The invention relates to a centrifuge for drying containers with a bottom and a peripheral wall standing upright from the bottom, such as crates, lids or trays.

For transport and display of food products, for instance in supermarkets, use is often made of containers, such as crates, with a bottom and a peripheral wall standing upright from the bottom. After use these crates are cleaned so that they can then be used again. Use is generally made for cleaning purposes of liquid such as water, wherein it is then necessary to dry the crates. Use is traditionally often made here of driers based on supply of heat which have a relatively high energy consumption, this being expensive and undesirable. A shift is discernible toward the alternative use of

centrifuges .

An example of a centrifuge suitable for this purpose is the centrifuge as described in the publication of the Spanish patent application with publication number ES 2284349 Al . In this centrifuge boxes such as crates are supplied successively on a conveyor belt, removed from the conveyor belt by a gripper and rotated around a rotation axis transversely of the surface of the conveyor belt in order to dry the crates. Rotation speeds of up to 1000 revolutions per minute are possible here. In order to achieve a high drying capacity it is desirable to place the crates in close

succession or even against each other in the centrifuge. This can however result in problems in balancing the crates. Imbalance can hereby occur in the centrifuge, which can result in wear and malfunctions.

Another centrifuge which is also suitable for drying crates is known from the publication of the PCT patent application with publication number WO 2015/003709 Al . In said centrifuge crates are supplied on a first conveyor belt and pressed via a lateral movement onto a holder. This holder lifts the crate to a gripper which is arranged above the holder and on which a motor is arranged in order to rotate the crate around a rotation axis parallel to the direction in which the crate has been lifted. The holder with crate is then carried to and along a second conveyor belt with which the dried crate is discharged. Released during use of said

centrifuge are large quantities of water to which the

equipment in the centrifuge is exposed. There is wear to the machine as a result and malfunctions soon occur. It is hereby not possible to achieve a higher drying capacity than about 600 crates per hour.

The object of the invention is to reduce or even prevent the above stated problems.

This object is achieved by means of a

centrifuge for drying containers with a bottom and a

peripheral wall standing upright from the bottom, such as crates, lids or trays, comprising:

- a holder comprising two guide edges arranged on either side of a bottom surface, and an inlet opening extending therebetween, which holder is rotatable around a rotation axis in the centre of the holder and transversely of the bottom surface, which holder is suitable for receiving one or more adjacently placed containers in an insertion direction via the inlet opening;

- a gripper movable parallel to the rotation axis between an opened position, in which the gripper is placed at a distance from the holder, and a closed position in which the gripper clamps in the holder a container placed in the holder; and

- a drive for rotating at least the holder around the rotation axis.

In the centrifuge according to the invention containers with a bottom and a peripheral wall standing upright from the bottom, such as crates, lids or trays, can be placed through the inlet opening in the holder so that they are supported or carried by both guide edges. When the

container, such as a crate, is carried only by the guide edges, this then has the advantage that older containers, which for instance have a bulging bottom, can also be dried with the centrifuge.

From the opened position a gripper will then be arranged, for instance under computer control, over the container in order to clamp the container in a closed position against the holder. For simple operation of the centrifuge it is preferred here to keep the inlet opening at a fixed

position during this arrangement and to have the movement take place solely through movement of the gripper.

At the moment the gripper presses the container against the holder, the holder can then be rotated, preferably together with the gripper, around the rotation axis by the drive in a centrifuging step. With most usual crates it is possible here to reach a speed of up to 1300 revolutions a minute, wherein within a time period of about 1.8 seconds a force of up to about 4.5 G can be exerted on the crate and the rotation speed is brought to a standstill, this resulting in an effective and rapid drying. In some conditions a drying capacity can hereby be achieved of up to as much as 900 crates per hour per centrifuge. The centrifuge is moreover relatively energy-efficient, particularly compared to driers based on supply of heat.

Although it is possible for one container at a time, such as a crate, to be placed in the holder, it is also possible to place a plurality of smaller containers, such as crates, simultaneously in the holder, wherein a placing adjacently of each other is preferred to for instance a stacked configuration because of the greater stability. It is however important here that each of the containers, such as crates, is supported by the guide edges.

