Cleaning and liquid contact with solids – Processes – Combined
Patent
1995-07-17
1998-08-11
Ludlow, Jan
Cleaning and liquid contact with solids
Processes
Combined
134 252, 134 34, 134 57D, 134 58D, 134105, B08D 310
Patent
active
057922764
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to dishwashing apparatus, and in particular to a method and apparatus for controlling a dishwasher.
2. Description of Related Art
In the field of dishwashing apparatus, it is known that hot water is generally more effective in washing than cold water. Consequently, dishwashers are sometimes provided with means for heating water input thereto for the purposes of washing and rinsing phases of the dishwasher. In use, a dishwasher generally runs through a cycle including a number of washing and rinsing phases which are timed by the use of cam timers or, more recently, electronic or hybrid timers. Typically, in a dishwasher, a thermostat is used to regulate the water temperature used in the wash and final rinse phases of the dishwashing cycle. Once the required temperature is reached, the wash or rinse phase continues for a fixed time. The disadvantage with such a system relates to variations in the time taken to reach the required temperature. For example, if the water input to a dishwasher is cold then the heating time will be vastly different from the time to reach the required temperature when hot water is input. This leads to a large variation in program duration, and means that a program optimised for cold water input will be far from optimum on hot water connection, and vice versa. This may also apply where variations in water supply temperature occur even without changing the input. For example, variations may occur where the hot water supply runs out of hot water, or where the hot water supply is distal from the location of the dishwasher and thus the temperature of water input to the dishwasher is not consistent, particularly on the initial fill when water in the pipes may have cooled, and or the pipes themselves are initially cold.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided apparatus for controlling a dishwasher which includes heating means for heating washing and/or rinsing water, comprising means for determining a time period taken for said water to reach a first temperature when heated by said heating means, and controlling means effective to control a washing and/or rinsing duration of the dishwasher which occurs after the water reaches a second temperature on the basis of said time period.
The present invention also provides a method for controlling a dishwashing apparatus in which washing and/or rinsing water introduced thereto is heated by the apparatus, comprising the steps of measuring a time period required to heat said water to a first temperature, and controlling a washing and/or rinsing duration which occurs after said water reaches a second temperature on the basis of said time period.
Preferably, said first temperature is in the range 40.degree. C. to 50.degree. C., said second temperature is in the range 60.degree. C. to 70.degree. C., and said washing and/or rinsing duration is determined according to: temperature;
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail hereinafter, by way of example only, with reference to the accompanying drawings in which like elements are referred to by like reference numbers throughout, wherein:
FIG. 1 is a graph of water temperature against time in a prior art dishwashing cycle having a hot water connection;
FIG. 2 is a graph of water temperature against time for a prior art dishwashing cycle having a cold water connection;
FIG. 3 is a graph of temperature against time illustrating an example of a dishwashing cycle in a dishwasher controlled in accordance with an embodiment of the invention;
FIG. 4 is a schematic diagram of controlling apparatus in accordance with an embodiment of the invention; and
FIGS. 5A and 5B join at point "A" to form a flowchart illustrating the washing procedure of the embodiment of the invention.
DETAILED DESCRIPTIONS
FIGS. 1 and 2 are water temperature against time graphs relating to previously known dishwashing cycles. FIG. 1 indicates a dishwashing cycle 2 in which t
REFERENCES:
patent: 4159211 (1979-06-01), Hoffman et al.
patent: 4241400 (1980-12-01), Kiefer
patent: 4289543 (1981-09-01), Vallor
patent: 4743820 (1988-05-01), Veach
patent: 5331984 (1994-07-01), Isagawa
Ludlow Jan
Southcorp Manufacturing Pty. Ltd.
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