width-direction ends 144 a of the cap portion 144 can be slid along the slits 142 b. In the assembly of the tank 140, the ends 144 a of the cup portion 144 protrude from the outer surface of the side wall portion 142 through the slit 142 b.
In the mounting of the second plate member 140B at the first plate member 140A, the ends 144 a of the cap portion 144 are respectively slid along the slits 142 b so that the nail portion 149 of the cap portion 144 is inserted into the notch 148 of the first plate member 140A.
Because the second plate member 140B (cap portion 144) can be guided along the slits 142 b to be mounted at the first plate member 140A, the mounting performance of the plate members 140 a and 140B is improved.
According to this embodiment, the cap portion 144 of the second plate member 140B intersects (crosses) the side wall portions 142 of the first plate member 140A. Therefore, in the brazing of the plate member 140A and 140B, the contact area (range) between the plate members 140A and 140B is increased, as compared with the case where the cap portion 144 confronts the side wall portions 142 (that is, width of cap portion 144 is equal to distance between two side wall portions 142).
Accordingly, a brazing material fillet is readily formed in the brazing. For example, referring to FIG. 14, in the case where the brazing material is provided at the outer surfaces of the plate members 140A and 140B, the fillet can be formed at three positions a, b, and c at the one slit 142 b. Therefore, the brazing performance of the side wall portion 142 with respect to the cap portion 144 can be improved.

Fifth Embodiment

A fifth embodiment of the present invention will be described with reference to FIGS. 15 and 16. In this case, the junction of the cap portion 144 and the side wall portion 142 s is changed, as a third modification of the first embodiment.
As shown in FIG. 15, the cap portion 144 is provided with two slits 144 b (second slit). The slits 144 b are respectively disposed at the width-direction ends of the cap portion 144 and respectively have an opening facing the side (i.e., lower side in FIG. 15) of the core plate portion 141, so that the side wall portions 142 of the side of the opposite wall portion 143 can be respectively inserted into the slits 144 b, referring to FIG. 16.
The width (being dimension perpendicular to longitudinal directions of second plate member 140B and tube 110) of the slit 144 b is substantially equal to the thickness of the side wall portion 142. The side wall portion 142 of the side of the opposite wall portion 143 will be engaged with the slit 144 b.
In the mounting of the second plate member 140B at the first plate member 140A, the second plate member 140B is guided by the slit 144 b, into which the longitudinal-direction end (of side of opposite wall portion 143) of the side wall portion 142 is inserted. The nail portion 149 of the cap portion 144 is inserted into the notch 148 of the first plate member 140A.
Because the second plate member 140B is guided by the slit 144 b to be mounted at the first plate member 140A, the mounting performance of the plate members 140 a and 140B can be improved.
According to this embodiment, the side wall portions 142 are fixed to the cap portion 144 by engagement of the side wall portions 142 with the slits 144 b. Therefore, the gap caused between the side wall portion 142 and the cap portion 144 can be reduced, so that the brazing performance of the two plate members 140A and 140B can be improved.
In this embodiment, the length (being dimension in erection direction of cap portion 144) of the slit 144 b can be set corresponding to the gap caused between the side wall portion 142 and the cap portion 144.