The centrifuge is preferably arranged in a housing. In addition to the possibility of arranging one centrifuge in one housing, it is also possible to arrange a plurality of centrifuges in one housing. The centrifuges can be used simultaneously here in order to further increase capacity. With for instance two centrifuges a capacity is possible of up to as much as 1800 crates per hour. The construction is preferably modular here, so that for instance one of the centrifuges can be taken temporarily out of the housing for replacement or maintenance, while the other centrifuge ( s ) can continue to operate normally.

When a plurality of centrifuges are used adjacently of each other, it is then preferred that they are controlled centrally with a central unit which is connected to the centrifuges in a master-slave network configuration. Each of the centrifuges has its own IP address on the network and, when further centrifuges are replaced or added, this is then easily possible by changing or adding an IP address at the central unit. The continuity of use of the centrifuges is hereby ensured.

It is preferred that the bottom surface of the holder is horizontal. It is simpler with a horizontal bottom surface to insert the containers, such as crates, into the holder and to clamp them in the holder with the gripper. Rotation around a vertical rotation axis has the advantage here that released water will be released in more controlled manner .

It is also preferred to arrange the drive under the holder and enclosed by a moisture-tight housing. The construction of the centrifuge hereby becomes simpler in respect of the displaceability of the gripper and, where applicable, the presence of aligning means. By arranging a moisture-tight housing here around the holder, liquid

dislodged during the step of centrifuging the container, such as a crate, will not get into the drive, thereby further reducing the possibility of malfunctions occurring.

With strong preference the container placed in the holder is placed with the bottom downward in the holder, so that the upper side remains open.

In a preferred embodiment of the centrifuge according to the invention the centrifuge further comprises aligning means for aligning a container placed in the recess in the holder at least in the direction opposite to the direction of insertion.

It may occur that the container is not inserted into the holder in a wholly balanced position relative to the rotation axis. This can for instance occur because a container is inserted too far in the insertion direction. The centrifuge is for this reason provided with aligning means which, following placing of a container in the holder, can align the container relative to the rotation axis by pushing it back in the direction opposite to the insertion direction.

In a preferred embodiment of the centrifuge according to the invention the aligning means comprise at least one pivot arm, which pivot arm is arranged close to a first outer end for pivoting between a first position and a second position around a pivot axis running transversely of the insertion direction and parallel to the bottom surface, and which arm comprises a stop close to a second free outer end, which outer end lies close to the inlet opening, wherein in the first position the arm lies outside the holder and wherein in the second position the stop is pivoted from the first position into the holder and is preferably freely suspended .

The embodiment of the centrifuge with these aligning means is particularly suitable for aligning crates, although use with containers other than crates can also be envisaged. During insertion of a crate into the holder the arm lies outside the container in the first position so that the crate can be carried without problem into the holder without being obstructed here by the pivot arm. Once the crate has been arranged in the holder, and for instance from the moment that the gripper is moved toward the holder, it is possible to carry the pivot arm, which is possibly mounted on the gripper but which also can be separate from the gripper, for instance under computer control to the second position in which the stop lies within the upright walls against the bottom of the crate. By moving the gripper together with the pivot shaft of the pivot arms toward the holder the stop will be urged toward the side wall of the crate and pushed thereagainst , whereby the crate is aligned in a correct position. Urging of the stop takes place most easily when the pivot arm is freely suspended in the second position. Although the stop can in principle also lie against the bottom in the second position, the stop is preferably L-shaped, wherein the first leg of the L-shape lies on this side wall, and wherein the second leg of the L- shape lies against this side wall from the inner side. It is in this way also possible to apply the pivot arm in the case of relatively deep crates where a pivot arm lying against the bottom would make the pivoting movement more difficult. It is possible to provide a plurality of pivot arms, for instance two or more pivot arms arranged adjacently of each other between the guide edges. It is alternatively or additionally possible to arrange a plurality of pivot arms successively so as to bring about a correct alignment in reliable manner during drying of a plurality of crates placed adjacently of each other.

