[0001] The invention relates to a washing machine for washing empty containers and to an
operating method thereof.
[0002] In general, washing machines are known with the purpose of cleaning the empty containers
upstream of a filling and a labelling station, in which the containers are respectively
filled with a pourable product and labelled with respective labels.
[0003] An example of washing machine is known, e.g. from
EP2727660 in the name of the same Applicant.
[0004] Known washing machines essentially comprise:
- a feeding system;
- a washing tunnel;
- a looped chain conveyor advancing the containers along a closed washing path and extending
inside the washing tunnel from an inlet station to an outlet station; and
- a plurality of sequential treatment zones arranged between the inlet station and the
outlet station, and through which the chain conveyor advances the containers.
[0005] In detail, the chain conveyor comprises a plurality of beams, which are fed at the
inlet station by the feeding system with respective rows of containers.
[0006] In particular, each beam comprises a plurality of aligned pockets, which receive,
convey and outlet the respective washed containers.
[0007] Each beam is discharged of the respective washed containers at the outlet station
and then is returned to the inlet station, where it receives new empty containers
to be washed.
[0008] According to the advancing direction of containers along the washing tunnel, the
treatment zones comprise, in sequence, a prewash zone, a first cleaning zone, a second
cleaning zone and a plurality of consecutive rinsing zones.
[0009] The prewash zone, the first cleaning zone, and the second cleaning zone comprise
respective cleaning baths, which are filled with a washing chemical agent at high
temperature and through which the containers are advanced.
[0010] Each rinsing zone comprises a corresponding rinsing bath filled with rinsing liquid
and/or ejecting devices for directing sprinkles of rinsing liquid toward the containers.
[0011] The rinsing liquid delivered to the containers has both the function of removing
therefrom any residuals of washing chemical agent and of cooling down the same containers
after being conveyed out from the cooling baths.
[0012] As the containers are sequentially conveyed through the treatment zones, also the
conveying beams are exposed to the washing chemical agent and then to the rinsing
liquid.
[0013] Therefore, the beams tend to show limescale deposits after many washing cycles, such
that the same beams need periodical treatments in order to be recovered to the initial
operating conditions.
[0014] Moreover, after a deep using of the washing machine, the beams may also show encrusted
dirt deposit, including for instance rust, which should be removed to avoid corrosion
of the beams themselves or contaminations in general.
[0015] Generally, the beams are one by one disassembled from the washing machine and are
separately restored in a manual manner or even replaced, if conditions thereof are
particularly critic.
[0016] The above general approach, however, results scarcely satisfactorily due to the significant
operation time taken for disassembling and reassembling each beam, as well as due
to the inherent risks of assembling errors, which could lead to inconvenient downtimes.
[0017] In view of that, a need is felt within the sector for a washing machine integrating
both the function of washing the empty containers and of periodically restoring the
beams without stops of the washing machine operation.
[0018] It is an object of the invention to provide a washing machine for washing empty containers,
which allows meeting the abovementioned need in a simple, economic and energy efficient
manner.
[0019] This object is achieved by the invention as it relates to a washing machine for washing
empty containers, as claimed in claim 1.
[0020] The invention further relates to an operating method of a washing machine for washing
empty containers, as claimed in claim 10.
[0021] One preferred embodiment is hereinafter disclosed for a better understanding of the
present invention, by way of non-limitative example and with reference to the accompanying
drawings, in which:
- Figure 1 is a lateral view of a washing machine for washing empty containers, according
to the invention; and
- Figure 2 is a lateral view in an enlarged scale of some components of the washing
machine of Figure 1.
[0022] With reference to Figure 1, numeral 1 indicates a washing machine for washing containers
2, in particular empty bottles intended to be filled with a pourable product.
[0023] Each container 2 has an external surface 2a delimiting an inner volume 2b adapted
to receive the pourable product and extends along an axis A (lying on a vertical plane,
in the embodiment shown) from a base portion 2c to a neck portion 2d.
[0024] The neck portion 2d is provided with an inlet opening 2f about axis A, which allow
the filling of the inner volume 2b of the corresponding container 2.
