Heat exchanger

Abstract

In a heat exchanger in which the number of parts is small, assembling is easy, bonded portions between each part are fewer and reliability of brazing is improved, a core body is constituted by turning up and bending a strip-shaped metal plate in a fanfold manner, and first flow passages and second flow passages are formed alternately in the thickness direction. Both ends of each of the first flow passages are blocked by each comb tooth of a pair of comb-state members, and a fin is set within the second flow passages so as to constitute a core. And a cylindrical casing is fitted with the outer periphery of the core body, and the casing is constituted by a channel-state material covering three faces of the outer periphery of the core body and a lid material blocking an opening of the channel-state material. In the core body, a starting end and a terminating end of the turning-up/bending of the strip-shaped metal plate are both located on the turned-up end edge on one side, the starting end the terminating end form a fitting edge portion turned-up with the section in the U-shape conforming to the plate thickness of the channel-state material, and the end edge of the opening of the channel-state material is fitted with the fitting edge portion so as to braze/fix the both.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a heat exchanger in a simple structure which can be applied to a heat exchanger (EGR cooler) used in an exhaust gas recirculation apparatus in an automobile and other heat exchangers, in which a core body formed by turning up and bending a strip-shaped metal plate in a fanfold manner and having flat first flow passages and second flow passages alternately in the thickness direction of the metal plate, each of the first flow passages of the core body being blocked by each comb tooth of a pair of comb-state members at both end positions.

A conventional EGR cooler is made of an assembly of a large number of flat tubes or a large number of plates, a large number of fins, a casing and a header, in which cooling water is made to communicate through the casing side and an exhaust gas is made to communicate inside each of the flat tubes or the like as proposed in the invention described in Japanese Patent Application Laid-Open No. 5-18634.

Another heat exchanger in which a core of the heat exchanger is formed by a strip-shaped metal plate bent in a fanfold manner and a pair of comb-state members, the outer periphery being fitted with a cylindrical casing, and tanks are provided at both ends in the longitudinal direction as proposed in the invention described in WO 2004/065876 A1.

In the former heat exchanger such as the EGR cooler, the number of parts is large, which makes assembling cumbersome and increases the number of brazing portions on the parts, and there is a problem that a leakage tends to occur at the brazing portion.

In the core of the latter heat exchanger, comb teeth of the comb-state member are arranged at every other portion of the large number of flat groove portions in a core body formed in the fanfold state, and the groove bottom and the tip end of the comb tooth are bonded. And the casing is fitted with the outer periphery of the core. The casing is formed in the cylindrical state with a channel-state material covering three faces of the outer periphery of the core body and a lid member blocking the opening of the channel-state material, and the both ends are connected to the header. In this type of heat exchanger, there is a problem that a crack tends to occur at a joint between the casing and the core body, from which leakage of a fluid easily occurs. Along with that, leakage tends to occur at the brazing portion between the tooth base of the comb-teeth and the side face of the core body.

The present invention has an object to provide a reliable heat exchanger in which the number of parts is small, assembling is easy, strength at the brazing portion is high, and leakage is hard to occur.

SUMMARY OF THE INVENTION

The present invention in accordance with a first aspect thereof is a heat exchanger comprising

a core body (5) in which a strip-shaped metal plate is turned up and bent in a fanfold manner with turned-up end edges (1), (2) alternately formed at one end and the other end of a rectangular flat face portion (1a) and flat first flow passages (3) and second flow passages (4) are provided alternately in the thickness direction of the metal plate,

each of the first flow passages (3) of the core body (5) being blocked by each comb tooth (6b) of a pair of comb-state members (6) at both end positions of the turned-up end edge (1), and a fin (7) being set within the second flow passages (4) so as to constitute a core (8),

the outer periphery of the core body (5) being fitted with a cylindrical casing (9) so as to block the adjacent turned-up end edges (1), (2),

a first fluid (10) being guided to each of the first flow passages (3) by a pair of ports (11) on the outer face of the casing (9), while a second fluid (12) being guided from one of cylindrical openings (13) to the other opening (13) through each of the second flow passages (4), wherein

the casing (9) comprises a channel-state material (9a) covering three faces of the outer periphery of the core body (5) and a lid material (9b) blocking the opening of the channel-state material (9a);

in the core body (5), a starting end and a terminating end of the turning-up of the strip-shaped metal plate are both located at the turned-up end edge on one side;

a fitting edge portion (15) with a section turned up in the U-shape conforming to the plate thickness of the channel-state material (9a) is provided at the starting end and the terminating end; and

the end edge of the opening of the channel-state material (9a) is fitted with the fitting edge portion (15) and the both are brazed and fixed.

The present invention in accordance with a second aspect of the invention is a heat exchanger in accordance with a first aspect of the invention, wherein

an end edge of the lid material (9b) is turned up and the turned-up portion is brazed to be fitted with the outer periphery of the fitting edge portion (15) in the contact state.

