[0001] The present invention relates to a radiator, in particular a light-alloy radiator
suitable for installation in civil and industrial heating systems, and characterized
by a geometry imparting a high resistance to internal pressure.
[0002] As is known, modern heating system radiators may comprise a number of standard modules
packed side by side in fluidtight manner and connected to the system piping. The modules
may be molded from light alloy, and comprise a tubular portion, along which the heat
exchange fluid flows, and a finned portion formed integrally in one piece with the
tubular portion, and which receives the heat conveyed by the heat exchange fluid and
exchanges this heat with the environment by convection and radiation.
[0003] To enable compact, side by side connection of the modules, the tubular portion normally
has a flat cross section, as shown for example in Figure 1, which is normally constant
along the whole length (height) of the tubular portion, and is substantially in the
form of a lozenge, rectangle or double isosceles trapezium with rounded edges and
maximum transverse dimensions measured parallel to two perpendicular axes of symmetry
indicated X (major axis, i.e. parallel to the major dimension) and Y (minor axis).
From the end edges of the lozenge at opposite ends of the major axis X, there originate
two ribs, from which originate a number of transverse fins; and further fins originate
directly from the lateral wall of the tubular portion, and in particular from the
same end edges as the ribs.
[0004] Radiators comprising known modules of the above type have a low resistance to internal
pressure. In particular, when burst tested, known radiators are damaged by a 14-24
bar internal heat exchange fluid pressure, while radiators capable of withstanding
higher pressures normally have a tubular portion with a thicker lateral wall, which
increases both weight and cost.
[0005] It is an object of the present invention to provide a low-cost, lightweight radiator
for civil heating systems, which may be molded from light alloy (or similar), and
which provides for both effective heat exchange and a burst resistance well in excess
of that of known radiators, e.g. of over 30 bars.
[0006] According to the present invention, there is provided a radiator comprising at least
one module, in turn comprising a tubular portion with a flat cross section; opposite
top and bottom ends having respective lateral hydraulic fittings substantially aligned
along a minor axis of the cross section; and a finned portion formed integrally in
one piece with a lateral wall of the tubular portion; the finned portion including
first fins originating directly from the tubular portion, and second fins originating
transversely from respective front ribs in turn originating from the tubular portion
and perpendicular to the first fins; the ribs being substantially aligned with a major
axis of the cross section; characterized in that the cross section has a dimension,
measured along the major axis, smaller than or equal to approximately 45% of the depth
of the module, also measured along the major axis.
[0007] Moreover, a root portion of each rib has no fins, and comprises a number of respective
ridges connecting the rib both to the lateral wall of the tubular portion, and to
a respective second fin carried by the rib and immediately adjacent to the tubular
portion.
[0008] The geometry defined by the above parameters provides for achieving radiators capable
of resisting internal pressures of over 35-40 bars, while at the same time maintaining
a relatively thin tubular portion wall (2.4 to 4.5 mm) and, hence, light weight and
low cost, and maintaining overall module dimensions perfectly compatible with currently
used heating systems (module depth of over 80 mm; any module height, measured along
the tubular portion axis; and high-density side by side packing in confined spaces).
[0009] These favourable, unexpected characteristics, determined experimentally, are attributed
to the favourable stress distribution achieved by the geometry of the present invention,
which, defined by an appropriate combination of dimensional and shape parameters,
enables the tubular portion to better distribute the stress induced by internal pressure,
while at the same time enabling the fins to contribute actively in absorbing at least
part of the stress and so improving the mechanical resistance of the tubular portion.
[0010] A non-limiting embodiment of the present invention will be described by way of example
with reference to the accompanying drawings, in which:
Figure 1 shows a cross section of a known radiator module (with a lozenge-shaped water
chamber);
Figure 2 shows, not to scale, various cross sections at various heights of a radiator
module in accordance with the present invention;
Figure 3 shows three smaller-scale views of the Figure 2 radiator module: namely,
a longitudinal section (Figure 3a), a rear view (Figure 3b), and a side view (Figure
3c).
