EP3656479A1

EP3656479A1 - Washing machine and relative method for washing empty containers

Info

Publication number: EP3656479A1
Application number: EP18207283.5A
Authority: EP
Inventors: Claudio Berzaghi; Andrea Sterzi
Original assignee: Gebo Packaging Solutions Italy SRL
Current assignee: Sidel SpA
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-05-27
Anticipated expiration: 2038-11-20
Also published as: EP3656479B1

Abstract

A washing machine for empty containers (2) includes a conveyor (4) for advancing containers (2) with respective base portions (2c) and respective opposite inlet openings (2f) along a washing treatment path (Q) from an inlet station (I) to an outlet station (O), an acid treatment zone (A1) arranged along the path (Q) and provided with an acid emitting apparatus (28) for introducing an acid medium into the inner volumes (2b) of the containers (2), and a descaling zone (D1) arranged downstream of the acid treatment zone (A1) and in which the conveyor conveys the containers (2) with inlet openings (2f) above the base portions (2c), such that at least one portion of the acid medium received by the containers (2) at the acid treatment zone (A1) is kept inside the inner volumes (2b) of the same containers (2) due to gravity action.

Description

The invention relates to a washing machine for washing empty containers.
The invention also relates to a method for washing empty containers, in particular through the same washing machine.
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.
An example of washing machine is known, e.g. from EP2727660 in the name of the same Applicant.
Known washing machines comprise, essentially:

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.

In detail, the chain conveyor comprises a plurality of bars, which are fed at the inlet station by the feeding system with respective rows of containers.
In particular, each bar comprises a plurality of aligned pockets, which receive, convey and outlet the respective washed containers.
Typically, the treatment zones comprise a prewash zone, a first cleaning zone, a second cleaning zone and a final rinsing zone.
The prewash zone, the first cleaning zone, and the second cleaning zone comprise respective baths that are filled with a washing chemical agent and through which the containers are advanced.
In particular, each of the treatment zones comprises a respective plurality of nozzles for ejecting the same washing chemical agent inside the inner volume of the containers, as they are upside down advanced.
A few known washing machines available on the market further include the functionality of removing possible tough calcium deposits from containers by sprinkling the inner volumes and the outer surfaces of the containers themselves with an acid solution. In other words, these washing machines are used to descale the inner volumes and/or the external surfaces of the containers.
In this kind of machines, the treatment zones further comprise an acid washing zone, which is arranged immediately upstream of the final rinsing zone along the washing path.
The acid washing zone is provided with nozzles for injecting the acid solution inside the inner volume of the advancing containers.
The peculiar position of the acid washing zone immediately upstream of the rinsing zone requires a rapid removal of the acid solution from the containers immediately after the completion of the descaling function of the acid solution itself.
The acid solution is normally an aqueous solution comprising a strong corrosive acid, like nitric acid, in high concentrations, such as 5.6% of the total volume of the solution.
Such a high concentration is required in order to remove almost the totality of the calcareous residues in the shortest possible time before the containers are advanced through the immediately upstream rinsing zone.
However, the usage of strong acids in the acid solution has the inconvenience of an increased overall cost of the washing machine related to the specific high cost of strong acids and to precautions needed in view of the strong corrosive and polluting power thereof.
A need is therefore felt for a washing machine in which the acid treatment of containers is performed using a low concentrated acid solution or, possibly, a weak acid instead of a strong one, without having losses of descaling performances in respect to the known machines.
It is an object of the invention to provide a washing machine for empty containers, which allows meeting the abovementioned need in a simple and economic manner.
This object is achieved by the invention as it relates to a washing machine for washing empty containers, as claimed in claim 1.
The invention further relates to a method for washing empty containers, as claimed in claim 17.
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 pourable product containers, according to the invention;
Figure 2 is a perspective view, in an enlarged scale and with parts removed for clarity, of some components of the washing machine of Figure 1;
Figure 3 is lateral section view, in an enlarged scale and with part removed for clarity, of an acid treatment zone of the washing machine of Figure 1;
Figure 4 is a partial perspective view of an acid injector assembly arranged in the acid treatment zone of Figure 3; and
Figure 5 is a section of the acid injector assembly of Figure 4 taken according to line V-V of Figure 4.

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.
In detail, as better visible in Figure 3, 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.
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.
Washing machine 1 comprises (Figure 1):

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.

As shown in Figures 1 and 3, chain conveyor 4 comprises specifically:

a pair of chains 15 elongated parallel to path P and parallel to one another;
a plurality of subsequent conveying beams 16, which extend between chains 15 in a transversal and, more in particular, orthogonal manner to chains 15 and path P; and
a stationary guide 80 that supports chains 15 and is shaped in the same way as path P.

Each beam 16 extends between two ends 16a, 16b that are each fastened to a corresponding one of chains 15, in particular by means of bolted joints 16c.
In particular, each beam 16 comprises a horizontal support element 52 and a plurality of pockets 17, which are arranged between the ends 16a, 16b, aligned orthogonally to path P, fixed to the support element 52, and adapted to receive corresponding containers 2.
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.
The stationary guide 80 (Figure 3) comprises a frame 81 straddling beams 16 and a couple of tracks 82 arranged on opposite sides of beams 16, facing each other orthogonally to path P, and respectively engaged by chains 15.
In detail, each of tracks 82 has an upper wall 82a and a lower wall 82b fixed to the frame 81 and both cooperating in contact with a corresponding chain 15.
Washing machine 1 comprises also a feeding system 8 (Figure 1), which is configured to feed a sequence of rows 20 (Figure 3) of empty containers 2 along a direction F and at an inlet station I of washing tunnel 3.
Feeding system 8 comprises:

a plurality of endless conveyors 103 (of which only one is schematically shown) configured to convey the rows 20 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 20 at a time from conveyors 103 and to feed the received row 20 to the chain conveyor 4 at inlet station I.