[0025] Washing machine 1 comprises:
- a washing tunnel 3, in which empty containers 2 are fed and accordingly washed; and
- a chain conveyor 4 for advancing containers 2 inside washing tunnel 3 along a closed
loop path P, in particular lying on a vertical plane.
[0026] In detail, chain conveyor 4 comprises:
- a pair of chains 15 elongated parallel to path P and parallel to one another; and
- a plurality of subsequent conveying beams 16, which extend between chains 15 in a
transversal and, more in detail, orthogonal manner to chains 15 and path P.
[0027] Specifically, each beam 16 comprises a row of pockets 17 aligned orthogonally to
path P and adapted to receive corresponding containers 2.
[0028] In such a manner, containers 2 carried by a corresponding beam 16 are aligned orthogonally
to path P and housed inside the respective pockets 17.
[0029] Washing machine 1 comprises also a feeding system 8 for feeding a sequence of empty
containers 2 along a direction F and at an inlet station I of washing tunnel 3. In
particular, containers 2 fed along direction F are arranged in rows orthogonal to
path P.
[0030] Feeding system 8 comprises:
- a plurality of endless conveyors 103 (of which only one is schematically shown) configured
to convey the rows of containers 2 towards the inlet station I;
- a motor (not shown), which drives conveyors 103; and
- a sequencing device 105, arranged between inlet station I and endless conveyors 103
and configured to receive a row of containers 2 at a time from conveyors 103 and to
feed the received row to the chain conveyor 4 at inlet station I.
[0031] In particular, the most forward containers 2 of each row of containers 2 are transferred
by sequencing device 105 to the respective pockets 17 of the beam 16 that is travelling
at inlet station I.
[0032] The operation and construction of the sequencing device 105 in known as such and,
therefore, not described further in detail.
[0033] In the embodiment shown, direction F is horizontal and orthogonal to axes A of containers
2 fed along the same direction F.
[0034] Washing machine 1 further comprises an outfeed conveyor 14, which receives rows of
cleaned containers 2 from chain conveyor 4 at an outlet station 0 of washing tunnel
3.
[0035] In view of the above, path P comprises:
- a washing branch Q, which extends from inlet station I to outlet station 0 and along
which containers 2 are advanced by chain conveyor 4; and
- a return branch R, which extends from outlet station 0 to inlet station I and defines
a return zone R1, through which beams 16 return towards inlet station I without containers
2.
[0036] Furthermore, according to the advancing direction of the same containers 2, washing
machine 1 comprises in sequence along washing branch Q:
- a prewash zone P1;
- a first cleaning zone C1;
- a second cleaning zone C2;
- a first heat exchange zone H1; and
- a second heat exchange zone H2.
[0037] In the foregoing of the present disclosure, for the sake of clarity, terms like "upstream
of" and "downstream of" are to be intended throughout the whole description with reference
to such advancing direction of the containers 2 along path P.
[0038] Within prewash zone P1, first cleaning zone C1, and second cleaning zone C2, washing
machine 1 comprises respective baths 11, 12, 13 filled with a cleaning agent, preferably
a basic aqueous solution comprising sodium hydroxide.
[0039] Moreover, within prewash zone P1, washing machine 1 comprises also a plurality of
sprinkling devices 106 arranged in sequence along washing branch Q.
[0040] Sprinkling devices 106 deliver, in use, sprinkles of the above cleaning agent to
external surfaces 2a and inner volumes 2b of containers 2, while the latter are advanced
through the prewash zone P1 itself.
[0041] The cleaning agent within bath 11 and the cleaning agent ejected by sprinkling devices
106 are brought to a relatively high temperature, for instance between 45 °C and 60
°C, so that the encrusted dirt on containers 2 starts to dissolve as containers 2
themselves advance through prewash zone P1.
[0042] On the other hand, the cleaning agent within baths 12, 13 is brought to a higher
temperature, for instance between 65 °C and 80 °C, so that dirt on advancing containers
2 is fully removed together with possible labels arranged thereon.
[0043] Therefore, containers 2 come out from bath 13 cleaned and heated up to a temperature
likely between 60 °C and 70 °C, so that the same containers 2 needs to be cooled down
to environmental temperature before being discharged at outlet station 0.
