Patent Application
20080209670
The invention relates to a cleaning appliance according to the preamble of claim 1.
Cleaning appliances in the present connection, for example, comprise air cleaning appliances, air-conditioning systems and in particular, vacuum cleaners.
Conventional vacuum cleaners operate on the principle that air laden with foreign particles is sucked in, filtered in the vacuum cleaner and blown out from the vacuum cleaner in purified form. Since the sucked-in air can contain various foreign particles or foreign bodies, particular requirements are to be imposed on the filter devices inside the vacuum cleaner. For this reason, it is usual to arrange various filter devices one after the other in relation to the principal direction of flow of the foreign-particle-laden air, where these filter devices fulfill different functions. For example, it is known to collect coarser foreign particles in a filter bag and to then pass the air flowing out from the filter bag through a fine-pore filter cloth so that any remaining fine foreign particles can also be filtered out before the air is blown out into the atmosphere. The pore size of the respective filter device must be suitably selected for such a functional allocation to the individual filter devices.
In order to filter out very fine foreign particles from the air, so-called HEPA (High Efficiency Particulate Air) filters are frequently used in vacuum cleaners. These mostly consist of a glass fibre composite which is disposed in a support material, for example, paper. Very small particles damaging to health, especially allergy-triggering substances can be removed from the air to be blown out by means of these HEPA filters. These substances include, for example, pollen, fungi and mites or their metabolic products or constituents.
Although good results are achieved using these HEPA filters, it is nevertheless to be considered as disadvantageous that the filters have an expensive structure and must be exchanged after a certain operating time because they are contaminated. It is also known to use filters made of ceramic material. An example of a vacuum cleaner with a ceramic filter device is disclosed in WO 01/41619 A1.
In connection with ceramic filter devices, it has already been suggested in an unpublished patent application to use such a filter which can be cleaned pyrolytically, that is by heating. Ceramic foams consisting of aluminium dioxide, for example, are suitable for this purpose.
The term ceramic filter device is to be understood in the present connection as any filter device which is provided in a cleaning appliance for air to be cleaned to flow through. In connection with vacuum cleaners, the ceramic filter device can, for example, form a preliminary, main or final filter device. At the same time, it is especially also possible for the ceramic filter device to form completely or partly a dust collecting container which replaces a conventional filter bag. Furthermore, a ceramic filter device provided according to the invention can additionally or alternatively replace a conventional HEPA filter.
In the generic cleaning appliances it is provided to clean pyrolytically at least one ceramic filter inside the cleaning appliance. For this purpose the heating device provided in the cleaning appliance heats the ceramic filter to 400° C. or higher. However, the maximum limiting temperature at an ABS part provided adjacent to the filter must not exceed 90° C. for example and 110° C. at a PP part for example. Thus, sections of the housing adjacent to the filter are cooled during and after the pyrolytic cleaning by a cooling air stream which can be produced, for example, by means of the main drive motor of the cleaning appliance which is supplied by the primary energy source in the same way as the heating device. In this case, in known solutions it is absolutely essential that the cleaning appliance is supplied up to the end of the cooling process by the primary energy source, which can be formed in particular by the public power supply without being restricted thereto. If the primary energy source fails, for example, because a user pulls the mains plug prematurely, as a result of the lack of cooling, overheating can occur in the device and result in a fire in the worst possible case.
It is the object of the invention to further develop generic cleaning appliances such that any overheating or a fire can be reliably avoided if the primary energy source fails during or (shortly) after a pyrolytic cleaning of the filter.
This object is solved by the features of claim 1.
Advantageous embodiments and further developments of the invention are obtained from the dependent claims.
The cleaning appliance according to the invention builds on the generic prior art by the fact that a secondary energy source is provided which can be used to generate the cooling air stream at least if the primary energy source fails. By means of this solution the cooling air stream required to avoid overheating or a fire can be generated in any case, even if the primary energy source fails. A failure of the primary energy source is to be understood in this connection as any state in which the required cooling air stream cannot be generated without the secondary energy source although a cooling air stream is required.
