GB2308430A - Tumble drier with a rotatably mounted laundry drum - Google Patents

Description

2308430 Tumble drier with a rotatably mounted laundry drum The invention

concerns a tumble drier according to the preamble of claim 1.

Tumble driers of this kind are generally known. In such tumble driers during the usual drying process for the largest part of the drying time the laundry drum is turned in one direction or in changing directions. The damp laundry is thereby moved in the laundry drum and loosened at the same time. Through the mechanical treatment of the laundry carried out during the course of the drying process an intense abrasion of the individual items of the laundry occurs however both mutually and at the circumference of the laundry drum, which can lead to damage primarily to sensitive items of the laundry. If the rotation of the laundry drum is not changed, the laundry remains lying in the bottom part of the laundry drum and the warm drying airstream flows over it virtually ineffectively.

The object of the invention, is to improve a tumble drier of the kind referred to so that drying of laundry therein is possible with reduced and/or least mechanical requirement. To this end it should also be ensured that the laundry is sufficiently treated with drying air primarily in the regions directed towards the laundry dru m wall.

This object is, achieved according to the invention by the features of the characteristicing part of claim 1 and/or 2.

Further preferred features and advantages of the invention are indicated in the subordinate claims.

Through the proposal according to the invention the mechanical demand on the laundry during the drying process is significantly reduced, so that in a tumble drier thus equipped easy-care items of the laundry in particular and above all, small loads of washing can be dried gently.

2 The invention will be described by way of example with reference to two embodiments shown in the drawings.

The invention is illustrated diagrammatically in the drawings, in which:

Figs 1 and 2 each show a tumble drier in section,and Fig. 3 shows a section through the laundry drum.

A rotating laundry drum 1 of an electric tumble drier 2 has in its interior 3 a cylindrical laundry holding insert 4 (laundry drum insert) of smaller diameter and in its drum rear wall 5 a drying air feed 6, which consists of a plurality of openings 7. The laundry holding insert 4 is entrainingly inserted in the interior 3 of the laundry drum 2. That is to say that it is joined interlockingly with the laundry drum 2 and thereby entrained by the latter. The drying air feed 6 extends in an annular shape around the central region of the drum bearing 8.

The laundry drum 1 is sealed relatively to the dryer outside casing 9 with a sealing ring 10 in known manner. In the rear wall of the dryer outside casing 9 a drying air-shaft 11 is formed, through which drying air supplied from a blower not shown passes over an electric heating element 12 to the annular drying air feed 6 and through the openings 7 thereof into the interior 3 of the laundry holding insert 4 and thereby reaches the laundry 13 to be dried and located therein. This drying air leaves again via the laundry drum loading opening 14 The openings 7 of the annular drying air feed 6 in the rear wall 5 of the laundry drum correspond with the interior 3' of the laundry holding insert 4 (laundry drum insert). The drying air-shaft 11 ends at the outer circumference 15 of the annular drying air feed 6 and thus in the circumferential area 4' of the laundry holding insert 4. Thereby a concentrated supply of the drying air emerges in the interior 3' of the laundry holding insert 4. The drying load 13 is held in the center of the laundry holding insert 4, is randonfly tumbled there and thus is treated by the drying air that is suppIlied and aimed directly so that it flows around the load and acts thereon from all sides. The drying process can be accomplished according to program interpretation with a stationary or only slightly moving laundry drum 1 or with a normally moved laundry drum. The circumferential area 4" of the laundry holding insert 4 is constructed with a closed periphery.

3 A perforated construction of the periphery of the laundry holding insert would however be conceivable.

In the embodiment according to Fig. 2, in which the same parts are indicated with the same reference numerals, the rotating laundry drum 1 has in its interior 3 at least two laundry entraining ribs 16, 1C, which serve to turn the laundry 13 during the drying process. The laundry entraining ribs 16, 16' are somewhat V-shaped in cross-section are wellrounded towards the interior 3 of the laundry drum 1. In addition the periphery 17, 17' of each of the laundry entraining ribs 16, 16' is perforated and/or punched and their rearwardly directed ends are open. Respectively each one of the laundry entraining ribs 16, 16' when in a lower position is then connected with the rear air-shaft 11 for the drying air via its lower air outlet opening 27. The rear drying air feed for the interior 3 of the laundry drum 1, which is formed from a plurality of openings 7 existing is in this embodiment divided expediently into two separate drying air feed partial planes 26a and 26b, whereby via the outer partial plane 26a, only the laundry entraining rib 16 and/or 16' which is respectively in the lower position, and via the inner partial plane 26b, which is constructed as an annulus in the rear wall 5 of the laundry drum, only the interior 3 of the laundry drum 1, is supplied with drying air. To ensure this and to enable the respective laundry entraining rib 16 andlor 16' to feed a certain proportion of the drying air supplied through the air-shaft 11, these ribs are furnished with a raised air guide wall 19 to increase the drying air access from the air-shaft 11 to the interior 18 of the entraining ribs, the wall 19 ending in the region of the air-shaft outlet opening 27. The air-shaft 11 is extended above the laundry drum mounting 20 to such an extent that it lies opposite and in the same plane as the end piece 19' of the laundry enchanging rib air guide wall 19 bounding the air-shaft outlet opening 27, so that the laundry enchanging rib 16 or 16' that is respectively in the upper position has no air flow connection to the air- shaft 11. Thus, it is ensured that the drying load 13 in the interior 3 of the laundry drum is only supplied with drying air respectively via the laundry enchanging rib 16 or 16' that is in the lower position, over its length, as well as via the annular feed partial plane 26b. A laundry drum with only one larger laundry enchanging rib or more smaller laundry enchanging ribs would also be conceivable. A suitable drive can be provided in each case for the laundry drum and the blower for the supply of drying air. If only a single drive is available for the laundry drum and the blower, the laundry drum can be coupled 4 or uncoupled with the drive as required.

