CHEMICAL DOSING SYSTEM

Abstract

Disclosed herein is a chemical dosing system for an appliance, such as a laundry washing machine or a dishwashing machine, having a water inlet, the system comprising a meter for determining the volume of water supplied to the appliance, a pump for dispensing a quantity of a chemical to the appliance and a control unit arranged to receive a signal from the meter and to cause to be dispensed to the appliance a volume of chemical that is proportional to the quantity of water supplied to the appliance. The disclosed system may enable a correct quantity of chemical to be automatically dispensed to many types of appliance, without the need to know anything about the appliance, or to derive electrical signal from the appliance.

Claims

1. An external chemical dosing apparatus arranged to be located external to an appliance having a water inlet, the apparatus comprising: a meter arranged to be located external to the appliance and arranged to determine a volume of water supplied, or a rate at which water is being supplied, to the appliance via the water inlet; a pump or valve arranged to be located external to the appliance for dispensing a volume of chemical to the appliance; and a control unit arranged to be located external to the appliance, the control unit being arranged to receive a signal from the meter and to determine from said signal a stage in a cycle the appliance is at and to control the pump or valve in dependence thereon, to cause the pump or valve to dispense a chemical to the appliance appropriate for the stage of the cycle the appliance is at and to control the quantity of chemical dispensed, in dependence on the volume of water supplied via the water inlet to the appliance at that stage of the cycle, wherein the control unit is arranged to determine the stage of a cycle an appliance is at by determining the volume of water drawn through the meter for that particular stage of the cycle, during one continuous intake of water, or within a predetermined period.

2. A chemical dosing apparatus as claimed in claim 1, wherein the control unit is arranged to determine the stage of a cycle an appliance is at if the volume of water drawn through the meter during one continuous intake of water, or within a predetermined period, exceeds a predetermined volume, is less than a predetermined volume or is in a predetermined range.

3. A chemical dosing apparatus as claimed in claim 1, wherein all water supplied to the appliance is supplied through the water inlet, and wherein the control unit is arranged to monitor, via the meter, all quantities of water supplied to the water inlet.

4. A chemical dosing apparatus as claimed in claim 1, arranged to be used with a dishwashing machine, and further comprising a chemical detergent, a separate chemical rinse aid, and pumps or valves arranged to dispense quantities of the detergent and of the rinse aid, in proportion to the volume of water supplied or being supplied to the appliance at a particular stage, as determined by the meter.

5. A chemical dosing apparatus as claimed in claim 4, wherein the control unit is arranged: to cause rinse aid, or rinse aid and detergent, to be dispensed to said dishwashing machine in proportion to a quantity of water supplied through the water inlet if the quantity of water supplied at a particular stage does not exceed a predetermined quantity or is within a first predetermined range; and to cause detergent only to be added to said dishwashing machine in proportion to the quantity of water supplied at a particular stage if the quantity of water supplied at a particular stage exceeds a predetermined quantity or is within a second predetermined range, greater than the first predetermined range.

6. A chemical dosing apparatus as claimed in claim 4, wherein the control unit is arranged such that if the quantity of water supplied through the water inlet at a particular stage exceeds a predetermined value then no chemicals are dispensed.

7. A chemical dosing apparatus as claimed in claim 4, arranged to dispense detergent directly to a first chemical inlet of a dishwashing machine connected to a wash tank of said dishwashing machine and to dispense rinse aid directly to a second chemical inlet of said dishwashing machine connected to a boiler of said dishwashing machine, which chemical inlets are separate to the water inlet of said dishwashing machine.

8. A chemical dosing system comprising an external chemical dosing apparatus as claimed in claim 1 and the appliance embodied in a dishwashing machine.

9. A chemical dosing system as claimed in claim 8, wherein the dishwashing machine comprises: a boiler; a wash tank; a chemical inlet directly into the boiler through which rinse aid is dispensed into the boiler by the control unit after the boiler has been filled with water; a wash tank; a chemical inlet into the wash tank through which detergent is dispensed by the controller directly into the wash tank, and a single water inlet, wherein the control unit is arranged to monitor via the meter all quantities of water supplied to the inlet and to determine the stage the dishwashing machine is at from the quantity of water drawn through the inlet for any one stage of a cycle and to dispense an appropriate quantity of rinse aid or detergent for that stage of the cycle.