In order to achieve a further reduction in the mass to be rotated, it is advantageous, after alignment and before rotation, to return the pivot arm to the first position and not have the pivot arm co-rotate with the holder. The mass to be rotated is hereby smaller and a high rotation speed can be achieved with a reduced energy consumption.

In a further preferred embodiment of the centrifuge according to the invention the centrifuge comprises transport means for inserting at least one container via the inlet opening into the holder.

By providing driven transport means it is no longer necessary to insert containers such as crates, lids or trays manually into the holder.

In a further preferred embodiment of the centrifuge according to the invention the transport means comprise :

- a guide extending in the insertion direction; and

- a pusher element extending in a plane

transversely of the insertion direction and movable along the guide in the insertion direction between a first position, in which the pusher element is adjacent to the inlet opening of the holder, and a second position in which the pusher element is placed at a distance from the holder in the direction opposite to the insertion direction relative to the first position for the purpose of placing a container between the inlet opening of the holder and the pusher element.

Pushing of the container into the holder can for instance take place by pushing this container into the holder with a pusher element, such as a plate-like a pusher element extending transversely of the insertion direction, which engages on the container at any location from the second to the first position of the pusher element. The movement along the guide takes place here with a drive.

The guide is here an elongate arm which is possibly suspended under, but preferably above the container and along which the pusher element is guided, although it is also possible to envisage the pusher element comprising such an arm as well as the described pusher element, wherein these are movable as an entity relative to a guide.

In another preferred embodiment of the

centrifuge according to the invention the aligning means comprise a clamping element arranged on the guide and movable along the guide, which clamping element is arranged in a closed position closer to the holder in the insertion

direction than the pusher element for the purpose of clamping the container between the pusher element and the clamping element .

By also incorporating a clamping element in addition to the pusher element, and preferably parallel to the pusher element, which can clamp the container between the clamping element and the pusher element there is the

possibility of moving the clamping element and pusher element together in the direction opposite to the insertion direction in order to align a crate placed in the holder. The clamping element and the pusher element are preferably attached to each other for this purpose.

The clamping element can for instance engage here on a wall or edge of the container, this also being understood to mean a hole or recess in the container, such as for instance holes in the bottom of the container.

The clamping element is preferably adjustable between the described closed position and an opened position in which at least the pusher element can be moved from the first position in the direction of the second position without the clamping element also carrying a container placed in the holder out of the holder. The clamping element can for this purpose preferably be pivotable around an axis, such as preferably an axis parallel to the pusher element.

In yet another preferred embodiment of the centrifuge according to the invention the holder comprises an outlet opening arranged opposite the inlet opening.

By also incorporating an outlet opening the centrifuge is more efficient in use because it is not

necessary to also use the inlet opening for discharge

purposes. It is in this way easy to separate dry from wet containers, and there is thus a reduced possibility of already dried containers being made wet again by the fresh supply of wet containers.

In a further preferred embodiment of the centrifuge according to the invention the transport means lie in line with the inlet opening and the outlet opening for the purpose of inserting at least one container via the inlet opening into the holder and thereby discharging via the outlet opening a further container placed in the recess.

In this embodiment transport means such as a conveyor belt or roller conveyor are respectively arranged close to the inlet opening and the outlet opening. This conveyor belt consists of a first conveyor belt part and a second conveyor belt part. These parts serve respectively for insertion or discharge of the containers in the holder and can be moved independently of each other, but also with the same speed and direction. The conveyor belt parts are preferably arranged here such that during insertion of a container from the insertion side this container pushes the container already placed previously in the holder onto the conveyor belt part on the discharge side.

When a plurality of centrifuges are used, it is then also possible that there is a distribution system which distributes the containers for drying over the available centrifuges. When for instance two centrifuges placed

adjacently of each other are used, each provided with

respective first and second transport means, it is then advantageous that from the inlet, possibly provided with main transport means, the containers are pushed alternately onto the respective first and second transport means which

preferably surround the main transport means.

In another preferred embodiment of the

centrifuge according to the invention the gripper is provided with at least two, and preferably four clamping parts oriented toward the holder and arranged at least on either side of the rotation axis and preferably at the corner points of the gripper .