[0044] In view of that, washing machine 1 comprises a cooling apparatus 101, which is arranged
within heat exchange zone H1 and allows containers 2 and beams 16 to come in thermal
contact with heat transfer medium having a temperature lower than that of the cleaning
agent within bath 13, such that the same containers 2 and beams 16 are cooled for
a first time while the corresponding heat transfer medium is heated.
[0045] Moreover, washing machine 1 comprises another cooling apparatus 102, which is arranged
within heat exchange zone H2 and allows containers 2 and beams 16 to come in thermal
contact with further heat transfer medium having a lower temperature, such that the
same containers 2 and beams 16 are cooled for a second time while the corresponding
heat transfer medium is heated.
[0046] In detail, each mentioned heat transfer medium comprises a rinsing medium, in particular
water, which is brought in contact with containers 2 and beams 16, while the latter
are advanced through heat exchange zones H1, H2.
[0047] In this manner, the cleaning agent remaining onto containers 2 and onto beams 16
is gradually removed therefrom, as well as dissolved in the rinsing medium.
[0048] In particular, the equilibrium temperatures respectively reached by containers 2,
beams 16 and the heat transfer medium at heat exchange zone are between 45 °C and
60 °C, while the equilibrium temperatures respectively reached by containers 2, beams
16 and the heat transfer medium at heat exchange zone H2 is between 25 °C and 35 °C.
[0049] In the embodiment shown, cooling apparatus 101 comprises a basin 70 suitable for
holding heat transfer medium and arranged within heat exchange zone H1, in particular
along a stretch Q1 of washing branch Q.
[0050] Basin 70 is filled with heat transfer medium and is arranged in a position such that
beams 16 are conveyed by chains 15 through the same basin 70.
[0051] In such a manner, beams 16 and external surfaces 2a of containers 2 advancing through
the basin 70 are fully in contact with such heat transfer medium and, in particular,
immersed therein.
[0052] Since the above heat transfer medium comprises a rinsing medium, basin 70 may be
considered part of a rinsing apparatus aimed to remove cleaning agent from containers
2 and from beams 16 by delivering rinsing medium to the containers 2 and beams 16
themselves.
[0053] Immediately downstream of stretch Q1, washing branch Q comprises a stretch Q2 within
heat exchange zone H1 and along which containers 2 are advanced with their axes A
inclined with respect to a vertical direction.
[0054] In other words, each container 2 advancing along stretch Q2 has a corresponding orientation
that is intermediate in respect of two extremal orientations, according to which axis
A is vertical and inlet opening 2f is respectively above and below the base portion
2c.
[0055] More in detail, while advancing throughout the whole stretch Q2, each container 2
assumes a plurality of progressive orientations, among which at least one is distinguished
by that the corresponding axis A is horizontal.
[0056] In particular, containers 2 are conveyed through stretch Q2 with respective axes
A that progressively form angles with the vertical direction between 30° and 140°,
more in particular between 60° and 120°.
[0057] In such a manner, containers 2 and beams 16, which advance through basin 70 push
a portion of the heat transfer medium toward stretch Q2, at which the same portion
falls down from containers 2 and beams 16 themselves due to gravity action.
[0058] Moreover, still with reference to the embodiment shown, washing machine 1 comprises
a basin 74 that is suitable for holding heat transfer medium and is arranged in heat
exchange zone H1 below stretch Q2, so as to receive and gather the portion of the
heat transfer medium fallen down from containers 2 and beams 16.
[0059] Furthermore, cooling apparatus 102 comprises a rinsing apparatus arranged within
heat exchange zone H2, and configured to deliver a rinsing medium onto containers
2 and beams 16, while the latter are advanced through heat exchange zone H2.
[0060] Specifically, the above rinsing apparatus is defined by an ejection assembly 77 and
the rinsing medium comprises a liquid defining the heat transfer medium within heat
exchange zone H2.
[0061] Ejection assembly 77 comprises a plurality of sprinkling devices 78 arranged in sequence
along washing branch Q for delivering sprinkles of the rinsing medium to external
surfaces 2a and inner volumes 2b of containers 2, as well as to beams 16 carrying
the same containers 2.
[0062] At least one of the sprinkling devices 78 is supplied by a source of rinsing medium;
specifically washing machine 1 comprises a tank T4 defining the above source of rinsing
medium.
