TECHNICAL FIELD
[0001] The present invention relates to an overflow duct for a washing machine.
BACKGROUND ART
[0002] To comply with regulations governing water mains connection of electrical appliances
to prevent backsiphoning, a commercial washing machine usually has at least one overflow
duct, of a given cross section, connecting the detergent dispenser or wash assembly
to the outside, and which, in the event of a malfunction of the washing machine resulting
in water leakage from the detergent dispenser or wash assembly, drains the water off
to the outside to prevent backflow (backsiphoning) of detergent-containing water or
similar to the water mains.
[0003] In other words, the overflow duct connects the inside of the washing machine directly
to the outside. As a result, however, the noise generated inside the washing machine
is also transmitted to the outside along the overflow duct, thus increasing the noise
level of the washing machine.
DISCLOSURE OF THE INVENTION
[0004] It is an object of the present invention to provide an overflow duct for a washing
machine, designed to eliminate the aforementioned drawbacks, and which, in particular,
is cheap and easy to implement.
[0005] According to the present invention, there is provided an overflow duct for a washing
machine, as claimed in the accompanying Claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] 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 schematic view of a washing machine featuring an overflow duct in
accordance with the present invention;
Figure 2 shows a schematic view in perspective of an overflow duct of the Figure 1
washing machine;
Figure 3 shows a front view of a noise trap device located along the Figure 2 overflow
duct; and
Figure 4 shows a plan view of the noise trap device located along the Figure 2 overflow
duct.
PREFERRED EMBODIMENTS OF THE INVENTION
[0007] Number 1 in Figure 1 indicates as a whole a laundry washing machine comprising a
detergent dispenser 2; and a cylindrical wash assembly 3 comprising a revolving drum
(defining a wash tub) which rotates about a horizontal rotation axis (in alternative
embodiments not shown, the rotation axis may be tilted or vertical), and front access
to which is closed by a hinged door.
[0008] Washing machine 1 also comprises an overflow duct 4 connecting the inside of washing
machine 1 to the outside, and having two opposite openings 5 and 6. As shown more
clearly in Figure 2, an inner opening 5 faces inwards of washing machine 1, and an
outer opening 6 outwards of washing machine 1.
[0009] As shown in Figures 2 and 3, overflow duct 4 has a circular cross section and a longitudinal
axis 7, and comprises a noise trap device 8 housed inside overflow duct 4 and forming
a labyrinth path 9 (shown in Figure 4) extending between openings 5 and 6 of overflow
duct 4.
[0010] In a preferred embodiment, noise trap device 8 comprises a number of flat plates
10 arranged inside, and perpendicular to longitudinal axis 7 of, overflow duct 4.
Each plate 10 is the same circular shape as the cross section of overflow duct 4,
and is smaller than, and over half the size of, the cross section of overflow duct
4.
[0011] Plates 10 are located on alternate opposite sides of overflow duct 4 to define a
"zigzag" labyrinth path 9. That is, as shown clearly in Figure 4, one plate 10 is
located on the left side of overflow duct 4, while the preceding plate 10 and following
plate 10 are located on the right side of overflow duct 4 (in a different embodiment,
the plates may be located on the top and bottom, as opposed to the right and left,
sides of overflow duct 4). More specifically, as shown in Figure 3, each plate 10
has a portion overlapping the preceding plate 10 and following plate 10, and of a
width ranging between 0.05 and 0.3 (preferably 0.07-0.15) times the diameter of overflow
duct 4. It is important to point out that the overlapping portions should be wide
enough to form an effective noise barrier, but not so wide as to impede water flow
along overflow duct 4.
[0012] In a preferred embodiment, noise trap device 8 comprises two supporting bars 11 parallel
to longitudinal axis 7 of overflow duct 4 and connected rigidly to each plate 10.
Preferably, a top supporting bar 11 defines a longitudinal slit 12 running parallel
to longitudinal axis 7 of overflow duct 4; and overflow duct 4 comprises a longitudinal
rib 13, which engages longitudinal slit 12 of overflow duct 4 to immobilize noise
trap device 8 inside overflow duct 4, in particular (but non only) when transporting
washing machine 1.
[0013] Overflow duct 4 as described above has numerous advantages, by being cheap and easy
to produce, by having substantially the same performance as a corresponding standard
overflow duct, and by greatly reducing noise transmission to the outside of washing
machine 1.
1. An overflow duct (4) for a washing machine (1); the overflow duct (4) connecting the
inside of the washing machine (1) to the outside of the washing machine (1), and having
two opposite openings (5, 6);
the overflow duct (4) being characterized by comprising a noise trap device (8) housed inside the overflow duct (4) and forming
a labyrinth path (9) extending between the two openings (5, 6) of the overflow duct
(4).
2. An overflow duct (4) as claimed in Claim 1, wherein the noise trap device (8) comprises
a number of plates (10) arranged inside the overflow duct (4).
3. An overflow duct (4) as claimed in Claim 2, wherein the plates (10) are flat and are
perpendicular to a longitudinal axis (7) of the overflow duct (4).
4. An overflow duct (4) as claimed in Claim 2 or 3, wherein each plate (10) is the same
shape as the cross section of the overflow duct (4), is smaller than the cross section
of the overflow duct (4), and is over half the size of the cross section of the overflow
duct (4).
5. An overflow duct (4) as claimed in Claim 4, wherein each plate (10) is located on
one side of the overflow duct (4), while the preceding plate (10) and the following
plate (10) are located on the opposite side of the overflow duct (4), so as to define
a "zigzag" labyrinth path (9).
6. An overflow duct (4) as claimed in Claim 5, wherein each plate (10) has a portion
overlapping the preceding plate (10) and the following plate (10), and of a width
ranging between 0.05 and 0.3 times the diameter of the overflow duct (4).
7. An overflow duct (4) as claimed in Claim 5, wherein each plate (10) has a portion
overlapping the preceding plate (10) and the following plate (10), and of a width
ranging between 0.07 and 0.15 times the diameter of the overflow duct (4).
8. An overflow duct (4) as claimed in any one of Claims 2 to 7, wherein the noise trap
device (8) comprises at least one supporting bar (11) parallel to a longitudinal axis
(7) of the overflow duct (4) and connected rigidly to each plate (10).
9. An overflow duct (4) as claimed in Claim 8, wherein the noise trap device (8) comprises
two supporting bars (11) located on opposite sides of the overflow duct (4).
10. An overflow duct (4) as claimed in Claim 8 or 9, wherein at least one supporting bar
(11) defines a longitudinal slit (12) running parallel to the longitudinal axis (7)
of the overflow duct (4).
11. An overflow duct (4) as claimed in Claim 10, and comprising a longitudinal rib (13)
engaging the longitudinal slit (12) of the overflow duct (4).