FI117665B - Steam generator - Google Patents

Description

117665 Steam generator

The invention relates to a steam generator comprising a water tank, a heating element for vaporizing the water in the water tank, and a temperature sensor outside the tank in heat transfer communication with the wall of the tank to monitor the water surface in the tank.

The steam generator described herein is intended primarily for use in saunas, but may be used, for example, in a household where hot steam is required, such as steam irons.

Preventing the water tank of evaporators from drying out has been one of the major orv problems for manufacturers of evaporators. There have been efforts to monitor the water level by known mechanical and electronic pin-15 level sensors placed inside the tank, which however have the problem of limescale-like deposits inside the tank which impede the operation of the sensors and make the mechanisms difficult to operate. For example, these deposits may obscure the electronic sensor, preventing it from operating at all.

Another solution is to allow the evaporator to empty the water tank until the thermostat on the bottom switches off the heating element. However, this causes the heating element to breathe and shorten its life, as parts are exposed to very high temperatures. In addition, a dried water tank may i.j 'cause unpleasant odors to the environment.

: 25 * * * * '. ···. It is known to use temperature sensors to determine whether the water level * * in the tank has dropped below a certain level. The use of such sensors is based on the fact that when the tank part is heated, its temperature • · · M: depends on whether the heated spot is above water (temperature higher • · * 30 amps) or below (temperature lower), because water evaporation the heat keeps the temperature constant. Solutions that work on this principle are known as '.' net mm. U.S. Patent 5,881,207; EP 193863; and U.S. Patent 4,881,493.

U.S. Patent No. 5,881,207, corresponding to European Patent EP-772000, discloses a tube (30) embedded inside a container at a desired surface height, 2 117665 having a temperature sensor (12) and an electric current. Heated resistor (13) Even though this sensor is not directly affected by the precipitation, if the resistor breaks, heating will no longer work and when the water level drops below the pipe, the temperature will not rise and a warning of drying will not be obtained.

European patent EP-193863, in turn, discloses a steam generator in which heating resistors (5,6,7) are placed at a suitable height outside the container wall. Temperature sensors (16,17,18) are also placed at the same height to monitor the wall temperature, which depends on the location of the water surface. In this case, the position of the heating resistors is determined by the level of the desired water surface, which limits the design of the steam generator. It is often desirable that the heating resistors can be located below the tank.

A similar structure and principle as above is also found in U.S. Patent No. 4,881,493, in which a heating resistor (9) is screwed on the outside of a vertical cylindrical container, and a temperature sensor (10) is screwed parallel to the upper part of the resistor. ; It is an object of the invention to provide a simpler solution which does not require separate heating at the temperature sensor and in which the layout of the heating elements is not dependent on the location of the height being monitored. To this end, ··; In order to accomplish this, the steam generator of the invention is essentially characterized in that the heating element is connected in a thermally conductive manner to the temperature sensor via a heat conductor separate from the outer wall of the container. In a way, this heat conductor forms a bridge through which * · · heat is brought to the desired height (at the water surface to be monitored) in the tank: in the wall at which the temperature sensor is also located. The heating element may then, for example, be located underneath the container, which is often a * * * ··· * 30 advantageous investment.

• · • · * • · · • ·. ···. The solution of the present invention is not impaired by tank deposits or possible malfunctions of the different heating element, since the heat is introduced by conducting · ... · the outside of the tank from the same heating element which enters the vapor to the tank: 35%.

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The point where the heat conductor is connected to the tank wall determines the level to be monitored. When the water surface is above the junction, the heat entering the junction through the conductor is transferred through the heat-conducting wall to the internal mass of water having high thermal capacity and heat of vaporization.

5 When the water drops below this point, the end of the heat conductor connected to the wall and the wall will rapidly heat up because there is no water absorbing heat at the same height inside the wall. A temperature sensor at the same location detects a rapid rise in temperature above a certain predetermined threshold and informs the supervisor / user, or 10 if the temperature sensor is part of the thermostat, the thermostat performs an automatic adjustment (supplying additional water to the tank and / or heating off).

A further advantage of the solution is that no penetrations or recesses are required inside the container, but all components and functional parts are outside the container.

15

According to a preferred embodiment, two thermostats having different operating points are used, whereby the thermostat operating at a higher temperature will serve as a backup switch if the main thermostat fails.