10. A chemical dosing system as claimed in claim 9, wherein the control unit is arranged to cause rinse aid and detergent to be dispensed to the dishwashing machine in proportion to the quantity of water supplied if the quantity of water supplied at a particular stage does not exceed a predetermined quantity, or is within a first predetermined range, and to cause detergent only to be added to the dishwashing machine in proportion to the quantity of water supplied at a particular stage if the quantity of water supplied at a particular stage exceeds a predetermined quantity, or is within a second predetermined range greater than the first predetermined range.

11. A chemical dosing system as claimed in claim 10, wherein the dishwashing machine further comprises a water softening unit which is arranged to draw a predetermined quantity of water, or arranged to draw water for a predetermined period of time, during a purge stage of a water softening cycle, which quantity of water exceeds a predetermined quantity or which period exceeds a predetermined period of time and wherein the control unit is arranged not to dispense either rinse aid or detergent when said predetermined quantity or predetermined period of time associated with the purge stage is exceeded.

12. A chemical dosing apparatus as claimed in claim 1, wherein the control unit is arranged to operate without any electrical or other control signal passing either way between the appliance and the control unit.

13. A chemical dosing apparatus as claimed in claim 1, further comprising a water hardness sensor for detecting a parameter related to hardness of water being supplied to the water inlet, the control unit being arranged to receive a signal from the water hardness sensor and modify the quantity of chemical dispensed to the appliance in dependence on the detected parameter.

14. A chemical dosing apparatus as claimed in claim 1, wherein the control unit has an “Energy Saving” switch which, when activated, results in the control unit causing a greater proportion of chemical to be dispensed to the appliance.

15. A chemical dosing apparatus as claimed in claim 1, wherein the control unit has a “Water Saving” switch which, when activated, results in the control unit altering the proportion of chemical to be dispensed.

16. A chemical dosing apparatus as claimed in claim 1, further comprising a reader arranged to read information from a chemical container relating to at least one of a type or concentration of the chemical within the chemical container, wherein the control unit is arranged to control the quantity of chemical dispensed to the appliance in dependence on a signal obtained from the reader.

17. A chemical dosing apparatus as claimed in claim 16, wherein the reader is arranged to read a radio frequency identification device (RFID) on, or in, the chemical container.

18. A chemical dosing apparatus as claimed in claim 1, further comprising a sensor arranged to identify a chemical and/or concentration of a chemical by analysis of the chemical or an identifier in the chemical, wherein the control unit is arranged to control the quantity of chemical dispensed to the appliance in dependence on a signal obtained from the sensor.

19. A chemical dosing apparatus as claimed in claim 1, wherein the control unit monitors the number of wash cycles performed, or a period of time, and after a predetermined number of cycles, or period of time, determines that a maintenance cycle is to be performed and advises the operator or causes the appliance to perform such a cycle, wherein the control unit is then arranged to cause to be dispensed to said appliance during that maintenance cycle a quantity of a different chemical which is specifically associated with the maintenance cycle.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0070] Two embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0071] FIG. 1 schematically illustrates a dosing system in accordance with the present invention applied to a commercial dish washer; and

[0072] FIG. 2 illustrates a dosing system in accordance with the present invention applied to a commercial laundry washing machine.

DETAILED DESCRIPTION

[0073] Referring first to FIG. 1, a chemical dosing system in accordance with the present invention is indicated generally as 1 and, in the illustrated embodiment, this comprises a commercial dishwashing machine, indicated generally as 2, comprising a wash cabinet 3, a boiler 4, a wash pump 5 and a water softener 54.

[0074] The cabinet 3, boiler 4, wash pump 5 and water softener 54 will normally be housed in a common housing be housed within a common housing, not shown, with the cabinet 3, or they may be located separately from the cabinet 3. The boiler 4 receives clean water from a water supply 6 and heats this water which is then used to rinse the contents of the dishwashing machine via rinse arms 8 and 9.

[0075] The wash pump 5 is arranged to receive used wash water from a wash tank 10, formed by the bottom of the cabinet 3 and recirculates this via wash arms 11 and 12.

