Note: Descriptions are shown in the official language in which they were submitted.
, .. ~Z~5~3~
TANK-~EADER PLATE CONNECTION
Field of the Invention
This invention relates to heat exchangers of the
type having a header plate supporting the open ends of a
plurality of tubes and a tank secured to the header
plate; and more specifically, to an improved connection
between the tank and the header plate.
Background of the Invention
Prior art of possible relevance includes the
following United States Letters Patents, both to Hesse:
4,378,174 issued March 29, 1983 and 4,331,201 issued May
25, 1982.
The effort by the automotive industry to reduce the
weight of vehicles to thereby improve mileage has seen an
increasing use of non~metallic materials in various parts
of vehicles. ~eat exchangers, more commonly termed
radiators, are no exception. While metal materials are
still employed in the cores for such heat exchangers
because of their greater thermal conductivity over
plastics, other heat exchanger components that do not
require good thermal conductivity are being made of
plastic. ~ primary example is the so-called tanks which
are fitted to the heat exchanger core most typically by
securement to the header plates which define the ends of
such cores.
Because the joint between the header plate and the
tank is one of dissimi ar materials, prior techniques of
brazing or soldering the joints can no longer be
employed. In lieu thereof, to effect the necessary seal,
a gasket is disposed between the tank and the header
plate and any of a variety of means are employed to hold
1~Z475~3~
the components in assembled relation with the gasket
under compression to assure a seal at the operating
pressures for which the heat exchanger was designed.
It is, of course, necessary that the means employed
to effect the connection be strong and long lived to
prevent leakage. At the same time, it is desirable that
the means be such that disassembly of the component parts
can be effected when required for servicing. It is also
desirable that the means utilized lend themselves to use
in mass production to minimize cost.
Attempts to achieve these objects have resulted in
proposals wherein a header plate is provided with a
peripheral groove in which the gasket to be compressed
may be disposed. The tank is provided with a peripheral
Elange sized to be received in the groove and adapted to
compress the gasket therein. The outer wall of the
groove is then de~ormed in part to overlie the flange on
the tank and hold the same in a position compressing the
gasket. This approach is exemplified by the above
identified Hesse patents.
Unfortunately, because this approach involves
deformation of a metal wall which necessarily may be
sufficiently thin as to be easily deformed, the same may
not always be as strong as might be desired. Pressure
within the system during operation will act against the
deformed material and tend to deform it back toward its
original configuration. When such occurs, the
compressive forces exerted on the gasket are lessened and
leakage may occur.
The present invention is directed to overcoming one
or more of the above problems.
12~5gl
Summary of the Invention
The invention primarily seeks to provide a new and
improved connection between the header of a heat ex-
changer and a tank to be connected thereto. More
specifically, the invention seeks to provide such a
connection that is made by deformation and yet has
sufficient strength to resist deformation back towards
its original configuration.
An exemplary embodiment of the invention provides
a structure including a metal header plate supporting the
open ends of a plurality of tubes and provided with
a gasket receiving area extending about the periphery
of the header plate. The area has a bottom wall surrounded
by a deformable side wall terminating in an edge. A
compressible gasket is disposed in the area and a tank having
an opening surrounded by an outwardly extending flange is
provided. The ~lange is sized and configured to be fitted
within the area with one side oE the flange abutting the
gasket and the opposite side of the flange being disposed
`~ within the area and spaced from the edge. The tank compresses
the gasket so that the gasket effects a seal between the
tank and the hea,der plate. ~ plurali~y of tabs are
disposed in the ~ide wall below the edge and overlie the
opposite side of the flange to hold the tank in
compressing relation to the gasket. Each of the tabs is
formed by deformation of the side wall to a generally
nominally planar, free edge displaced from the side wall
and in contact with the opposite side of the flange.
Each such tab tapers from the free edge toward the side
wall edge to merge into the side wall prior to or at the
side wall edge.
~2~'75~L
In a highly preferred embodiment, the gasket
receiving area i~ defined by a groove.
The invention also contemplates that the tabs merge
into the side wall at locations ~paced from the side wall
edge.
In a highly preferred embodimen~, the side wall is
deformed toward the tank to at least partially overlie
the flange.
Typically, the tank will be formed of plastic and in
a highly preferred embodiment, each of the tabs is
generally egg shaped or spherically shaped.
The chosen configuration of the tabs provides
excellent force distribution to the side wall of the
gasket receiving area or groove so as to provide
excellent resistance to deformation back toward the
original shape. At the same time, the tabs are easily
formed according to mas~ production techniques and, where
necessary, may be intentionally deformed back to their
original con~iguration to allow disassembly of the
components.
The tabs m~y be formed in the side wall by punching
or piercing. No restraint is placed on the portion of
the side wall wherein the tabs are formed such that such
portion may be slightly bent toward the tank. Thereafter
the side wall is rolled or bent from the vertical to
partially overlie the flange such that the free edges of
the tabs are parallel to the upper surface of the flange.
Other aspects and advantages will become apparent
from the following specification taken in connection wi~h
the accompanying drawings.
