EP1105034B1

EP1105034B1 - Method for the separation of granules from a cleaning fluid mixture for cleaning objects placed in a warewasher and warewashingmachine with a granules separator

Info

Publication number: EP1105034B1
Application number: EP99925507A
Authority: EP
Inventors: Bertil Rogmark
Original assignee: NATIONAL CONVEYOR Corp
Current assignee: NATIONAL CONVEYOR Corp
Priority date: 1998-05-26
Filing date: 1999-04-13
Publication date: 2003-07-02
Anticipated expiration: 2019-04-13
Also published as: DE69909296D1; WO1999060914A1; JP2002516129A; AU4176999A; CN1303246A; SE9801836L; SE9801836D0; CN1143655C; DE69909296T2; SE521116C2; EP1105034A1

Abstract

A method and a device for separating granules from a return flow of a cleaning fluid being a mixture of a liquid and granules having a higher density than the liquid, the return flow appearing through a treatment chamber (1) and a tank (6) below the treatment chamber (1) in a washing machine having at least one granule collector (11), a primary pumping device (7) pumping the mixture through a first discharge pipe (5) and through first nozzles (4) against goods (2), and a secondary pumping device (18) pumping liquid only against the goods (2). The granules are collected in a lower part of the tank (6) in a self-contained detachable granule collector (11). The mixture from within the self-contained detachable granule collector (11) and the liquid only is obtained from a position in the tank (6) outside the self-contained detachable granule colletor (11). The liquid pumped by the secondary pumping device (18) is directed through a second discharge pipe (9) and second nozzles (10), at least the second nozzles (10) being designed for a lower flow than the first nozzles (4).

Description

TECHNICAL FIELD

This invention relates to a method and a device in a cleaning machine to clean goods using as a cleaning fluid either a liquid mixed with granules or the liquid itself only. The granules have a density higher than that of the liquid. The liquid can be any liquid with cleaning properties but usually consist of water with various additives to enhance and improve the cleaning properties. Goods in this context refer to the soiled objects that are to be cleaned. Goods could be any objects that require to be cleaned but usually refers to pots, pans and other kitchen and cooking utensils that are difficult to clean with traditional cleaning machines.

BACKGROUND ART

The cleaning fluid is pumped by a primary pumping device in a primary flow from a tank and discharged under pressure against the goods disposed in a treatment chamber. If the goods are heavily soiled the cleaning fluid consists of a liquid mixed with granules. Less or normally soiled goods can be cleaned with liquid only. After having been discharged against the goods the cleaning fluid is allowed to flow back as a return flow into the tank from which it is re-circulated for as long as it is desired that the cleaning cycle should last. At the end of the cleaning operation it is necessary to flush the goods with a liquid without any granules in order to remove the granules from the goods. This is done by means of a secondary pumping device which pumps liquid only in a secondary flow.
Cleaning machines functioning according to the principle described above exist, using various methods to separate the granules from the cleaning fluid. Such cleaning machines may have a partition of the tank which is kept free of granules by means of a sieve or deflector.
An example of such a cleaning machine is disclosed in WO-A-84/03616 together with a corresponding method. Liquid only is drawn from a level above the surface of granules. A mixture of liquid and granules is drawn from the bottom of a tank in the cleaning machine.
Another solution for the separation of granules from liquid is disclosed in EP-A-0016895 directed to a cleaning machine. The machine includes a cassette providing a magazine for the granules. The cassette is connected to the suction side of a pump through a valve-controlled opening. Through the opening either a mixture of liquid and granules or liquid only can be sucked.
While these machines operate satisfactorily, they have one weakness in common insofar that they are difficult to clean at the end of a working shift. This is due to the fact that the granules remain in the tank in or around the separation device which makes access to cleaning the tank bottom difficult. In view of the increasing demands from users for improved hygienic properties of cleaning machines, some manufacturers have addressed this problem by supplying additional granule collectors in the treatment chamber instead of goods to enable users to remove the granules from the machine. Most machines, however, due to their design, are difficult to clean internally.
Existing machines utilise the same discharge pipe and nozzles for the primary flow and for the secondary flow. One drawback is that a mechanical check valve device is required where the discharge pipes from the two pumps join. The secondary pumping device also has to be larger than otherwise necessary to make the secondary flow powerful enough to flush the granules off the good.
Finally there is a risk of damage to or blockage of the primary pumping device if the liquid being sucked into the pump is too rich in granules when the pump starts.

