The present invention relates to a tumble dryer and here in particular to a domestic tumble dryer as claimed in the preamble of the independent claim.
It repeatedly occurs with tumble dryers that certain small items, such as lint or fluff or other impurities, such as wear material from drive belts, can collect and form deposits in the drum or in the floor region of the housing. On reaching a certain temperature it may occur that these items catch fire. This is to be avoided. In a number of countries, there are already appropriate test procedures in force, or are intended to be brought into effect shortly, such as to prove that fire cannot break out in the tumble dryer. To this end, for example, in the USA as from 2013 tests will be conducted to ensure that a cloth laid over the tumble dryer cannot ignite during the test.
Manufacturers of tumble dryers are therefore concerned with being able to offer tumble dryers whereby a fire in the interior of the tumble dryer can be actively extinguished, or whereby at least the spreading of the fire to the outside can be prevented. In this situation the principle is known from DE 10 2007 061 521 A1 of undertaking active fighting of a fire by extinguishing it with water or other chemicals from a container arranged above the drum, after the extinguishing process has been activated by a temperature sensor. Such a solution, however, is as a rule dependent on a functioning power supply for the operation of the temperature sensor, the control technology and evaluation circuitry relating to it, as well as other devices if appropriate.
As an alternative, passive fighting of a fire is also possible, inasmuch as no easily combustible components made of plastics materials are used any longer, but only fire-resistant plastics, metals, or other materials. This is only possible, however, if increased manufacturing costs are taken into account.
From DE 38 09 754 A1 a fire extinguishing device for tumble dryers is known, as claimed in the preamble of claim 1. A container is provided beneath the worktop, with several cells in which an extinguishing agent is stored. Holes are provided on the underside of the cells, which are closed with the aid of a protective sheath or destructible membrane and are destroyed in the presence of flames or at a temperature above a predetermined limit temperature. Upon the limit temperature being reached, the extinguishing agent is therefore released and falls downwards in order to extinguish the fire which has broken out. According to an alternative embodiment, a container subjected to pressure is provided with an extinguishing agent, from which lines lead to points which are regarded as subject to the risk of fire. In the event of the onset of a fire or the occurrence of a high temperature, the lines can melt and are therefore interrupted and opened respectively. The extinguishing agent is thereby released.
From US 2010/0175898 A1 a fire protection device for a tumble dryer is known, comprising a device for the detection of a temperature inside the tumble dryer. The device is connected to an extinguishing agent releasing device, to which a pulse can be issued by the temperature detection device if a specific temperature is reached. As a result, extinguishing agent can be released by the extinguishing agent releasing device.
The tumble dryers known from the aforecited publications are disadvantageous however in that a relatively large amount of water or extinguishing agent must be retained in order for an outbreak of fire to be reliably extinguished.
It is an object of the present invention to propose a tumble dryer, such as, in particular, a domestic tumble dryer, with which a fire which may break out in the drum or outside cannot spread from the drum and will be extinguished, as far as possible automatically, without a connection to the power supply being necessary. This should be possible with the smallest possible store of extinguishing agent.
This object is achieved with a tumble dryer as claimed in the independent claim. Advantageous developments of the invention are the object of the dependent claims, the following description, and the appended drawings.
A tumble dryer according to the invention comprises a drum intended to accommodate the laundry which is to be dried, as well as a container which can accommodate or already contains extinguishing agent, which as a rule is capable of flowing. The outflow from the container is closed by means of a first temperature-activated valve, which opens automatically at a temperature such as is produced, for example, by a fire, or correspondingly high temperatures. The tumble dryer according to the invention is characterized in that the container is connected by means of a first a line to the interior of the drum, and the valve is arranged in the first line in such a way that it is in good thermal contact with the interior of the drum. This good thermal contact can be attained, among other methods, by the first valve being arranged in the immediate vicinity of the drum or even inside the drum. According to the invention, provision is also made for a second line connected to the container, which opens in the region of a base plate of the tumble dryer, and is closed in the region of its mouth by a second temperature-activated valve. This second valve is also arranged in such a way that it opens automatically when a high temperature produced by a fire or similar cause is reached. As a rule, it may be assumed that a fire or a substantial temperature increase will not occur simultaneously at two places, wherein it may be assumed that these places will be predominantly in the region of the base plate and inside the drum. In order not to have to provide for or store so much extinguishing agent that a possible fire at two places can be reliably extinguished, the arrangement according to the invention is such that either the first valve or the second valve opens automatically at the temperature produced by the fire. It is therefore sufficient for extinguishing agent to be provided only in that quantity which is required to extinguish a fire at one place, and not at two or even more places. The container, together with the lines and the valves, forms an extinguishing system.