By incorporating on the gripper at a number of corner points clamping parts which can be placed round the corner points of a container such as a crate placed in the holder, the container, such as a crate, is clamped more firmly in the holder. The number of four clamping parts is preferred here because the clamping hereby takes place from all sides and is thereby further enhanced.

In a further preferred embodiment of the centrifuge according to the invention the centrifuge further comprises :

- a floor part placed at an incline between the drive and the holder; and - a drain placed close to the lowest point of the incline for draining water.

The liquid released during the centrifuging step will in this way flow over the incline in the direction of the drain, where it can be further discharged. The amount of liquid which is dispersed through the apparatus is in this way reduced. The incline preferably runs transversely here of the insertion direction of the holder.

The floor part can here form part of an

optional moisture-tight housing which encloses the drive.

In a further preferred embodiment of the centrifuge according to the invention the centrifuge further comprises an air outlet channel, wherein the entrance of the air outlet channel debouches close to the highest point of the incline.

Incorporating an air outlet channel facilitates the discharge of air, whereby the drying will take place more quickly. In order to further accelerate this drying a

discharge pump can also be received in the air outlet channel in order to increase the driving force.

When the entrance to this channel debouches close to the highest point of the incline, water and air are then separated in the most effective manner.

In yet another preferred embodiment of the centrifuge according to the invention the centrifuge further comprises an air inlet channel, the exit of which debouches on the upper side of the holder.

Drying is further enhanced by also providing an air inlet channel. It is here also possible to incorporate a feed pump in the channel in order to increase the driving force. Air from the air outlet channel is possibly

recirculated back to the air inlet channel.

The air supplied by the air inlet channel is preferably (pre) heated here using the heat released during braking of a drive, such as in particular the drive for the rotation around the rotation axis, following a centrifuging step, preferably in a heat exchanger device suitable for the purpose.

Through placing above the holder an efficient drying takes place. It has been found that excellent drying results are obtained particularly in the case of a combination of a crate placed with the bottom downward in the holder, with an air outlet channel debouching close to the highest point of the incline and an air inlet channel with an exit which debouches on the upper side of the holder, and with strong preference close to the rotation axis. This creates an airflow from the air inlet channel to the centre of the container which flows from here in the direction of the peripheral edge of the container and subsequently over the peripheral edge in the direction of the air outlet channel. The liquid is

dislodged from the container by the centrifuging and the dislodged liquid is discharged effectively by the airflow. Such an airflow has as stated been found to be extremely effective in drying containers.

In a further preferred embodiment of the centrifuge according to the invention the centrifuge also comprises centering means for centering the gripper in a starting rotation position relative to the rotation axis.

It is possible as a result of the rotation that the gripper does not return fully to the starting position in which it is in line with the holder. In order to return the gripper to this position it is advantageous to provide

centering means which return the gripper to this starting rotation position, for instance in the form of an actuator arranged against and preferably round a centering slide.

In another preferred embodiment of the centrifuge according to the invention the centrifuge is provided with a cover adjustable between a first position, in which it is arranged at a distance from the holder, and a second position in which it encloses the side parts and upper part of the holder.

In order to further reduce the effect of water on the equipment placed around the centrifuge, and thereby further reduce the possibility of wear or malfunction, it is preferred to provide a cover which in any case encloses the holder during the centrifuging step. This cover can for this purpose be moved for instance simultaneously with the gripper over the holder, but can also be moved separately.

The cover moreover ensures that no crates can enter the holder from outside the cover at the moment that the centrifuging step takes place, this reducing the risk of j amming .

When there is an air inlet channel, it is then advantageous for this air supply channel to extend through the cover so that direct supply of air is guaranteed through the cover to the holder.

The cover is preferably moved here between the first position and the second by a number of, for instance two, cylinders. It is advantageous here for the cylinder to use a high pressure (for instance 6 bar) when carrying the cylinder from the second position to the first in order to open the cover quickly, while a low pressure (for instance about 3 bar) is used during the movement from the first position to the second. Through the use of a low pressure the cover closes more slowly than it opens, which has the

advantage that detection of crates which are too high or too low is possible should these come into contact with the cover. The cylinder is set to the expected height of the crate. In the case of crates with a differing crate height the cover overruns (in the case of a crate which is too low) or clamps the crate prematurely (in the case of a crate which is too high) . This closure with cylinders is an alternative to a movement of the cover with for instance a servomotor.