The fundamental working principle of the above described tumble drier is as follows: the drying air stream fed to the laundry drum 1 is in this case divided into two planes so that a partial flow is supplied via the feed partial plane 26 directly axially into the interior 3 of the laundry drum, whereas the other partial flow is supplied via the outer partial feed plane 26 and via the laundry enchanging ribs 16 or 16' that is respectively below the laundry 13 to be dried. During this drying air supplying process the laundry drum can be moved continuously intermittently with a very low rotary speed of, for example, 1-10 revolutions per minute. For the loosening of the laundry it is useful to move the laundry drum in a programmably determined time sequence through one or more full rotations at a higher rotary speed of, for example, about 50-60 revolutions per minute, it also being possible to carry out such a movement of the drum with reversing rotation.

A program-controlled drying process could also be carried out in such a manner that the laundry drum is moved intermittently so that when the laundry drum is stationary at least one of the open laundry enchanging ribs corresponds with the air outlet opening 27 of the air shaft 11 and remains in this position for some time. In this drying process the individual laundry enchanging ribs are moved successively into the lower position for supply of drying air in a programcontrolled time sequence. This time sequence represents an optimum as regards loosening of the laundry to be dried with most careful movement of the laundry. An extremely slow continuous movement of the laundry drum would also be conceivable with the same result. A reversible drive of the laundry drum would likewise be applicable. As an alternative to this drying process, during continuous to and fro movement of the laundry drum the respective laundry enchanging rib could be maintained in a region of approximately 60' of angle from the lower dead centre of the laundry drum. Then one or more full rotations of the laundry drum at a higher rotary speed could be effected intermittently for the loosening of the laundry.

Claims (12)

Claims

1. A tumble drier with a rotatably mounted laundry drum with a perforated rear wall and a front loading aperture and a device for passing heated air through the laundry drum, wherein the heated air enters through the perforated rear wall and passes back out through the loading aperture, comprising a circular annular drying air feed in the rear wall of the laundry drum and a cylindrical laundry-holding insert which corresponds to the feed and which is inserted drivingly in the laundry drum interior.

2. A tumble drier with a rotatably mounted laundry drum with laundry driving ribs and a perforated rear wall and a front loading aperture and a device for passing heated air through the laundry drum, wherein the heated air enters through the perforated rear wall and passes back out through the loading aperture, comprising a drying air feed in the laundry drum rear wall, which is divided into two feed partial planes in such a manner that via the one feed partial plane the laundry drum interior can be directly supplied with drying air from the drying air shaft, whilst via the other feed partial plane only one of the laundry drive ribs in each case corresponds to the air outlet aperture of the drying air shaft in a certain position of the laundry drum and thus acts on the interior with drying air, the casing of the laundry drive ribs being formed with perforations.

3. A tumble drier acording to claim 1, wherein the drying shaft ends at the outer annular circle of the annular circular drying air feed and thus in the casing region of the laundry-holding insert.

4. A tumble drier according to claim 2, wherein the laundry drive ribs are provided with a drying air outlet from the air shaft to a raised air guiding wall which enlarges the drive ribs' interior, the air guide wall ending in the region of the air shaft outlet aperture.

5. A tumble drier according to claim 2 or 4, wherein the air shaft extends so far over the laundry drum mounting that it lies opposite or in the same plane as the end member of the laundry drive ribs air guiding wall which extends in the air shaft outlet aperture.

6. A tumble drier according to claim 2, wherein the drying air feed partial plane is in the 6 form of an annular circle, which corresponds to the interior of the laundry drum.

7. A method of operating a tumble drier according to claim 1 or claim 2, wherein during the drying air feed process the laundry drum is moved continuously or intermittently at a very low speed of e.g. up to ten r.p. m.

8. A method according to claim 7, wherein in a time sequence set by a program, the laundry drum is moved intermittently at a higher speed by one or more complete revolutions of approximately 50 to 60 r.p.m.

9. A method of operating a tumble drier according to claim 2, wherein the laundry drum is briefly stopped when a laundry drive rib corresponds with the air outlet aperture of the air shaft.

10. A tumble drier substantially as described herein with reference to Fig. 1 of the accompanying drawings.

11. A tumble drier substantially as described herein with reference to Fig.2 of the accompanying drawings.

12. A tumble drier substantially as described herein with reference to Figs. 2 and 3 of the accompanying drawings.