In particular, the most forward containers 2 of each row 20 are transferred by sequencing device 105 to the respective pockets 17 of the beam 16 that is travelling at inlet station I.
The operation and construction of the sequencing device 105 is known per-se and therefore not described further in detail.
In the embodiment shown, direction F is horizontal and orthogonal to axes A of containers 2 fed along the same direction F. Moreover, direction F is the alignment direction of the rows 20.
Washing machine 1 further comprises an outfeed conveyor 14 (Figure 1), which receives a sequence of rows 20 of cleaned containers 2 from chain conveyor 4 at an outlet station 0 of washing tunnel 3.
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 O to inlet station I and in which chain conveyor 4 returns without containers 2.

Furthermore, still with reference to Figure 1, in order to perform washing of the advancing containers 2 through conveyor chain 4, washing machine 1 comprises a plurality of treatment zones 5 arranged inside washing tunnel 3 along washing branch Q of path P.
Treatment zones 5 comprise a prewash zone P1, a first cleaning zone C1, and a second cleaning zone C2 arranged along the washing branch Q in sequence, according to the advancing direction of containers 2.
From now on, for a matter 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.
The prewash zone P1, the first cleaning zone C1, and the second cleaning zone C2 comprise respective baths 11, 12, 13 filled with a cleaning agent, preferably a basic aqueous solution comprising sodium hydroxide.
The cleaning agent within baths 11, 12, 13 is brought to a relatively high temperature, for instance between 60° and 85° Celsius, so that containers 2 are heated up and cleaned as they travel inside bath 11, 12, 13.
Moreover, the temperature of the cleaning agent is sufficient to guarantee the removal of possible labels arranged on containers 2.
Advantageously, in order to remove possible tough calcium deposits within the inner volumes 2b of the empty containers 2, washing machine 1 further comprises:

an acid treatment zone A1 arranged along washing branch Q and comprising an acid emitting apparatus 28 configured to allow the introduction of an acid medium into the inner volumes 2b through the corresponding inlet openings 2f; and
a descaling zone D1 arranged along a stretch Q1 of washing branch Q and downstream of the acid treatment zone A1;

chain conveyor

containers

inlet openings

corresponding base portions

containers

inner volumes

In other words, the containers 2 are conveyed along the stretch Q1 by chain conveyor 4 in a right side up configuration.
According to the advancing direction of containers 2, washing machine 1 further comprises in sequence along washing branch Q:

a heat exchange zone H1, which is arranged in a position directly interposed between cleaning zone C2 and acid treatment zone A1;
acid treatment zone A1;
descaling zone D1;
a dripping zone D2 for allowing the escaping of the acid medium from the inner volumes 2b;
another acid treatment zone A2, which is aimed to provide a further descaling stage to containers 2 and comprises another acid emitting apparatus 73 for delivering another acid medium to advancing containers 2;
another descaling zone D4; and
a rinsing zone R1, which comprises a rinsing apparatus 77 that rinses the acid medium off containers 2.

The heat exchange zone H1 comprises a cooling device 102 for decreasing the temperature of containers 2 conveyed out from bath 13, while the same containers 2 advance through the heat exchange zone H1 itself.
The usage of cooling device 102 is aimed to reduce the chemical risks inherent to delivering an acid medium into relatively hot elements such as the containers 2 conveyed out from the bath 13.
In greater detail, containers 2 are conveyed through the acid treatment zone A1 in an upside down configuration, i.e. with the inlet openings 2f arranged below the corresponding base portions 2c.
More precisely, washing branch Q has through acid treatment zone A1:

a horizontal stretch Q2, along which containers 2 are conveyed with respective axes A oriented vertically; and
a curved stretch Q3 that joins stretches Q1, Q2, so that containers 2 there conveyed pass from the upside down configuration to the right side up configuration.

Containers 2 are conveyed throughout the whole stretch Q1 having inside their inner volumes 2b a portion of the acid medium delivered at acid treatment zone A1.
Therefore, such acid medium performs its descaling function within containers 2 also outside from acid treatment zone A1.
In other words, the descaling action of the delivered acid medium is exploited for a relatively prolonged amount of time, during which no need is felt of constantly introducing new acid medium in the inner volumes 2b downstream of acid treatment zone A1.
In particular, containers 2 are conveyed throughout the whole stretch Q1 in a time lapse of at least 5 minutes. Such time lapse is due to the length of stretch Q and to the speed at which containers 2 are conveyed by chain conveyor 4.
For example, containers 2 are conveyed along stretch Q1 with a speed between 0.03 and 0.07 m/s, while stretch Q1 has a length between 2.5 and 7 m.
Conveniently, stretch Q1 has at least one horizontal portion Q11 along which containers 2 are conveyed with respective axes A oriented vertically.
Preferably, the delivered acid medium is a weakly acid aqueous solution containing, in particular, nitric acid with a concentration in the aqueous solution between 0.5% and 2% of the total volume thereof.
Alternatively, the supplied acid medium may comprise weak acids in higher concentrations, such as citric acid.
In greater detail, acid emitting apparatus 28 comprises at least one injector assembly 29 (Figures 2, 3, and 4). More precisely, acid emitting apparatus 28 comprises a couple of identical injector assemblies 29.
Each injector assembly 29 is configured to direct jets of the abovementioned acid medium toward inner volumes 2b of containers 2, while the latter are advancing through the acid treatment zone A1.
In the embodiment shown, injector assemblies 29 are both supplied with acid medium from an acid source; specifically, washing machine 1 comprises a tank T1 that contains the acid medium itself and is fluidly connected to both injector assemblies 29, so to define the above acid source.
In particular, with reference to Figures 3 and 4, the injector assemblies 29 have respective bases 30 fixed with respect to the stationary guide 80; such bases 30 are horizontally spaced from one another along stretch Q2 and vertically spaced from chains 15 according to respective equal vertical distances, such that injector assemblies 29 are both arranged below advancing containers 2.
Each injector assembly 29 comprises:

a corresponding plurality of nozzles 31 aligned along a respective axis B, which is fixed with respect to the stationary guide 80, is horizontally oriented, and is preferably orthogonal to path P; and
an ejection channel 34 extending along the corresponding axis B, fluidly connected to the acid source and carrying nozzles 31 that are supplied with the acid medium through the ejection channel 34 itself.

