The present invention relates to an apparatus for cleaning of textile objects by a densified liquid state treatment gas, such as liquid carbon dioxide, in a treatment chamber in which a high pressure prevails during the treatment process in order for the treatment gas to remain in liquid phase at essentially ambient temperature, said treatment chamber, at one side gable thereof, being closable by means of a door and encloses a rotatably mounted wash drum supporting the textile objects to be cleaned, said wash drum being rotated by a driving device comprising an electric motor and possibly a transmission.
In an apparatus of the kind referred to, regularly, the choice has been made to place the driving device outside of the treatment chamber. There are a number of reasons for this and a first one is the high pressure prevailing in the treatment chamber during operation of the machine. Another reason is the treatment agent itself which in case of placing of the driving device in the treatment chamber can penetrate into the motor and the transmission affecting vital parts therein. One possible effect is electric short-circuit in the motor winding caused by the decomposition of the insulating varnish of the winding due to the contact with the treatment agent. Moreover, it is to be feared that the bearings of the motor may corrode and, as a result of the pressure cycling appearing during operation of the machine, the bearing grease can ferment to disappear from the bearings. As the treatment agent, liquid carbon dioxide or the like, is aggressive against certain kinds of rubber and plastics it is to be feared that the transmission, usually comprising a V-belt or a cogged belt made from rubber or plactics, can decompose and be destroyed.
In order to avoid the problems indicated the driving motor and the transmission can be placed outside of the treatment chamber but the solutions for transmitting rotational movement from the driving motor to the drum, situated in the treatment chamber, will be expensive. If a certain leakage is accepted a relatively complex sealing box can be used for a rotational shaft attached to the treatment drum, and in this way said rotational shaft can extend through a wall of the treatment chamber to be connected to the driving motor on the outside. Another solution, described in the patent publication US-A-5,267,455, involves the use of a magnetic coupling constituting a very expensive alternative.
Another solution to the problem of securing a good contact between the textiles and the treatment agent in the wash drum is disclosed in the patent publication US-A-5,651,276. According to this solution, instead of using a rotatable drum, a plurality of arrays of nozzles have been provided through which jets of treatment liquid are emitted. The intention is that these jets shall bring about the stirring of the laundry in the wash drum. The obvious drawback of this arrangement is that the jets of treatment agent give an uneven cleaning result as compared to the case in which a wash drum is rotated in a treatment drum partly filled with a treatment agent.
A further solution to the problem discussed is disclosed in the patent publication US-A-5,669,251. According to this solution the rotatable drum in the treatment chamber has been retained and in addition a plurality of rows of nozzles have been provided which emit jets of a treatment agent. These jets are used a.o. for rotating the wash drum. One drawback associated with this arrangement is that the jets of treatment liquid gives an uneven cleaning result. Another drawback is that by means of the jets only, it can be difficult to achieve a reliable rotation of the wash drum and, accordingly, an adequate stirring of the laundry.
Accordingly, it is an object of the invention to remedy the drawbacks associated with the use of jets of a treatment liquid for the cleaning of the laundry and for stirring of the same and/or rotation of the wash drum. Another object of the invention is to eliminate the need for couplings between the wash drum in the treatment chamber and a driving device situated outside of the treatment chamber. A further object of the invention is to facilitate service on a driving device provided for the rotation of the drum.
The objects indicated are achieved in an apparatus which, in accordance with the invention, have been given the characteristic features indicated in the appendant claims.
A closer study of the conditions for placing the driving device, and the possible transmission, inside of the treatment chamber has shown that such placing is actually possible if certain measures are taken. It has been noticed that electric short-circuits can only take place via impurities in CO2-liquid. A first measure is therefore to see to it that the liquid level in the treatment chamber does not exceed half of the drum height and to place the driving motor as high as possible in the treatment chamber. Both as liquid and as gas carbon dioxide is a good insulator, however, by this placing, where the motor will get into contact with gaseous carbon dioxide only and to a minor extent will be exposed to splashes of liquid carbon dioxide, the risk is highly reduced that impurities in the CO2-liquid accompany the liquid splashes to penetrate into the motor. In order to further reduce the risk of electric short-circuit due to CO2-liquid attacking the protective varnish of the motor winding the latter is chosen with a quality not influenced by the liquid.
