GB2073389A - Tumbler dryer - Google Patents

Abstract

A tumbler dryer for clothes has a drying drum (11) driven by an electric motor (10) through the intermediary of a belt (20) passing around a first pulley wheel (19) mounted on the motor (10) and a second pulley wheel (21) on the drum (11). The pulley wheel (19) has a coaxial integral friction wheel (17) and the pulley wheel (19) and its associated friction wheel (17) are mounted in bearing means carried by the housing of the electric motor (10) such that the friction wheel (17) is constantly urged into driving engagement with a motor shaft (16) of the electric motor. <IMAGE>

Description

SPECIFICATION Tumbler dryer The invention relates to a tumbler dryer, particularly but not exclusively for domestic use.

Such previously proposed tumbler dryers incorporate a drying drum driven by an electric motor through the intermediary of a belt drive system.

In previously proposed tumbler dryers of this kind, such as described, for example, in German OS 2,412,233, on the armature or motor shaft of the electric motor, a gear wheel is axially mounted and drives a pinion axi-ally parallel to it which in turn is non-rotatably connected to the belt pulley which drives the belt of a belt drive system. This form of construction however is expensive.

An object of the present invention is to provide a tumbler dryer having a drive arrangement which is constructed and arranged in a manner which is simpler and less expensive to manufacture than previously proposed arrangements.

According to the present invention, there is provided a tumbler dryer for clothes and having a drying drum driven by an electric motor, characterised in that there is provided a first pulley wheel for driving a belt connectible to the drying drum; bearing means carried on the housing of the electric motor and on the outside of which said first pulley wheel is mounted; and a friction wheel non-rotatably connected to said first pulley wheel so as to be coaxial therewith and mounted on said bearing means whereby it can be constantly urged into contact with an axially parallel motor shaft of the electric motor both prior to and during operation of the tumbler dryer.

This arrangement of the wheel drive system, in which the armature or motor shaft itself provides the primary drive wheel of the drive system, is an extremely simple structure and inexpensive to manufacture. Moreover, since the friction wheel and the first pulley wheel are mounted on bearing means such as an end bearing plate of the electric motor, the accurate positioning of their common rotary axis relative to the rotary axis of the armature shaft presents no problem and can be executed with minimum cost.Furthermore, the distance between these two rotary axes remains constant in operation because the bearing for the armature or motor shaft adjacent the friction wheel is also mounted on the bearing plate, and in the case where, as is preferably provided, the distance between the rotary axes of the armature shaft and of the friction wheel is adjustable, the particular adjustment made also remains constant. The friction wheel is preferably located in close priximity to a first bearing plate, so that the pressure exerted by the friction wheel on the motor shaft is largely taken up by the bearing for the motor shaft located in this bearing plate.In this way it is possible to obtain a very satisfactory arrangement, and if necessary, adjustment of the friction, wheel relative to the motor shaft, so that wear on the facing of the friction wheel is reduced and also slip of the friction wheel is maintained at a low level. By this arrangement, the reliability of the friction wheel drive in operation is also improved. Structurally, this arrangement of the first pulley wheel is also extremely simple and inexpensive to produce.

The friction wheel is preferably urged against a portion of the motor shaft which extends outwardly beyond the aforesaid end bearing plate. Thus, the friction wheel is positioned outside the motor housing and is consequently very easily accessible and also very efficiently cooled. It is also possible to produce the pulley wheel as an integral part of the body of the friction wheel which carries friction facing material. This reduces the cost of production further and automatically ensures an extremely accurate and permanent alignment of the friction wheel with the first pulley wheel. The friction wheel, however, may be mounted on its associated bearing plate within the housing of the electric motor, provided that there is sufficient room in the housing to accommodate it.

A particularly simple rotary bearing for the friction wheel and the first pulley wheel is provided if the friction wheel and the pulley are rotatably carried on a journal mounted in the bearing plate in question. If desired, this journal may also be cast integral with the bearing plate or be fitted separately. The journal is preferably in the form of an eccentric shaft which is journalled in a bore of the bearing plate and can be locked in various angular positions for the purpose of adjusting the distance between the rotary axis of the friction wheel and that of the motor shaft. The arrangement for locking the journal of the eccentric shaft is preferably one in which the bearing which supports the journal is constructed for this purpose. Other locking systems are also possible which preferably permit of stepless adjustment of the shaft's angular position.

An arrangement is also possible, although admittedly generally somewhat more costly to produce, whereby the friction wheel and the first pulley wheel are mounted on a shaft which is journalled in a bearing provided on the appropriate end bearing plate of the electric motor and is freely rotatable at all times about its longitudinal axis. The bearing mounted on the bearing plate is preferably a roller bearing. It may also be possible to employ a plain bearing, preferably one of sintered steel.