[0063] In the embodiment shown, tank T4 supplies only the last sprinkling device 78 of the
respective sequence, according to the advancing direction of containers 2.
[0064] To supply all the other sprinkling devices 78, ejection assembly 77 comprises also
a plurality of basins 79 respectively arranged in sequence below sprinkling devices
78 and fluidly connected thereto.
[0065] The last basin 79 in the respective sequence gathers the rinsing medium that is ejected
by the corresponding sprinkling device 78, since the same ejected rinsing medium falls
down from containers 2 and beams 16 that advance above the same last basin 79.
[0066] As it will be explained in the foregoing of the disclosure, the previously referred
last basin 79 supplies, in use, all the other basins 79, which in turn supply the
corresponding sprinkling devices 78.
[0067] In detail, as schematically illustrated in Figure 1 and according to the advancing
direction of containers 2, each basin 79, with exception of the first of the respective
sequence, comprises at the top a corresponding spillway 80 toward the immediately
upstream basin 79.
[0068] Therefore, when a basin 79 (excluded the first one of the respective sequence) is
completely filled with rinsing medium, a superficial portion of the latter falls by
means of the spillway 80 into the immediately upstream basin 79.
[0069] The last basin 79 in the respective sequence is the first one that is completely
filled since indirectly receiving rinsing medium from tank T4 via the corresponding
sprinkling device 78; the other basins 79 are completely filled in succession according
to a direction opposite to the advancing direction of containers 2.
[0070] In the embodiment shown, the first basin 79 of the respective sequence is adjacent
to basin 74 and comprises at the top a spillway 81 toward the same basin 74.
[0071] Washing machine 1 further comprises:
- a circulation system 35 for circulating heat transfer medium between first heat exchange
zone H1 and return zone R1; and
- a heating apparatus 36 for heating beams 16 at return zone R1 by allowing thermal
contact between the same beams 16 and the circulated heat transfer medium, such that
the same heat transfer medium is cooled by transferring part of the heat absorbed
at first heat exchange zone H1 to the beams 16 themselves before being returned to
first heat exchange zone H1 for cooling containers 2.
[0072] In particular, the equilibrium temperatures respectively reached by beams 16 and
heat transfer medium at return zone R1 are between 25 °C and 35 °C.
[0073] Advantageously, washing machine 1 further comprises a cleaning device, which is arranged
within return zone (R1) and is configured to clean beams 16, while the latter advance
through the return zone (R1).
[0074] With greater detail, the cleaning device comprises a basin 104 arranged so as to
allow therein a recovering bath treatment for beams 16.
[0075] In other words, path P extends through the basin 104 itself.
[0076] Preferably, heating apparatus 36 comprises the basin 104, which is also suitable
for holding heat transfer medium.
[0077] Basin 104 is filled with heat transfer medium, such that beams 16 advanced through
basin 104 result fully in contact with the heat transfer medium itself and, in particular,
immersed therein.
[0078] Circulation system 35 comprises a fluidic circuit 110, which:
- withdraws a first portion of heat transfer medium heated at heat exchange zone H1
to supply the same first portion to the basin 104; and
- withdraws a second portion of heat transfer medium cooled within the basin 104 to
convey the same second portion back to heat exchange zone H1.
[0079] In particular, fluidic circuit 110 comprises a fluidic line L1, which fluidly connects
the basin 104 to the basin 70 so as to allow flowing of the above second portion from
basin 104 to basin 70.
[0080] More in particular, fluidic line L1 is provided with a tank T1, which is filled with
the heat transfer medium at the same temperature of the second portion, is arranged
below basin 104, and is connected to basin 104 for receiving the second portion.
[0081] Moreover, fluidic circuit 110 is provided also with a pump 114 arranged along fluidic
line L1 for pumping the second portion from tank T1 to basin 70, which is arranged
above both tank T1 and basin 104.
[0082] Fluidic circuit 110 further comprises another fluidic line L2, which fluidly connects
basin 104 to basin 74 so as to allow transport of the above first portion from basin
74 to basin 104.
[0083] Basin 74 is arranged above basin 104, such that the first portion is conveyed by
fluidic line L2 due to gravity action, without the needing of any pump.