[0011] Number 1 in Figures 2 and 3 indicates as a whole a radiator for civil and industrial
heating systems, and of which only one module 2 is shown for the sake of simplicity.
As is known, radiator 1 may comprise any number of modules 2 connected side by side
in a group and in fluidtight manner to one another.
[0012] For which purpose, each module 2 comprises a tubular portion 3 having a substantially
vertical longitudinal axis and a flat radial cross section 4; and a finned portion
5 formed integrally in one piece with a lateral wall 6 of tubular portion 3. Section
4 is flat by comprising widely differing transverse dimensions measured parallel to
two perpendicular axes of symmetry indicated X and Y. More specifically, since the
X axis dimension is greater than the Y axis dimension, the X axis is hereinafter referred
to as the "major axis", and the Y axis as the "minor axis".
[0013] The opposite top and bottom longitudinal ends 7, 8 of tubular portion 3 are provided,
laterally, with respective cylindrical hydraulic fittings 10 substantially aligned
along the minor axis Y of the corresponding cross section 4, i.e. with the respective
axes of symmetry substantially coaxial with the Y axis of section 4 located at the
same height as the axes of fittings 10, i.e. in the same longitudinal position (with
respect to the axis of symmetry of portion 3) as fittings 10.
[0014] Each module 2 is preferably injection molded from light alloy or similar material,
for which purpose, the bottom end 8 is open, and is closed, in use, in known manner
by a welded plug 8a.
[0015] Finned portion 5 comprises a first number of fins 11 originating directly from tubular
portion 3; and a second number of fins 12 originating transversely from respective
front ribs 13, in turn originating from tubular portion 3 and perpendicular to fins
11. Ribs 13 are substantially aligned with the major axis X of all the cross sections
4 of tubular portion 3.
[0016] According to a first characteristic of the invention, each cross section 4 of tubular
portion 3 has an inside dimension D, measured along major axis X, smaller than or
equal to approximately 45% of the depth P of module 2, also measured parallel to the
X axis of the corresponding section 4 (Figure 2). That is, for each section 4, the
following inequality applies :

[0017] Equation (1) applies in particular to cross section 4 in plane C-C (Figure 2), i.e.
to section 4 corresponding to the bottom end (i.e. closest to fittings 10 of end 8)
of a finned portion 15 of tubular portion 3, defined by the longitudinal portion of
portion 3 provided with fins 11.
[0018] Equation (1) also applies to the rest of finned portion 15, except that, modules
2 being injection molded, value D, as any injection expert will know, must be further
reduced by the amount due to the draft angle.
[0019] Depending on the overall dimensions of module 2 (total length, i.e. height, of tubular
portion 3, which may be of any length; and depth P, which must be over 80 mm), the
thickness S of lateral wall 6 of tubular portion 3 ideally ranges between approximately
2.4 and 4.5 mm. These values refer to a "mean" thickness S calculated as the arithmetic
mean of two wall 6 thicknesses measured at diametrically opposite points of respective
section 4.
[0020] According to a preferred characteristic of the invention, each cross section 4 of
tubular portion 3 has a dimension L, measured along minor axis Y, equal to or greater
than approximately 15% of dimension D of the same cross section 4, measured along
the major axis X. The following equation therefore applies :

[0021] Equation (2) applies in particular to cross section 4 in plane C-C (Figure 2).
[0022] According to a third characteristic of the invention, each rib 13 has a root portion
20 with no fins 12, and which originates from a corresponding portion, with no fins
11, of lateral wall 6 of tubular portion 3; portion 20 of each front rib 13 comprises
a number of respective ridges 22 along the whole length of finned portion 15; and
ridges 22 are so formed as to connect each rib 13 both to the portion of lateral wall
6 of tubular portion 3 from which root portion 20 originates, and to the fin 12 closest
to root portion 20, i.e. the one on rib 13 immediately adjacent to tubular portion
3.