The invention further relates to a combination of a centrifuge according to the invention and at least one container with a bottom and a peripheral wall standing upright from the bottom, such as a crate, lid or tray, placed in the holder, wherein during movement of the gripper from an opened position to the closed position, when the arm is or has been carried into the second position, the stop is pressed against an inner wall of the container placed close to the inlet opening .

Figure 1 is a perspective view of a centrifuge according to the invention with the cover in the second position .

Figure 2 shows a cross-section of the

centrifuge according to figure 1 with the cover in the second position, the gripper in the closed position and the pivot arm in the first position.

Figure 3 shows a cross section of the

centrifuge according to figure 1 with the gripper in the opened position.

Figure 4 shows a cross-section of the

centrifuge according to figure 1 with the gripper in the closed position.

Figure 5 is a top view of the centrifuge according to figure 1.

Figures 6A to 6C show schematically the

operation of the pivot arm.

Figure 7 shows a schematic view of the

operation of a setup with two centrifuges according to the invention . Figure 8 is a perspective view of the centering means .

Figure 9 shows a further embodiment of a centrifuge according to the invention.

Figure 10 is a top view of a part of the centrifuge according to figure 9.

Figures 11A to 11D are perspective views of the process of inserting a container into a holder of a centrifuge according to the invention.

Figure 12 shows schematically an airflow in an embodiment of a centrifuge according to the invention.

A centrifuge 1 according to the invention is shown in figures 1 to 5. Centrifuge 1 comprises a housing 2. Arranged in housing 2 is a cover 3, shown in the second position in which it is closed. Crates can be inserted into centrifuge 1 from an inlet 4. After use it is possible to discharge the crates via the outlet 5 located opposite inlet 4.

Centrifuge 1 is shown in more detail in figure 2. This figure shows that under cover 3 there is arranged a holder 6, one guide edge 7 of which is shown. In this holder 6 two crates 8, 9 are received adjacently of each other, each with a bottom 8a, 9a and upright walls 8b, 9b. The two bottoms 8a and 9a are parallel to the base plane of holder 6. Holder 6 is rotatable around an upright rotation axis 10 in the centre of the holder by a drive 11 arranged under holder 6.

Arranged over holder 6 is a gripper 12 which in the shown closed position clamps crates 8, 9 in holder 6. Also shown are aligning means 13 arranged over holder 6 and

comprising four pivot arms which are arranged close to the corner points of holder 6 and of which two identical pivot arms 14, 15 are shown in figure 2. The movement of pivot arms 14, 15 can, as shown here, be provided with a coupling means 16 for a synchronous movement of the two pivot arms. The pivot arms (described here with reference to pivot arm 14) are arranged for pivoting with a first outer end around a pivot axis 17, and comprise close to a second outer end a stop 18 for aligning crates 8, 9 in the direction opposite to

insertion direction 4.

It will further be apparent from figure 2 that cover 3 is constructed from a fixed upper part 19 and a movable side shell 20 which in the closed position lies around the periphery of upper part 19 on a flange 21 of upper part 19. An air inlet channel 22 is arranged through cover 3.

Arranged between drive 11 and holder 6 is a floor part 23 placed at an incline with which released liquid can be

collected in a drain (not shown) close to the lowest point of floor part 23. An air outlet channel 24 is arranged close to the highest point of floor part 23. Further shown is the moisture-tight housing 25 for drive 11 which transposes into floor part 23.

Figures 3 and 4 also show, in addition to first guide edge 7, the opposite guide edge 26 of the centrifuge. Furthermore arranged on the gripper at the corner points are four clamping parts, of which two clamping parts 27, 28 are shown in figures 3 and 4. Also shown is the drain 29 placed close to the lowest point of floor part 23.