[0084] Furthermore, washing machine 1 comprises another fluidic circuit 111, which withdraws
a further portion of the heat transfer medium heated at heat exchange zone H1 to convey
the same further portion to prewash zone P1.
[0085] In particular, fluidic circuit 111 comprises a fluidic line L3, which fluidly connects
basin 74 with sprinkling devices 106, so as to supply the same sprinkling devices
106 with the above further portion of the heat transfer medium.
[0086] Preferably, the aforementioned cleaning device comprises an ultrasonic wave generator
UG, which is coupled to the basin 104 and is configured to propagate ultrasonic waves
through the heat transfer medium within basin 104 itself, such that beams 16 may receive
an ultrasonic cleaning treatment while advancing through basin 104.
[0087] More in detail, the ultrasonic wave generator comprises a plurality of ultrasonic
transducers 90 (Figure 2), which are conveniently plate-shaped, configured to convert
electric power into ultrasounds, and sequentially arranged adjacent and parallel to
each other along a stretch R2, which is part of return branch R and is placed within
basin 104.
[0088] Ultrasonic transducers 90 preferably emit ultrasonic waves having an action range
of at least 350 mm and a frequency between 25 kHz and 28 kHz.
[0089] Specifically, ultrasonic transducers 90 are parallel to stretch R2 and fixed with
respect to basin 104, so as to be placed immediately below the advancing beams 16.
[0090] In particular, ultrasonic transducers 90 have a maximum clearance from beams 16 that
is equal to 10 mm, according to a direction orthogonal to stretch R2.
[0091] While beams 16 advances through stretch R2, the same beams 16 have respective portions
facing ultrasonic transducers 90 in close proximity.
[0092] Stretch R2 is preferably rectilinear and, more preferably horizontal. Moreover, stretch
R2 conveniently has a length between 0.5 m and 2 m.
[0093] Preferably, beams 16 are advanced throughout the whole stretch R2 during a time interval
between 20 s and 60 s, in order to have optimal performances of the ultrasonic cleaning
treatment.
[0094] Washing machine 1 further comprises:
- an electric power generator EG connected to ultrasonic transducers 90; and
- a control unit ECU connected to the electric power generator EG and configured to
control power supply of each ultrasonic transducer 90 by operating electric power
generator EG.
[0095] In particular, control unit ECU controls the activation of ultrasonic transducers
90 in a periodic or discontinuous manner, e.g. for a duration of 30 s after each period
of 420 working hours of the washing machine 1.
[0096] Ultrasonic waves generated by ultrasonic wave generator UG have a relative periodic
motion with respect to the heat transfer medium in which the same waves propagate;
therefore, local micro-zones within the heat transfer medium pass periodically from
a depressurized to a pressurized state.
[0097] During the depressurized state, air dissolved within the heat transfer medium tends
to form many microbubbles, which implode when pressure increases, so as to release
energy towards beams 16 that are advanced through basin 104.
[0098] Such energy is useful to disaggregate possible tough calcium deposit or encrusted
dirt on the beams 16 themselves.
[0099] The operation of washing machine 1 is described in detail in the following.
[0100] Feeding system 8 advances a plurality of rows of containers 2 to be washed through
conveyor 103 in a parallel manner to direction F.
[0101] The properly positioned containers 2 are arranged with respective axes A orthogonal
to path P and with respective base portions 2c lying on conveyor 103.
[0102] Beams 16 of chain conveyor 4 withdraw respective rows of containers 2 at inlet station
I from sequencing device 105, advance containers 2 inside washing tunnel 3 along the
washing branch Q, discharge rows of cleaned containers 2 at outlet station 0 onto
outfeed conveyor 14, and return along return branch R without containers 2.
[0103] In detail, containers 2 of each row are first carried by pockets 17 through prewash
zone P1, where containers 2 are preliminary washed and heated through immersion within
bath 11 and by means of sprinkling devices 106.
[0104] Hence, the same containers 2 are conveyed also through following baths 12, 13, respectively
at cleaning zones C1, C2, so that containers 2 are completely cleaned and deprived
of any labels attached thereon.
[0105] Here, both containers 2 and beams 16 continue to receive heat from cleaning agent
within baths 12, 13 up to reach elevated temperatures, for instance between 60 °C
and 70° C.