Sixth Embodiment

A sixth embodiment of the present invention will be described with reference to FIG. 17. In this case, the junction of the cap portion 144 and the side wall portions 142 is changed, as a fourth modification of the first embodiment.
According to this embodiment, the periphery of the cap portion 144 of the first plate member 140A is provided with a bend edge 144 c (first bend edge), which is bent with respect to the cap portion 144 to be capable of contacting the inner surfaces of the side wall portions 142 and the core plate portion 141 in the assembly of the tank 140. That is, the bend edge 144 c can be arranged substantially in the thickness direction of the cup portion 144.
Thus, the bend edge 144 c can be joined to the core plate portion 141 and the side wall portions 142 by brazing, so that the brazing area of the plate members 140A and 140B is increased. Therefore, the brazing performance of the core plate portion 141, the side wall portions 142 and the cap portion 144 is improved.
Alternatively, the cap portion 144 can be also provided with the bend edge 144 c which contacts at least one of the core plate portion 141 and the side wall portion 142. That is, the periphery of the cap portion 144 can be also partially provided with the bend edge 144 c.
More alternatively, as shown in FIG. 18, the periphery of the opposite wall portion 143 can be also provided with a bend edge 143 c (second bend edge), which are bent with respect to the opposite wall portion 143 to be capable of contacting the inner surfaces of the side wall portions 142 in the assembly of the tank 140. That is, the bend edge 143 c can be arranged substantially in the thickness direction of the opposite wall portion 143. Thus, the brazing performance of the side wall portion 142 with respect to the opposite wall portion 143 can be improved.
As described above, the opposite wall portion 143 is provided with the nail portions 149 which are also formed at the periphery thereof. Therefore, the material of the opposite wall portion 143 can be formed to include the nail portions 149 along with the bend edge 143 c, which is arranged in the thickness direction of the material. Thus, the yield can be increased.
More alternatively, the bend edge 144 c can be also arranged to contact the outer surface of at least one of the core plate portion 141 and the side wall portion 142, and the bend edge 143 c can be also arranged to contact the outer surface of the side wall portion 142.

Seventh Embodiment

A seventh embodiment of the present invention will be described. In this case, the junction of the core plate portion 141 and the cap portion 144 is changed, as a fifth modification of the first embodiment.
Referring to FIG. 19, each of the longitudinal-direction ends of the trapezoid-shaped core plate portion 141 is provided with two penetration holes 141 b, which are respectively formed at two slant portions of the core plate portion 141. The slant portions of the core plate portion 141 lean from the portion thereof where the notch 148 is formed. The width (being dimension in longitudinal direction of first plate member 140A) of the penetration hole 141 b is substantially equal to the thickness of the second plate member 140B (cap portion 144).
As shown in FIGS. 19 and 20, the erection-direction end 144 d (of opposite side to opposite wall portion 143) of the cap portion 144 has two corners with a substantial right-angle shape or the like, so that at least a part of the corner can be inserted through the penetration holes 141 b to protrude from the outer surface of the core plate portion 141 in the assembling of the two plate members 140A and 140B. The erection-direction end 144 d is provided with the nail portion 149, which is arranged between the two corners and will be inserted through the notch 148 formed at the core plate portion 141.
Thus, the gap caused between the cap portion 144 and the core plate portion 141 can be reduced, as compared with the case where the cap portion 144 contacts the inner surface of the core plate portion 141 without protruding from the outer surface of the core plate portion 141. Therefore, the brazing performance of the core plate portion 141 with respect to the cap portion 144 can be improved.
FIGS. 21-23 show a modification of the seventh embodiment. In this case, as shown in FIG. 21, each of the longitudinal-direction ends of the trapezoid-shaped core plate portion 141 is provided with a single penetration hole 141 b, which extends to the whole core plate portion 141 in the width direction thereof. Referring to FIG. 23, the penetration hole 141 b of the core plate portion 141 is provided with a brim 141 c by burring. The brim 141 c can be bent to the inner side of the tank 140, with respect to the core plate portion 141. The brim 141 c is disposed around the penetration hole 141 b. According to the modification, the whole of the end 144 d of the cap portion 144 can be inserted through the penetration hole 141 b, referring to FIG. 22. In this case, the nail portions 149 arranged at the cap portions 144 and the notches 148 formed at the core plate portion 141 are omitted.
According to this modification, the brazing area of the cap portion 144 and the core plate portion 141 can be increased, so that the brazing performance of the core plate portion 141 with respect to the cap portion 144 is improved.
Alternatively, the brim 141 c can be also bent toward the outer side (reverse to that shown in FIG. 23) of the tank 140 with respect to the core plate portion 141, responding to the insertion performance of the end 144 d and the penetration hole 141 b.