Nozzles 31 are equally spaced from each other along axis B, so that each of them results arranged under a corresponding pocket 17 of any beam 16 advancing above axis B.
With reference to Figure 5, each nozzle 31 specifically comprises:

a distributor 32 angularly fixed with respect to axis B and fluidly connected to with ejection channel 34; and
a shutter 33 rotatable about axis B.

Each shutter 33 is movable between:

a plurality of respective open angular positions (of which one is shown in Figure 5), in which the shutter 33 itself allows the ejection of the acid liquid from ejection channel 34 towards advancing containers 2; and
a plurality of respective closed angular positions, in which it prevents the ejection of the same acid liquid from ejection channel 34.

In particular, each distributor 32 and the corresponding shutter 33 respectively comprise an angularly fixed duct 35 in fluid communication with ejection channel 34 and a rotary duct 36 radially extending with respect to axis B.
In closed angular positions of shutters 33, rotary ducts 36 are fluidly isolated from the corresponding angularly fixed ducts 35.
On the other hand, in the respective open angular positions of shutters 33, rotary ducts 36 fluidly communicate with the corresponding angularly fixed ducts 35 and have ideal prolongations aligned with inlet openings 2f of containers 2 that are carried by a beam 16 advancing above axis B.
In fact, the rotation of shutters 33 and the translational motion of each of the beams 16 are co-ordinately controlled so that the directions of the jets of acid medium are actually toward the inlet openings 2f of the containers 2 carried by such translating beams 16.
More in detail, when a beam 16 is being advanced above axis B, shutters 33 are co-ordinately controlled such to rotate through their respective open angular positions, in which the acid medium is delivered within the inner volumes 2b of containers 2 carried by the same beam 16.
Here, rotary ducts 36 are aligned with corresponding injection direction, which are fixed and radially oriented with respect to axis B, in the embodiment shown.
Conveniently, as better visible in Figures 4 and 5, each injector assembly 29 comprises an acid-resistant shield 40 arranged about ejection channel 34, such to cover radially the ejection channel 34 itself.
In the embodiment shown, shield 40 is made of metal. In particular, shield 40 comprises:

a couple of parallel vertical walls 41, which extend upwards from the respective base 30; and
a sloping roof 42, which is supported in a fixed position by vertical walls 41 and is specifically consisting of two inclined walls 42a, 42b.

Inclined walls 42a, 42b are connected to one another at an upper edge 43 that is vertically aligned above axis B.
Moreover, shield 40 is provided with a plurality of through openings 45, which are respectively aligned along the aforementioned injection directions.
In other words, openings 45 are aligned with the prolongations of rotary ducts 36 in the respective open angular positions of shutters 33.
In particular, each opening 45 is obtained onto sloping roof 42 and is shaped as a slit arranged orthogonally to axis B. More in particular, each opening 45 is obtained onto both the walls 42a, 42b in a symmetric manner with respect to upper edge 43.
Therefore, shield 40 prevents the delivery of acid jets along directions outside from the injection directions. On the contrary, jets directed along such injection directions pass through the openings 45 to reach inlet openings 2f of the advanced containers 2 above axis B.
To allow the control of the simultaneous rotation of all the relative shutters 33 about the corresponding axis B, each injection assembly 29 comprises a transmission wheel member 47 (Figure 4) that is arranged about axis B and is fixed with respect to shutters 33, so that a rotation of the transmission wheel member 47 itself about axis B corresponds to an equal rotation of all shutters 33.
In other words, shutters 33 rigidly rotate with transmission wheel member 47.
In particular, transmission wheel member 47 comprises a star shaped wheel 48 coaxial to ejection channel 34, i.e. arranged about axis B, and fixed at an end of the same ejection channel 34.
Star shaped wheel 48 comprises, in turn, a star shaped plate 49 orthogonal to axis B and a plurality of knobs 50 respectively protruding from the tips of the star shaped plate 49 along parallel directions to axis B from the side of the ejection channel 34.
In order to drive transmission wheel member 47, each beam 16 comprises a driving element 51 (Figures 2 and 3), which is arranged at end 16a, is fixed to support element 52, and is preferably defined by an elongated bar extending orthogonally to path P from support elements 52.
Each driving element 51 has dimensions such to meet in contact one transmission wheel member 47 when the corresponding beam 16 approaches the respective axis B.
Here, while the corresponding beam 16 advances along stretch Q2 above axis B, driving element 51 exerts a driving torque on transmission wheel member 47 based on the contact with the latter.
In particular, driving element 51 touches one knob 50 and pushes the knob 50 itself along a direction parallel to stretch Q2, i.e. along a direction tangential to transmission wheel member 47.
Each driving element 51 is fixedly mounted to the corresponding support element 52 with an actual position, which is the result of a known mounting procedure of the washing machine 1.
To guarantee a correct operation of the washing machine 1, each driving element 51 needs to be mounted correctly, namely the actual position thereof has to coincide with a nominal desired position.
In fact, if the actual positions of all the driving elements 51 coincide with the corresponding nominal desired positions, transmission wheel member 47 rotates in a perfectly coordinated manner with the translation of each driving element 51, so that shutters 33 rotate exactly through their open angular positions.
On the contrary, an incorrect actual position of only one driving element 51 results in an erroneous ejection of acid medium from nozzles 31 toward the outside of the containers 2.
To monitor the actual position of each driving element 51, washing machine 1 further comprises a sensor assembly SS, which:

is arranged along washing branch Q between inlet station I and acid treatment zone A1; and
is configured to detect at least one physical quantity indicative of a deviation of such actual position from the nominal desired position.