[0106] At this point, a cooling process is carried out for cooling the hot washed containers
2 before the same containers 2 are discharged at outlet station 0.
[0107] In particular, containers 2 and beams 16 are advanced through basin 70 within heat
exchange zone H1, where the containers 2 and the beams 16 themselves are immersed
into the heat transfer medium and establish a thermal equilibrium with the latter,
so as to reach intermediate temperatures, for instance between 45 °C and 60 °C.
[0108] Here, part of the heated heat transfer medium, at a similar temperature to the above
intermediate temperatures, is dragged out from basin 70 by containers 2 and beams
16, while the latter are conveyed out from the basin 70 itself.
[0109] The dragged part falls down within basin 74 while the same containers 2 and the same
beams 16 advance through the stretch Q2.
[0110] The entire heat transfer medium gathered within basin 74 has a temperature essentially
equal to that of the above part; then, two different further parts of the heat transfer
medium within the same basin 74 are split to be respectively supplied to sprinkling
devices 106 via fluidic line L3 and transported to basin 104 via fluidic line L2.
[0111] When containers 2 and beams 16 reach the heat exchange zone H2, the containers 2
and beams 16 themselves receive the heat transfer medium by means of sprinkling devices
78, so as to be further cooled down to low temperatures, for instance between 25 °C
and 35 °C.
[0112] Then, cooled beams 16 advance through the return branch R whereas containers 2 at
the above low temperatures are discharged at outlet station 0.
[0113] Cooled beams 16 are immersed within basin 104 while advancing through the return
branch R; here, a heat exchange occur between the heat transfer medium within basin
104 and the cooled beams 16.
[0114] During heat exchange, beams 16 receive a complete ultrasonic cleaning treatment by
means of ultrasonic wave generator UG, with above described modes.
[0115] After such heat exchange, beams 16 are warmed and conveyed toward inlet station I,
whereas the heat transfer medium is cooled down.
[0116] Then, part of the cooled down heat transfer medium is transported to basin 70, so
as to be re-used for cooling other containers 2 and beams 16, which advance through
basin 70 itself.
[0117] From an analysis of the features of washing machine 1 and of the method according
to the invention, the advantages they allow to obtain are apparent.
[0118] Return zone R1, which, in the known solutions, is only aimed to allow the return
of beams 16 to inlet station I, is here provided with cleaning means to allow removal
of limescale or encrusted dirt deposits during the operation of washing machine 1.
[0119] Thanks to that, stops of washing machine 1 for disassembling beams 16 are totally
avoided. In the same way, manual maintenance operations on beams 16 are unnecessary
and any related assembling errors waived.
[0120] In particular, the waves generated by ultrasonic generator UG through basin 104 reveals
significantly effective in restoring beams 16.
[0121] The flattened shape of ultrasonic transducers 90 allows a simple and compact arrangement
of ultrasonic wave generator UG within basin 104 under the advancing beams 16 through
stretch R2.
[0122] In particular, the reduced spacing between ultrasonic transducers 90 and beams 16
optimizes the effectiveness of the cleaning treatment of beams 16 themselves, since
an increased amount of energy affects the limescale or encrusted dirt deposits thereon.
[0123] The energetic impact of the operation of ultrasonic wave generator UG is particularly
limited thanks to the intelligent control performed by electronic control unit ECU,
which selectively activate each ultrasonic transducer 90 according to a predetermined
optimized period.
[0124] The relatively high temperature of the heat transfer medium, which enables the ultrasonic
wave transmission, enhances the cleaning performances of the transmitted ultrasonic
waves.
[0125] Finally, the length of stretch R2 is chosen according to an optimized compromise
between energetic expenditure and cleaning performances, as demonstrated by several
experiments accomplished by the Applicant.
[0126] Clearly, changes may be made to washing machine 1 and to the method as described
and illustrated herein without, however, departing from the scope of protection as
defined in the accompanying claims.
[0127] In particular, the shape and arrangement of each ultrasonic transducer 90 may be
different from what described and illustrated in the above disclosure.