In specific embodiments of the cleaning appliance according to the invention, it can be provided that the secondary energy source comprises a fuel cell. In this connection so-called “mini fuel cells” are especially considered. These mini fuel cells can deliver a power output of 50 W or more, for example, with a space requirement and weight as for conventional batteries or rechargeable batteries.
Additionally or alternatively, it can be provided that the secondary energy source comprises an energy storage device, especially an energy storage device which is charged by the primary energy source. In the simplest case, the energy storage device can be formed, for example, by conventional disposable batteries.
In especially preferred embodiments of the cleaning appliance according to the invention, it can however be provided that the energy storage device is formed by a rechargeable battery which is charged by a charging device supplied by the primary energy source. Possible rechargeable batteries in this context are commercially available types of batteries, especially lithium ion cells. In many cases, an electrical fast charger can advantageously be used as charging device.
Furthermore, in preferred embodiments of the cleaning appliance according to the invention it is provided that the cooling air stream is generated by at least one fan at least if the primary energy source fails. The at least one fan is preferably a fan provided separately from the drive motor of the cleaning appliance.
If is furthermore preferred if a control and/or regulating device is provided, especially a control and/or regulating device which controls the fan. The control and/or regulating device can in this case especially comprise a microprocessor and at least in certain embodiments it can also be provided for controlling or regulating the normal operation of the cleaning appliance.
In this context it is preferred that the control and/or regulating device controls the charging device. This solution is especially considered when the charging device comprises a electrical fast charger.
In a preferred further development of the cleaning appliance according to the invention it is provided that current temperature information is supplied to the control and/or regulating device. The current temperature information preferably relates to the temperature in the areas adjacent to the filter since the temperature in these areas is the first to reach critical values if the primary energy source fails.
In this case, it is preferably provided that the current temperature information is obtained by means of at least one temperature sensor. A Pt 100, for example, is considered as a temperature sensor.
A likewise advantageous further development of the cleaning appliance according to the invention provides that information on the current state of the secondary energy source is supplied to the control and/or regulating device. For this purpose, for example, the initial voltage of a rechargeable battery forming the secondary energy source can be tapped and supplied to the control and/or regulating device. In this way, the charging process of the rechargeable battery can be optimised among other things.
It is also considered to be advantageous if it is provided that information on the current state of the primary energy source is supplied to the control and/or regulating device. This in particular allows the control and/or regulating device to directly detect a failure of the primary energy source and introduce suitable measures immediately, especially by activating the fan.
Independently thereof, it can be provided that the control and/or regulating device controls the heating device. For example, the control and/or regulating device can control a control circuit associated with the heating device, in the form of a driver circuit, for example, in order to adjust suitable temperatures for the pyrolytic cleaning in normal operation depending on the output signal of one or more temperature sensors.
A particularly preferred further development of the invention provides that the control and/or regulating device only activates the heating device for carrying out a pyrolytic cleaning of the filter when the secondary energy source can provide sufficient energy for generating the cooling air stream. Whether the secondary energy source can provide sufficient energy for generating the cooling air stream can be determined, for example, by monitoring the charging state of a rechargeable battery forming the secondary energy source.
For all embodiments of the invention it is preferred that the filter is a ceramic filter. The advantages explained initially are achieved using the ceramic filters currently available. However, the invention is fundamentally also applicable to filters made of different material if these filters are cleaned by pyrolysis.
