GB2129838A

GB2129838A - Variable speed drive

Info

Publication number: GB2129838A
Application number: GB08328356A
Authority: GB
Inventors: Antonio Marangoni
Original assignee: Domar SA
Current assignee: Domar SA
Priority date: 1982-11-10
Filing date: 1983-10-24
Publication date: 1984-05-23
Also published as: FR2535747A1; GB2129838B; ES517250A0; ES8400515A1; GB8328356D0; IT1169607B; FR2535747B3; IT8323449A0; DE3338726A1

Abstract

A mechanism for driving the rotating drum of a washing machine is described, of which an automatically varying diameter pulley (Fig. 3) enables the drive ratio from the motor to the rotating drum of the washing machine to vary as the motor starts up, so allowing the torque supplied by the motor to be adapted to match the resistant torque. The annular pulley halves 18, 19 are both axially movable up to annular stops 16, 17 and intermediate speeds may be obtained by the use of undisclosed adjusting devices.

Description

SPECIFICATION A mechanism for driving the rotating drum of a washing machine This invention relates to a mechanism for driving the rotating drum of a washing machine.

As is known, automatic clothes washing machines are provided with a group of mechanisms designed to cause the rotary movement of the drum containing the clothes, a movement which is actioned by means of a transmission, usually consisting of a belt or belts and a pulley driven by an electric motor situated in the lower part of the machine. The electric circuit of the motor is on a programmed cycle and its stages of operation and cut-off are in accordance with the succession of stages required for the pre-washing, washing, draining the clothes and other operations.

In the course of this cycle of operations the clothes undergo various phases in the process of washing and therefore require a variation in the times of exposure to the water as well as a variation in the composition of the same with the products added to it for the correction of the properties of the clothes. Thus a greater or lesser exposure is needed to the water used in pre-wash, washing or rinsing and to the action of the fragrances and softeners, etc. From the mechanical viewpoint the said varation can be caused by means of an assembly of the electromagnetic and mechanical components of the machine, but it is not usual for this variation to be caused by alterations in the speed of rotation of the drum containing the clothes, this remaining constant in all the models of automatic washing machines available up till now.

Given the capacity of the drum and consequently the weight of clothes which can be placed therein, the electric motor needs to be capable of exerting a high torque on starting up the rotation of the drum from its position of rest and during the relatively long period of time needed for the drum to attain its operational speed at each stage in the cycle.

Futhermore, in order to provide the high torque referred to above, a motor of considerable power output is necessary, resulting in a high cost and considerable electric energy consumption in use, even during periods of operation with small loads.

According to the present invention, there is provided in, or for use in, a clothes washing machine, a mechanism for driving the rotatable drum of the clothes washing machine, wherein the mechanism is provided with a mechanical means for the continuous variation, between two limits, of the speed of rotation of a pulley fitted to the drum shaft and driven, by means of a a transmission belt, from a device in the form of a variable diameter pulley fitted to the operating motor shaft, the mechanical means comprising two adjacent annuli components fitted symmetrically and each having the possibility of axial movement over a predetermined distance, the transmission belt being held between the two adjacent annuli.

The present invention provides means for varying automatically the speed of rotation of the driven component of the washing machine comprising the drum thereof with its load of clothes within it such that, the torque supplied by the driving motor, which during start-up is amply variable can be adpated to the resistant torque, with accuracy, by means of the above mentioned variation in the speed of rotation.

This necessitates, to achieve the most efficient result, a continuous variation in the ratio of transmission between the motor drive shaft and the drum shaft during the said start-up phase and in general, during the cycle or stages of starting, stopping or reversing of rotation to which the drum is subject in the course of the various functions of washing, drying, spinning, etc.

The variation of speed is obtained, in accordance with the present invention, by alteration in the effective diameter of the pulley associated with the motor and which carries the belt which in turn embraces and drives the pulley attached to the drum shaft. A tensioning device on the belt, in permanent contact therewith, maintains the latter in continuous operation and in its correct length whatever may be the diameter of the driving pulley. In a variation of this system of transmission two variable devices may be used in conjuction with the two transmission pulleys respectively and in such a variation the tensioning device can be dispensed with.

