Heat exchanger

A heat exchanger includes a pair of substantially parallel header pipes and a plurality of substantially parallel tubes disposed between the pair of header pipes. Each tube defines a pair of end portions which are connected to the pair of header pipes. A plurality of rows of fins are provided along sides of the tubes. A pair of reinforcement members are provided along sides of each of the top and bottom rows of fins. Each of the pair of header pipes has a plurality of holes for inserting the end portions of the tubes to connect the tubes to each pipe of the pair of header pipes. At least one slit is formed on the end portions of each header pipe. The end portions of the reinforcement members extend through the slits to close the open ends of the header pipes. In one embodiment, each of the end portions of the reinforcement members extend through each header pipe through a pair of opposed slits and is bent to fix itself to the header pipe. The number of heat exchanger parts is thus reduced and the manufacture thereof is simplified.

TECHNICAL FIELD 
The present invention relates to a heat exchanger, e.g., for use as a 
condenser and a radiator of an air conditioner for an automotive vehicle 
or the like. 
BACKGROUND OF THE INVENTION 
FIG. 5 shows a typical conventional heat exchanger which requires the heat 
exchange between a heat medium (for example, a cooling medium 
(refrigerant) or a brine) flowing in the heat exchanger and air passing 
through the heat exchanger. A heat exchanger, as shown in FIG. 5, is 
comprised of a pair of header pipes 1 extending in parallel relation to 
each other, a plurality of tubes 2 disposed between the header pipes and 
connected to the header pipes at their end portions, a plurality of 
radiation fins 3 provided on the sides of the tubes, a pair of 
reinforcement members 4 disposed on the top and bottom radiation fins, and 
brackets (not shown) for supporting the heat exchanger which are attached 
to the upper and lower portions of each header pipe. 
Each header pipe 1 is constructed from a straight pipe having a circular 
cross section. A plurality of connection holes 11 are formed on the 
periphery of the header pipe with a predetermined pitch in the axial 
direction of the header pipe. The end portion of each tube 2 is inserted 
into a corresponding connection hole 11. Both ends of each straight pipe 
are closed by caps 1a. An inlet tube 1b for introducing the heat medium 
into the heat exchanger is connected to one of the header pipes 1, and an 
outlet tube 1c for delivering the heat medium out from the heat exchanger 
is connected to the other header pipe. 
Tube 2 is formed as a straight tube which is flattened in the horizontal 
direction. The end portion of tube 2 is inserted into connection hole 11 
of header pipe 1, and fixed therein by, for example, brazing. Corrugated 
type radiation fins 3 are fixed on the upper and lower surfaces of each 
tube 2 by, for example, brazing. 
In the above construction of the heat exchanger, it is necessary to use 
four caps to close the open ends of header pipes 1 thereby adding to the 
number of parts of the heat exchanger. 
In addition, the heat exchanger has to be preassembled before the heat 
exchanger is introduced into a furnace for brazing. Accordingly, it is 
necessary to use several jigs to fix tubes 2 and reinforcement members 4 
to header pipes 1 in the preassembly of the heat exchanger, thereby 
complicating the process of assembling the heat exchanger. 
Furthermore, reinforcement member 4 disposed on the surface of radiation 
fin 2 cannot be securely connected to header pipes 11 since the outer 
peripheral surface of header pipe 11 is curved. This arrangement thus 
fails to provide adequate overall strength of the heat exchanger. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a heat exchanger with a small 
number of parts. 
It is another object of this invention to provide a heat exchanger with a 
simple assembly process. 
It is yet another object of this invention to provide a heat exchanger 
exhibiting improved overall structural strength. 
A heat exchanger according to one embodiment of the present invention 
includes a pair of substantially parallel header pipes and a plurality of 
substantially parallel tubes disposed between the pair of header pipes. 
Each tube defines a pair of end portions which are connected to respective 
pipes of the pair of header pipes. A plurality of rows of fins are 
provided along sides of the tubes, including uppermost and lowermost rows 
of fins. A pair of reinforcement members are provided along side of each 
of the uppermost and lowermost rows of fins. Each pipe of the pair of 
header pipes has a plurality of holes into which the end portions of the 
tubes extend to connect the tubes to the respective pipes of the pair of 
header pipes. A pair of opposed slits is formed on at least one end 
portion of at least one header pipe. An end portion of at least one of the 
reinforcement members extends through the at least one header pipe through 
the pair of slits and closes off an adjacent end opening of the at least 
one header pipe. 
In addition, a heat exchanger according to another embodiment of the 
present invention includes a pair of substantially parallel header pipes 
and a plurality of substantially parallel tubes disposed between the pair 
of header pipes. Each tube defines a pair of end portions which are 
connected to respective pipes of the pair of header pipes. A plurality of 
rows of fins are provided along sides of the tubes, including uppermost 
and lowermost rows of fins. A pair of reinforcement members are provided 
along sides of each of the uppermost and lowermost rows of fins. Each pipe 
of the pair of header pipes has a plurality of holes into which the end 
portions of the tubes extend to connect the tubes to each of the pipes of 
the pair of header pipes. A slit is formed on at least one end portion of 
at least one header pipe. An end portion of at least one of the 
reinforcement members extends into the at least one header pipe through 
the slit and closes off an adjacent end opening of the at least one header 
pipe. 