In particular, sensor assembly SS is arranged immediately upstream of acid treatment zone A1 and comprises a couple of sensors S1, S2 arranged at respective separate points V, W of washing branch Q.
Sensors S1, S2 are configured to detect corresponding physical quantities that are respectively indicative of the presence of driving elements 51 at points V, W.
Points V, W are spaced one another of a distance equal to that of two driving elements 51 having a nominal position and belonging to corresponding two consecutive beams 16.
Therefore, the simultaneous detection of two driving elements 51 respectively present at points V, W, is indicative that both the same driving elements 51 have respective nominal positions.
Otherwise, the detection of the presence of only one of such two driving elements 51 at point V or at point W, is indicative that at least one of the driving elements 51 themselves has an actual position that differs from the nominal position.
In the embodiment shown, both sensors S1, S2 are of inductive type and are specifically defined by respective magnetic rods fixed with respect to stationary guide 80.
Such magnetic rods extend parallel to axis B through the corresponding points V, W, such to face driving elements 51 at the same points V, W.
In the embodiment shown, each driving element 51 comprises a magnetic material, so that two currents are respectively induced through the magnetic rods once two corresponding driving elements 51 are at points V, W. Such currents are the above physical quantities indicative of the respective presences of driving elements 51 at points V, W.
According to non-shown alternatives, sensors S1, S2 may be respectively of optic or conductive types.
According to a further non-shown alternative, sensor assembly SS may comprise a group of cameras configured to take images of beams 16, so that the actual position of each driving element 51 may be derived from such images.
In order to stop the operations of washing machine 1, in case the actual position of any one of the driving elements 51 differs from the nominal position thereof, the same washing machine 1 further comprises a control unit 60 that is connected to sensor assembly SS.
Control unit 60 is configured to receive from the sensor assembly SS all the physical quantities detected by the latter and to stop operations of washing machine 1 when at least one of such physical quantities is indicative that the actual position of at least one driving element 51 differs from the nominal position thereof.
Therefore, the presence of control unit 60 and of sensor assembly SS allows the monitoring of the correct positions of driving elements 51, so that the jets of acid medium ejected by acid emitting apparatus 28 result correctly directed toward inner volumes 2b of containers 2.
Washing machine 1 further comprises for each chain 15 a corresponding covering structure 61 (Figure 3), which is arranged around the corresponding chain 15 in the area of the acid emitting apparatus 28, i.e. within acid treatment zone A1.
Each covering structure 61 is configured to cover the corresponding chain 15 from possible sprinkles of acid medium emitted by acid emitting apparatus 28 and comprises a couple of sheet metals 62, 63 arranged in a fixed position with respect to path P and respectively above and below the corresponding covered chain 15.
In such a manner, soaking of chains 15 due to sprinkles of acid medium is completely avoided.
With greater detail, sheet metals 62 are fixed to frame 81 through respective fastening elements (specifically, screws).
Moreover, more precisely, each sheet metal 62 comprises two portions 62a, 62b, preferably horizontal, that are respectively arranged above the corresponding track 82 and beams 16.
Similarly, sheet metals 63 are fixed to frame 81 through respective fastening elements (specifically, screws).
Moreover, each sheet metal 63 comprises two portions 63a, 63b, of which the portion 63a is horizontal and the portion 63b extends vertically downward from the portion 63a, so to face beams 16 and in particular driving elements 51.
Making now reference to Figure 2, washing machine 1 further comprises an acid-resistant cover 65, which is arranged in acid treatment zone A1 and in a fixed position above acid emitting apparatus 28, in particular above both the injector assemblies 29.
Cover 65 comprises a deflecting grate 66, preferably horizontal, and a plate roof 67 arranged over grate 66.
Cover 65 is intended to collect the jets of the acid medium ejected by injector assemblies 29, so as to contain spreading of acid sprinkles outside acid treatment zone A1.
Indeed, the fins of deflecting grate 66 are particularly suitable for withholding the received acid medium due to friction exerted on the medium itself.
Therefore, cover 65 is particularly useful in case one or more pockets 17 of a beam 16 are devoid of respective containers 2. Indeed, in the latter case, the jets of acid medium ejected by nozzles 31 would be directed toward cover 65, which would prevent an excessive spreading of the acid medium throughout acid treatment zone A1.
In the embodiment shown, cover 65 and covering structures 61 are made of stainless steel, so as to constitute valid protections for the components of washing machine 1 from the corrosive power of the acid medium.
With reference to Figure 1, washing machine 1 comprises in one embodiment also a bath 70 holding a basic medium and arranged downstream of acid treatment zone A1, in particular within descaling zone D1.
Bath 70 is arranged along stretch Q1 in a position such that beams 16 are conveyed by chains 15 through bath 70, so that possible residues of acid medium remaining onto beams 16 are neutralized by the basic medium within bath 70.
More in detail, containers 2 are conveyed through bath 70 in a right side up configuration and the respective external surfaces 2a of the same containers 2 are here almost totally immersed.
In particular, only neck portions 2d emerge from bath 70, so that the basic medium remains outside of inner volumes 2b.
In this manner, external surfaces 2a are neutralized together with carrying beams 16, while the acid medium delivered to inner volumes 2b at acid treatment zone A1 operates its descaling function.
In the embodiment shown, bath 70 is supplied by a basic source; in particular, washing machine 1 comprises a tank T2 containing the basic medium and fluidly connected to bath 70, such to define the above basic source.
Preferably, the basic medium is of the same kind of that held by baths 11, 12, and 13.
According to a variant of the washing machine 1, tank T2 contains a further acid medium, whereby the bath 70 itself holds the same further acid medium. Therefore, also external surfaces 2a of containers 2 and the beams 16 carrying the same containers 2 are treated through bath 70 with the further acid medium.
