Heat exchanger

Abstract

A protective cover 7 is disposed on an airflow upstream side of a tube 2. Even when relatively large flying materials such as gravel impinge against a radiator 1, the flying materials are prevented from directly striking the tubes 2. As the tube 2 can thus be protected from the relatively large flying materials such as gravel, the radiator 1 can continue operating, and the reliability of the radiator 1 can be improved.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a heat exchanger, and can be effectively applied to a radiator of large construction machine such as bulldozer or a shovel loader and an agricultural machine such as a tractor.

[0003] 2. Description of the Related Art

[0004] A large construction machine such as a bulldozer and a shovel loader and an agricultural machine such as a tractor are used in environments where relatively large flying materials such as gravel exist. Therefore, the possibility is extremely high that flying materials such as gravel may impinge against a radiator of these machines.

[0005] Once the flying materials, such as gravel, damage tubes of the radiator, cooling water leaks out and the radiator is very likely to stop operating.

SUMMARY OF THE INVENTION

[0006] In view of the background described above, the invention is directed to protect the tubes from relatively large flying materials such as gravel.

[0007] To accomplish the object, one aspect of the invention provides a heat exchanger comprising a plurality of tubes (2) arranged in parallel with one another in an airflow direction, and allowing a fluid to flow therethrough; header tanks (3) arranged at end portions of the tubes (2) in a longitudinal direction, and communicating with these tubes (2); and tube protective members (7) for protecting the tubes (2), disposed on an airflow upstream side of the tubes (2), and being separate members from the tubes (2).

[0008] This construction makes it possible to prevent relatively large flying materials such as gravel from directly striking the tubes (2) even when the flying materials impinge against the heat exchanger, and thus to protect the tubes (2) from the relatively large flying materials such as gravel. Because the heat exchanger thus continues operating, reliability of the heat exchanger can be improved.

[0009] In another aspect of the invention, each of the tubes (2) described above is shaped into a compressed flat shape in such a fashion that the airflow direction is coincident with a major diameter direction; a fin (6) for increasing a heat transfer area with air is bonded to a compressed flat surface (2a) of an outer surface of each of the tubes (2); and the fin (6) extends to a portion corresponding to the tube protective member (7) beyond an end portion of the tube (2) in the major diameter direction.

[0010] According to this construction, the fin (6) and the tube protective member (7) encompass each tube (6). Therefore, the tube (2) can be reliably protected from the flying materials.

[0011] Incidentally, the tube protective member (7) may be a round rod-like member.

[0012] Still another aspect of the invention provides a heat exchanger comprising a plurality of tubes (2) through which a fluid flows; and fins (6) each bonded to an outer surface of each of the tubes (2), for increasing a heat transfer area with air; wherein the fin (6) extends to at least a front side of the tube (2) and encompasses the front side of the tube (2).

[0013] Still another aspect of the invention provides a heat exchanger comprising a plurality of tubes (2) through which a fluid flows; and fins (6) each bonded to an outer surface of each of the tubes (2), for increasing a heat transfer area with air; wherein the tube (2) is shaped into a compressed flat shape so that an airflow direction coincides with a major diameter direction, and the fin (6) is bonded to the compressed flat surface (2a) in such a fashion as to substantially cover the whole area of the compressed flat surface (2a) of an outer surface of the tube (2).

[0014] Still another aspect of the invention provides a heat exchanger comprising a plurality of tubes (2) arranged in parallel with one another in an airflow direction, and allowing a fluid to flow therethrough; header tanks (3) arranged at end portions of the tubes (2) in a longitudinal direction, and communicating with these tubes (2); and fins (6) each brazed to an outer surface of each of the tubes (2), for promoting heat exchange between the fluid and air; wherein a tube protective portion (8) is formed by a filler metal on an airflow upstream side of the tube (2) when the filler metal is solidified in a brazing process of the tube (2) and the fin (6).

[0015] The present invention may be more fully understood from the description of preferred embodiments of the invention, as set forth below, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the drawings:

[0017] FIG. 1 is a perspective view of a radiator according to a first embodiment of the invention;

[0018] FIG. 2 is a schematic view showing a mounting structure of a radiator according to the first embodiment of the invention;

[0019] FIG. 3 is a sectional view when the radiator according to the first embodiment of the invention is viewed from a longitudinal direction of tubes;

[0020] FIG. 4 is an explanatory view useful for explaining operation and effects of the radiator according to the first embodiment of the invention;

[0021] FIGS. 5A and 5B are explanatory views each being useful for explaining a radiator according to a second embodiment of the invention;

[0022] FIGS. 6A and 6B are explanatory views each being useful for explaining a radiator according to a third embodiment of the invention;

[0023] FIG. 7A is an explanatory view being useful for explaining a radiator according to a fourth embodiment of the invention; and

[0024] FIG. 7B is an enlarged view of a portion A shown in FIG. 7A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

[0025] This embodiment represents the application of the invention to a radiator of a large construction machine such as a bulldozer or a shovel loader. FIG. 1 is a perspective view showing the appearance of the radiator 1 in this embodiment and FIG. 2 is a schematic view showing a mounting state of the radiator 1.