The present invention in accordance with a third aspect of the invention is a heat exchanger in accordance with the first or second aspect of the invention, wherein

the section of the opening of the fitting edge portion (15) and the channel-state material (9a) is wound/tightened and bent in the L-shape.

The present invention in accordance with a fourth aspect of the invention is a heat exchanger in accordance with the second or third aspect of the invention, wherein

the plate thickness of the channel-state material 9a and the lid material 9b is formed larger than that of the core body 5.

The present invention in accordance with a fifth aspect thereof is a heat exchanger in accordance with any of the first to fourth aspects thereof, wherein

a tooth base (6c) and the comb tooth (6b) of the comb-state member (6) are made to cross perpendicularly to each other, a root (14) of the comb tooth (6b) is bent in the L-shape, and each connection portion between the comb-state member (6) and the core body (5) as well as the lid material (9b) is brazed/fixed integrally in the state where the tooth base (6c) is held between a side face of the core body (5) and the lid material (9b).

The present invention in accordance with a sixth aspect thereof is a heat exchanger in accordance with any of the first to fifth aspects thereof, wherein

a high heat-resistant/corrosion-resistant material is used for the channel-state material (9a) constituting the casing (9), while the lid material (9b) is formed by a material with lower heat-resistance/corrosion-resistance than that of the channel-state material (9a);

both ends of the casing (9) in the longitudinal direction constitute a pair of header portions (31) projecting outward from the both ends of the core body (5), and both opening ends of the casing (9) are blocked by header end lids (16), (17) made of a high heat-resistant/corrosion-resistant material; and

the header end lids (16), (17) have extension portions (16a), (17a) covering the inner surface of the lid material (9b) of the header portion (31).

The heat exchanger of the present invention is constructed as above and has the following effects.

In the present invention, the casing 9 is formed by the channel-state material 9a and the lid material 9b, the fitting edge portion 15 with the section in the U-shape is formed at both edge portions of the core body 5 bent in the fanfold manner, and a tip end portion of the channel-state material 9a is fitted with the fitting edge portion 15 and the both are brazed/fixed. Therefore, brazing strength at the joint between the core body 5 and the casing, where a crack is particularly easy to occur, is increased, and reliability of brazing can be improved.

In the above construction, in the state where the end edge of the lid material 9b is bent and the bent portion is fitted with the outer periphery of the fitting edge portion 15 in contact and the both are brazed together, a brazing area between the lid material 9b and the core body 5 is sufficiently ensured, a gap between the both is eliminated and reliability of brazing can be improved.

In the above construction, in the state where the section at the end of the opening of the fitting edge portion 15 and the channel-state material 9a is wound/tightened and bent in the L-shape, reliability of brazing can be further improved.

In the above construction, in the state where the plate thickness of the channel-state material 9a and the lid material 9b is made larger than that of the core body 5, manufacture of the core body 5 bent in the complicated state is facilitated, accuracy of the U-shaped sectional portion can be increased, and brazing accuracy of the core body 5 and the channel-state material 9a as well as the lid material 9b can be improved.

In the above construction, in the state where the tooth base 6c and the comb tooth 6b of the comb-state member 6 are made to cross perpendicularly to each other, the root 14 of the comb tooth 6b is bent in the L-shape and each connection portion of the comb-state member 6 and the core body 5 as well as the lid material 9b is integrally brazed/fixed with the tooth base 6c held between the side face of the core body 5 and the lid material 9b, a brazing area between the tooth base 6c and the lid material 9b as well as the core body 5 can be ensured to be large, a gap can be eliminated, and leakage can be prevented.

In the above construction, a material with higher heat-resistance/corrosion-resistance than that of the lid material 9b can be used for the channel-state material 9a, a pair of header portions 31 may be provided at both ends of the casing 9 in the longitudinal direction comprised by them, the openings of the header portions 31 may be blocked by a pair of high heat-resistant/corrosion-resistant header end lids 16, 17, and the inner surface portion of the header portion 31 of the lid material 9b is covered by the extension portions 16a, 17a extended from the header end lids 16, 17. In this case, the heat exchanger can be provided at a lower cost, because a portion with lower heat-resistance/corrosion-resistance of the header portion 31 can be compensated only by the small extension portions 16a, 17a, and a material of the lid material 9b can be obtained inexpensively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a heat exchanger of the present invention.

FIG. 2 is a perspective view illustrating an assembled state of the heat exchanger.

FIG. 3 is an explanatory view of an assembly of a core body 5 and a comb-state member 6 of the heat exchanger.

FIG. 4 is a perspective view of the comb-state member 6.

FIG. 5 is an enlarged perspective view of an essential part illustrating a state where the comb-state member 6 is inserted into the core body 5.