[0076] Although not shown, two drains are provided to wash tank 10, the first being in the form of an overflow, which maintains used wash water within the tank at a predetermined level and a drain by which the wash tank 10 can be drained periodically, for example at the end of the day. Additionally, a heating element, not shown, may be provided in the wash tank to heat the wash water, particularly if the machine has been inactive for a period of time. The cabinet 3 also has a detergent inlet, represented by arrow 13, by which detergent can be injected into the cabinet 3 in order to add detergent to the wash tank 10.

[0077] All the components described above of the dishwashing machine 2 are typical of most commercial dishwashing machines. Such a dishwashing machine 2 will additionally comprise control circuitry, not shown, for controlling the boiler 4, wash pump 5, a valve (not shown) for letting water from the water supply 6 into the boiler 4, for controlling any additional heating element within the wash tank 10, for controlling the water softener 54 and for controlling a final discharge from the machine, which may either be via a separate drain, not shown, or by a valve, not shown, diverting water from the wash pump 5 to the drain.

[0078] In use, the dishwashing machine 2 will be controlled in the normal manner by its own control circuitry, with approximately 10 litres of water being drawn in from the water supply 5 through the water softener 54 and into the wash tank 10, as indicated by the arrow 55, in order to provide an initial fill of the wash tank 10 for its first use, for example at the start of each day. The level of the wash tank may be monitored during this period by a sensor, not shown, in the dishwashing machine 2, to determine when this initial fill is complete.

[0079] A dose of detergent is then added, as explained below, at an inlet represented by the arrow 13, which dose is appropriate for a wash to be performed and the dishwashing machine can then be loaded with a first load of dirty dishes. The dishwashing machine is then activated and the wash pump 5 is energised for a period, which may typically be 90 seconds, with the water in the wash tank 10 being recycled by the wash pump 4 through the wash arms 11 and 12 in order to clean the dishes. The boiler 4 will already be filled with a quantity of water and rinse aid from the previous day, and this is heated from the time the machine is first switched on.

[0080] At the end of the wash stage of the cycle, a rinse stage commences, where heated water and rinse aid is then pumped from the boiler 4, by an additional pump (not shown), through the rinse arms 8 and 9 to rinse the dishes within the dishwashing machine 2. The additional water, in this example 2.5 litres, displaces water from the wash tank 10 to the drain.

[0081] Once the dishwashing machine 2 has been emptied, of the now clean dishes, and loaded with a second load of dirty dishes, the cycle is repeated, but this time there is no requirement to initially fill the wash tank 10. However the depleted detergent in the wash tank 10 is topped up and the boiler 4 is refilled, with both water obtained from the water supply 6 via the water softener 54 and with rinse aid received directly at a rinse aid inlet into the boiler 4, as represented by the arrow 14. The next wash stage then commences, with the water and rinse aid in the boiler 4 being heated during this process.

[0082] As previously mentioned, all of the components and operation described above are fairly standard to many commercial dishwashing machines.

[0083] In the chemical dosing system of FIG. 1, the dishwashing machine 2 receives rinse aid chemical at an inlet, as represented by the arrow 14, connected directly to an inlet on the boiler 4. Similarly the dishwashing machine 2 receives detergent along a line 15 connected to the detergent inlet, represented by arrow 13. On many machines, an inlet on the boiler 4 for rinse aid is provided as standard, but where such an inlet is not provided on the boiler 4, or at any other location on the dishwashing machine 2, or it is inconvenient to access the injection point, or it is more commercially viable to inject the rinse aid directly into the water supply, then the line for the rinse aid chemical 14 can instead be attached to a water supply line 16, extending between the water supply 6 and boiler 4.

[0084] Supply of rinse aid and detergent is controlled by a dosing unit 18 which comprises a control circuit 19, a detergent pump 20 and associated detergent valve 21, a rinse aid pump 22 and an associated rinse aid valve 23. The control circuit 19 controls the dispensing of detergent and rinse aid from respective containers 24 and 25 to the dishwashing machine 2.