The external diameter of the friction wheel is preferably greater than that of the first pulley wheel. This arrangement enables the motor shaft to be extended to a point above the first pulley, or over and beyond said pulley, preferably in order to accommodate the impeller of a blower which is secured to the end-portion of the shaft extending beyond the first pulley.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing in which: Figure 1 shows an electric motor which drives a domestic drying drum, having friction wheel drive means and belt drive means, according to an embodiment of the invention, the motor being shown "broken" and the equipment partly in section and partly cutaway, and Figure 2 is a fragmentary sectional view on the line 2-2 of Fig. 1 and to an enlarged scale.

Referring- now to Fig. 1, an electric motor 10 is housed in a cabinet (not illustrated) of a domestic tumbler dryer for clothes and drives a rotatable drying drum 11 in which the clothes to be dried are loaded. When the drum is in operation, it rotates about a horizontal axis, with a reversing action, so that a strong current of warm, drying air circulates through the clothes in the drum. This warm air can then be drawn off as exhaust air, or, where recirculation is employed, may be demoisturised in a condenser and returned under pressure to the drying drum 11 to continue the drying process.The conveyance of this warm air is preferably effected by a blower impeller (shown chain-dotted at 13), which is secured to a motor (armature) shaft 16 of the electric motor 10 at its left-hand end-portion 15 (as shown in Fig. 1) which extends out and beyond a left-hand end bearing plate 14 of the motor 10.

The electric motor is in drive connection with the drying drum 11 by way of a friction wheel drive between the motor shaft 16 and a friction wheel 17. The friction wheel drive comprises a first pulley 19 integrally associated with the friction wheel 17, a belt 20, and a cylindrical end-portion 21 of the drying drum 11 which is coaxial with the axis of rotation of said drum 11. Thus, the endportion 21 of the drying drum 11 forms a second belt or pulley wheel, partly encompassed by the belt 20 and forming an integral part of the wall of the drum 11.

Body 22 of the friction wheel 17 located in close proximity to end bearing plate 14' of the motor 10 carries on its circumferential periphery a facing 23 of friction material. In this embodiment, the wheel body 22 is integral with the pulley 19, so that the wheel body 22, together with the first pulley 19.

may be produced inexpensively as a single composite component, for example, by metal diecasting. A solid connection and also accurate alignment are thus ensured, whilst their rotary bearing has been simplified and is thus less costly. In this preferred embodiment, the friction wheel 17 and the pulley 19 are rotatably mounted by means of a single ball-bearing race 24 on an eccentric spindle 25 of an eccentric shaft 26, the circular cylinder shaft journal 27 of which is offset and axially parallel to the longitudinal axis of the eccentric spindle 25. The shaft journal 27 is rotatably carried in a throughbore in a right-hand end bearing plate 14' of the electric motor 10, which bore provides a bearing 28 for the journal.The periphery of this bearing 28 is intersected, however, by a vertical slot 29 extending radially therefrom, which is continued through the bearing plate 14', whereby the diameter of the bearing 28 can be restricted for the purpose of clamping the journal 27 by means of a tensioning screw 30 passing through the slot 29. The screw 30 passes firstly through a smooth cylindrical bore 31 in the bearing plate 14' with lateral play, and is then screwed into a blind threaded bore 32 on the other side of the slot 29. It will be readily understood from Fig. 2 that, by tightening this screw 30, the journal 27 can be clamped securely in the bearing aperture 28, so that it can no longer rotate.

When the tensioning screw 30 is released, the eccentric shaft 26 can be rotated, so that, by rotating the journal 27 in the bearing 28, the distance between the axis of rotation of the friction wheel, which coincides with the longitudinal axis of the eccentric spindle 25, and the axis of rotation of the motor shaft 16 can be adjusted until the friction wheel 17 is pressed sufficiently firmly against the motor shaft 16. On completion of this adjustment of the friction wheel 17, the screw 30 is again tightened, so that the eccentric shaft 26 can no longer rotate.

Should any further adjustment of the friction wheel 17 be required, or desired, this is easily carried out by releasing once again the tensioning screw 30 and rotating the eccentric shaft 26 into a new angular position, in which the friction wheel 22 again exerts sufficient pressure upon the motor shaft 16, whereupon the tensioning screw 30 is once more tightened.

The belt 20 is preferably a POLY-V-belt which has a plurality of parallel, longitudinal grooves on its tread and permits of a relatively small radius of flat annular groove 19' of- the first pulley 19, in which groove 19' the belt 20 runs, being guided upon the base of the pulley groove by its longitudinally grooved profile. The belt 20 requires no guidance upon the second belt or pulley wheel 21 formed by the periphery of the drying drum.