Preferably, such acid medium is of the same kind of that delivered to inner volumes 2b at acid treatment zone A1.
In this manner, even external surfaces 2a and beams 16 are descaled but, accordingly, it comes necessary that the same beams 16 would consist of an acid-resistant material, e.g. stainless steel.
Conveniently, after having been advanced throughout the whole stretch Q1, containers 2 are conveyed through dripping zone D2 with their axes A inclined with respect to a vertical direction.
In other words, each container 2 advancing through dripping zone D2 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.
Moreover, while advancing throughout the whole dripping zone D2, each container 2 assumes a plurality of progressive orientations, among which at least one is distinguished by that the corresponding axis A is horizontal.
Preferably, containers 2 are conveyed through dripping zone D2 with respective axes A forming angles with the vertical direction between 30° and 140°, more preferably between 60° and 120°.
In particular, dripping zone D2 is arranged along a stretch Q4 of washing branch Q and comprising at least one curvilinear portion so as to provoke centrifugal acceleration of the acid medium in inner volumes 2b toward the respective inlet openings 2f.
In such a manner, the dripping of the acid medium from the same inner volumes 2b is significantly eased.
Conveniently, after having been advanced throughout the whole stretch Q4, containers 2 to be further descaled are conveyed by chain conveyor 4 through acid treatment zone A2 in an upside down configuration.
In the embodiment shown, washing machine 1 comprises a bath 74 that is arranged in acid treatment zone A2, holds the acid medium and stays along washing branch Q, so that containers 2 are conveyed through the bath 74 itself by chain conveyor 4.
In particular, bath 74 is arranged at a vertical distance from chains 15, such that only neck portions 2d of containers 2 are immersed into bath 74, while the same containers 2 are advanced through acid treatment zone A2.
Preferably, acid emitting apparatus 73 in acid treatment zone A2 is constructively and functionally similar to acid emitting apparatus 28 in acid treatment zone A1; specifically, acid emitting apparatus 73 comprises a couple of injector assemblies 75 that are identical to injector assemblies 29 and, therefore, are not described further in detail.
In addition or in replacement to injector assemblies 75, acid emitting apparatus 73 may also comprise one or more acid ejectors (not shown), e.g. acid sprinkling devices like acid showers, adapted to distribute the acid medium onto external surfaces 2a, while the corresponding containers 2 are conveyed through acid treatment zone A2.
Such ejectors would constitute an ejection assembly together with injector assemblies 29.
In the embodiment shown, both the acid emitting apparatus 73 and the bath 74 are supplied by same acid source; in particular, washing machine 1 comprises a tank T3 defining the above acid source.
Tank T3 is fluidly connected to both the acid emitting apparatus 73 and the bath 74, and contains the acid medium that, more in particular, is of the same kind of that delivered at acid treatment zone A1.
Downstream of acid treatment zone A2, containers 2 to be further descaled are conveyed by chain conveyor 4 through descaling zone D4 still in an upside down configuration.
Descaling zone D4 is arranged along a stretch Q5 that is significantly shorter than stretch Q1, since a preliminary descaling stage of containers 2 has been already performed by the acid medium delivered at acid treatment zone A1.
Making now reference to rinsing zone R1, immediately downstream of descaling zone D4, rinsing apparatus 77 preferably comprises a plurality of sprinkling devices 78.
The latter sprinkling devices comprise, for instance, a series of showers arranged along the washing branch Q and acting one after the other on external surfaces 2a of containers 2.
Moreover, in the embodiment shown, rinsing apparatus 77 comprises also a plurality of injector assemblies 79 respectively arranged below sprinkling devices 78 and constructively identical to injector assemblies 29, 75.
Rinsing apparatus 77 is supplied by a source of rinsing medium; specifically washing machine 1 comprises a tank T4 defining the above source of rinsing medium.
Tank T4 contains the rinsing medium and fluidly communicates, in particular, with at least one sprinkling device 78 and to at least one injector assembly 79.
Preferably, rinsing zone R1 has an identical layout with respect to heat exchange zone H1. In other words, rinsing apparatus 77 is identical to cooling device 102, which is aimed to cool down containers 2 while the latter are advanced through heat exchange zone H1.
Cooling device 102 is therefore defined by a rinsing apparatus that, in particular, is supplied by a further source of rinsing medium, in order to remove cleaning agent from containers 2 prior to the acid treatment at the acid treatment zone A1.
Specifically, washing machine 1 comprises a tank T5 that is fluidly connected to the same rinsing apparatus and contains the rinsing medium, so as to define the above source of rinsing medium.
The above rinsing medium has a temperature lower than the temperature of containers 2 conveyed out from the bath 13 in second cleaning zone C2.
Conveniently, the rinsing apparatus defining cooling device 102 is further supplied with rinsing medium withdrawn in a known and not described manner from rinsing zone R1.
In addition or in replacement of such rinsing apparatus, heat exchange zone H1 may be provided with other known cooling means adapted to decrease the temperature of containers 2.
Furthermore, washing machine 1 comprises a rinsing apparatus 106 similar to rinsing apparatus 77; rinsing apparatus 106 is provided at prewash zone P1 along washing branch Q, immediately upstream of bath 11. Preferably, rinsing apparatus 106 has a reduced number of sprinkling devices and injector assemblies with respect to rinsing apparatus 77.
Finally, washing machine 1 further comprises a bath 104 holding a further basic medium and arranged along return branch R.
Bath 104 is supplied by a further basic medium source; specifically, washing machine 1 comprises a tank T6 fluidly connected to the bath 104 and containing the further basic medium, so to define the above further basic medium source.
Preferably, such further basic medium is of the same kind of that filling bath 70.
Beams 16 devoid of containers 2 (discharged at the outlet station 0) are conveyed through bath 104, so that the pH level of the same beams 16 is neutralized therein.
The operation of washing machine 1 is described in detail in the following.