[0085] A flow meter 7 detects and measures the flow of water along water supply line 56 and the control circuit 19 of dosing unit 18 uses this to control the detergent pump 20, associated valve 21, rinse aid pump 22 and associated valve 23 to provide a quantity of detergent and rinse aid at appropriate times and dependent on the volume of water drawn by the machine 2 for any particular stage of a wash cycle. The detergent pump 20 and rinse aid pump 22 may be peristaltic pumps or other pumps that provide a known displacement, or alternatively centrifugal pumps could be used with an additional meter to measure the quantity dispensed.

[0086] The dosing unit 18 can be used with most types of existing dishwashing machines 2 and requires no physical electrical connection to be made to the dishwashing machine 2, or the circuitry within that dishwashing machine 2, requiring only to be connected to the rinse aid inlet and a detergent inlet 13 on the dishwashing machine 2.

[0087] The dosing unit 18 may be installed with a new dishwashing machine 2 or subsequently installed to an existing dishwashing machine 2, requiring only the provision of the flow meter 7 in the water supply line 16.

[0088] The flow meter 7 provides a signal 26 to the control circuit 19, which signal 26 may be in the form of a series of pulses, each representing a known volume of water. When the control circuit 19 detects the flow of water along the water supply line 16 it measures this and if the flow stops before 7 litres of water have been measured, it determines that the boiler 4 has been replenished with water and then operates the rinse aid pump 22 and valve 23 to inject a desired quantity of rinse aid into the boiler 4 which is proportional to the volume of water measured. This is then heated and used to rinse the dishes in the normal manner.

[0089] At the same time the detergent pump 20 and associated valve 21 are also activated to inject an appropriate quantity of detergent, proportional to the volume of water measured, into the cabinet 3 via the detergent inlet, represented by the arrow 13, ready for the next cycle. Thus when the clean dishes are removed and the dishwashing machine 2 is reloaded, the water in the wash tank 10 will again contains the correct dose of detergent for the next wash cycle when the wash pump 5 is again energised.

[0090] If, when the dishwashing machine 2 is being initially filled from empty, a quantity of between 7 and 15 litres of water is drawn through the flow meter 7, then the control circuit 19 will cause detergent only to be dispensed and the volume of this will be dependent on the volume measured, ensuring the concentration of detergent in the initial fill of the wash tank 10 is correct.

[0091] Where, as in the illustrated embodiment, a water softener 54 is incorporated in the dishwashing machine 2, this will periodically perform a purge cycle. This will draw in excess of 15 litres of water into the machine through the common inlet and pass this directly from the water softener 54 to a drain, not shown. This quantity of water drawn into the machine 2 will be detected and measured by the meter 7. However, as this exceeds 15 litres, the control circuit 19 will ignore this, avoiding the unnecessary dispensing of detergent or rinse aid, which may not only be wasteful but could result in poor performance due to excessive frothing in the machine 2.

[0092] The dishwashing machine 2 may have a facility to perform a wash cycle at a lower temperature. Because detergents do not work as well at a lower temperature, the control circuit 19 has an operator input by which an operator may indicate that a low temperature wash cycle is to be performed, in response to which the control circuit will increase the dose of detergent for that cycle. The operator input may also be used to manually boost the proportion of detergent if required, for example when the dishwashing machine is loaded with dishes containing an unusually high quantity of grease, for example when cleaning cooking trays or pans.

[0093] Referring now to FIG. 2, this schematically illustrates a second embodiment of a chemical dosing system in accordance with the present invention and this is indicated generally as 27. The system 27 comprises a laundry washing machine 28 and, in the illustrated embodiment, this has three water inlet valves 29, 30 and 31 associated with it. The valves 29 to 31 may be located separately from the laundry machine 28, or they may be housed within the laundry machine 28.

[0094] The laundry machine 28 additionally has an inlet represented by arrow 32 for a detergent, but the machine 28 will normally have multiple inlets for the introduction of chemicals into a drum 47.

[0095] Although not shown, the laundry machine 28 will have an associated control circuit that controls the wash cycle and water inlet valves 29 to 31 in a conventional manner.