FIG. 6 is a perspective view illustrating an assembled state of the comb-state member 6 and the core body 5.

FIG. 7 is an explanatory view illustrating another example of comb-teeth 6b of the comb-state member 6.

FIG. 8 is a cross sectional view of the heat exchanger of the present invention.

FIG. 9 is an enlarged view of IX part of FIG. 8.

FIG. 10 is the same enlarged view of an intermediate portion of the core in the longitudinal direction.

FIG. 11 is a cross sectional view of an essential part illustrating still another example of FIG. 9.

FIG. 12 is a perspective explanatory view illustrating a buffer plate of the heat exchanger of the present invention.

FIG. 13 is a plan view of a longitudinal section of the heat exchanger.

DETAILED DESCRIPTION OF THE INVENTION

Next, an embodiment of the present invention will be described based on the attached drawings.

FIG. 1 is an exploded perspective view of a heat exchanger of the present invention, FIG. 2 shows its assembled state and FIG. 3 is an explanatory view of an assembly of a core body 5 and a comb-state member 6. Also, FIG. 4 is a perspective view of the comb-state member 6, FIG. 5 is a partially cutaway enlarged perspective view illustrating the assembled state, and FIG. 6 is a perspective view of the assembled state.

Further, FIG. 8 is a cross sectional view of the heat exchanger, and FIG. 9 is an enlarged view of IX part of FIG. 8.

This heat exchanger has the core body 5, a large number of fins 7, a casing 9, a pair of headers 16, 17, and the pair of comb-state members 6.

The core body 5 is comprised by turning up and bending a strip-shaped metal plate in a fanfold manner as shown in FIG. 3 so that turned-up end edges 1, 2 are formed alternately at one end and the other end of a rectangular flat face portion 1a, and flat first flow passages 3 and second flow passages 4 are provided alternately in the thickness direction of the metal plate. In this example, a space of the first flow passage 3 is formed smaller than that of the second flow passage 4. It is needless to say that the spaces of the both can be the same or vice versa.

A large number of dimples 29 are formed on the first flow passage 3 side of the strip-shaped metal plate. In this example, the opposing dimples 29 are brought into contact with each other at their tip ends so as to hold the space of the first flow passage 3 constant. To each of the first flow passages 3, each of the comb-state members 6 is fitted at the both end positions of the turned-up end edges 1, and the fitted portions are integrally brazed/fixed. Also, instead of the dimples, an inner fin may be inserted into the first flow passage 3 and the inner face and both sides in the thickness direction of the inner fin may be brazed/fixed together.

In the comb-state member 6, a tooth base 6c is provided to be perpendicular to a comb tooth 6b, and a root 14 of the comb tooth 6b is bent in the L-shape along the comb base 6c (FIGS. 4, 5).

The comb-state member 6 constructed as above is, as shown in FIG. 5, has its tooth base 6c in contact with the end face of the turned-up end edge 2, and the root 14 is in contact with the corner part and further, it is in contact with a lid member 9b as shown in FIG. 9 so that a brazed area of each contact portion is large. By this, reliability of brazing is improved.

The root 14 and the tooth base 6c are in contact or fabricated with an extremely slight gap.

Next, the fins 7 are set between each of the second flow passages 4 as shown in FIG. 3. Though the first flow passage 3 at the uppermost position is shown in the lifted state in FIG. 3 so that the fin 7 is easy to be seen, the lower face side of the first flow passage 3 at the uppermost position is actually in contact with the fin 7 on the uppermost stage as shown in FIG. 6. This fin 7 is formed by bending a metal plate in the waveform in the cross-sectional direction and also in the longitudinal direction of its ridge line and trough portion so as to improve agitating effect of a fluid communicating through the second flow passage 4.

A core 8 in FIG. 6 is constituted by an assembly of the core body 5, the comb-state member 6, and the fin 7 as above. Instead of the above fin 7, a slit fin, an offset fin or a louver fin, not shown, may be inserted into the second flow passage 4.

Next, the casing 9 fitted over the outer periphery of this core 8 is formed in the cylindrical shape with a rectangular section longer than the length of the core 8 and has a pair of header portions 31 (See FIGS. 12, 13) outside the both ends of the core 8. This casing 9 is comprised by a channel-state material 9a and a lid material 9b in this embodiment as shown in FIGS. 1 and 8. The plate thickness of the channel-state body material 9a and the lid material 9b is formed sufficiently larger than that of the core body 5 as shown in FIG. 9. This increases the strength of the casing 9, facilitates forming of the core body 5 bent in the complicated state, and improves machining accuracy of a fitting edge portion 15 with the U-shaped section provided at its both ends as well as brazing accuracy of the joint between the casing 9 and the core body 5.

