GB2078357A

GB2078357A - Tumble drier drive

Info

Publication number: GB2078357A
Application number: GB8113022A
Authority: GB
Original assignee: G Bauknecht GmbH
Current assignee: G Bauknecht GmbH
Priority date: 1980-04-30
Filing date: 1981-04-28
Publication date: 1982-01-06
Also published as: NL8101969A; FR2481722A1; SE8102680L; GB2078357B; DE8011829U1

Abstract

A tumble dryer for drying clothes has a drying drum 11, driven by an electric motor 10 through the intermediary of a wheel drive system, 16, 17, and a belt drive system 23, 24. The belt drive system incorporates a belt pulley 23 which is mounted on the housing of the electric motor 10 and the electric motor is pivotally mounted under tension whereby the belt pulley 23 can be urged into contact with belt 24 in order to maintain tension on the belt. <IMAGE>

Description

SPECIFICATION Tumbler dryer The invention relates to a tumbler dryer for drying clothes or the like.

Such tumbler dryers incorporating a drying drum driven by an electric motor through the intermediary of a wheel drive system and belt drive system has previously been proposed, for example in West German - OS 24 12 233. In such tumbler dryers the belt drive is powered by way of reduction gearing so that the electric motor may be of an inexpensive low-pole type. The gear drive is expensive, however, and the belt of the belt drive system must be tensioned by at least one tensioning roller, as is shown in the case of the tumbler dryer described in West German - OS 2207372. In this tumbler dryer, the drive belt pulley is mounted directly on the motor shaft, so that the gear drive can be dispensed with.However, because of the necessarily low rotational speed of the drying drum, in conjunction with the fact that the radius of the belt pulley must not be too small because of the belt, the motor must be of an expensive high-pole type due to the low rotational speed which this necessitates. Also, due to the low rotational speed, a fan serving to supply air for drying the clothes or the like cannot be mounted on the motor shaft.

Accordingly, it is an object of the invention to provide a tumbler dryer of the foregoing type in which the mechanism for driving the drying drum can be manufactured at lower cost.

According to the present invention, there is provided a tumbler dryer for drying clothes or the like, having a drying drum driven by an electric motor by way of through the intermediary of a wheel drive system and a belt drive system, characterised in that there is provided a belt pulley for driving a belt said belt pulley being mounted adjacent one end of the electric motor; a friction wheel coaxial with the pulley and formed integrally therewith, said wheel being capable of being urged into contact with a motor shaft of the electric motor, said shaft being axially parallel to the friction wheel axis but of a smaller diameter; and tensioning means for the belt whereby of the belt driven system pivotal movement of the electric motor can be effected about an axis which coincides with that of the motor shaft so that the belt pulley can maintain tension on the belt.

Since the belt pulley of the belt drive system which is driven by the friction wheel drive serves to tension the belt, special tensioning rollers are no longer required, whereby economies are gained in cost and in space which advantages are accompanied by improved reliability of operation and less wear on the belt.

Moreover, the friction wheel drive is structurally less complicated and less costly than a gear drive.

The electric motor can be a suitable low-pole asynchronous motor, preferably a two-pole squirrel cage motor.

A preferred arrangement is that the electric motor is pivotable about its axis of rotation during operation and is subject to a torsional moment which tends to move it in a pivotal direction resulting in the application of tension to the belt. This torsional moment can be produced preferably automatically or essentially by spring means. Alternatively, it can be produced by other means, for example by magnetic means or by gravity.

Where there is no risk of permanent stretching of the belt and where the belt is somewhat resilient longitudinally, it can also be possible for the electric motor to be capable of being locked in a given pivotal position in order to tension the belt, that is to say, the entire motor is pivoted about its axis or rotation, e.g. by hand, until the belt of the belt drive system has reached the required degree of tension.

The electric motor is then secured against further rotation, for example by its pivotal bearing being clamped to prevent rotation or by the motor being secured by a bolt engageable in an arcuate slot or the like.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a front view of a drive system for a drying drum, no other details of which drum are shown, the drum merely being indicated by part of its circumference, and Figure 2 is a side view of the drive system of Figure 1, partly in section.

A drive system for a clothes drying drum, which is indicated by a line 11 forming part of its circumference incorporates an electric motor 10 which is mounted on two pedestal bearings 13,13' secured to a base 12 of a housing for the tumbler dryer, so that it can be rotated about the rotational axis of its motor shaft 16. On each of two end plates 14, 14' of the casing of the electric motor 10 an annular cylindrical collar 18, 18' coaxial with the longitudinal axis ofthe motor shaft 16 is provided, each of which collars is carried, with enough play for rotation, in an annular cylindrical bearing aperture or journal bearing 19 in each of the pedestal bearings 13, 13'.