The invention will now be described with reference to the accompanying drawings, in which: * 1 · Fig. 1 shows a steam generator from above, · *: Fig. 2 shows a steam generator from the front, * · ·: Fig. 3 shows a side generator. 2 on the right), • * · 25 Figure 4 shows the steam generator from below, Figure 5 shows the steam generator in cross-section along line AA1 in Figure 1: Figure 6 shows the steam generator in an isometric view, and ···. ' Fig. 7 shows the temperature at the measuring point as a function of the height of the water surface.

φ φ φ · φ φ φ φ • **. ** ·. The system of the invention can be used in many different forms depending on the mode of use. In the following description, there is only one embodiment, given by way of example, which is not intended to limit the invention. The water container shown in Figure -35 also includes a steam outlet and a water supply channel and a container closure lid, not shown.

4, 117665

Figure 1 shows four options for the location of the heat conductor 1 (designated by reference numerals 1-1, 1-2, 1-3, 1-4). The heat conductor 1 is a metal plate or strip which can be bent to a desired shape and which one end 5 can be connected to the heating element 5 and the other end to the sidewall of the evaporator water tank 2 at a desired height so as to transfer heat from the heating element 5 to the sidewall. Between the ends, the heat conductor 1 is insulated from the container 2, in the figures with an air gap between them, but it is also possible to use insulators.

10

Hereinafter, reference is made to a solution in which the heat conductor 1 is connected to the right side wall of the container 2 (option 1-1). At the point where the end of the heat conductor 1 is connected to the side wall of the container 2, at least one temperature sensor is placed which monitors the temperature at said junction according to the principle described above. The heat conductor 1 is at a junction with the wall of the container 2 in a region of a certain size, and in this area the sensor is located on the heat conductor 1. As shown in the figures, the sensor is part of a thermostat 3 which forms a switch for controlling heating and / or water supply. In the embodiments of the figures, the two thermostats 3, 4 are arranged in parallel at the same height at the junction, whereby the lower temperature thermostat 3 forms the main switch and the higher temperature thermostat 4 a safety switch. A second thermostat 4 may not be required.

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· ** · * · * · * ί As shown, thermostat 3 / thermostats 3, 4 are located on the part of: 25 bent sheet or strip heat conductors 1 fixed: against the wall of the tank 2 in the direction of the wall.

* · ·: A conductive metal plate or strip serving as heat conductor 1 is shaped and placed so that minimal heat is lost **; · '30 as it moves from the heating element to the junction 5 where the sensor or : V: The thermostat is located The plate or strip is placed underneath against the heating element 5 of the bottom 2 of the tank 2 so as to cover a portion of the surface of the element 5 sufficient for heat transfer, as shown in Figure 4. in contact with different portions of the elongated element 5 long enough *: **; 35 As shown in the figures, the heating element 5 may be a conventional electrically heated resistor .The plate or strip is bent upward and this upward portion 5 117665 is sufficiently distant from the container 2 wall to prevent heat transfer to the wall. The plate or strip is bent upwards at the joint end towards a straight section which is against the wall and forms a junction for transferring heat to the wall. The portion at a distance from the container 5 may be C-shaped towards the container or, as option 6 in Fig. 2, may be folded at an acute angle so that the portion is directed obliquely upward at the junction. The point where the conductor 1 touches the tank again is placed at such a height (level 7 in Figure 5) with respect to the bottom that sufficient water is always left in the tank, even if the water level is lowered below this height. For example, the height may be at least twice the desired minimum water height. The tank is made of metal so that its wall has good thermal conductivity.

The water tank can be fitted with a suitable enclosure which also covers the heat conductor 1 15 and the sensor / thermostat. The heat conductor and the sensor / thermostat can be placed on the side of the tank where it is most suitable for the location and use of the evaporator (alternatives shown in Figure 1).

Figure 7 shows the temperature as a function of water level. When the surface of the water 20 is above the point of contact of the conductor 1 (level 7), the temperature measured by the sensor is · · boiling when the water is evaporated in the tank. When: the water level drops below level 7, the temperature rises rapidly, and when it ·· ': * reaches a preset switching temperature above boiling point, the sensor will either notify or, if it is part of thermostat 3, 25 statuses automatically switch off the heating and / or provide additional water supply ***. into the tank. The thermostat may have an operating point, for example, at least 110 ° C.

The thermostat automatically resets at a lower temperature.

• t • I ·

The second thermostat 4, which is a safety thermostat, operates at a higher temperature, preferably at least 25 ° C, higher than the end temperature. the thermostat 3. It is not automatically reversible, but must be done manually, since this is a malfunction of the main thermostat 3, and the φ "* master thermostat must then be replaced.