The channel-state material 9a has its inner circumferential face in contact with both the upper and lower faces and one side of the core body 5 so as to block between the adjacent turned-up end edges 1 of the core body 5. The lid material 9b blocks the opening side of the channel-state material 9a, blocks the other side of the core body 5 and in the longitudinal direction. The L-shaped portions of the upper and lower both ends of the lid material 9b are fitted with the outer face side of the fitting edge potion 15. FIG. 11 illustrates a state where the sections of the ends are stood in the L-shape and wound/tightened. In this case, the tip end of the lid material 9b is made into the shape conforming to that.

Next, opening ends of the header portions 31 of the both ends of the casing 9 in the longitudinal direction are blocked by header end lids 16, 17 made of a pair of high heat-resistant/corrosion-resistant materials, and a flange 25 is fitted to the outside thereof. The header end lids 16, 17 are swollen outward in the pot shape in this embodiment, and a port for the second fluid 12 is opened at the center. Moreover, on one side of each of the header end lids 16, 17, extension portions 16a, 17a are integrally extended and the extension portions 16a, 17a cover the inner surfaces of the both ends of the lid material 9b as shown in FIG. 13.

Brazing material is overlaid or arranged between connected portion of such heat exchanger as described above, and the whole in the assembled state shown in FIG. 2 is integrally brazed/fixed in a high-temperature furnace.

And as shown in FIG. 7, the first fluid 10 is supplied to the first flow passage 3 side, while the second fluid 12 is supplied to the second flow passage 4 side. As an example, the first fluid 10 made of cooling water is supplied to each of the first flow passages 3 through one of the pipes 26 and the small tank portions 28 projected on one side of the casing 9 and it communicates in the longitudinal direction and flows out of the other pipe 26. Also, as an example, the second fluid 12 made of a high-temperature exhaust gas is supplied to each of the second flow passages 4 through the opening of the header end lid 16 and an opening 13 of the casing 9.

The pair of comb-state members 6 (FIG. 1) constitutes the header plates.

This comb-state member 6 can have its tip end portion formed in a curved portion 24 as shown in FIG. 7, and in this case, the flow of the first fluid 10 can be smoothly guided in the longitudinal direction at the end of the comb-state member 6. By this, retention portion of the first fluid 10 can be eliminated, and if the first fluid 10 is cooling water, boiling at that part can be prevented, and heat exchange can be promoted.

Next, FIGS. 12, 13 illustrate a state where a buffer plate 30 is provided at the inlet side of the first fluid 10 so as to enable even communication of the cooling water in each part of the first flow passages 3. In the embodiment of FIG. 2, since the pair of small tank portions 28 exist at the both ends of the lid material 9b, the first fluid 10 flowing from the pipe 26 tends to flow more on the lid material 9b side when communicating through each part of the first flow passages 3. Then, the buffer plate 30 is opposed to the opposite face on the outlet side of the cooling water of the pipe 26, and an opening is formed in the slit state only on the left side, in FIG. 13, so that the flow velocity of the first fluid 10 flowing out of the opening is increased. The first fluid 10 is guided by the motion energy to a position separate from the lid material 9b. That is, the first fluid 10 bypasses the buffer plate 30 and flows out to the first flow passage 3 in the narrowed state as shown by an arrow.

Claims

1. A heat exchanger comprising a core body in which a strip-shaped metal plate is turned up and bent in a fanfold manner with turned-up end edges alternately formed at one end and the other end of a rectangular flat face portion and flat first flow passages and second flow passages are provided alternately in the thickness direction of the metal plate,each of the first flow passages of the core body being blocked by each comb tooth of a pair of comb-state members at both end positions of said turned-up end edge, and a fin being set within said second flow passages so as to constitute a core,the outer periphery of the core body being fitted with a cylindrical casing so as to block the adjacent turned-up end edges,a first fluid being guided to each of the first flow passages by a pair of ports on the outer face of said casing, while a second fluid being guided from one of cylindrical openings of said casing to the other opening through each of the second flow passages, whereinsaid casing comprises a channel-state material covering three faces of the outer periphery of said core body and a lid material blocking the opening of the channel-state material, said channel-state material being formed of a high heat-resistant and corrosion-resistant material, said lid material being formed of a material having lower heat-resistance and corrosion-resistance than the channel-state material;the casing having a pair of longitudinal ends and header portions extending outward from each of the ends of the casing, the longitudinal ends each being provided with a header end lid that blocks its end of the casing, each header end lid being formed of a high heat-resistant and corrosion-resistant material;each header end lid having an extension portion covering an inner surface of each header portion;in said core body, a starting end and a terminating end of the turning-up of said strip-shaped metal plate are both located at said turned-up end edge on one side;a fitting edge portion with a section turned up in the U-shape conforming to the plate thickness of said channel-state material is provided at the starting end and the terminating end; andthe end edge of said opening of the channel-state material is fitted with the fitting edge portion and the both are brazed and fixed.