DISCLOSURE OF INVENTION

It is an object of the present invention to overcome the drawbacks of prior art machines and to provide a method and a device for the separation of granules from the cleaning fluid. A further object of the invention is to provide through the design of said apparatus, a simple method for removing the collected granules from the machine. The objects are achieved by the method and washing machine defined in inpendent claims 1 and 7.
Still further, this invention provides a separate secondary discharge pipe with nozzles designed specifically for the secondary flow, thus making it possible to reduce the size of the secondary pumping device which in turn lowers the manufacturing costs.
This invention addresses these problems by offering a simple method of combining the separation and the collection of the granules, leaving the tank interior accessible for cleaning and also facilitating the cleaning of the granules themselves as well as the measuring of the amount of granules in the machine to see if more granules are needed.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described in more detail with reference to the accompanying drawings, in which

FIG 1: is a sectional view of a first embodiment of a device according to the invention, the device including an upwards orientated outlet for cleaning fluid with granules,
FIG 2: is a perspective view of the device according to FIG 1,
FIG 3: is a sectional view of a second embodiment of a device according to the invention, the device including a downwards orientated outlet for cleaning fluid with granules,
FIG 4: is a perspective view of the device according to FIG 3,
FIG 5: is a sectional view of a third embodiment showing an alternative way of pumping the outgoing secondary granule-free flow from the tank with the same type of primary flow as in FIG 3, and
FIG 6: is a perspective view of the device according to FIG 5.

DETAILED DESCRIPTION

The cleaning machine according to FIG 1 and FIG 2 comprises a treatment chamber 1 in which goods 2 are placed in a washing rack 3. First nozzles 4 in a first discharge pipe 5 are provided through which the cleaning agent is discharged under pressure against the goods. Below the treatment chamber 1 there is a tank 6 into which the cleaning agent is allowed to flow in a return flow from the treatment chamber 1. From the tank 6, the primary flow of cleaning agent mixed with granules is taken by a primary pumping device 7 which discharges the cleaning agent into a first conduit 20 leading to the first discharge pipe 5. From the tank also the secondary flow of cleaning agent without granules is taken by a secondary pumping device 18 and discharged through a second conduit 8 to a second discharge pipe 9 with a set of second nozzles 10.
This secondary flow can be much smaller than the primary flow since it is not intended to clean the goods with granule mixed liquid but to flush the remaining granules off the goods, and the discharge pipe 9 with its second nozzles 10 is designed accordingly. However, less heavily soiled goods can be cleaned by the secondary flow with liquid only through the second nozzles 10. By starting either of the two pumping devices, it is possible to control the outgoing flow to be mixed, or not mixed with granules.
In the bottom of the tank 6 there is placed a granule collector 11 in such a way that a space 16 is created below the collector. The granule collector 11 is perforated with holes small enough to catch granules and let liquid through. The collector 11 can be lifted out of the machine together with the collected granules thus leaving the interior of the tank 6 free from granules and easily accessible for cleaning purposes.
In the embodiment shown in FIG 1 the fluid in the tank is pumped off in the following way. A lower conduit 12 extends through a hole 17 in the bottom of the collector 11 and leads to the primary pumping device 7. To prevent granules from entering this conduit when the primary pumping device 7 is not in operation and from falling out of the collector 11 when the collector 11 is lifted out of the machine, there is a deflector 13 positioned above the hole in the collector bottom. Preferably, the deflector 13 is connected to the collector at some distance above the bottom of the collector 11. In a preferred embodiment the deflector 13 is integral with the collector 11.
When the cleaning operation is finished, the primary pumping device 7 stops and the secondary pumping device 18 starts pumping liquid from the space 16 below the collector through a liquid receiving conduit 21. Since the collector is perforated and will not let granules through, the resulting outgoing flow will consist of liquid only.
In the embodiment shown in FIG 3 and FIG 4 a modification is made in the bottom of the collector 11. Above the bottom of the collector 11 there is a suction conduit 14 leading to the primary pumping device 7. The direction of the primary flow from the collector is upwards against the force of gravity which prevents granules from entering the primary pumping device 7 when it is not in operation. The working of the secondary flow is the same as described above with reference to FIG 1.
In a further embodiment according to FIG 5 the secondary flow of cleaning agent without granules is taken by the secondary pumping device through a large sieve 15 above the collector 11. The sieve 15 can be positioned in such a way that it does not impede the removal of the collector. The working of the primary flow is the same as described above with reference to FIG 3.
In order to make it possible to remove the collector 11 containing the collected granules in the embodiments according to FIG 3 to FIG 5, the suction conduit 14 should be removable or hinged to swing out of the way. A coupling or joint 19 is then provided between a fixed section of the suction conduit 14 and a movable section.
It is also possible to combine the embodiment shown in FIG 1 with the embodiment shown in FIG 5. In such an embodiment liquid is sucked from a position above the granule collector 11, preferably through a sieve 15, while the granule mixture is sucked through the hole 17 in the bottom of the granule collector 11.