A likewise preferred further development of the invention provides that the capacity of the secondary energy source is at least so large that the maximum stored thermal energy in the filter during a pyrolytic cleaning process is released to the surroundings by means of the cooling air stream. The required cooling time is determined according to the size or the mass of the filter used and the specific heat capacity c. The quantity of heat is calculated using Q=c*m*Δt. For example, for a ceramic filter a temperature change At of 400° C. and a mass of about 0.75 kg can be assumed. The specific heat capacity of ceramic, between 0.8 and 1.2, thus yields a quantity of heat Q of 360 kJ. If a desired cooling time is about 60 min and the conversion 1 Wh=3.6 kJ, the electrical power is calculated as 100 Wh/2 h=50 W. This would, for example, require a rechargeable battery storage device of about 24 type Sub C cells (capable of delivering between 1.2 and 2.4 Ah) (=24*1800 mAh*1.2 V).
The basic idea of the invention is to be able to maintain cooling even when the power is interrupted at an unsuitable time. In this way, in many cases it is possible to dispense with secondary safety devices (for example, warning lamps or signalling devices) which would otherwise need to be provided for thermal cleaning processes of the ceramic filter. A user of the cleaning appliance according to the invention need not take any special precautionary measures although high temperatures must be produced in the cleaning appliance during the pyrolytic cleaning of the filter. In an especially advantageous fashion the energy storage device of the secondary energy source can be charged in any normal cleaning process if its charging state requires this.
A preferred embodiment of the invention is now explained as an example with reference to the drawings.
In the figures:
In normal operation the cleaning appliance shown is supplied with energy by means of the power supply 18 forming the primary energy source. For example, after a pre-determined number of operating hours has been reached or it is established as a result of pressure losses that the filter 10 needs to be cleaned, the control and/or regulating device 26 activates the heating device 12 by means of the control circuit 30. The heating device 12 heats the filter 10 for example to 400° C. or higher for the purpose of pyrolytic cleaning. In order that ABS and PP components of the filter housing 32 provided adjacent to the filter 10 are not heated above temperatures of 90° C. or 110° C., during or after the pyrolytic cleaning of the filter 10 a cooling air stream is passed between areas of the filter housing 32 at risk and the filter 10. In normal operation of the cleaning appliance this cooling air stream can optionally be generated by devices other than the fan 24. Before the control and/or regulating device 26 triggers the pyrolytic cleaning of the filter 10, in the embodiment shown it checks the charging state of the energy storage device 20 which, in normal operation of the cleaning appliance, is charged by means of the fast charger 22 likewise controlled by the control and/or regulating device 26. As an additional safety measure the control and/or regulating device 26 only triggers the cleaning process of the filter 10 when the current charging state of the energy storage device 20 ensures that the required cooling air stream 16 can be generated in any case if the primary energy source 18 fails.
It is assumed hereinafter that the user of the cleaning appliance disconnects the cleaning appliance from the mains 18 at the point when the filter 10 has been heated by the heating device 12 to the maximum temperature of 400° C. or more. Since the control and/or regulating device 26, as shown, is also connected to the supply leads provided for connection to the mains 18, the control and/or regulating device 26 immediately detects that the primary energy source 18 has failed. In response thereto, the control and/or regulating device 26 activates the fan 24 which immediately generates the cooling air flow shown 16. In the case shown the control and/or regulating device 26 controls the fan 24 as a function of temperature information supplied by the temperature sensor 28 so that a closed control circuit is formed. As soon as the temperature detected by the temperature sensor 28 has fallen to non-critical values, the control and/or regulating device 26 deactivates the fan 24 since there is no longer a risk of overheating or a fire at this point.
The features of the invention disclosed in the preceding description, in the drawings and in the claims can be important for the implementation of the invention both individually and in arbitrary combination.
10 Filter
12 Heating device
14 Adjacent areas
16 Cooling air stream
18 Primary energy source
20 Secondary energy source
22 Charging device
24 Fan
26 Control and/or regulating device
28 Temperature sensor
30 Control circuit
32 Filter housing
34 Air inlet
36 Air outlet
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 21 976.5 | May 2003 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/05304 | 5/17/2004 | WO | 00 | 11/20/2006 |
