Patent Application
20220268533
The present invention relates to a reinforcing structure of heat exchangers such as radiators for cooling engine cooling water, charge air coolers and EGR coolers.
In heat exchangers for cooling engine cooling water, temperature difference is generated between a plurality of flat tubes arranged in parallel and a side plate at an end portion of a heat exchanger, and cracks may be generated in the vicinity of a brazed portion of a tube insertion hole lying at an end portion in a longer side direction of a header plate of the heat exchanger and a brazed portion of a flat tube.
In the same way, also in EGR coolers that cool a high temperature exhaust gas, there is a fault such that cracks tend to occur at an end portion in a longer side direction of an opening end portion of a flat tube.
Conventionally, as a countermeasure, a reinforcing structure of a heat exchanger described in Patent Literature 1 below is known.
In this structure, a planar T-letter shaped portion is formed in an end portion of an opening of a flat tube as a reinforcing member and two insertion portions with an L-letter shaped cross-section are provided for respective front edges of the T-letter. Then, board thickness of the reinforcing member is matched with an opening length in a shorter side direction of the flat tube, and the insertion portion is inserted into an opening edge of the flat tube to be brazed.
The reinforcing structure of a conventional heat exchanger requires an additional reinforcing member and a brazing process of these, which is troublesome.
Accordingly, the present invention is directed to provide a heat exchanger that does not require an additional reinforcing member and can be assembled easily.
The present invention according to a first aspect is a heat exchanger, including:
a header plate 3, in which major axis directions of a plurality of flat holes 1 are disposed along a shorter side direction of the header plate 3, respective flat holes 1 are arranged in parallel separately at regular intervals in a longer side direction of the header plate 3, an opening end portion 2a of a flat tube 2 is inserted into the respective flat holes 1 while positioning a longer side direction thereof in a shorter side direction of the header plate 3, and the insertion portion is brazed; and a tank main body 4 with which a peripheral border of the header plate 3 is connected, and the tank main body 4 supplying a high temperature fluid 6 into the respective flat tubes 2, in which:
an end portion cover body 5 that covers at least one end portion in a longer side direction L of the opening end portion 2a is constituted integrally with the tank main body 4, lying at at least one end portion in a longer side direction of the header plate 3 and at at least one end portion in the longer side direction L of the opening end portion 2a of the flat tube 2.
The present invention according to a second aspect is a heat exchanger, in which a pair of plates formed in a groove shape constitute a flat tube 15 while facing groove bottom portions thereof, the flat tube 15 has an evaginating portion 15a in a vertical direction to the groove bottom portion at an opening end portion, a plurality of the flat tubes 15 are stacked at the evaginating portion 15a to form a core 13, an outer circumference of the core 13 is covered with a casing 9, a header 14 is provided for an end portion of the casing 9, and a high temperature fluid 6 is supplied into respective flat tubes 15 from the header 14 and a cooling water 10 is guided to an outer circumference of the flat tube 15, in which:
an end portion cover body 5, which covers an end portion on the core 13 side and an end portion in a longer side direction L of an opening end portion 15b of the flat tube 15, is constituted integrally with the header 14, and at an end portion on the core 13 side of the header 14 and at at least one end portion position in the longer side direction L of the opening end portion 15b of the flat tube 15.
In the heat exchanger according to the first aspect of the invention, the end portion cover body 5, which covers at least one end portion in the longer side direction L of the opening end portion 2a of the flat tube 2, is formed integrally with the tank main body 4, lying at at least one end portion in the longer side direction of the header plate 3 and at at least one end portion in the longer side direction L of the opening end portion 2a of the flat tube 2.
This end portion cover body 5 covers at least one end portion of the opening end portion 2a of the flat tube 2 to suppress circulation of the high temperature fluid 6 therein. Hereby, there is an effect of protecting the end portion in the longer side direction L of the opening end portion 2a of the flat tube 2 where cracks tend to occur due to thermal strain to improve durability of the heat exchanger. In other words, thermal strain due to cooling/heating cycles of operation/stop of the heat exchanger can be reduced effectively.
In the heat exchanger according to the second aspect of the invention, the core 13 of interest is constituted of a stacked body of the flat tube 15 having the evaginating portion 15a at the opening end portion, where the end portion cover body 5 is provided at at least one end portion on the core 13 side of the header 14.
Also in this instance, similar to that in the first aspect of the invention, at least one end portion in the longer side direction L of the opening end portion 15b of the flat tube 15 is covered with the end portion cover body 5 lying at the end portion on the core 13 side of the header 14 to suppress circulation of the high temperature fluid 6 therein. Accordingly, thermal strain due to cooling/heating cycles of operation/stop of the heat exchanger can be reduced effectively.
Next, embodiments of the present invention will be explained on the basis of the drawings.
This heat exchanger can be used as a radiator that cools an engine cooling water, in which a flat tube 2 and a corrugated fin 8 are arranged alternately in parallel to form a core and a side plate is disposed at an end portion in a longer side direction of a header plate of the core.