Figures 6A to 6C show in more detail the operation of pivot arms 14, 15 and the identical pivot arms 30, 31 not shown in the view of figure 2. Shown in figure 6A is the starting position in which pivot arms 14, 15, 30, 31 and gripper 12 are placed at a distance from crates 8, 9. In a subsequent step pivot arms 14, 15, 30, 31 are pivoted to the second position shown in figure 6B . Stop 18 is L-shaped and comprises a first leg 32 which lies on side wall 8b and a second leg 33 which lies from the interior of crate 8 against this side wall 8b. Arranged for the other pivot arms 14, 15 are similar stops which operate in similar manner. At the moment that gripper 12 and pivot arms 14, 15, 30, 31 arranged thereabove are moved transversely of bottoms 8a and 9a toward the crates the stop 18 will carry crate 8 along in the

direction opposite to insertion direction 4. Pivot arms 14, 15, 30, 31 can subsequently be lifted again to the first position shown in figure 6C, after which the setup is ready to begin a centrifuging step.

Figure 7 shows a setup 40 of two centrifuges

41, 42 placed adjacently of each other. The housing of centrifuges 41, 42 is L-shaped so that both centrifuges can be easily placed sliding one into the other. Supplied on a main conveyor belt 43 are crates 44, 45, 46 which are placed adjacently of each other and which are distributed alternately over first and second side transport means 47, 48 by a

distributing arm (not shown) . For drying purposes they are inserted on the respective parts 47a and 48a into centrifuges 41, 42. Following drying they are discharged on parts 47b and 48b and set onto the second main conveyor belt 49 for further transport .

Figure 8 shows a part of gripper 12. Clamping parts 50, 51 are arranged at the corner points. Gripper 12 is provided with a centering slide 52. Actuator 53 is provided with two arms 54, 55 which can be placed round centering slide 52 in order to return centering slide 52, and thereby gripper 12, to a starting rotation position.

Shown in figure 9 is a centrifuge setup 60 comprising a frame 61 with an inlet opening 62, an outlet opening 63 and a centrifuge 64 according to the invention placed therein.

Figure 10 is a top view of the insertion side of centrifuge setup 60 wherein centrifuge 64 is omitted. Containers such as crates, lids or trays are inserted through inlet opening 62 and come to lie on plate 65. Arranged around this plate, and in this case under plate 65, is a transport means for introducing the container in insertion direction 66 into centrifuge 64, this being further elucidated with

reference to figures 11A to 11D.

Figures 11A to 11D show an embodiment of transport means 70 which can be used to insert a container 71 in insertion direction 66 into a holder 72 with guide edges 73, 74 and an inlet opening 75 between these edges 73, 74. Container 71 is provided in this case with holes 76 on the upper side. The transport means comprise a guide 77 having arranged thereon a pusher plate 78, extending transversely of the insertion direction 66, and clamping elements 79a, b, which clamping elements 79a, b are pivotable around axis 80.

In the starting situation shown in figure 11B container 71, for instance because it has been pushed in laterally as shown in figure 11A, lies against pusher plate 78. Clamping elements 79a, b are in the opened position.

Clamping elements 79a, b then pivot to the closed position

(figure 11C) and container 71 is pushed in insertion direction 66 into holder 74 using pusher plate 78, and thereby also with clamping elements 79a, b attached thereto, until it lies in holder 74 (figure 11D) . In order to align container 71 correctly in holder 74 the clamping elements 79a, b can if necessary be retracted in the direction opposite to insertion direction 66 together with pusher plate 78 attached thereto. At the moment container 71 is correctly aligned in holder 74, clamping elements 79a, b are then pivoted to the opened position and clamping elements 79a, b and pusher plate 78 are retracted (in the direction opposite to insertion direction 66), wherein container 71 in that case remains in holder 74.

Figure 12 shows schematically a centrifuge with a container 90 which is placed therein and which is placed with bottom 91 downward and with peripheral wall 92 oriented upward on a holder (not shown) . From air supply openings 93 arranged close to rotation axis 94 hot air is supplied which flows in the direction of container 90, then in the direction of and over peripheral wall 92 and in the direction of air outlet openings 95.