[0096] The water inlet valve 29 may be associated with a prewash, the water inlet valve 30 with a main wash and water inlet valve 31 may be associated with a final rinse, in which a fabric conditioner may be added to a drum 47 of the laundry machine 28. As is conventional, the purpose of the multiple valves 29 to 31 is to enable control of those valves to enable the administration of different chemicals at different parts of the cycle into the drum of the laundry machine 28, if these have been manually added by an operator into compartments associated with each valve, as previously discussed. However, many machines are arranged to also be used with an external dosing system, where chemicals, such as a detergents or fabric conditioners may be dispensed automatically from containers directly into the drum and for this reason the washing machine 28 has a number of inlets directly into the drum, as represented in FIG. 2 by the arrow 32.

[0097] In the embodiment illustrated in FIG. 2, a dosing unit 33 is provided, which may be the same as that described with reference to FIG. 1. The dosing unit 33 does not need to be electrically connected or receive any controls signals from the laundry machine 28. Instead, the dosing unit 33 receives signals 34, 35 and 36 from respective flow meters 37, 38 and 39, which are positioned in respective water supply lines 40, 41 and 42, each extending between water supply 43 and a respective one of the water inlet valves 29 to 31. The signals 34 to 36 may each be in the form of pulses, with each pulse representing a volume of water passing through a respective flow meter 37 to 39.

[0098] The signals 34 to 36 are received by a control circuit 44 within dosing unit 33, which control circuit 44 controls a number of pumps 45, only one of which is shown, each associated with a respective chemical within a respective container 48, only one of which is shown, for pumping that chemical from the container 48 along a respective line 46, only one of which is shown, to a respective inlet on the laundry machine 28, represented by arrow 32.

[0099] In operation, the control circuit 44 identifies from respective signals 34, 35 and 36 the stage of the cycle the laundry machine is at and causes to be dispensed an appropriate quantity, of an appropriate chemical, which quantity is proportional to the volume of water drawn through the respective meter 37, 38 or 39.

[0100] In all the above embodiments, an additional water hardness meter may be included in a water supply line and a signal from this may be received by the control circuit and used to modify the quantity of a chemical independence of the hardness of the water detected.

[0101] In the two embodiments previously described, it has been assumed that the chemicals being dispensed will be of a standard concentration or a concentration known by an engineer, who may set the dosing unit 18 of FIG. 1, or 33 of FIG. 2 accordingly. However, in either embodiment this may be automated by the dosing unit being able to identify the chemical. This optional feature, which may have applications other than to dosing systems of the type illustrated in FIGS. 1 and 2 will now be described with reference to FIG. 2.

[0102] Referring to FIG. 2, a container 48 is illustrated for a chemical to be dispensed. This container 48 has either a device 49, such as a bar code or similar on the packaging, which can be read by an optical reader 50 or a radio frequency identification device (RFID) 51 which can be read by an RFID reader 52, either of which can be used to identify to the control circuit 44 both the chemical and the concentration of the chemical. The control circuit 44 can then use this to adjust the quantity of chemical dispensed accordingly. Additionally it may be arranged to prevent the dispensing of a chemical unless the chemical is in a container with an appropriate device or RFID.

[0103] As an alternative to the above the chemical in the container may have an identifier in it, which may be a trace element such as an optical brightener, a coloured element or smart water, which can be detected by a detector 53 of FIG. 2, as the chemical is drawn from the container 48. This can also then be used to identify the chemical and the concentration of the chemical and again prevent dispensing if the chemical does not contain an appropriate identifier. A number of variations of an identifier may be used in order to identify different chemical types and or concentrations. Alternatively properties of the chemical itself may be identified by a physical parameter, such as absorbing one or more light wavelengths, emitting light on one or more wavelengths after photoexcitation, conductivity or turbidity. Or it could be a chemical identifier, such as determining the presence of a specific chemical or ion. Or the chemical could be identified using ratios of two or more of the above parameters.

[0104] Two embodiments of the present invention have been described by way of example only with reference to a chemical dosing system for a dishwashing machine and a chemical dosing system for a laundry machine. However, chemical dosing systems in accordance with the present invention, as defined by the following claims, may have other applications and in addition many variations with embodiments shown will be apparent to those skilled in the art without departing from the scope of the invention as defined by the following claims.