[0026] The radiator 1 is mounted so that cooling air blown from a blower 10 mounted on an upstream side of an air flow can blow onto the radiator 1 as shown in FIG. 2. The blower 10 acquires power from an engine E/G and is driven by this power.

[0027] As shown in FIG. 1, the radiator 1 includes a plurality of tubes 2 made of aluminum, through which cooling water flows, and header tanks 3 formed of aluminum, disposed at both ends of the tubes 2 in a longitudinal direction and communicating with the tubes 2. In this embodiment, about 50 to about 100 tubes 2 and the header tanks 3 communicating with these tubes 2 constitute one unit 4. When a plurality of these units 4 is combined with one another, they constitute the radiator 1.

[0028] More concretely, second header tanks 5 communicating with the header tanks 3 of each unit 1 connect the header tanks 3 to constitute one radiator 1. Incidentally, each unit 4 has a heat radiation capacity of from about 100 to about 200 W.

[0029] The tubes 2 of each unit 4 are flat tubes shaped into a compressed flat shape so that the flowing direction of air coincides with a direction of a major diameter, and are arranged in parallel with one another relative to the air flowing direction. An aluminum fin 6 for increasing a heat transfer area with air and for promoting heat exchange is brazed to a compressed flat surface 2a of the outer surface of each tube 2 as shown in FIG. 3. These fins 6 are arranged in such a fashion as to describe a corrugated shape when viewed from the air flowing direction (see FIG. 1).

[0030] The term “brazing” means a bonding technique that bonds an article by use of a brazing material or a solder without melting a base metal. The technology using a filler metal having a melting point of 450° C. or above is called “brazing” and the material used at this time is called the “brazing material”. The technology using a filler metal having a melting point of 450° C. or below is called “soldering” and the filler metal is called the “solder”.

[0031] A protective bar 7 as a round rod-like tube protective member is disposed at an end portion of each tube 2 in its major diameter direction and on the more upstream side of the air flowing direction than the tube 2. The protective bar 7 is produced as a member separate from the tube 2 and at least both of its ends in the longitudinal direction are brazed to the header tank 3. Each fin 6 extends to at least a portion corresponding to this protective bar 7 beyond the end portion of the tube 2 in the major diameter direction.

[0032] Next, the operation and effects of this embodiment will be described.

[0033] In this embodiment, the protective bar 7 is disposed on the airflow upstream side of the tube 2. Therefore, even when relatively large flying materials such as gravel impinge against the radiator 1, the flying materials are prevented from directly striking the tubes 2. In other words, as the tubes 2 can be protected from the relatively large flying materials such as gravel, the radiator 1 can be prevented from stopping its operation and reliability of the radiator 1 can be improved.

[0034] As the fin 6 extends to the portion corresponding to the protective bar 7 beyond the end portion of the tube 1 in its major diameter direction, the fin 6 and the protective bar 7 encompass the tube 2, and the tube 2 can be reliably protected from the flying materials.

[0035] Incidentally, the fin 6 extends to the portion corresponding to the protective bar 7 beyond the end portion of the tube 2 in its major diameter direction in this embodiment. However, the embodiment is not particularly limited to this construction, and the fin 6 need not always extend beyond the end portion of the tube 2 in its major diameter direction.

[0036] The protective bar 7 is not limited to the round rod-like bar, either, but may be a round pipe, a rectangular rod or a rectangular pipe.

[0037] It may be possible to employ means for forming a protective member 7a corresponding to the protective bar 7 integrally with the tube 2 as shown in FIG. 4. However, this means is not advantageous because the sectional shape of the tube 2 is distorted and the tube 2 cannot be fitted and bonded easily to the header tank 3.

Second Embodiment

[0038] This embodiment does not use the protective bar 7 but extends the fin 6 to at least the front side of the tube 2 in such a fashion as to cover the front side of the tube 2 as shown in FIGS. 5A and 5B. Incidentally, the term “front side” of the tube 2 means the airflow upstream side of the tube 2.

[0039] FIG. 5A is a sectional view when the tube 2 and the fin 6 are viewed from the longitudinal direction of the tube 2, and FIG. 5B is a front view when the tube 2 and the fin 6 are viewed from the airflow upstream side.

[0040] As the fin 6 covers the tube 2 in this way, the flying materials are prevented from directly impinging against the tube 2. Therefore, because the tube 2 can be protected from the relatively large flying materials such as the gravel, the radiator 1 can continue operating, and the reliability of the radiator 1 can be improved.

Third Embodiment

[0041] In the foregoing embodiments, the fin 6 is shaped into a rectangular wave shape or a sine wave shape. In this embodiment, however, the fins 6 shaped into the rectangular wave shape are crushed in the traveling direction of the wave in such a fashion as to describe a truss structure as shown in FIGS. 6A and 6B. In consequence, the fins 6 are brazed to the compressed flat surfaces 2a of the tubes 2 so as to cover substantially the full areas of the compressed flat surfaces 2.