On those sections of the motor shaft 16 extending beyond each end of the motor 10, fans 20,20' (shown chain-dotted) can be mounted, one of which is intended to supply air for drying the clothes. In the case where there is fitted a condenser for removing the moisture from the drying air for the clothes, the second fan is intended to provide air for cooling the condenser. The motor shaft 16 of the electric motor 10 drives the drying drum 11 through the intermediary of a friction drive and a subsequent belt drive.

The friction drive comprises the motor shaft 16 and a friction wheel 17 urged permanently into contact with it and having a diameter several times larger than that of the motor shaft 16. The friction wheel 17 is rotatably mounted on a cylindrical journal 21 which is secured to the end plate 14' and is axially parallel to the motor shaft 16.

A drive belt pulley 23 is integrally formed and is coaxial with the body of the friction wheel 17 which has a friction surface. The belt pulley 23 forms part of the belt drive system, a belt 24 of which embraces a cylindrical non-recessed sector of the periphery of the drying drum 11 so as to subtend an angle of some 270 thus driving the drum. The belt 24 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 a flat annular groove of the drive pulley 23, in which groove the belt 24 runs and is guided on the base of the pulley groove by its multiple longitudinal grooves. The belt 24 requires no lateral guidance on the periphery of the drying drum 11.

In order to avoid the necessity for special tensioning rollers to tension the belt 24, the electric motor 10 is rotatably mounted in the pedestal bearings 13, 13' and is subject to the action of a tension spring 29 anchored to an eyelet 27 cast on to the end plate 14'.

The tension spring 29 exerts on the motor 10 a torsional moment in the direction of the arrow M, whereby the belt 24 is maintained constantly tensioned by the drive belt pulley 23. Due to the position of the axis of rotation of the belt pulley 23 (Figure 1) relative to the axis of rotation of the motor shaft 16 which is parallel thereto, this torsional moment M urges the belt pulley 23 in the direction of the arrow P, i.e. at right-angles to a line connecting these two rotational axes 23 and 16, so that tension is thus applied to the belt 24. Thus, the belt 24 is permanent lyundertension of the spring 29 irrespective of whether the motor shaft 16 is rotating in an anticlockwise direction or in a clockwise direction during reverse drive of the drying drum 11.

Since, in this preferred embodiment, the motor 10 is mounted on the pedestal bearings 13, 13' so asto be freely rotatable at all times, should the length of the belt 24 increase, the tension on the belt 24 is automatically adjusted by the tension spring 29 because it causes the electric motor 10 to pivot, thus maintaining the tension on the belt 24.

Claims

1. A tumbler dryer for drying clothes or the like, having a drying drum driven by an electric motor by way of through the intermediary of a wheel drive system and a belt drive system, characterised in that there is provided a belt pulley for driving a belt, said belt pulley being mounted adjacent one end of the electric motor; a friction wheel coaxial with the pulley and formed integrally therewith said wheel being capable of being urged into contact with a motor shaft of the electric motor, said shaft being axially parallel to the friction wheel axis but of a smaller diameter; and tensioning means for the belt whereby of the belt drive system pivotal movement of the electric motor can be effected about an axis which coincides with that of the motor shaft so that the belt pulley can maintain tension on the belt.

2. A tumbler dryer according to claim 1, in which the electric motor is pivotable about its axis of rotation and means are provided for producing a torsional moment on said motor to maintain it constantly in an angular position in which the belt is maintained under tension.

3. A tumber dryer according to claim 2, in which the torsion-producing means comprises spring means.

4. Atumbler dryer according to claim 1, in which securing means are provided for locating the electric motor against further pivotal movement when it has been adjusted to a position required to tension the belt.

5. A tumber dryer according to any preceding claim, in which the electric motor is pivotally mounted on pedestal bearing means located adjacent each end of the motor and having journal bearings aligned with the axis of rotation of the motor shaft, each end of the motor having a projecting annular collar adapted to be rotatably located in said bearing means.

6. A tumbler dryer as claimed in any preceding claim in which each end of the motor has housing end plates on one of which the belt pulley and friction wheel are mounted.

7. A tumbler dryer for drying clothes or the like, substantially as hereinbefore described with reference to the accompanying drawing.