The tumble dryer according to the invention, with the extinguishing system described, operates passively, i.e. no electrical, electronic, or control technology is present which would make connection to a power supply necessary.
In order to ensure that always only the first valve or the second valve opens automatically, it is preferred that the mouth of the second line is located at least 5 cm, for preference at least 10 cm, and for particular preference at least 20 cm from the drum, into which the line which is closed by the first valve opens. In other words, this means that by maintaining a certain minimum distance between the two valves it can be ensured that the valve in the vicinity of which the fire has developed will open due to the higher temperatures prevailing there, while the other valve, which is still located in a region of low temperature, remains closed. As an alternative, it would also be possible, for example, for both the valves to be arranged such that they open automatically at different temperatures, if this is technically feasible with corresponding analyses of the temperature distributions of different locations at which a fire breaks out. It is also conceivable for the two valves to be designed in such a way that as soon as the first valve has opened the extinguishing agent will be released so rapidly, and therefore the pressure drop will be so sharp, that the second valve, not yet opened, remains closed. This can of course only be achieved if, for the automatic opening of the valves, not only a temperature component but also a pressure component is required.
According to an advantageous embodiment of the invention, the first line and the second line do not run directly from the container but are both a continuation of a third line, which in turn runs from the container. By way of this measure, less material is used for the manufacture of the lines.
It advantageous if the first valve and the second valve comprise a thermo-bulb. A thermo-bulb is a glass cylinder filled with a fluid which, upon reaching a specific temperature, as in the present case the temperature caused by an outbreak of fire, bursts, due to the fact that the fluid expends so vigorously due to the rise in temperature that the radial circumferential walls of the glass cylinder break. These thermo-bulbs are designed in such a way that they exhibit a perceptibly higher stability in the axial direction. Upon the bursting of the glass cylinder, a valve opens in the axial direction. In the present case, extinguishing agent can flow through the opened valve out of the line concerned. The glass cylinder is arranged in this process in such a way that it can accommodate perceptibly higher forces in the axial direction, in order, for example, to keep the valve closed under water pressure, than in the radial direction, in which it bursts at the rise in temperature.
It is advantageous if the first line in the front end shield, which is provided for mounting the drum, opens into the interior of the drum. This allows for a structurally simple design for the guiding of the extinguishing agent into the drum. In this situation, it is preferred for the first line to open above the mid-axis of the drum, and in this case, preferably, in the region of the upper end of the drum. The water which is jetted or sprayed into the drum in the event of an outbreak of fire is then, due to the force of gravity, distributed approximately uniformly over the drum.
According to an advantageous embodiment of the invention, the container is arranged on the underside of the upper delimitation of the tumble dryer, which is frequently designed as a worktop. In this case, no provision needs to be made for any other pump or pressure application device for the extinguishing agent in order to conduct it, if required, the same to the target location, gravity can be used instead. Naturally, an appropriate pressure application device can additionally be provided, such as, for example, a pressure cartridge, which can then be designed with lower capacity. The container can advantageously be arranged with an adequately dimensioned pump/ pressure cartridge at any desired location in or at the tumble dryer.