The feared risk of bearing corrosion has been found groundless because water and moisture are bound to the CO2-liquid. Likewise, feared fermentation effects in the bearing grease have not come up. However, due to the pressure cycling it is important that the bearings be kept ventilated. This is achieved by means of bearings of the type RS provided with sheet metal sleeves having the effect of shielding but still ventilating the ball races.
As to the transmission, i.e. usually a V-belt or a cogged belt, such belt is usually chosen to be made from a material not penetrated and broken down by the carbon dioxide. One such material is PPSE, a TEFLON™ type material. In a practical embodiment a belt has been chosen made from polycloroprene marketed under the name "Poly-V-profile" by the German company OPTIBELT.
The invention will now be described more in detail in connection with an embodiment and with reference to accompanying drawings, in which:
The invention relates to an apparatus for cleaning of textile objects by a densified liquid state treatment gas, such as liquified carbon dioxide, in a treatment chamber. The apparatus, hereinafter referred to as a washing machine, in addition to the treatment chamber and the wash drum rotatably disposed therein, comprises a plurality of further components and a control device for the control of the washing machine. A view of the design of such washing machine can be obtained from the patent publication US-A-5,267,455, referred to above. The description given below will be restricted to the treatment chamber and the arrangement therein.
With reference to Fig. 1 a treatment chamber 10 is shown in the form of a drum-shaped outer container in which a wash drum 12 is rotatably disposed. The treatment chamber 10 is designed to resist high pressures and is closable by means of a door 14 together with suitable locking means, not shown. The wash drum 12 is provided with a shaft 16 journalled in bearings 18, 20 provided in a bearing housing 22. A pulley 24 is attached to the free end of the shaft 16 and is intended, via a transmission belt 26, to be connected to a corresponding pulley 28 provided on the shaft of an electric drive motor 30. The drive motor is excentrically disposed with respect to the shaft 16 of the wash drum at as high level as possible in the treament chamber 10.In order to prevent the treatment liquid, in the example the liquid carbon dioxide, from filling up spaces where it is of no use, i.e. outside of the space where the wash drum is rotating and the cleaning of the laudry takes place, the spaces not occupied by the shaft support and the driving device for the wash drum are filled with a suitable material, such as a plastics material or aluminium, as schematically indicated by 32 in Fig. 1. The power supply to the electric motor 30 takes place via a pressureproof coupling device 34 to which connects an outer lead 36. A corresponding inner lead 38 connects to the motor 30. Such pressureproof coupling devices are available in the market where a suitable design can be chosen.
During the cleaning process in the washing machine the wash drum 12 is rotated by the drive motor 30 via the transmission belt 24 in the same way as in washing machines intended for water wash. By placing the drive motor 30 excentrical with respect to the drum shaft 16, axially the motor will occupy essentially the same space as the support 18, 20 for the drum shaft 16 resulting in a very compact design of the driving device. By the built-in design of the driving device no drive components will be required which call for space outside of the treatment chamber 10.
Even if components of the driving device can be made very reliable the washing machine should still be designed so as to facilitate service on the driving device and the drum support components. Hence, in accordance with the invention the treatment chamber 10 comprises a sledge device 40 provided to movably support the wash drum with the shaft support and the driving device, the sledge device 40 being adapted to alternatively take a first position in the treatment chamber 10 or a second position outside the same. As shown in Figs. 2 and 3 the sledge device is formed mainly by the bearing housing 22 provided for the bearings 18, 20, said bearing housing (22) having wheels 42 suitably distributed along the inner periphery of the treatment chamber 10. The wheels 42 are rolling on and steered by longitudinal races 44 fixedly mounted to said inner periphery of the treatment chamber 10. On repair and maintenance of the components of the sledge device 40 said device is manually moved from its position in the treatment chamber to a service position adjacent to the loading opening of the treatment chamber. In case of more extensive service the sledge device 40 and components supported thereon can be transferred to a handling carriage, or the like, by means of which it can be transported to a suitable workshop. Of course, the sledge device can be moved from its normal position in the treratment chamber to the service position by means of motor operated means of a suitable design.
Above, the invention has been described in the form of an embodiment of no-limiting nature. Accordingly, a plurality of modifications can be made within the scope given by the appendant claims. For example, the wheels of the sledge device can be replaced by gliding cushions or the like.