Feeding system 8 advances a plurality of rows 20 of containers 2 to be washed through conveyor 103 in a parallel manner to direction F.
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.
Beams 16 of chain conveyor 4 withdraw respective rows 20 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 20 of cleaned and descaled containers 2 at outlet station 0 onto outfeed conveyor 14, and return along return branch R without containers 2.
In detail, containers 2 of each row 20 are first carried by pockets 17 through the prewash zone P1, where the same containers are preliminary rinsed through rinsing apparatus 106 and then immersed through bath 11.
Hence, the same containers 2 are conveyed also through following baths 12, 13, respectively at cleaning zones C1, C2, so that containers 2 are cleaned and deprived of any labels attached thereon.
At this point, containers 2 are advanced in an upside down configuration through the heat exchange zone H1, where rinsing medium is delivered into the corresponding inner volumes 2b and onto the external surfaces 2a to cool down the containers 2 themselves before any acid treatment.
Before containers 2 reach the acid treatment zone A1, the corresponding carrying beam 16 reaches the point W, in which sensor S2 detects the presence of the beam 16 itself.
If sensor S1 simultaneously detects the preceding beam 16 at point V, then conveyor chain 4 continues in advancing containers 2 toward acid treatment zone A1; otherwise, the operation of machine 1 is stopped to allow the maintenance of the same machine 1.
Then, the same containers 2 reach acid treatment zone A1, where the corresponding inner volumes 2b receive in separate times acid medium from each injector assembly 29, correspondingly while the containers 2 themselves are successively conveyed in an upside down configuration above axes B of ejection channels 34.
In particular, when a row 20 of containers 2 is advanced above one axis B by a corresponding beam 16, the driving element 51 thereof pushes one knob 50 parallel to stretch Q2 driving in rotation the transmission wheel member 47 about such axis B.
Accordingly, shutters 33 rotate about the axis B itself through the open angular positions thereof, such that nozzles 31 eject acid medium through openings 45 towards inlet openings 2f of containers 2.
Here, shield 40 operates to avoid sprinkles of acid medium along directions outside from the aforementioned injection directions.
At the same time, covering structures 61 protects chains 15 from possible sprinkles of acid medium within acid treatment zone A1. The same protective function is carried out by cover 65, which contains possible received sprinkles of acid medium, especially in case of pockets 17 lacking of containers 2.
Then, once containers 2 leave acid treatment zone A1, the same containers 2 are conveyed for at least a time lapse of 5 minutes and in a right side up configuration through descaling zone D1 with inner volumes 2b filled with acid medium.
Here, possible calcareous residues deposited onto the inner surfaces of containers 2 are almost totally dissolved by the stagnant acid medium in the corresponding inner volumes 2b.
In the meantime, containers 2 and in particular external surfaces of base portions 2c have been immersed into bath 70 already filled with basic medium, so that the pH levels of both the corresponding external surfaces 2a and the corresponding beam 16 are neutralized after having been possibly soaked by acid sprinkles at the acid treatment zone A1.
Containers 2 are then advanced through the dripping zone D2, where the acid medium escapes from inner volumes 2b due to gravity action and centrifugal acceleration imparted to the acid medium itself through stretch Q4.
At this point, the same containers 2 are conveyed again in an upside down configuration through acid treatment zone A2, where they further receive acid medium, such that a complete elimination of any calcareous residues occurs.
Then, containers 2 are perfectly rinsed at the rinsing zone R1, so that no acid medium remains on containers 2 discharged at outlet station O.
Finally, before returning to inlet station I, the beam 16 is conveyed through bath 104 in order to be completely neutralized.
In view of the above, the advantages of the disclosed washing machine 1 are apparent.
In particular, the presence of an elongated stretch Q1, through which containers 2 are advanced in a right side up configuration, allows the acid medium kept within the corresponding inner volumes 2b to perform its descaling function for a prolonged time with respect to prior-art solutions.
Therefore, the strength of the acid medium can be reduced without having losses of overall descaling performances of washing machine 1 with respect to such prior-art solutions.
The above acid strength reduction has a significant effect on overall costs and increases, moreover, environmental safety and reliability of washing machine 1, in view of the reduced corrosive and polluting power of the weaker acid medium used.
Such environmental safety and reliability of washing machine 1 are further increased by the several safety and/or protective components provided to acid treatment zone A1, like in particular sensor assembly SS, shield 40, covering structures 61, and cover 65.
In particular, the latter cover 65 is particularly effective in protecting the components of machine 1 in case of pockets 17 lacking of respective containers 2.
Thanks to the particular conformation of stretch Q4 in dripping zone D2, the acid medium comes easily out of containers 2 after having performed its descaling function.
Moreover, baths 70, 104, filled with a basic medium are particularly effective in preserving the integrity of beams 16, which are in any case subjected to receive sprinkles of acid medium.
This preserving function of baths 70, 104 makes it possible to avoid making beams 16 in stainless steel, which is more expensive than the typical steel used for manufacturing such beams 16.
Eventually, rinsing apparatus 102 is a particularly effective kind of cooling means for decreasing the temperature of containers 2 before the acid treatment at acid treatment zone A1.
Indeed, rinsing apparatus 102 is at least partially supplied by rinsing medium already used to supply rinsing apparatus 77. In such a manner, the energy expenditure to cool down containers 2 is reduced at minimum.
Clearly, changes may be made to the washing machine 1 as described and illustrated herein without, however, departing from the scope of protection as defined in the accompanying claims.
In particular, each nozzle 31 may be supplied by a respective acid source, instead of being supplied by acid medium flowing through ejection channel 34. Moreover, nozzles 32 may be lacking of distributors 32, so to be entirely rotating about the respective axes B.