A process for manufacturing a heat exchanger in accordance with the present 
invention comprises the following steps. A pair of open-ended header pipes 
is provided, each having a plurality of holes along its length and a slit 
at each of opposite end portions thereof. An assembly of a plurality of 
substantially planar tubes and a plurality of rows of fins extending along 
the tubes is secured between the pair of header pipes by inserting 
opposite end portions of the plurality of tubes into respective holes of 
the plurality of holes in the header pipes. Reinforcement members are 
secured between the pair of header pipes and along uppermost and lowermost 
rows of fins by inserting opposite end portions of the reinforcement 
members into respective ones of the slits and into each said header pipe 
such that the open ends of the header pipes are closed off by the end 
portions of the reinforcement members. The assembled header pipes, tubes, 
fins and reinforcement members are then brazed together. 
Further objects, features and aspects of this invention will be apparent 
and fully understood from the following detailed description of the 
preferred embodiments of this invention, taken in connection with the 
attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, FIGS. 1-3 illustrate a heat exchanger according 
to a first embodiment of the present invention. In FIG. 1, a heat 
exchanger has a pair of header pipes 5 extending in parallel relation to 
each other. Header pipes 5 have a plurality of connection holes 51 and 
slits 5a and 5b with a predetermined pitch arranged in the longitudinal 
direction thereof. A plurality of substantially parallel tubes 2 are 
disposed between the pair of header pipes 5. The tubes 2 are formed as 
flat tubes in this embodiment. The tubes 2 are connected at their end 
portions to respective pipes of the pair of header pipes 5. A plurality of 
corrugate type radiation fins 3 are provided on the sides of flat tubes 2 
and fixed to the flat tubes by, for example, brazing. Reinforcement 
members 6 are provided on the upper surface of the top (uppermost) row of 
radiation fins 3 and the lower surface of the bottom (lowermost) row of 
radiation fins 3, respectively. The reinforcement members 6 are fixed to 
the upper and lower surfaces of the respective rows of radiation fins and 
the sides of header pipes 5. An inlet tube 7 is connected to the upper 
portion of one of the header pipes 5, and an outlet tube 8 is connected to 
the lower portion of the other header pipe. A heat medium (for example, a 
cooling medium or a brine) is introduced through inlet tube 7, flows 
through header pipes 5 and flat tubes 2, and flows out of outlet tube 8. 
Connection holes 51 are formed along the peripheral surfaces of header 
pipes 5 for insertion of the end portions of tubes 2. Slits 5a are also 
formed on the peripheral surfaces of header pipes 5, at upper and lower 
end portions thereof, in alignment with connection holes 51. Slits 5b are 
formed on peripheral end surfaces of header pipes 5 in opposition to slits 
5a. The width of slits 5a and 5b is equal to the inner diameter of header 
pipes 5 and the width of reinforcement members 6. As illustrated in FIGS. 
3(a) and 3(b), in the assembly process of the heat exchanger, both end 
portions of tubes 2 are inserted into header pipes 5 through connection 
holes 51. Fins 3 are disposed between the upper and lower surfaces of each 
of tubes 2. Both end portions of reinforcement members 6 extend outwardly 
through header pipes 5 through slits 5a and 5b, and are bent downwardly to 
extend in an axial direction along the outer peripheral surface of header 
pipe 5. Accordingly, the end portions of reinforcement members 6 close off 
the end openings of header pipes 5 without the need for separate caps, and 
securely fix tubes 2 and fins 3 to header pipe 5 without using any jigs 
before brazing. 
FIG. 4 illustrates a connection portion of the header pipe and the 
reinforcement member of a heat exchanger in accordance with a second 
embodiment of this invention described below. 
Connection holes 51 are formed as mentioned above. Slits 5c are formed at 
both end portions of header pipes 5 in alignment with connection holes 51, 
respectively. The width of slits 5c is equal to the inner diameter of 
header pipe 5 and the width of reinforcement members 9. The end portions 
91 of reinforcement members 9 are formed in a semicircular shape to 
correspond with the inner annular peripheral surfaces of header pipes 5. 
The end portions 91 of reinforcement members 9 are inserted into header 
pipes 5 through slits 5c until the end portions 91 contact (abut with) the 
inner annular surfaces of header pipes 5. Accordingly, the end portions of 
reinforcement members 9 close the open ends of header pipes 5, similar to 
the first embodiment. 
This invention has been described in detail in terms of presently preferred 
embodiments thereof. It will be understood by those skilled in the art 
that many variations on and modifications of the preferred embodiments are 
also within the scope of this invention as defined by the appended claims.