It may be advantageous if the container exhibits a closable filling opening for the extinguishing agent. A user can then regularly check, for example, that the container is completely filled with extinguishing agent. This configuration also makes it possible for a tumble dryer according to the invention to be transported to the place of use without being filled with extinguishing agent, and for the container to only then be filled with extinguishing agent on site. The possibility of filling the container by means of the filling opening offers the further advantage that the container can be refilled if the extinguishing system described has become active, without the entire container with its associated lines and valves etc. needing to be replaced. This is of advantage in particular if the damage caused by the fire is so delimited that the further use of the tumble dryer after the actuation of the extinguishing system and replacement or repair of the damaged parts make the reuse of the tumble dryer worthwhile.
It is an advantage of the present invention that the container must exhibit a volume of a maximum of some three to four liters, since experience has shown this to be sufficient for the complete extinguishing of a fire which has broken out.
According to an advantageous embodiment of the tumble dryer according to the invention, the container is already filled by the manufacturers with water, with the addition of an extinguishing additive to enhance the extinguishing effect. As a result, the possibility can be excluded of a tumble dryer according to the invention inadvertently being taken into operation without being filled with extinguishing agent, without this having to be detected, for example, by electronic monitoring sensor means.
Further advantages, features, and special details of the invention are to be derived from the following description of advantageous embodiments of the invention, making reference to the figures of the appended drawings, in which:
Accordingly, as soon as, for example, a fire breaks out in the drum 20, and the temperature accordingly exceeds a specific limit value, the first valve 50 opens, activated by this limit value being exceeded, and extinguishing agent 9 can flow out of the container 30 into the drum 20. The spraying or jetting of extinguishing agent 9 into the drum 20 is indicated schematically by an arrow A with a broken line. Since the fire has developed in the drum 20, the temperature rises inside the drum 20 much more substantially than outside, such as, in particular, in the region of the base plate 12. Accordingly, the second valve 52 will not open, since, as already explained, this has been arranged far enough away from the drum 20. If, by contrast, a fire develops in the region of the base plate 12, then the second valve 52 “feels” this temperature rise much more quickly and more strongly than the first valve 50, and actuates when the temperature limit value is exceeded, i.e. it opens. The extinguishing agent 9 can then flow out and extinguish the fire in the region of the base plate 12. The emergence of the extinguishing agent 9 from the second valve 52 at the end of the second line 42 is indicated schematically by an arrow B. Due to the fact that the first valve 50 is subjected to a lower temperature, it remains closed. Accordingly, all the extinguishing agent is conducted to the respective location of the fire, and is not wasted at a place at which it is not required.
The valve 50 is represented as arranged in the valve chamber 17. Arranged at the base of the valve chamber 17, which forms an impact surface 18, is a tensioning spring 55. Arranged between the tensioning spring 55 and the lower end of the conical element 57, engaging in a depression at its lower end, is a thermo-bulb 54. The tensioning spring 55 presses the thermo-bulb 54 upwards and thereby holds the valve 50 closed against the pressure of the extinguishing agent 9. The thermo-bulb 54 comprises a glass tube 54a, in which a fluid 54b is contained. In addition, in the fluid 54b of the glass tube 54a, is an air bubble, not shown. The glass tube 54a is arranged in such a way that in the axial direction (according to
As a result of this, the situation is achieved, without a connection to the electricity supply, in a technically simple, economical, and reliable manner, that the valve 50, on reaching or exceeding a limit value of the ambient temperature, opens spontaneously, i.e. automatically, and allows for the extinguishing procedure for the fire to be carried out.
Naturally, the invention described heretofore is not restricted to the two embodiments described in detail. The different variants of the extinguishing system can be used both with condensation dryers as well as with exhaust air dryers, and in each case guarantee a reliable and automatic extinguishing of a fire, should one occur, not requiring any influence from the outside. Since no connection to the mains electricity supply or the provision of a battery etc. is required for operation of or for the maintaining of readiness of the extinguishing system, the reliability of the extinguishing system against failures is very high.
It is to be noted that features of the invention described in relation to individual embodiments, such as the design and arrangement of the container and the valves and lines, can also be provided in other embodiments, individually or cumulatively, unless indicated otherwise or inherently not feasible for technical reasons.
Number | Date | Country | Kind |
---|---|---|---|
10 2011 087 608.1 | Dec 2011 | DE | national |