[0128] Moreover, ultrasonic wave generator UG may even be lacking and basin 104 may be filled,
for instance, with an acid solution suitable for descaling beams 16. Clearly, in the
latter case, circulation system 36 would not be present and basin 104 would be isolated
from heat exchange zones H1, H2.
1. A washing machine (1) for washing empty containers (2), the washing machine comprising:
- a plurality of beams (16) cyclically movable along a closed-loop path (P) for carrying
and advancing a plurality of containers (2) along said path (P); said path (P) comprising:
- an inlet and an outlet station (I, 0) respectively configured to allow said beams
(16) to withdraw and discharge said containers (2); and
- a return zone (R1) arranged downstream of said outlet station (0), according to
an advancing direction of said beams (16);
characterized by further comprising cleaning means arranged within said return zone (R1) and configured
to clean said beams (16) during their advancement through said return zone (R1).
2. The washing machine of claim 1,
characterized in that said cleaning means comprise:
- a basin (104) arranged within said return zone (R1) and suitable for allowing therein
a recovering bath treatment for said beams (16); said path (P) extending through said
basin (104); and
- an ultrasonic wave generator (UG) coupled to said basin (104) and configured to
propagate ultrasonic waves through a wave transmission medium filling said basin (104),
such that said beams (16) can receive an ultrasonic cleaning treatment during their
advancement through said basin (104);
3. The washing machine of claim 2, wherein said ultrasonic wave generator (UG) comprises
at least one ultrasonic transducer (90) being plate-shaped, configured to convert
electric power into ultrasounds, and arranged within said basin (104) in such a manner
to face respective portions of said beams (16) in close proximity during the advancement
of said beams (16) through said basin (104).
4. The washing machine of claim 3, further comprising a control unit (ECU) connected
to said ultrasonic transducer (90) and configured to control power supply of said
ultrasonic transducer (90).
5. The washing machine of claim 4, wherein said control unit (ECU) is configured to activate
said ultrasonic transducer (90) according to a predetermined period and for a predetermined
activation duration; said predetermined period and duration being, in particular,
selected in view of an advancing velocity of said beams (16) to guarantee an optimized
balance between cleaning performance of said ultrasonic cleaning treatment and energy
expenditure.
6. The washing machine of any one of claims from 2 to 5, wherein said ultrasonic wave
generator (UG) comprises a plurality of ultrasonic transducers (90) being plate-shaped,
configured to convert electric power into ultrasounds, and sequentially arranged adjacent
and parallel to each other along a stretch (R2) of said path (P); said stretch (R2)
extending within said basin (104).
7. The washing machine of claim 6, wherein said ultrasonic transducers (90) are arranged
in such a manner to be placed, in use, below said beams (16) during their advancement
through said basin (104).
8. The washing machine of claim 6 or 7, wherein said stretch (R2) has a length between
0.5 m and 2 m.
9. The washing machine of claim 1, wherein said cleaning means comprise a basin (104)
suitable for holding a descaling agent, in particular an acid solution; said path
(P) extending through said basin (104).
10. An operating method of a washing machine (1) for washing empty containers, the method
comprising the steps of:
- cyclically advancing a plurality of beams (16) along a closed loop path (P) comprising
an inlet and an outlet station (I, 0), and a return zone (R1) arranged downstream
of said outlet station (0), according to an advancing direction of said beams (16);
- charging said beams (16) with a plurality of containers (2) at said inlet station
(I);
- discharging said containers (2) from said beams (16) at said outlet station (0);
characterized by further comprising the step of cleaning said beams (16) during their advancement
through said return zone (R1).
11. The operating method of claim 10, wherein said step of cleaning said beams (16) comprises
the steps of:
- filling a basin (104) arranged within said return zone (R1) with a wave transmission
medium; said path (P) extending through said basin (104); and
- propagating ultrasonic waves through said wave transmission medium during the advancement
of said beams (16) through said basin (104), such that said beams (16) receive an
ultrasonic cleaning treatment.
12. The operating method of claim 10, wherein said step of cleaning said beams (16) comprises
the step of:
- filling a basin (104) arranged within said return zone (R1) with a descaling agent,
in particular an acid solution; said path (P) extending through said basin (104),
such that said beams (16) come in contact with said descaling agent during their advancement
through said basin (104).