Claims

A washing machine (1) for washing empty containers (2) comprising conveying means (4) for advancing a plurality of said containers (2) along a washing treatment path (Q) from an inlet station (I) to an outlet station (0), said containers (2) comprising:
- respective base portions (2c);

- respective end portions (2d) spaced from said base portions (2c) along corresponding axes (A) and provided with corresponding inlet openings (2f); and

- respective external surfaces (2a) delimiting corresponding inner volumes (2b), which are adapted to receive a pourable product;
characterized by further comprising:
- a first acid treatment zone (A1) arranged along said path (Q) and comprising a first acid emitting apparatus (28) configured to allow the introduction of a first acid medium into said inner volumes (2b) through said inlet openings (2f); and

- a first descaling zone (D1) arranged along a first stretch (Q1) of said path (Q) and downstream of said first acid treatment zone (A1) according to the advancing direction of said containers (2) along said path (Q);
said conveying means (4) being configured to convey, in use, said containers (2) through said first descaling zone (D1) with said inlet openings (2f) respectively above the corresponding said base portions (2c), such that at least one portion of said first acid medium received by said containers (2) at said first acid treatment zone (A1) is kept, in use, inside the corresponding said inner volumes (2b) due to gravity action.
The washing machine of claim 1, wherein said first acid emitting apparatus (28) comprises an injection assembly (29) configured to direct jets of said first acid medium toward said inner volumes (2b) through said inlet openings (2f) .
The washing machine of claim 1 or 2, further comprising:
- a second acid treatment zone (A2) arranged along said path (Q) between said first descaling zone (D1) and said outlet station (0); said second acid treatment zone (A1) comprising a second acid emitting apparatus (73) configured to deliver a second acid medium to said containers (2).

- a second descaling zone (D4) arranged along a second stretch (Q5) of said path (Q) between said second acid treatment zone (A2) and said outlet station (0).
The washing machine of claim 3, wherein said conveying means (4) are configured to convey, in use, said containers (2) through said second descaling zone (D4) with said inlet openings (2f) respectively below the corresponding said base portions (2c).
The washing machine of claim 3 or 4, wherein said first stretch (Q1), placed between said first and second acid treatment zone (A1, A2), is longer than said second stretch (Q5).
The washing machine of any one of claims from 3 to 5, wherein:
- said second acid emitting apparatus (73) comprises an ejection assembly (75) configured to direct jets of said second acid medium toward said inner volumes (2b) through said inlet openings (2f) and/or to distribute said second acid medium onto said external surfaces (2a); and/or

- said second acid treatment zone (A2) comprises an acid treatment bath (74) for holding said second acid medium, said conveying means (4) being configured to convey said containers (2) through said acid treatment bath (74), so that at least said end portions (2d) are immersed into said second acid medium.
The washing machine of any one of the foregoing claims, further comprising a bath (70) for holding a liquid treating medium and arranged downstream of said first acid treatment zone (A1) according to the advancing direction of said containers (2); said conveying means (4) being configured to convey, in use, said containers (2) through said bath (70), so that external surfaces of said base portions (2c) are immersed into said liquid treating medium.
The washing machine of claim 7, further comprising:
- an acid source (T2) connected to said bath (70) for filling said bath (70) with a third acid medium, in order to descale the external surfaces (2a) of the containers (2) advancing, in use, through said bath (70) and the conveying means (4) of the same containers (2); and/or

- a basic source (T1) connected to said bath (70) for filling said bath (70) with a basic medium, in order to neutralize the external surfaces (2a) of the containers (2) advancing, in use, through said bath (70) and the conveying means (4) of the same containers (2).
The washing machine of any one of the foregoing claims, further comprising:
- a neutralizing bath (104) for holding a basic liquid treating medium and arranged downstream of said outlet station (0), according to the advancing direction of said containers (2); said conveying means (4) comprising a plurality of members (16) movable along said path (Q) and through said neutralizing bath (104), so that said members (16) are immersed into said basic liquid treating medium; and

- a further basic source (T6) connected to said neutralizing bath (104) for filling said neutralizing bath (104) with said basic liquid treating medium, in order to neutralize said members (16) advancing, in use, through said neutralizing bath (104).
The washing machine of any one of the foregoing claims, further comprising:
- a hot washing zone (C2) arranged along said path (Q) between said inlet station (I) and said first acid treatment zone (A1); and

- a heat exchange zone (H1) arranged along said path (Q) in a position directly interposed between said hot washing zone (C2) and said first acid treatment zone (A1) and comprising cooling means configured to decrease temperature of the containers (2) conveyed out, in use, from said hot washing treatment zone (C2) towards said first acid treatment zone (A1).
The washing machine of claim 10, wherein said cooling means comprise a preliminary rinsing apparatus (102) configured to distribute a rinsing medium at a first temperature lower, in use, than a second temperature of the containers (2) conveyed out from said hot washing treatment zone (C2) into the inner volumes (2b) and/or onto the external surfaces (2a) of said containers (2) conveyed out from said hot washing treatment zone (C2);
the washing machine preferably comprising a final rinsing zone (R1) arranged along said path (Q) upstream of said outlet station (O), according to the advancing direction of said containers (2) along said path (Q); said final rinsing zone (R1) comprising a rinsing apparatus (77) configured to rinse the inner volumes (2b) and/or the external surfaces (2a) of said containers (2); said rinsing medium being withdrawn, in particular, from said final rinsing zone (R1).
The washing machine of any one of the foregoing claims, further comprising a dripping zone (D2) arranged along said path (Q) and immediately downstream of said first descaling zone (D1), according to the advancing direction of said containers (2) along said path (Q); said conveying means (4) being configured to convey said containers (2) through said dripping zone (D2) with progressive intermediate orientations between a first orientation, in which said inlet openings (2f) are vertically aligned above said base portions (2c), and a second orientation, in which said inlet openings (2f) are vertically aligned below said base portions (2c), in such a manner to allow dripping of said first acid medium from said containers (2).
The washing machine of any one of the foregoing claims, further comprising an acid-resistant cover (65) arranged in said first acid treatment zone (A1) in a fixed position above said first acid emitting apparatus (28) and adapted to locally contain sprinkles of said first acid medium; said cover (65) comprising a deflecting grate (66) and a plate roof (67) arranged over said grate (66).
The washing machine of any one of the foregoing claims, characterized in that said conveying means (4) comprise:
- a plurality of beams (16) suitable for carrying respective rows (20) of said containers (2) and extending transversally to said path (Q) between respective first and second end portions (16a, 16b);

