A DRYING MACHINE FOR LAUNDRY

Abstract: Clothes drying machine comprising an outer cabinet (4) in which a drum (5) for conlaining the clothes to be dried is rotatable about a horizontal axis. The drum ist formed by two metal half shells (7,8) which are separated by an electri­ cally insulating ring (9) and are connected with the electri­ cal mains and the ground of the machine, respectively, in or­ der to act as electrodes for detecting the moisture degree of the clothes. The electrodes are associated with a per se known residual moisture control means. The drum (5) has a central opening (10) which is supported by a corresponding collar (13) arranged inside the cabinet and provided with means for slidingly supporting the drum. At least one (16) of the means for slidingly supporting the drum also performs the electrical connection between the drum (5) and the residual moisture control device.

Description: The present invention relates to a drying machine for laundry, in particular a domestic dryer provided with a drum for the laundry supported within the cabinet of the machine to rotate about a horizontal axis and equipped with sensor electrodes for measuring the degree of residual moisture in the laundry. As is known, this type of machine is provided with sensor electrodes adapted to measure the conductance of the laundry and thus the degree of residual moisture therein in order to control the drying process and prevent the laundry from being damaged by any overdrying and overheating. These electrodes are joined up to the electric circuit of the machine and connected to the driving motor of the drum, to the motor of the fan and to the heating elements for the drying air. The sensor electrodes are generally disposed within the drum in such a way as to be in contact with the laundry during the entire drying phase and to produce electrical output signals corresponding to the different degrees of drying of the laundry during the operation of the machine. This drying machine for laundry is also provided with a suitable moisture control means consisting, for example, of an electronic comparator of the conventional type connected to the sensor electrodes by means of sliding contacts on the drum and designed to perform comparison between the electrical signals from the electrodes and further electrical reference signals corresponding to the various states of drying of the laundry. Upon attainment of the desired degree of drying, the control means switches off the heating elements and the driving motors of the drum and the fan, thereby ending the drying process of the laundry. European patent application no. 0136.491 from the same applicant discloses means for sliding support of the front flange of the drum consisting of bearings housed, either in fixed or in pivoting fashion, within a collar disposed inside the cabinet of the machine. It is known from the same applicant's European patent no. 0106283 to realize the sensor electrodes by means of the two metal half shells which form the laundry drum. The two metal half shells are separated by an insulating ring and connected to the moisture control means by means of the sliding contact of a brush on the raised edge of the front flange of the drum. It is evident that this sliding contact brush constitutes an additional component that complicates the construction of the machine and impairs exploitation of its internal space. It would thus be favorable, and is the main object of the invention, to obtain the electrical sliding contact function without using disadvantageous additional components. This and other objects are attained according to the invention by a drying machine for laundry, in particular of the domestic type as known from EP-A-0136491 and comprising the features of the characterising part of claim 1. The advantageous features of the invention will become clearer from the following description, intended as a nonrestrictive example, with the help of the adjoined schematic drawings, in which Fig. 1 represents a global perspective view of an inventive drying machine for laundry; Fig. 2 illustrates an enlarged radial section of the support means for the front flange of the laundry drum. Referring to Fig. 1, inventive drying machine 3 consists substantially of an outer cabinet 4 housing a drum 5 for the laundry to be dried and rotated by a motor 6 and by transmission means known per se and not shown. Machine 3 also comprises all those mechanical and electrical means (for example fans, pneumatic conduits, heating means for the drying air) necessary for its operation and sufficiently well known that they can be disregarded in the following description. As described in the above-cited European patent no. 0106283, drying machine 3 is provided with at least two single sensor electrodes for measuring the residual moisture in the laundry. In particular, drum 5 has a front opening 10 and consists of two half shells 7, 8 functioning directly as sensor electrodes and separated from each other by a ring 9 made of electrically insulating material. Drum 5 is supported in rotating fashion within cabinet 4 both in correspondence with the rear pivot pin, not shown, and in correspondence with the edge of front opening 10. Rear half shell 7 is connected electrically to ground in correspondence with the contact between the pivot pin of drum 5 and cabinet 4 of machine 3. Front half shell 8 is made alive by means of a sliding contact which will be described below and realizes the connection both with the power supply of machine 3 and with the terminal of a conventional electronic moisture control means joined up to the electrical circuit of the machine and not shown. The other terminal of the electronic moisture control means is connected to ground. As described in the above-cited European patent application no. 0136.491, the edge of front opening 10 of drum 5 is bent toward the front side of cabinet 4 (Fig. 2) by a horizontal piece 11 having an end 12 curved toward the rear side of cabinet 4. On the inside surface of the front wall of cabinet 4, a circular support collar 13 having an S-shaped radial section is fixed in correspondence with the edge of opening 10 of drum 5. Collar 13 has a portion 14 disposed internally at opening 10 of drum 5 and in a position below horizontal piece 11 of the edge thereof, and a portion 15 supported on curved end 12 of said edge. Portion 14 of collar 13 houses at least two bearings (only one bearing 16 being visible in the figures) made of antifriction material and adapted to effect the sliding support of edge 11 of drum 5. It must be pointed out that in inventive drying machine 3 at least one supporting bearing 16 is realized in antifriction material incorporating integrally an expedient percentage of material with elevated electrical conductivity (for example graphite). In this way, support bearing 16 advantageously also realizes the sliding contact for the residual moisture control means for the laundry, thus avoiding the use of a disadvantageous additional component (brush contacts or the like). Furthermore, this rationalizes in a simple way both the construction and the exploitation of the space inside the entire drying machine. Obviously, the invention can be modified and varied without going beyond the scope of the main features as claimed below. For example, the electrical conductivity of support bearing 16 can be realized by incorporating therein the metal elements or coating the surface thereof in contact with the drum by means of metal layers or metallic plating.

Claims: A drying machine (3) for laundry, in particular of the domestic type and comprising an outer cabinet (4) supporting in its interior, in such a way that it rotates about a horizontal axis, the drum (5) adapted to contain the laundry to be dried, the drum also being provided with a central opening (10) supported in a corresponding collar (13) disposed within the cabinet and provided with support bearings (16) for sliding support of the drum, characterized in that the drum (5) consists substantially of two metal half shells (7, 8) separated by an electrically insulating ring (9) and connected to the power supply and to the ground of the machine, respectively, in order to function as electrodes for sensing the moisture of the laundry and to co-operate with a drying control means (MC) known per se and connected with the sensor electrodes, whereby at least one sliding support (16) of the drum (5) also realizes the electric contact between the drum (5) and the means for controlling the residual moisture in the laundry contained in the drum (5) and that the sliding support is realized in anti-friction material and incorporates material with elevated electrical conductivity. The drying machine of claim 1, characterized in that the elcectrically conductive material incorporated integrally in the support bearing (16) consists of graphite.

Inventors: GRANDIN, GRAZIELLO, SACCIA, MAURIZIO
Applicants: INDUSTRIE ZANUSSI S.P.A.
Application year: 1989
Main classification: D06F58
IPC codes: D06F58