Eighth Embodiment

An eighth embodiment of the present invention will be described with reference to FIGS. 24 and 25. In this case, the junction of the core plate portion 141 and the cap portion 144 is changed, as a sixth modification of the first embodiment.
As shown in FIG. 24, each of the longitudinal-direction ends of the core plate portion 141 is provided with a window 141 d (i.e., penetration hole). The erection-direction end 144 d (of the side of core plate portion 141) of the cap portion 144 is provided with a protuberance 144 e (i.e., engagement protuberance), which protrudes from the end 144 d toward the side of core plate portion 141 and will be inserted through (engaged with) the window 141 d.
The protuberance 144 e has a neck portion 144 g which is to contact the surface of the window 141 d and disposed at the root of the protuberance 144 e, and an overhang portion 144 f which extends from the neck portion 144 g to the side of the core plate portion 141. The overhang portion 144 f has a larger width (being dimension perpendicular to erection direction of cap portion 144) than the neck portion 144 g, referring to FIGS. 24 and 25.
When the second plate member 140B is mounted at the first plate member 140A, the protuberance 144 e is inserted through the window 141 d, so that the overhang portion 144 f protrudes from the core plate portion 141 and is engaged with the outer surface of the core plate portion 141.
According to this embodiment, the gap caused between the core plate portion 141 and the cap portion 144 can be reduced by insertion of the protuberance 144 e through the window 141 d, without increasing the load exerted at the core plate portion 141, as compared with the case where the cap portion 144 is provided with the nail portion 149 bent to contact the outer surface of the core plate portion 141 (referring to first embodiment). Thus, the brazing performance of the core plate portion 141 with respect to the cap portion 144 can be improved.

Ninth Embodiment

A ninth embodiment of the present invention will be described with reference to FIGS. 26-27B. In this case, the constructions of the first plate member and the second plate member of the tank 140 are changed, as compared with the above-described embodiments.
According to the ninth embodiment, referring to FIG. 26, the first plate member 260 includes the core plate portion 141 and the two cap portions 144, which are constructed of a single metal plate (formed by punching, for example) by bending. The second plate member 250 includes the opposite wall portion 143 and the two side wall portions 142, which are constructed of a single metal plate (formed by punching, for example) by bending.
The side wall portion 142 of the second plate member 250 is provided with the multiple notches 148, which are to be engaged with the multiple nail portions 149 formed at the cap portions 144 and the core plate portion 141 of the first plate member 260.
FIG. 27A is a cross-sectional view (of longitudinal direction of tank 140) showing a part of the tank 140. FIG. 27B is an enlarged view of the part XXVIIB in FIG. 27A.
Referring to FIG. 27B, the brazing material layers 151 and 161 are respectively arranged at the outer surface 150 a of the second plate member 250 and the outer surface 160 a of the first plate member 260. The end surface 162 of the first plate member 260 (cap portion 144) contacts the inner surface 150 b of the second plate member 250 (opposite wall portion 143). Thus, the fillet 161A can be formed between the inner surface of the extension portion 153 of the second plate member 250 and the shear droop 162A of the first plate member 260.
According to this embodiment, the junctions between the plate members 250 and 260 have the same constructions with that (shown in FIG. 27B) between the opposite wall portion 143 of the second plate member 250 and the cap portion 144 of the first plate member 260.
In this case, the tank 140 is not provided with the overlap construction at the brazing junction in the inner space 145 of the tank. The brazing material can be accumulated at the shear droop 162A (formed at cap portion 144, for example) so that the brazing area of the fillet 161A is enlarged, while the capacity of the inner space 145 is maintained. Thus, the stable brazing performance can be maintained.

