Optics: measuring and testing – For light transmission or absorption – Of fluent material
Reexamination Certificate
2002-03-28
2004-08-03
Smith, Zandra (Department: 2877)
Optics: measuring and testing
For light transmission or absorption
Of fluent material
C356S072000
Reexamination Certificate
active
06771373
ABSTRACT:
FIELD OF THE INVENTION
In general, the present invention relates to sensors for household appliances using cleaning media and, in particular, to sensors for sensing of the turbidity and temperature of cleaning media, e.g. used in washing machines and dishwashers.
BACKGROUND OF THE INVENTION
An essential feature of efficiency of a washing machine or a dishwasher is a low consumption of energy and water which essentially depends on the dirt level of products to be cleaned. Since the dirt level of a product to be cleaned can hardly be directly determined or can not be determined directly at all, it is known to employ so-called turbidity sensors to determine the dirt level of a product to be cleaned indirectly by means of the turbidity or dirtying of a cleaning medium.
By means of turbidity sensors, in general, utilizing a sensing beam propagating through a cleaning medium, the turbidity and dirtying, respectively, of the cleaning medium, for example cleaning or washing water, is determined. On the basis of the determined turbidity or dirtying of the cleaning medium, the current dirt level of the product to be cleaned is determined and the operation of a washing machine or a dishwasher is accordingly controlled to obtain an effective cleaning with a minimized consumption of energy and water.
Further, the effectiveness of the cleaning by means of a washing machine or a dishwasher depends from the temperature of the cleaning medium, since the temperature of the cleaning medium and, in particular, a temperature corresponding to a given temperature or a given temperature course corresponding to a given temperature course determines the removal of dirt particles from the product to be cleaned.
For that purpose, temperature sensors are employed which are arranged in the washing or cleaning area of a respective machine and sense the temperature of the cleaning medium. Further, temperature sensors shell ensure that the temperature of the cleaning medium does not exceed a value given for the product to be cleaned, in order, for example, not to damage pieces of clothes by too high temperatures during the washing.
Usually, washing machines or dishwashers are equipped with turbidity sensors and temperature sensors embodied as separate components which accomplish the respective measurements of the cleaning medium at different locations in the household appliance. This can lead to a non-effective operation, in particular in the case the turbidity values determined by a turbidity sensor and the temperature determined by a temperature sensor are combined to optimize the operation of the machine.
In addition, known sensors which determine the turbidity and the temperature of a cleaning medium of a washing machine or a dishwasher exhibit large sizes which occupy a respective area in the machine. Moreover, such sensors having large dimensions can distort the results of the measurements in the case, in the areas in the machine wherein the sensors are located, static and dynamic conditions of the cleaning medium result due to the sensor dimensions, which are different compared to the areas wherein the actual cleaning is performed.
A further problem of such combined sensors is that the components for a temperature registration are often distorted by the temperature generation from the sensors itself and/or temperature changes of cleaning medium are determined too slow because of its arrangement in the sensor.
OBJECT OF THE INVENTION
Object of the present invention is to overcome the above mentioned drawbacks of known solutions. In particular, the present invention shall provide a sensor for household appliances, such as washing machines or dishwashers, which determines fast and reliable both the turbidity and the temperature of a cleaning medium, has small dimensions and can be installed in a simple manner in a household appliance.
SHORT DESCRIPTION OF THE INVENTION
The object of the present invention is solved by a sensor which comprises a housing having two housing fingers extending from a basis. The both housing fingers, namely a first housing finger and a second housing finger are formed such that they are extending into a cleaning medium for the case of a sensor installed in a washing machine or a dishwasher.
In the first housing finger, a first optical element is arranged, while in the second housing finger, a second optical element is arranged.
For a measurement of the turbidity or dirtying of the cleaning medium, a sensing beam is employed which propagates between the optical elements from one housing finger to the other through the cleaning medium. Interactions of the sensing beam on its propagation path through the cleaning medium are employed to deduce the turbidity or dirtying of the cleaning medium.
Further, in the second housing finger, a temperature sensor for sensing the temperature of the cleaning medium is arranged such that the distance between the temperature sensor and the basis is larger than the distance between the second optical element and the basis.
In this manner, it is accomplished that the portion of the second housing finger wherein the temperature sensor is arranged is extending further into the cleaning medium compared to the portion of the second housing finger comprising the second optical element. This makes it possible to sense the temperature of the cleaning medium faster and more reliable since, for example, a heating of portions surrounding the temperature sensor or the temperature sensor itself by heat generating portions of the sensor is largely avoided.
The housing fingers can be designed such that the longitude axis thereof include an angle, wherein the distance between the free ends of the housing fingers can be larger or smaller than between the portions of the housing fingers which are connected to basis. In the case, the housing fingers are extending in a V-shape from the basis, a larger measuring path is obtained, even for an opposing arrangement of the first and second optical elements which enables for a more precise registration of the turbidity or dirtying of the cleaning medium.
To obtain a larger measuring path, it is further contemplated to arrange the first and second optical elements in a displaced manner in relation to the longitudinal axis of the housing fingers such that the measuring path between the optical elements is extending diagonally between the housing fingers. This extension of the measuring path is in particular suitable in the case where the first and second housing fingers are extending essentially parallel from the basis, which is why, in contrast to, for example, two housing fingers being arranged in a V-form, an essentially constant distance between the housing fingers is given.
Further, it is contemplated to arrange the first and second optical elements relatively to each other such that they lie on an axis which coincides with a straight propagation path for the sensing beam. Alternatively, is it possible to arrange the first and second optical elements relatively to such an axis in a displaced manner in order to register special interactions of the sensing beam on its propagation path through the cleaning medium (for example scattering effects).
To enable for more compact design of the sensor it, is contemplated that the first and second housing fingers have a different lengths wherein the second housing finger comprising the temperature sensor is longer than the other, first housing finger.
A reduced design can particularly be obtained in the case where the first optical element is arranged in an end portion of the first housing finger, i.e. in a portion of the first housing finger which is most remote from the basis.
Preferably, in the case of an utilization of housing fingers been different long, the temperature sensor is arranged as remote as possible from the basis, i.e. in an end portion of the second housing finger, wherein the second optical element is located between the temperature sensor and the basis.
The different length of the housing fingers promotes a balance of cleaning medium being located between the hou
Schenkl Johann
Wilhelm Georg
Browning Clifford W.
Elektromanufaktur Zangenstein Hanauer GmbH & Co. KGAA
Geisel Kara
Smith Zandra
Woodard Emhardt Moriarty McNett & Henry LLP
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