WO2005024300A2

WO2005024300A2 - Universal device for checking the water level in steam boilers

Info

Publication number: WO2005024300A2
Application number: PCT/EP2004/010023
Authority: WO
Inventors: Ilaria Senno
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-09-10
Filing date: 2004-09-08
Publication date: 2005-03-17
Anticipated expiration: 2006-03-10
Also published as: WO2005024300A3; ITMI20031729A1

Abstract

The present invention is about a universal device for checking the water level in steam boilers of household appliances, provided with a bulb thermostatic feeler (32) which allows to maintain almost constant the water level in the boiler (10) and thus the quantity and quality of produced steam, by intermittently activating for short intervals the cold water loading pump thanks to the intervention of an electric resistance (28) for preheating the water coming into the pump.

Description

"UNIVERSAL DEVICE FOR CHECKING THE WATER LEVEL IN STEAM BOILERS" The present invention relates to a universal device for checking the water level in steam boilers of the type used in continuous steam supply household appliances. In said appliances it is very important that the steam is supplied in constant quantity and quality, and for this purpose it is essential that the water level in the boiler remains always constant within a strict oscillation range between the allowed highest and lowest levels. For this purpose, several devices have been studied, still without reaching fully satisfying results, mainly due to the thermal inertia of the materials and to the delay in response times of the thermostatic feeler and the loading pump, because of the temperature difference between the hot water in vaporization phase and the topping up cold water. Moreover, each kind of boiler requires its own particular level checking system, with an increase in productive costs. The device according to the present invention brilliantly solves both these problems, because it is a completely autonomous system on one side, which means it is a stand alone component that can be applied on any kind of boiler by simply providing for a generally threaded hole on the bottom of the boiler, in which the device has to be mounted, and it allows to maintain extremely narrow the oscillation range between highest and lowest water levels on the other side so that, introducing small quantities of topping up water at frequent intervals, not only an almost constant water level, but also a water temperature in the boiler which undergoes slight oscillations, and thus a steam production in almost uniform quantity and quality, are obtained. Objects, characteristics and advantages of the device according to the present invention will be clear and evident from the following detailed description of its preferred embodiment, given in an explanatory but not limiting way, with reference to the annexed figures of illustrative drawings, wherein: Figure 1 is a sectional elevational view of the device, mounted on a boiler which can be of any type suitable for this kind of household appliances; and Figure 2 is a bottom plan view of the device. Referring to the aforesaid figures of the annexed drawings, the illustrative boiler 10 has a bottom 12 in which the water heating resistance 14 is embedded, generating steam which is collected in the dome 16 to be delivered through the related steam outlet 18. In the bottom 12 a generally threaded hole 20 is obtained, in which the preferably cylindrical shaped device, generally indicated with numeral 22, is screwed. Three holes are obtained in the device body, and precisely a cold water inlet through hole 24, which comes into the steam dome 16 at the top of the device, and two blind holes, of which a hole 26 for housing a low power (for instance 100-150 W) electric resistance 28 and a hole 30 for housing a bulb thermostatic feeler 32. The upper part 34 of the device is made of a good heat conductive metallic material, for instance aluminium, formed together with the lower part 36, which is made of thermal insulating material, for instance plastic material. At the beginning of the boiler operation, the water level will correspond to the highest level H max. When the water will be heated, the steam production will start and thus the water level will begin to decrease. The metallic portion of the thermostatic feeler 32, initially submerged in the water, will detect the temperature increase due to its exposure to air and to the temperature induced by the resistance 28, as soon as the water level is decreased to a level comprised between hi max and hi min, representing the narrow oscillation range due to the environmental conditions, the materials tolerances, etc. This level represents the switching on point of the cold water loading pump, connected in parallel with the contact of the thermostat 32, just controlled by the thermostatic feeler 32. The incoming water will be slightly preheated and will subtract heat to the metallic portion of the feeler and to the feeler itself, which will check this temperature decrease so that, at the reaching of the H max level, the switching off point of cold water loading pump will be obtained. In substance, the device provides for a short intervals intermittent water feeding which allows the maintenance of the water level in the boiler within a strict oscillation range, thus allowing to obtain a practically constant steam quantity and quality. It is therefore evident from the foregoing description that the device according to the present invention fully achieves the intended objects and advantages, and it can be applied as a ready-to-use component to any type of steam boiler of this kind, but it should be pointed out that all those modifications of shape, size and elements, which will be introduced according to the productive and use needing and contingencies, could be made without falling outside its constructive principles and without departing from its scope of protection, as it is also defined in the appended claims.

Claims

1. A universal device for checking the water level in steam boilers, comprising a body to be applied inside the boiler, in order to be completely submerged in the water contained in the boiler when it is approximately at its highest level, characterized in that three vertical holes are obtained in said body, a through hole as a feeding conduit for the water coming from the loading pump and two blind holes respectively housing a bulb thermostatic feeler and an electric resistance for heating the metallic upper part of said body, said feeler detecting the temperature difference as soon as the water level decreases below a predetermined range which exposes to air the upper part of the body, thus switching on the water loading pump, said water being preheated by the resistance while it rises within the feeding conduit, and also causing the temperature decrease and the pump switching off when the initial filling level of the boiler is reached.

2. The device according to claim 1 , characterized in that the lower part of the body is made or covered with thermal insulating material, formed together with the metallic upper part.

3. The device according to claim 1 , characterized in that the water feeding conduit is arranged immediately near to the thermostatic feeler housing hole.

4. The device according to claim 1 , characterized in that the electric resistance is of low power.

5. The device according to claim 1 , characterized in that it is screwed in a threaded hole made in the bottom of the steam boiler.

6. Use of the device according to one or more of the preceding claims, as an autonomous component to be applied to any kind of steam boiler for continuous steam supply household appliances.