[0023] Finally, as shown clearly in Figure 2, dimensions D and L, measured along major and
minor axes X and Y, of each cross section 4 may vary along the axial extension of
tubular portion 3, or may remain substantially constant along the whole axial extension
of tubular portion 3, providing, obviously, equations (1) and (2) are met.
[0024] At least along the whole of finned portion 15, cross section 4 of tubular portion
3 may therefore be shaped as shown in planes A-A and B-B in Figure 2, i.e. in the
form of a substantially rectangular ring with rounded corners and slightly outward-curving
sides. Conversely, in plane C-C, it may resemble the lozenge shape, but with different
dimensional ratios between the major and minor axes X and Y in accordance with equations
(1) and (2).
[0025] The invention will now be described further by means of a test example.
EXAMPLE
[0026] To determine the actual difference in performance between the radiator described
and a conventional radiator, six two-module groups, i.e. six different radiators,
each comprising two side by side modules 2, were burst tested hydraulically.
[0027] Three known radiators - two manufactured by the present Applicant and one purchased
- all had a cross section as shown in Figure 1, a depth P of over 80 mm, and a major
inside dimension D of the water chamber (the conduit in which the heat exchange fluid
flows) equal to or greater than 0.50 P (50% of P) (particularly at cross section 4
in plane C-C in Figure 2).
[0028] The above three radiators and three according to the present invention were tested
successively by connecting them successively to a test circuit equipped with an adjustable-head
pump. Once connected, the water pressure inside each radiator was raised gradually
from 3 bars and by 1 bar per minute until the radiator burst. The pressure values
were monitored continuously using a recording manometer, and the results are shown
in Table 1.
TABLE 1
|
KNOWN ART |
INVENTION |
RADIATOR |
1 |
2 |
3 |
4 |
5 |
6 |
BURST PRESSURE |
14 bar |
15 bar |
21 bar |
35 bar |
40 bar |
38 bar |
1. A radiator comprising at least one module, in turn comprising a tubular portion with
a flat cross section; opposite top and bottom ends having respective lateral hydraulic
fittings substantially aligned along a minor axis of the cross section; and a finned
portion formed integrally in one piece with a lateral wall of the tubular portion;
the finned portion including first fins originating directly from the tubular portion,
and second fins originating transversely from respective front ribs in turn originating
from the tubular portion and perpendicular to the first fins; the ribs being substantially
aligned with a major axis of the cross section; characterized in that the cross section
has a dimension (D), measured along the major axis, smaller than or equal to approximately
45% of the depth (P) of the module, also measured along the major axis.
2. A radiator as claimed in Claim 1, characterized in that a root portion of each rib
has no fins, and comprises a number of respective ridges connecting the rib both to
the lateral wall of the tubular portion, and to a respective second fin carried by
the rib and immediately adjacent to the tubular portion.
3. A radiator as claimed in claim 1 or 2, characterized in that said cross section of
the tubular portion has a wall thickness (S) ranging between approximately 2.4 and
approximately 4.5 mm.
4. A radiator as claimed in one of the foregoing Claims, characterized in that said cross
section of the tubular portion has a dimension (L), measured along the minor axis,
equal to or greater than approximately 15% of the dimension (D) of the same cross
section measured along the major axis.
5. A radiator as claimed in any one of the foregoing Claims, characterized in that the
dimensions (D) (L) measured along the major axis (X) and minor axis (X) of each cross
section (4) may vary along the axial extension of the tubular portion (3), or may
remain substantially constant along the whole axial extension of the tubular portion
(3).
6. A radiator as claimed in any one of the foregoing Claims, characterized in that, at
least along an axial portion of the tubular portion having said first fins, said cross
section of the tubular portion is in the shape of a substantially rectangular ring
with rounded corners and slightly outward-curving sides.
7. A radiator as claimed in any one of the foregoing Claims, characterized in that the
depth (P) of the module, measured along the major axis of the cross section of the
tubular portion, is over 80 mm.