Claims

Method for separating granules from a return flow of a cleaning fluid which is a mixture of a liquid and granules having a higher density than the liquid, the method including the steps of directing a return flow through a soiled objects treatment chamber (1) and a tank (6) disposed below the treatment chamber (1) of said washing machine and pumping the mixture by means of a primary pumping device (7) through a first discharge pipe (5) and through a first set of nozzles (4) against soiled objects (2) arranged in the treatment chamber (1), characterised

by obtaining the mixture for pumping via the primary pumping device (7) from within a granule collector (11) and obtaining only liquid for pumping against the soiled objects from a position in the tank (6) outside the granule collector (11),

by pumping only liquid against the soiled objects (2) by a secondary pumping device (18),

by collecting the granules in the granule collector (11) disposed a lower part of the tank (6), said collector being self-contained and detachable from the tank (6), and

by directing the liquid pumped by the secondary pumping device (18) through a second discharge pipe (9) and a second set of nozzles (10) designed to supply fluid at a lower flow rate than does the first set of nozzles (4).
Method according to claim 1, wherein the mixture is sucked through a hole (17) in the bottom of the granule collector (11).
Method according to claim 2, wherein granules are prevented from falling vertically directly into said hole (17).
Method according to claim 1, wherein the mixture is sucked against the force of gravity from a position within the granule collector (11).
Method according to claim 1, wherein liquid is sucked from a space (16) below the granule collector (11).
Method according to claim 1, wherein liquid is sucked from a position above the granule collector (11).
A washing machine comprising a device for separating granules from a return flow of a cleaning fluid, wherein said fluid is a mixture of a liquid and granules having a higher density than the liquid, the return flow passing through a soiled objects treatment chamber (1) and a tank (6) disposed below the treatment chamber (1), the tank (6) being equipped with at least one granule collector (11) and a primary pumping device (7) pumping the cleaning fluid mixture through a first discharge pipe (5) and through a first set of nozzles (4) against the soiled objects (2) arranged in the treatment chamber (1), wherein a primary pumping device mixture supplying conduit (12; 14) having a mouth extending into the granule collector (11) and thus into the tank (6) and a liquid receiving conduit (21) is provided to obtain liquid from a position in the tank (6) exterior to the granule collector (11), characterised in

that a secondary pumping device (18) is connected to the liquid receiving conduit (21) for receiving liquid and pumping only liquid against the soiled objects (2),

in that said granule collector (11) being a self-contained detachable collector is provided in a lower part of the tank (6) and,

in that a second discharge pipe (9) and a second set of nozzles (10) are connected to the secondary pumping device (18) for discharging only liquid to the soiled objects (2), said second set of nozzles (10) being adapted for supplying fluid at a lower flow rate than said first set of nozzles (4).
A washing machine according to claim 7, wherein a hole (17) is formed in the bottom of the granule collector (11) and wherein the mixture receiving conduit (12) opens through said hole (17).
A washing machine according to claim 8, wherein the granule collector (11) is provided with a deflector (13) for preventing granules from falling vertically directly into said hole (17).
A washing machine according to claim 7, wherein the mixture receiving conduit (14) is formed as a suction conduit opening down into the granule collector (11) to suck the mixture against the force of gravity.
A washing machine according to claim 7, wherein the liquid receiving conduit (21) is arranged with an opening in a space (16) below the granule collector (11).
A washing machine according to claim 7, wherein the liquid receiving conduit (21) is arranged with an opening in a position above the granule collector (11).
A washing machine according to claim 12, wherein the liquid receiving conduit (21) is provided with a sieve (15) for preventing granules from entering into the liquid receiving conduit (21).