- a conveying chain (15) extending parallel to said path (Q) and coupled to said first end portions (16a) for conveying said beams (16) along said path (Q);
said washing machine (1) further comprising a covering structure (61) arranged in said first acid treatment zone (A1) around said conveying chain (15) in the area of said first acid emitting apparatus (28) and configured to cover said conveying chain (15) from sprinkles of said first acid medium; said covering structure (61) comprising a first sheet metal (62) and a second sheet metal (63) arranged in corresponding fixed positions with respect to said path (Q), respectively above and below said conveying chain (15).
The washing machine of claim 14, wherein said first acid emitting apparatus (28) comprises:
- a plurality of nozzles (31), which are aligned along a rotation axis (B) fixed and transversal to said path (Q) and are respectively configured to eject jets of said first acid medium towards said inlet openings (2f); and

- an ejection channel (34), which extends along said rotation axis (B), is fluidly connected to a source of said first acid medium (T1), and carry said nozzles (31);
wherein said nozzles (31) comprise respective shutters (33) rotatable about said axis B, selectively connectable to said source (T1) on the basis of angular positions thereof, and each movable between:
- a plurality of respective open angular positions, in which connection with said source (T1) occurs through said ejection channel (34) and ejection of said acid medium is allowed from said ejection channel (34) along a corresponding plurality of injection directions; and

- a plurality of respective closed angular positions, in which connection with said source (T1) is interrupted and ejection of said acid medium is prevented from said ejection channel (34);
said acid emitting apparatus (28) further comprising:
- a transmission wheel member (47) coaxial to said axis (B) and rigidly rotating with said shutters (33) about said axis (B); each of said beams (16) comprising a support element (52) and a driving element (51) being fixedly mounted on said support element (52) with an actual position such to cooperate in contact with said transmission wheel member (47) and accordingly drive in rotation said transmission wheel member (47) to rotate said shutters (33) through the respective said open angular positions, such that said first acid medium is ejected along said injection directions towards said inlet openings (2f); and

- an acid-resistant shield (40) arranged about said ejection channel (34) such to cover radially said ejection channel (34) and having a plurality of through openings (45) aligned along said injection directions.
The washing machine of claim 15, further comprising:
- a sensor assembly (SS) arranged along said path (Q) between said inlet station (I) and said first acid treatment zone (A1) and configured to detect at least one physical quantity indicative of a deviation of said actual position from a nominal desired position; and

- a control unit (60) connected to said sensor assembly (SS) and configured to receive from said sensor assembly (SS) the detected physical quantity and stop operations of said washing machine (1) when said detected quantity is indicative that said actual position differs from said nominal position.
A method for washing pourable product containers (2), the method comprising the steps of:
i) advancing a plurality of containers (2) along a washing treatment path (Q) from an inlet station (I) to an outlet station (0); said containers (2) comprising:
- respective base portions (2c);

- respective end portions (2d) spaced from said base portions (2c) along corresponding axes (A) and provided with corresponding inlet openings (2f); and

- respective external surfaces (2a) delimiting corresponding inner volumes (2b) adapted to receive a pourable product;
characterized by further comprising the steps of:

ii) introducing a first acid medium into said inner volumes (2b) through said inlet openings (2f) at a first acid treatment zone (A1) arranged along said path (Q);

iii) conveying said containers (2) through a first descaling zone (D1) with said inlet openings (2f) respectively above the corresponding said base portions (2c); said first descaling zone (D1) being arranged along a first stretch (Q1) of said path (P), downstream of said first acid treatment zone (A1) according to the advancing direction of said containers (2) along said path (Q); and

iv) keeping at least one portion of said first acid medium inside said inner volumes (2) of respective said containers, due to gravity action.
The method of claim 17, further comprising the step of:
v) conveying said containers (2) through a bath (70) arranged along said path (Q) between said first acid treatment zone (A1) and said first descaling zone (D1); said bath (70) being filled with a third acid medium or a basic medium, respectively in order to descale or neutralize the external surfaces (2a) of the containers (2) advancing through said bath (70) and the conveying means (4) of the same containers (2).
The method of claim 17 or 18, further comprising the steps of:
vi) introducing into said inner volumes (2b) through said inlet openings (2f) and/or distributing onto said external surfaces (2a) a second acid medium at a second acid treatment zone (A2) arranged along said path (Q) between said first descaling zone (D1) and said outlet station (0);

vii) conveying said containers through a second descaling zone (D4) arranged along a second stretch (Q5) of said path (Q) between said second acid treatment zone (A2) and said outlet station (0), in particular with said inlet openings (2f) respectively below the corresponding said base portions (2c); and/or

viii) dripping said first acid medium from said containers (2) at a dripping zone (D2) arranged along said path (Q) and immediately downstream of said first descaling zone (D1), according to the advancing direction of said containers (2) along said path (Q), by conveying said containers (2) through said dripping zone (D2) with progressive intermediate orientations between a first orientation, in which said inlet openings (2f) are vertically aligned above said base portions (2c), and a second orientation, in which said inlet openings (2f) are vertically aligned below said base portions (2c).
The method of any one of claims from 17 to 19, further comprising the steps of:
ix) washing said containers (2) at a first temperature higher than environment temperature at a hot washing zone (C2) arranged along said path (Q) between said inlet station (I) and said first acid treatment zone (A1);

x) cooling said containers (2) at a heat exchange zone (H1) arranged along said path (Q) in a position directly interposed between said hot washing zone (C2) and said first acid treatment zone; and/or

xi) rinsing the inner volumes (2b) and/or the external surfaces (2a) of said containers (2) at a final rinsing zone (R1) arranged along said path (Q) upstream of said outlet station (0), according to the advancing direction of said containers (2) along said path (Q);
wherein, said containers (2) are cooled in particular by delivering to said containers (2) a rinsing medium withdrawn from said final rinsing zone (R1) at a second temperature lower than said first temperature.