The second belt or pulley wheel 21 may have a diameter of, for example, 570 mm and the annular groove 19' of the pulley 19, a diameter of 50-mm. An idler may also be provided which is resiliently pressed against the belt 20 to tension it, and which is not shown.

In this embodiment, end-portion 15' of the motor shaft 16 extending beyond the bearing plate 14' enters the area encompassed by the belt 20, the arrangement being preferably such that the plane defined by the rotary axis of the drying drum 11 and that of the friction wheel 17 passes through the motor shaft 16, whereby the pressure exerted by the belt 20 upon the first pulley 19 acts in a direction which also urges the friction wheel 17 against the motor shaft 16, which improves still further the frictional contact between friction wheel 17 and shaft 16.

In this embodiment, the portion 15' of the motor shaft 16 extending beyond the bearing plate 14' is extended out beyond section 16, which is in contact with the friction wheel 17 and beyond the pulley 19, so that an impeller 13' (shown chain-dotted) of a blower can be mounted on the outer extremity of the shaft.

This arrangement permits circulation of air cooling the condenser in the case where the tumbler dryer is provided with air-recirculating means.

In many cases, the first pulley 19, together with the friction wheel 22, may also be so arranged that the portion 1 5' of the motor shaft does not pass through the area encompassed by the belt 20 but passes laterally outside this area defined by the belt 20. In this case, in order to fit the belt 20, or to replace it, when the impeller 13' is mounted on the portion 15' of the motor shaft, the axial distance between the impeller 13' and the eccentric shaft 26 must be sufficiently large to permit the belt 20 to be introduced between the shaft 26 and the impeller 13'.

Claims (16)

1. A tumbler dryer for clothes and having a drying drum driven by an electric motor, characterised in that there is provided a first pulley wheel for driving a belt connectible to the drying drum; bearing means carried on the housing of the electric motor and on the outside of which said first pulley wheel is mounted; and a friction wheel non-rotatably connected to said first pulley wheel so as to be coaxial therewith and mounted on said bearing means whereby it can be constantly urged into contact with an axially parallel motor shaft of the electric motor both prior to and during operation of the tumbler dryer.

2. A tumbler dryer according to claim 1, in which the friction wheel is urged into contact with a section of the motor shaft which extends outwardly beyond the bearing means, and is preferably located in close proximity to the bearing means.

3. A tumbler dryer according to claim 1 or 2, in which a body of the friction wheel carries on its periphery a facing of friction material, said body being integral with the first pulley wheel.

4. A tumbler dryer according to any preceding claim, in which the friction wheel and the first pulley wheel are rotatably mounted on a journal supported by the bearing means.

5. A tumbler dryer according to claim 4, in which said journal includes an eccentric shaft which can be-locked in various angular positions in said bearing means for the purpose of adjusting the position of the longitudinal axis of the eccentric shaft and on which the friction wheel is carried.

6. A tumbler dryer according to claim 4 or 5, in which the bearing means supporting the journal is adjustable to enable secure clamping of the journal.

7. A tumbler dryer according to any of claims 4 to 6, in which the bearing means includes a bore in the bearing means, a lot disposed radially to the bore along the length thereof, and a tensioning screw extending across said slot to enable clamping of the journal.

8. A tumbler dryer according to any preceding claim, in which the friction wheel and the first pulley wheel are secured to a shaft which is journalled in a bearing of the bearing means, so that they are freely rotatable at all times about their longitudinal axis.

9. A tumbler dryer according to any preceding claim, in which the external diameter of the friction wheel is greater than that of the first pulley wheel.

10. A tumbler dryer according to any preceding claim, in which the motor shaft extends through the area encompassed by the belt.

11. A tumbler dryer according to any preceding claim, in which the belt of the belt drive is, for drive purposes, in direct contact with a cylindrical portion of the drying drum.

12. A tumbler dryer according to claim 10 or 11, in which the plane defined by the rotary axis of the drying drum and that of the first pulley wheel passes through the motor shaft of the electric motor 10.

13. A tumbler dryer according to any preceding claim, in which an impeller of a blower is fixedly mounted on the extremity of the motor shaft adjacent the friction wheel.

14. A tumbler dryer according to any preceding claim, in which the motor shaft also extends beyond that end of the bearing means of the electric motor which is remote from the friction wheel, and an impeller of a blower is mounted on this shaft extremity.

15. A tumbler dryer according to any preceding claim, in which the bearing means comprises a pair of spaced end bearing plates each forming part of the electric motor housing.

16. A tumbler dryer substantially as hereinbefore described with reference to the accompanying drawing.