;,~,
- , ;;
,
75~
Description of the Drawings
Fig. l is a perspective view of a tank assembled to
a header plate by a connection made according to the
invention;
Fig. 2 is a fragmentary, enlarged elevation of the
assembly;
Fig. 3 is a further enlarged, sectional view taken
approximately along the line 3-3 in Fig. 2; and
Fig. 4 is a fragmentary enlarged view of the header
plate with a tab formed therein but with the tank removed
for clarity.
Description of the Preferred Embodiment
An exemplary embodiment of the invention is
illustrated in the drawing and with reference to Figs. 1
and 3 thereo, is seen to include a radiator tank 10,
typically formed of plastic, and a header plate 12 formed
of metal. Conventionally, the header plate 12 receives
the open ends 14 of a plurality of tubes 16 (only one of
which is shown). The tank 10 has an opening 18 which is
surrounded by an outwardly directed flange 20 having
upper and lower sides 22 and 24, respectively. One or
more coolant ports 26 are provided for the tank 10. As
best seen in Fig. 3, the header plate 12, at its
periphery, includes a groove, generally designated 28.
The groove 28 is defined by an upstanding, outer side
wall 30, a bottom wall 32 and an inner wall 34 generally
parallel to the outer wall 30 which merges with the main
body of the header plate 12 by means of a round 36. As
can be seen, the groove 28 and flange 20 are sized and
configured so that the latter may be received in the
former.
~Z~59~
A compressible gasket 40 is disposed in the groove
28 in abutment with the bottom wall 32 thereof and the
tank 10 oriented so that the flange 20 may be introduced
into the groove 28~ Upon introduction of the flange 20
into the groove, the surface 24 is brought into abutment
with the gasket 40 and continued urging of the tank 10
toward the header plate 12 will result in the gasket 40
being compressed to the desired degree. In the usual
case, somewhat more than the desired compression force
will be placed on the components to allow a series of
tabs 42 to be deformed from the wall 30 to overlie the
surface 22 of the flange 20. When the tabs 42 have been
formed, the compressive force may be released and the
structure will assume the confiyuration illustrated in
Fig. 3.
To assure good retentive strength and a resistance
to deformation in response to pressure within the tank
10, the tabs 42 have the shape of one quadrant of a
sphere or an egg. They include a curved lower free edge
44 which is nominally planar and overlies and abuts the
surface 22 of t:he flange 20. The tabs 42 gradually taper
from their ed~es 44 toward the outer side wall 30 to
line 4~. Generally, the edye 48 of the sidewall 30 is
reached such that a space 50 exists between the edge 48
and the tab 42
The tabs may be formed in one single operation with
an appropriate shaped tool which effectively pierces the
outer wall 30 to define a free edge 44 while deforming a
portion of the wall 30 to define the body of the tab 42.
This forming process is readily adaptable to mass
production techniques.
~4759~
To simplify the assembly operation, and to minimize
the tooling required, the upper portion 52 of the side
wall 30 wherein the tabs 42 are formed is not restrained
oppositely of the advancing punching or piercing tool
during the punching or piercing operation. This in turn
may result in the upper portion 52 of the side wall 30
being slightly bent toward the tank 10.
Because the tabs 42 are formed by deforming metal,
metal flow during the forming operation may result in the
free edges 44 of the tabs being increasingly spaced from
the upper surface of the flange 20 in the direction away
from the side wall 30 and toward the tank 10.
Consequently, to bring the entire extent of each free
edge 44 into contact with the upper surface of the flange
20, following the operation wherein the tabs 42 are
formed, a highly preferred embodiment of the invention
contemplates that the upper portion 52 of the side wall
may be further bent along a line 54 approximately at the
level of the ~ree edges 44 in the direction of the tank
As a consequence, the upper portion 52 of the side
wall 30 will remain upstandilg but will partially overlie
the flange 20 and the free edges 44 will be parallel to
and abut the upper surface of the flange 50. The bending
operation can be performed by any suitable process as,
for example, by rolling. In a preferred embodiment, the
upper portion 52 is bent approximately 30 from the
vertical toward the tank 10.
It will be appreciated that when necessary, the tabs
42 may be deformed back to their original shape if, for
any reason, it is necessary to remove the tank 10 from
the remainder of the assembly. In this regard, it is
desirable that the tabs 42 or the upper portion 54 of the
~759~
side wall 30 do not extend inwardly to be in contact with
a side wall 56 of the tank lO so as to allow insertion of
a tool to accomplish such deformation.
Finally, it will be appreciated that the geometry of
the tabs 42 assures that forces tending to separate the
tank 10 from the header plate 12 will be evenly
distributed to the outer wall 30 to resist deformation of
the same that could result in release of compressive
force on the gasket 40 that could in turn result in
leaks. The free edges 44 provide a substantial zone of
contact with the flange surface 22 and such forces as are
placed against the edges 44 are distributed to the
remainder of the respective tab 42 which will be placed
in compression without an appreciable bending moment
applied thereto. Consequently, an extremely reliable and
easily formed connection is provided by the invention.