Other Embodiments

Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.
In the above-described embodiments, the extension portion 153 of the plate member 140A, 250 extends so that the end surface 152 is positioned at the tank outer side with respect to the outer surface 160 a of the plate member 140B, 260. However, the extension portion 153 can also extend so that the end surface 152 is positioned at the tank outer side with respect to the contact part 163 of the plate member 140B, 260. For example, referring to FIG. 28, the end surface 152 of the extension portion 153 of the first plate member 140A can be arranged at the position corresponding to that of the outer surface 160 a of the second plate member 140B.
In the above-described embodiments, the notches 148 formed at the plate member 140A, 250 are engaged with the nail portions 149 formed at the plate member 140B, 260, to reduce the clearance at the brazing junction. However, the component where the notches 148 are arranged and the component where the nail portions 149 are provided can be also exchanged. Alternatively, the notches 148 can be also arranged at the two different components, to be engaged with the nail portions 149 which are also arranged at the two different components at the positions corresponding to those of the notches 148.
Moreover, referring to FIGS. 29 and 30, the second plate member 140B (opposite wall portion 143) and the first plate member 140A (side wall portions 142) can be also provided with multiple windows 148 a (i.e., engagement holes) and multiple engagement protrusions 149 a, instead of the notches 148 and the nail portions 149 in the above-described embodiments.
Specifically, one (e.g., second plate member 140B) of the two plate members 140A and 140B is provided with the windows 148 a, and the other (e.g., first plate member 140A) is provided with the protrusions 149 a. In this case, the protrusion 149 a is inserted through (engaged with) the window 148 a, to temporarily fix the two plate members 140A and 140B.
Moreover, the protrusion shape of the core plate portion 141 (protruding to the side of tube 110) can also have a substantial arc shape or the like.
The tank 140 can be also constructed of at least three metal plate members.
Furthermore, the heat exchanger 100 can be also made of metal other than the aluminum and the aluminum alloy. For example, the tank 140 can be made of stainless, and the plate member thereof is clad by copper brazing material or the like.
The heat exchanger 100 according to the present invention can be also suitably used for other heat exchangers, for example, a condenser, an evaporator and an inter cooler.
Such changes and modifications are to be understood as being in the scope of the present invention as defined by the appended claims.

Claims

1. A heat exchanger comprising:

a plurality of tubes which are stacked; and

at least one tank which extends in a stacking direction of the tubes, the tank being connected with longitudinal-direction ends of the tubes so that an inner space of the tank is communicated with those of the tubes, the tank having a first plate member and a second plate member which are integrated by brazing, wherein:

the first plate member includes a core plate portion which is connected with the tubes, and two side wall portions which are respectively disposed at two lateral-direction ends of the core plate portion and extend in a longitudinal direction of the core plate portion,

the two side wall portions facing each other and being spaced by the inner space of the tank,

the core plate portion and the side wall portions being constructed of a metal plate material by bending;

the second plate member includes an opposite wall portion which faces the core plate portion and is spaced from the core plate portion by the inner space of the tank, and two cap portions which are respectively arranged at two ends of the longitudinal direction of the core plate portion of the opposite wall portion and extend to sandwich the inner space of the tank therebetween, the two cap portions facing each other,

the opposite wall portion and the cap portions being constructed of a metal plate material by bending; and

the core plate portion has a cross section which has a shape protruding toward an outer side of the tank in the longitudinal direction of the tubes, the cross section being perpendicular to the stacking direction of the tubes.

2. The heat exchanger according to claim 1, wherein the second plate member has at least one rib.

3. The heat exchanger according to claim 2, wherein the rib protrudes into the inner space.

4. The heat exchanger according to claim 1, wherein the side wall portion has at least one junction groove, in which a lateral-direction end of the cap portion is inserted.

5. The heat exchanger according to claim 1, wherein

the side wall portion has at least one first slit, in which a lateral-direction end of the cap portion is inserted, the lateral-direction end of the cap portion protruding from an outer surface of the side wall portion.

6. The heat exchanger according to claim 1, wherein the cap portion has two second slit, in which the two side wall portions of a side of the opposite wall portion are respectively inserted, the second slit being arranged at the cap portion of a side of the side wall portion.

7. The heat exchanger according to claim 1, wherein

the cap portion has a first bend edge which is disposed at a periphery of the cap portion and bent to contact at least one of the core plate portion and the side wall portion.

8. The heat exchanger according to claim 1, wherein

the opposite wall portion has a second bend edge which is arranged at a periphery of the opposite wall portion and bent to contact the side wall portions.

9. The heat exchanger according to claim 1, wherein the core plate portion has at least one penetration hole, through which at least a part of an end of the cap portion is inserted, the end of the cap portion being disposed at an opposite side to the opposite wall portion.

