Steam iron with calcification indication

Details Steam iron with calcification indication Steam iron with calcification indication

1999-09-22

2001-01-30

Izaguirre, Ismael (Department: 3741)

Textiles: ironing or smoothing

Smoothing implements

Flatirons

Reexamination Certificate

active

06178671

ABSTRACT:

The invention relates to a steam iron with calcification indication. Such a steam iron is known from PCT International Application No. WO 95/16378. The present invention is concerned with the effects of mineral deposits, often referred to as calcification or scaling, in the steam chamber and the steam vents of a steam iron. In areas with so-called hard water the deposition of minerals in apparatus in which tap water is heated to temperatures above 68 degrees centigrade is inevitable. The effect of the calcification depends on the construction of the apparatus. In coffee brewers the calcification obstructs the water flow through the water conduit and therefore the coffee brewer must be periodically cleansed, for example, with vinegar to remove the scale. In practice, the user often forgets the regular decalcification of the apparatus. In the long run the thickness of the deposited layer of scale causes overheating and the apparatus may burn out. In steam irons similar problems may occur. The user is expected to perform a self clean action in order to remove the deposited scale from the walls of the steam chamber and the steam vents. For this purpose the user must disconnect the power cord of the hot iron from the A.C. mains voltage and fill the iron with cold water. The thermal shock caused by the cold water on the hot walls of the steam chamber and the steam vents removes the thin calcification layer from the walls. Also the users of steam irons often forget to regularly perform such a self-clean action.
Many solutions have been invented to warn the users that the calcification has reached a certain limit and that the apparatus has to be cleansed. In said PCT International Application No. WO 95/16378 the temperature of the hot water is repeatedly measured and compared with an initial temperature. If the temperature difference exceeds a given value, an acoustic or visual signal indicates that the apparatus is calcified. Offenlegungsschrift DE 32 23 969 discloses a coffee maker having a timer which measures the time to heat up the cold water. When the conduit is calcified this time is longer and the calcification indicator is activated when this time exceeds a predetermined value. However, these known techniques require a fixed volume of cold water to start with and are not suitable for steam irons, as the temperature and the volume of cold water are not fixed but variable.
It is therefore an object of the present invention to provide a steam iron with a suitable calcification indication. To this end, the steam iron with calcification indication is characterized in that it comprises an indicator for indicating calcification, timing means for measuring an accumulated time of use of the steam iron, and means for activating the indicator when the accumulated time exceeds a predetermined threshold level.
The timing means measure the time of use of the steam iron. The accumulated time of use is indicative of the amount of scale deposited in the steam chamber and steam vents. When the accumulated time of use exceeds a threshold the calcification indicator is activated to warn the user that a self-clean action is to be performed. A refinement of the time of use may be obtained by accumulating the time of use only during steam generation. A further refinement may be obtained by correcting the accumulated time of use with a weighting factor which depends on the steam rate. The higher the steaming rate, the faster the time-of-use accumulation proceeds. Alternatively, the weighting factor may be made dependent on the hardness of the water to be steamed. It is further possible to make the threshold level for activating the calcification indicator dependent on the hardness of the water. The softer the water, the longer the interval between two self cleans can be. The hardness of the water can be selected by means of a dial set by the user or by a hidden switch to be set in the shop.


REFERENCES:
patent: 4969393 (1990-11-01), Mahlick et al.
patent: 5063697 (1991-11-01), Valente et al.
patent: 3223969A1 (1984-01-01), None
patent: 489714 (1992-06-01), None
patent: 2632331 (1989-12-01), None
patent: 95/16378 (1995-06-01), None

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