35 · The actual adjustment procedure based on the sensor / thermostat 3 readings can be done automatically or manually. It is possible that exceeding the preset threshold value 117665 (temperature) will only become an alarm and then water will be added manually, or else the sensor reading above this threshold will automatically trigger the water supply device to add water to the tank. In either case, the sensor reading preferably also cuts off the heating, i.e. the energy supply to the heating element 5. The functions are easily accomplished by known thermostats.

The invention is not limited to the above-described embodiments, but may be modified within the scope of the inventive idea claimed. It is possible that there are more than one sensor or thermostat at different heights, whereby a separate heat conductor 1 from the heating element 5 can be introduced at each of them, or the heat conductor 1 from the same heating element 5 may branch into branches ending at different heights. The design of the thermal conductor and the positioning of the sensors / thermostats may be the same as described above.

The term sidewall refers to all walls that have a vertical dimension (direction of water surface variation), regardless of container shape. According to the embodiment described above, the horizontal section of the container 2 is a rectangular ·: ··· 20 angle, but may also have other shapes. For example, the water tank 2 may be cylindrical.

The invention is particularly well suited to the development of steam in saunas, but it can also be applied * 1 1! · Ϊ ϊ to other applications where steam is required, in particular · .1: 25 for steam generators in households and kitchens.

• 1 1 * · • · • · 1 • · * · · • φ · · 1 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · forward · · • 1 • · * 1 · · 1 1 ·

Claims (7)

117665 A steam generator comprising a water tank (2), a heating element (5) for vaporizing the water in the water tank, and a temperature sensor outside the tank for monitoring the water surface of the temperature sensor in connection with the tank wall, characterized in that the heating element (5) connected in a thermally conductive manner to a temperature sensor via a heat conductor (1) separate from the outer wall of the container (2). 10 Steam generator according to Claim 1, characterized in that the heating element (5) is disposed on the outside of the container (2) at its bottom, and the heat conductor (1) is brought from the bottom to a certain height to the side wall of the container. Steam generator according to claim 1 or 2, characterized in that the temperature sensor is disposed on the heat conductor (1) at a point where it is connected to the outer wall of the container (2). Steam generator according to one of the preceding claims, characterized in that the heat conductor (1) consists of a sheet of metal or a sheet which is bent so that it extends from the outer wall of the container to its ends between its ends. Steam generator according to any one of the preceding claims, characterized in that the temperature sensor is included in an automatic thermostat (3). • · · • · * · * · · Steam generator according to Claim 5, characterized in that the •. there are two thermostats, the main thermostat (3) and the safety thermostat (4). ····, '' '• · »· Use of a steam generator according to any one of the preceding claims for steam generation in a sauna. 1 · · 1 · · · · * • mm • m • m mm mm mm · 117665 1. Änggenerator, som omfattar en vattenbehallare (2), that color element (5) för att föränga i vattenbehällaren befintligt vatten, samt en utanför behällaren 5. en coloring-verföringsförbindelse med behällarens vägg befintlig-temperature-givare för att controller wattennivän i behällaren, tongue-and-groove (5) and copying of the color-setting setting of the temperature-givaren genom en sommeledare (1) 2) ytter-vägg. 2. The patent generator 1, the clamping elements, the color element (5), and the placeholder (2) for the bottleneck, and the colorant for the account (1). 3. The generator enligt patent krav 1 eller 2, the rotary cutters, the attemperurgivaren and the placerad after the snapshot (1) vid delt den and copplad account behällarens (2) yttervägg. 4. Änggenerator enligt face av de föregäende patentkraven, kännetecknad 20 av, att fluttered (1) bestär av en metallplät eller -remsa som är böjd sa att avsnittet mellan dess ändar är frän behällarens yttervägg. • 1: V 5. Änggenerator enligt ägot av de föregäende patentkraven, kännetecknad ..; j “av, attemperurgivaren hör account en automatisk thermostat (3). : 25 ·· * 1: 6. Änggenerator enligt patentkrav 5, kännetecknad av, att antalet thermo- »· ·. ***. stater y: thermostat (3) and thermostat (4). * ··. 7. Användning av en änggenerator enligt verge av de föregäende patent- • · · · Illt 30 kraven för alstring av änga i en bastu. . 'j • · ···. · 1 • · • 1 · · ··· * «• 1 • 1 · · · · · · · · · ·