In respective flat tubes 2, a horizontal cross-section is formed to be flat, a longer side direction L of the horizontal cross-section thereof is disposed in a shorter side direction of the header plate of the heat exchanger. Furthermore, both end portions (lower side is omitted) of respective flat tubes 2 are inserted into respective flat holes 1 of a header plate 3, and the insertion portion is brazed and fixed.
In the header plate 3, as shown in
The tank main body 4 is formed from a resin, in this example. On an outer periphery thereof, the small flange portion 4a is provided in a protruding condition, and an end portion cover body 5 is provided integrally in a protruding condition on an internal face of an end portion in a longer side direction of the tank main body 4. Thickness of the end portion cover body 5 is, as shown in
Meanwhile, in this example, there is a narrow space between the end edge on a flat tube 2 side of the end portion cover body 5 and the opening end portion 2a of the flat tube 2. Furthermore, as shown in
In
Then the small flange portion 4a of the tank main body 4 is fitted to the annular groove 3a of the header plate 3 via the seal 7, and the engaging claw 3b of the header plate 3 is caulked to the exterior surface side of the tank main body 4 to form a liquid-tight structure.
In the heat exchanger constituted as described above, a high temperature fluid 6 is guided into the tank main body 4 from an inlet (not shown) of the tank main body 4. Then, the high temperature fluid 6 is supplied to respective flat tubes 2, performs heat exchange with an air flow circulating along the exterior surface of the flat tube 2 and the corrugated fin 8, and is returned to an engine block from a tank (not shown) on the lower end side.
Heat is transferred to a side plate disposed to the end portion in the longer side direction of the header plate 3 of the core from the flat tube 2 via the corrugated fin 8 joined to the side plate, but increased temperature in the side plate is lower and increase rate is also lower as compared with temperature increase in the flat tube 2.
Difference in thermal expansions due to difference in temperatures in the side plate and the flat tube 2 generates thermal strain in the header plate 3, and, since board thickness of the flat tube 2 is thinner than board thicknesses of the side plate and header plate 3, thermal stress concentrates and cracks tend to occur at the end portion in the longer side direction L of the opening end portion of the flat tube 2, in a brazed portion between the header plate 3 and the flat tube 2 lying at the end portion in the longer side direction of the header plate.
On this occasion, in the tank main body 4 on an inlet side, the end portion cover body 5 exists in a position of the end portion in the longer side direction L of the opening end portion of the flat tube 2, and therefore in
In other words, in heat exchangers, thermal strain is generated in a tube due to operation/stop cycles thereof, and it is generated notably at the end portion in the longer side direction L of the opening end portion 2a of the flat tube 2 in particular. In the inside of a tank, it is generated more intensively at an end portion in the longer side direction of the header plate 3.
In the present invention, the section is covered with the end portion cover body 5, and therefore cracks due to thermal strain can be made as small as possible.
In addition, in this example, cracks are prevented with the end portion cover body 5 integrated with the tank main body 4, and therefore the heat exchanger is easily assembled and requires a small number of parts to lead to high mass productivity.
Next,
This example can be used as an EGR cooler that cools a high temperature exhaust gas.
In this example, a pair of plates are used, in which the plate is formed in a groove shape and the evaginating portions 15a are formed at both end portions of a groove bottom portion plane in the vertical direction to the groove bottom portion, and groove bottom portions of respective plates are faced and fitted to form the flat tube 15. Then respective flat tubes 15 are stacked at the evaginating portions 15a to form the core 13. Additionally, an outer circumference of the core 13 is covered with a casing 9, and the header 14 is disposed to one end thereof and a tank portion 16 is disposed to the other end.
A pair of pipes 12 are provided in a protruding condition for both end portions of the casing 9 in a direction connecting two opening end portions 15b of the flat tube 15 to supply a cooling water 10 to the outer circumference of respective flat tubes 15. With this, the high temperature fluid 6 is supplied into respective flat tubes 15 from the header 14, and heat exchange is performed between the cooling water 10 and the high temperature fluid 6.
In this example, the end portion cover body 5 is provided in a protruding condition integrally with the header 14, and, with that, the end portion in the longer side direction L of the opening end portion 15b of the flat tube 15 is covered.
In other words, it is constituted so that the high temperature fluid 6 is not guided to the end portions in the longer side direction L of the opening end portions 15b of respective flat tubes 15. Thus, temperature rise at the end portions in the longer side direction L of the opening end portions 15b of the flat tubes 15 is suppressed to prevent cracks as far as possible, which tend to occur relative to the casing 9 going with cooling/heating cycles.
Also in this example, the end portion cover body 5 may be disposed only to the end portion in a tube stacking direction of the tank (header), as in
Meanwhile, in this example, front-end edges of the opening end portions 15b of respective flat tubes 15 bend slightly toward a tank portion 16 side, which absorbs thermal strain.
In addition, in respective flat tubes 15, an inner fin 11 is placed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-107977 | Jun 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/020032 | 6/26/2020 | WO |