[0042] FIG. 6A is a perspective view of the tubes 2 and the fins 6, and FIG. 6B is a front view of the tubes 2 and the fins 6 when they are viewed from the airflow upstream side.

[0043] According to this construction, the fins 6 cover substantially the whole area of the compressed flat surfaces 2a, and the flying materials are prevented from directly striking the compressed flat surfaces 2a of the tubes 2. Consequently, as the tube 2 can be protected from the relatively large flying materials such as the gravel, the radiator 1 can continue operating, and the reliability of the radiator 1 can be improved.

[0044] In this embodiment, the flying materials may directly impinge against the end portion of the tubes 2 in the longitudinal direction. However, the fin 6 extends to the airflow upstream side beyond the end portion of the tube 2 in the major diameter direction as shown in FIG. 6A. In practice, the possibility that the flying materials directly impinge against the end portion of the tube 2 in the major diameter direction is low, but when the protective bar 1 is provided in the same way as in the first embodiment, the tube 2 can be protected more reliably from the flying materials.

[0045] By the way, the fin 6 extends to the upstream side beyond the end portion of the tube 2 in the major diameter direction in this embodiment. However, the embodiment is not particularly limited to this construction, and the fin 6 need not always extend the end portion of the tube 2 in the major diameter direction.

Fourth Embodiment

[0046] In this embodiment, the width of each fin 6 is increased so that the fin 6 reaches the airflow upstream side beyond the end portion of the tube 2 in the major diameter direction, as shown in FIGS. 7A and 7B. In this instance, a greater amount of the filler metal is applied to the outer surface of the tube 2 than in the foregoing embodiment so that when solidified, the filler metal connects the fin 6 to another fin 6 on the airflow upstream side of the tube 2 during brazing, and the filler metal forms the tube protective portion 8 as shown in FIG. 7B.

[0047] In this way, the flying materials are prevented from directly impinging against the tube 2 and the tube 2 can be protected from the relatively large flying materials such as the gravel. Therefore, the radiator 1 can continue operating and the reliability of the heat exchanger can be improved.

[0048] In this embodiment, the filler metal forms the tube protective portion 8. Therefore, it is necessary to conduct brazing while the units 4 are arranged inside a furnace in such a fashion as to be positioned either on the airflow upstream side or downstream side of the units 4.

[0049] In this embodiment, for example, in case of a radiator made of aluminum or aluminum alloys, the tube 2 is formed of a material selected from the JIS (Japanese Industry Standard), A6000 group, the fin 6 is formed of a material selected from the JIS, A7000 group, and the filler metal is a material selected from the JIS, A4000 group.

[0050] Though the filler metal is coated in this embodiment, the embodiment is not limited thereto. For example, spray coating may be employed, too. In the heat exchanger of the present invention, besides the aluminum or aluminum alloys as the material of the heat exchanger, copper or copper alloys can be used.

[0051] The foregoing embodiments represent the modular type radiator comprising the combination of a plurality of units 4, but the invention is not particularly limited thereto.

[0052] The invention is not particularly limited to the specific application such as construction equipment but can also be applied to a radiator of a passenger car, for example.

[0053] While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.

Claims

1. A heat exchanger comprising: a plurality of tubes arranged in parallel with one another, and allowing a fluid to flow therethrough; header tanks arranged at end portions of said tubes in a longitudinal direction, and communicating with said plurality of tubes; and tube protective members for protecting said tubes, disposed on an airflow upstream side of said tubes, and being separate members from said tubes.

2. A heat exchanger according to claim 1, wherein each of said tubes is shaped into a compressed flat shape in such a fashion that the airflow direction is coincident with a major diameter direction; a fin for increasing a heat transfer area with air is bonded to a compressed flat surface of an outer surface of each of said tubes; and said fin extends to a portion corresponding to said tube protective member beyond an end portion of said tube in the major diameter direction.

3. A heat exchanger according to claim 1, wherein said tube protective member is around rod-like member.

4. A heat exchanger comprising: a plurality of tubes through which a fluid flows; and fins each bonded to an outer surface of each of said tubes, for increasing a heat transfer area with air; wherein said fin extends to at least a front side of said tube and encompasses the front side of said tube.

5. A heat exchanger comprising: a plurality of tubes through which a fluid flows; and fins each bonded to an outer surface of each of said tubes, for increasing a heat transfer area with air; wherein said tube is shaped into a compressed flat shape so that an airflow direction coincides with a major diameter direction, and said fin is bonded to said compressed flat surface in such a fashion as to cover substantially the whole area of said compressed flat surface of an outer surface of said tube.

6. A heat exchanger comprising: a plurality of tubes arranged in parallel with one another, and allowing a fluid to flow therethrough; header tanks arranged at end portions of said tubes in a longitudinal direction, and communicating with said plurality of tubes; and fins each brazed to an outer surface of each of said tubes, for promoting heat exchange between said fluid and air; wherein a tube protective portion is formed by a filler metal on an airflow upstream side of said tube when said filler metal is solidified in a brazing process of said tube and said fin.