Refrigeration – With separator-clarifier for cooled fluid or ice-melt
Reexamination Certificate
1999-08-25
2001-03-13
McDermott, Corrine (Department: 3744)
Refrigeration
With separator-clarifier for cooled fluid or ice-melt
C062S239000
Reexamination Certificate
active
06199397
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an air-conditioning installation with an activated carbon filter for cleaning the air to be supplied to the interior of a motor vehicle, in which a device is provided for cleaning by heating of the filter and the air therein, and air laden with by-products can be driven out of the filter by a cleaning airflow.
BACKGROUND OF THE INVENTION
It is known to equip air-conditioning installations of motor vehicles with filters, particularly with activated carbon filters. The filters clean the air being supplied to the vehicle interior of strongly smelling and/or toxic components. However, the absorbing power of activated carbon drops off over time, so that the activated carbon has to be cleaned or exchanged. Because the exchanging of the activated carbon filter, particularly with motor vehicles, is associated with high expenditure and high cost, ways for effective regeneration of the activated carbon are sought.
It is known, for example, to install a heating device, on the air intake side, in series with the activated carbon filter. The heating device heats up the airflow through the filter and hence the filter itself, and which leads to a desorption of the residues in the filter. The contaminated airflow can then be led away to the environment. The disadvantage of this series-connected heating it is that the cleaning takes place in an adiabatic process. Because the airflow is cooled down on passing through the filter by vaporising of the contamination, the desorption process is longer and hence the external energy consumption for the blower is comparatively high.
On the other hand, filters with activated carbon filling are known, in which rod-shaped electrical heating elements are inserted directly into the mass of activated carbon, so that they heat the activated carbon itself. With the heating rods inserted vertically, it is not possible to heat the entire filter uniformly.
It is a further disadvantage that the heat conduction into the activated carbon surrounding the heating rod is so slight that the heating rods have to be heated to a particularly high temperature in order to produce a sufficient temperature for the cleaning. The heating rods, heated to high temperature, therefore present a great danger as regards ignition of the carbon in contact with the heating rods. A cleaning installation of this type does not meet modern-day safety standards, so that it is impossible to install it in motor vehicles.
OBJECT OF THE INVENTION
Hence the object of the invention is to provide an air-conditioning installation for motor vehicles, with a facility for cleaning the activated carbon filter in which risk-free and effective cleaning is possible at little expense in terms of construction.
SUMMARY OF THE INVENTION
An air-conditioning installation with an activated carbon filter for cleaning the air to be supplied to the interior of a motor vehicle, in which a device is provided for cleaning by heating of the filter and the air therein, and air laden with by-products is driven out of the filter by a cleaning airflow. The activated carbon is in physical contact with a temperature-regulated or temperature-controlled heating device, with which the activated carbon and the air present in the filter can be heated, while the cleaning airflow flows through the filter.
A first advantage of the heating device in accordance with the invention is that, in the uniformly heated filter, isothermal desorption can take place at a pre-set and regulated temperature of, for example, 90° C. In that way cleaning of every area is made possible, and thus a well-nigh complete regeneration of the filter. With heating strips implanted, and particularly with heating elements for PTC heating (Positive Temperature Coefficient heating) whose electrical resistance increases with increasing heating until a cut off, ignition of the activated carbon is precluded. Thus, the heating device in accordance with the invention meets the modern-day safety standards and can be built into motor vehicles. With the heating device in accordance with the invention, the temperature can therefore be continuously monitored, such that control and regulation of the temperature can take place via temperature probes integrated into the filter or positioned after the filter. It is particularly advantageous for even heating of the filter for the heat conduction to be increased by conducting webs. The heating device in accordance with the invention generally offers high dependability with compact installation within the air-conditioning system.
At the same time the heating elements installed in accordance with the invention guarantee low flow resistance in the filter, so that the performance required from the blower motor is comparatively low. This leads to a substantial reduction in the electrical energy requirements.
As an additional advantage, the device in accordance with the invention can be integrated into all normal activated carbon filters, for example in stacks of activated carbon pellets, but particularly in a filter of monolithic form. An advantage of the monolithic form of filter is that it can be particularly well sealed at its edges and therefore preclude leakage flows of uncleaned air. Because the heating strips laid out in loops, or the plate-shaped heating elements of the PTC heating facility arranged essentially horizontally, a particularly uniform heating of the entire filter is guaranteed.
In a particularly simple embodiment, the heating device is formed by a resistive strip, which is embedded in a zig-zag shape in the activated carbon, and through which a defined current flows. This method of heating will advantageously be used when the cleaning takes place on the occasion of an inspection in the workshop and the heating device can be connected to an external selectable supply voltage. In this case it is also advantageous for an external blower to be employed to produce the airflow required for the cleaning. The airflow in this case can be led in through an opening in the blower channel on the intake side of the filter, while contaminated air is led away out of the installation.
In another embodiment, the heating device is connected to the on-board voltage of the motor vehicle, so that cleaning is also possible outside the workshop while the vehicle is in operation. With this cleaning, which is autonomous and thus saves on maintenance costs, it should also be noted that the outgoing air originating from the cleaning can be led away completely out of the blower duct. To that end it is advantageous for the blower duct on the outflow side, after the filter, to have a closable exit aperture, through which air can be removed.
As explained, it is advantageous to install the heating device in solid blocks of activated carbon, which are constructed as honeycomb structures, perforated structures or as bundles of pipes of narrow internal diameter. In order to build in the heating device, recesses are milled into the solid block at the corresponding points at which the heating elements will be installed. In another manufacturing technique, the heating device, which is introduced into a spongy substrate, is enclosed in grown-on or sprayed-on activated carbon.
REFERENCES:
patent: 4696225 (1987-09-01), Weller
patent: 5954577 (1999-09-01), Meckler
patent: 19603866 (1992-01-01), None
patent: 196 03 866 (1997-08-01), None
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patent: 196 43 492 (1998-04-01), None
patent: 196 53 964 (1998-06-01), None
patent: 2248195 (1992-01-01), None
Germany Search Report dated Jan. 29, 1999.
Jirmann Horst
Khelifa Noureddine
Jiang Chen-Wen
McDermott Corrine
Morgan & Finnegan , LLP
Valeo Climatisation
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