10. The heat exchanger according to claim 9, wherein the penetration hole is provided with a brim.

11. The heat exchanger according to claim 1, wherein:

the core plate portion has a window; and

the cap portion has an engagement protuberance, which projects from an end of the cap portion of a side of the core plate portion and has an overhang portion,

the engagement protuberance being inserted through the window so that the overhang portion is engaged with an outer surface of the core plate portion.

12. The heat exchanger according to claim 1, wherein:

one of the first plate member and the second plate member has a plurality of concave-shaped engagement notches disposed at ends thereof; and

other of the first plate member and the second plate member has a plurality of engagement nail portions which are disposed at ends thereof and engaged with the engagement notches, tips of the engagement nail portions being engaged with an outer surface of the one of the first plate member and the second plate member.

13. The heat exchanger according to claim 1, wherein:

one of the first plate member and the second plate member has a plurality of engagement windows disposed at ends thereof; and

other of the first plate member and the second plate member has a plurality of engagement protrusions which are disposed at ends thereof and engaged with the engagement windows.

14. A heat exchanger comprising:

a plurality of tubes which are stacked; and

at least one tank which extends in a stacking direction of the tubes, the tank being connected with longitudinal-direction ends of the tubes so that an inner space of the tank is communicated with those of the tubes, wherein:

the tank includes at least two metal plate members, which are respectively provided with brazing material layers at least at outer surfaces thereof to be integrated by brazing, the outer surface of the plate member constructing a part of an outer surface of the tank;

at a brazing junction between the plate members, an inner surface of one of the plate members contacts an end surface of other of the plate members, the inner surface being at an inner side of the tank;

at the brazing junction, the one of the plate members has an extension portion, which extends so that an end surface of the extension portion is positioned at an outer side of the tank with respect to a contact part between the plate members;

at the brazing junction, the other of the plate members has a shear droop which is disposed at the outer surface thereof and formed by punching; and

a brazing material fillet is formed between the extension portion of the one of the plate members and the shear droop of the other of the plate members.

15. The heat exchanger according to claim 14, wherein

the end surface of the extension portion of the one of the plate members is positioned at the outer side of the tank with respect to the outer surface of the other of the plate members.

16. The heat exchanger according to claim 14, wherein

the tank is constructed of the first plate member having a core plate portion connected with the tubes, and the second plate member having an opposite wall portion which faces the core plate portion and is spaced from the core plate portion by the inner space of the tank.

17. The heat exchanger according to claim 16, wherein:

the first plate member further has two side wall portions which face each other and are spaced by the inner space of the tank, the side wall portions and the core plate portion being constructed of a single metal plate material by bending,

two lateral-direction ends of the core plate portion being respectively connected with those of the opposite wall portion by the two side wall portions; and

the second plate member further has two cap portions which face each other and are spaced by the inner space of the tank, the cap portions and the opposite wall portion being constructed of a single metal plate material by bending,

two longitudinal-direction ends of the core plate portion are respectively connected with those of the opposite wall portion by the two cap portions.

18. The heat exchanger according to claim 16, wherein:

the first plate member further has two cap portions which face each other and are spaced by the inner space of the tank, the cap portions and the core plate portion being constructed of a single metal plate material by bending,

two longitudinal-direction ends of the core plate portion are respectively connected with those of the opposite wall portion by the two cap portions; and

the second plate member further has two side wall portions which face each other and are spaced by the inner space of the tank, the side wall portions and the opposite wall portion being constructed of a single metal plate material by bending,

two lateral-direction ends of the core plate portion being respectively connected with those of the opposite wall portion by the two side wall portions.

19. The heat exchanger according to claim 16, wherein:

the first plate member has a plurality of engagement notches concaved from end surfaces of the first plate member; and

the second plate member has a plurality of engagement nail portions which are engaged with the engagement notches, tips of the engagement nail portions being engaged with the outer surface of the first plate member.

20. The heat exchanger according to claim 16, wherein:

the second plate member has a plurality of engagement notches concaved from end surfaces of the second plate member; and

the first plate member has a plurality of engagement nail portions which are engaged with the engagement notches, tips of the engagement nail portions being engaged with the outer surface of the second plate member.