EP0963532B1 - Steam generator - Google Patents

Abstract

The steam generator includes a cast aluminum hollow body in which is embedded a heating element, the ends of which are to be connected to a power source projecting from the body. A cover is sealed on a flange of the body, all the connections required for water inflow and outflow being arranged on the cover. The aluminum hollow body is cast over a receptacle disposed within the body.

Description

The present invention relates to a steam generator and more particularly a steam generator for domestic appliances such as irons or steam cleaners for example.

Usually steam generators for household appliances have a hermetically sealed container with a water inlet and a steam outlet as well as a safety valve, in which is disposed a heater. These steam generators have drawbacks in particular due to the fact that the heating body in contact with water will scale and is difficult to descale and that watertight passages must be provided through the wall of the container for the electrical supply of the heating body.

We know from document DE 44 43 798 C1 a steam generator comprising a hollow body having a flange surrounding its opening in which is embedded at least one heating body whose ends to be connected to a source of electrical energy emerge from this body, this body further comprising a cover tightly fixed to the flange, by through a joint.

It is known in the prior art EP 0.238.955 to produce tubes heated by stainless steel tubes on which is molded a aluminum casing in which are heated bodies. During temperature variations, differential expansion between steel tubes stainless steel and their aluminum sheath can lead to detachments. Such a solution is unsuitable for steam generators. In addition, the latter document relates to a media heater such as a fryer, working at very different temperature and pressure conditions of a steam generator.

The present invention relates to a steam generator tending to obviate the aforementioned drawbacks.

The object of the present invention is the inexpensive realization of a reliable, durable, easily scalable and high quality steam generator especially as regards its lifespan and its possibilities for adjusting the power delivered to the heater. Another object of the present invention is prevent the heating element from coming into contact with the water contained in the watertight container.

This steam generator is distinguished by the characteristics listed in claim 1.

The attached drawing illustrates schematically and by way of example a shape of the steam generator according to the invention.

Figure 1 is a perspective view of the steam generator.

FIG. 2 is an enlarged end view of the generator steam.

FIG. 3 is a view in longitudinal section on a larger scale of the steam generator.

Figure 4 is a side elevational view of the generator tank steam.

FIG. 5 is a view from A of the tank illustrated in FIG. 4.

Figure 6 is a perspective view of the steam generator tank.

Figures 7 and 8 illustrate in perspective an assembly formed of the tank and two heaters.

Figures 9 to 12 illustrate all of Figures 7 and 8 in plan below, in elevation and at the bottom side respectively opening side of the tank.

Figure 13 illustrates in perspective the solid aluminum body of the steam generator.

Figure 14 is a longitudinal section of this solid aluminum body.

FIG. 15 is an end view, seen from the bottom, of the solid body in aluminum.

Figure 16 is a perspective view of the flange or cover in aluminum.

FIG. 17 is a plan view of this cover, and

Figure 18 is a section along line A-A of Figure 17.

The steam generator illustrated has a solid hollow body made of injected aluminum 1 in the mass of which one or two heating bodies are embedded 2.3, the ends of which must be connected to a source of electrical energy emerging from the open front face of the body 1 in a part of it forming a circular flange 4. This flange 4 of the body 1 also has means for fixing a cover 5, here studs 6 embedded in the mass of the body 1.

In a variant, the fixing means may be constituted by tapped holes cooperating with screws or by non-tapped holes cooperating with self-tapping screws.

This massive body 1 made of injected cast aluminum is shrunk by its mode of manufacture on a tank 7 in stamped stainless steel. This tank 7 presents a circular or oval flared opening slightly set back from the front flange 4 and recesses allowing the positioning of the heating bodies 2.3 before injection of the aluminum mass.

The realization of this set is particular, the tank 7 and the bodies of heaters 2,3 are positioned as well as the studs 6, in their relative position illustrated in Figures 8 to 11, on the movable core of a mold. This mold in two parts are then closed on the core and the cast aluminum is injected into said mold. In doing so, the cast aluminum completely surrounds the heaters. 2,3 and ensures by shrinking or cooling its shrinking on the steel tank 7 stainless. We must of course preheat the tank 7 before injecting the cast iron of aluminum and determine the dimensions both of the mold and of this tank 7 for that the finished assembly ensures perfect plating of the tank 7 against the mass aluminum body 1 at the operating temperature of the generator steam, around 140 ° C, while avoiding excessive tension on the steel tank 7 stainless. This produces a monolithic assembly allowing excellent heat transmission and total protection of the heating elements 2.3. The presence of the stainless steel tank 7 gives this steam generator a much better quality, longevity and descaling possibilities.

We also note that the heating elements 2,3 are completely embedded in body 1 made of cast aluminum and are therefore never contact with water. The tightness of the tank 7 is done, as we will see more far away, on a diameter smaller than that on which the ends of the heating element 2,3 emerging from the flange 4, there are no sealed passages at provide for these heaters which also reduces the price and increases the reliability of the steam generator.

The body 1 in solid aluminum still includes housings, injection, 8.9 intended to receive temperature sensors which are connected to the steam generator control.

This body 1 is covered with an insulating sleeve (not shown) to avoid heat loss and users to burn themselves.

As seen in particular in Figure 14, the tank 7 made of stainless steel is slightly offset from the body 1 of injected aluminum. Of this way, the body aluminum mass 1 is larger around the bodies of heats 2,3 which ensures greater thermal inertia favorable to the regulation of the steam generator.

This steam generator also has a cover 10 made of aluminum injected or made of stainless steel fitting on the free face of the flange 4 of the body 1 and fixed to the latter by means of bolts 11 screwed onto the studs 6 of the body 1. The inner face of this cover 10 has a circular groove 12 intended to receive an O-ring seal (not shown). When this cover 10 is fixed in position on body 1 of the steam generator, the O-ring seal is supported on the one hand in the groove 12 of the cover but on the other hand on the flange 4 in aluminum or on the flared edge of the opening of the tank 7 in stainless steel when it is present. This ensures a minimum distance between the steel of the tank 7 and the aluminum of the cover 10 making it possible to avoid any battery effect while ensuring the tightness of the assembly. This also avoids any stack effect between tank 7 and body 1.

Apart from the five holes evenly distributed around its perimeter, giving passage to the studs 6, the cover 10 still has several holes threaded for connections or for fixing control elements or security.

The hole 13 is intended to be connected to a water outlet conduit during a tank descaling cycle. The hole 14 is intended to be connected to a cold water inlet pump. This hole is provided with a tube (not illustrated), usually a flexible silicone tube, extending inside the tank 7 until near the bottom of it. So during the descaling cycle automatic, the descaling mixture entering this tube must sweep the entire internal surface of the tank 7 before being evacuated by the bore 13. The hole 15 is intended to be connected to a steam exhaust duct produced. The hole 16 is used to fix a pressure limiting safety valve maximum inside the steam generator. Finally, the hole 17 serves to fix a relief valve allowing the penetration of air inside the steam generator when the pressure inside it drops below with a pre-established value, generally 1 bar. Finally, the central hole 18 is used to fixing a probe detecting the water level in the steam generator by through an angular sensor introduced into a float. Such a mechanical sensor is reliable and resistant to scaling.

The periphery of this cover 10 naturally also includes holes 19.20 giving passage to the ends of the heating bodies 2.3 in front be electrically connected.

Another advantage of the generator described is its versatility. When he is used with a steam cleaner that requires a high flow of water vapor two heaters 2,3 are supplied to obtain a power of maximum heating. However, if the generator is used with an iron or a vacuum motor requiring less steam flow, only one heating body is supplied. In this case using a device power supply identical to that used by the steam cleaner the remaining power available can be used for heating the iron.

The design of this steam generator allows its reliability, its optimization and its versatility. Indeed, due to the fact that the heaters are embedded in the body, these are no longer subject to scaling. Of more, the electrical supply of these heaters no longer requires sealed passage. Finally, the mass of the injected aluminum body is greater in the region where the heaters are embedded, which increases the inertia thermal and facilitates the regulation of the heating bodies.

All waterproof outlets are grouped together on the simplifying cover thus the realization of the body and the tank.

Finally, the fact of providing two independent heating bodies makes it possible to use the generator with the same supply device for different applications.

Providing a relief valve ensures stability set parameters, such as the generator water level during its which in turn allows for better optimization of the steam generator control.

Claims (10)

1. Steam generator comprising a hollow body (1) presenting a flange (4) surrounding its aperture in which is embedded at least one heating element (2) the ends of which to be connected to an electric power source are projecting from said body; this body (1) further comprises a lid (10) fixed on said flange (4) in a watertight manner, all the connections required for water inflow and outflow as well as for steam extraction being arranged on the lid (10), characterised by the fact that it comprises a stainless steel tank (7) placed at the interior of the body (1) and by the fact that said body (1) is made of injected aluminium and hoped on that tank (7) during fabrication.
2. Generator according to claim 1, characterised by the fact that it comprises two independent heating elements (2,3), both of them being embedded in the mass of the body (1).
3. Generator according to one of the preceding claims, characterised by the fact that the thickness of the wall of the body (1) is bigger in the region where the heating elements (2,3) are embedded than in the rest of the body.
4. Generator according to one of the preceding claims, characterised by the fact that the lid (10) further comprises connections for a temperature probe and a security valve.
5. Generator according to one of the preceding claims, characterised by the fact that the lid (10) further comprises a connection for a relieving valve permitting the entrance of air into the generator as soon as the pressure in the interior of the latter falls below a pre-established value.
6. Generator according to one of the preceding claims, characterised by the fact that a joint is embedded in a circular recess of the lid (10), this joint being in service position (12) crumpled between the lid (10) on the one side and the flange (4) of the body (1) or the edge of the tank (7) on the other side.
7. Generator according to one of the preceding claims, characterised by the fact that the tank (7) is beaten and comprises openings for the passage of the heating elements and doesn't present any built-up connection.
8. Generator according to one of the preceding claims, characterised by the fact that the passage of the lid (10) intended to serve for the entrance of cold water into the tank is provided with a tube reaching onto near the bottom of the tank.
9. Generator according to one of the preceding claims, characterised by the fact that the lid further comprises an evacuation channel (13) for the liquid for scale removing which is placed below the passage of water inflow into the tank (7) and communicates with the lowest point of the tank (7).
10. Generator according to one of the preceding claims, characterised by the fact that it comprises a water gauge made up of an angular gauge embedded in a floating body.

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