Tensioning may also be provided by means of fitting the motor on a hinged base.

As has been stated, the present patent invention is based fundamentally on the provision of an automatic variation in the transmission ratio obtaining between the motor driving pulley and the driven pulley attached to the drum of the machine, resulting thus in the automatic variation in the speed of the said drum. To achieve this there is provided a system of variation based on a special pulley attached to the output shaft of the electric motor which by virtue of its design can cause to vary automatically the effective diameter of the encircling belt and hence varying the ratio of transmission in the manner required. With the help of adjusting devices not shown in the drawings, intermediate speeds can be obtained, as may be desirable for the functioning of the machine.

In order to assist in the description drawings accompanying this specification show, as one example which is not limititive, one em bodiment of the improvements in the driving means of the rotating drum of a clothes washing machine in accordance with the pronciples of the claims.

In the drawings: Figures 1 and 2 are respectively side and front elevations of a clothes washing machine provided with the rotating drum driving device having the improvements that are the subject of the claims.

Figures 3 and 4 correspond to the start-up phase of the moving component (the drum) and in consequence the period of greatest resistant torque, with the driving pulley at its minimum diameter, giving the greatest multiplication and the lowest velocity.

Figure 5 is a cross-section through V-V of Fig. 3 and shows the position of two of the cylindrical components each within one of the radial rectangular spaces.

Figure 6 shows a cyclic diagram of a washing and drying machine during the washing phase and Fig. 7 shows it during the spindrying phase of its operation.

Figures 8 and 9 give a schematic representation of the ratio of the diameters and the speeds of the drum mounted pulley in a washing-spin-drying machine with respect to those of the variable diameter device which forms part of the claimed improvements.

Figure 10 is a diagram of the tangential force of the variable diameter driving pulley which is integral with the driving motor which actions the moving parts of the washing-spin dryer machine.

As may be seen in the drawings the casing -1- of the machine houses the containing cylinder -2- which is held on suspension means -3- in the conventional manner and the drum -4- with its horizontal axis fitted with the attached pulley -5- which is connected through the driving belt -6-, to the device -7- fitted to the axial shaft of the electric motor -8-, and which said device constitutes precisely the essential part of the improvements which are the object of this patent.

Given that the effective diameter of the pulley formed by the device -7- can vary between limiting values, the tensioning device of the belt -6-, in the embodiment shown in the example in Fig. 2, consists of a roller -9acting on -the belt fitted to the extremity of an arm -10-, articulated around a pivot -11and subjected continuously to the force of a spring -12- which is attached at its extremity to a point belonging to the casing of the cylinder of the machine as shown in Fig. 2.

The shaft -13- of the electric motor -8- is fitted with an externally serrated sleeve as may be seen in Figs. 3 and 4. The annuli -16- and -17- having parallel planes perpendicular to the axis -13- are securely fitted on the sleeve -14- by means of clips -15with between them, the components -18and -19- which also are in the shape of an annulus and both having splines in the central bore and able to move in an axial direction along a limited path, either becoming mutually separated or closed together.

The said annuli -18- and -19- have a lateral elevation in the shape of a "C" and in the frontal elevation show a multiplicity of radial divisions -20- and -21- which define, in adjacent pairs radial rectangular spaces in which are housed the cylindrical components -22- which same have their extremities protected by means of envelopping pieces -23-.

On initiation of the rotation of the moving system shown in Fig. 2 the belt -6- is in the position shown by the dotted line corresponding to the lowest effective diameter of the device -7-, the components -1 8- and -19having their maximum separation, as in Fig.

3, resulting in the maximum de-multiplication, or that is to say, the minimum speed for the pulley -5-: start-up and washing phase.

At the spin-dry phase, the energy generated by the centrifugal force acting on the components -22- results in the sliding movement of the latter in a radial direction, inside the components -18- and -19-, in consequence of which the belt -6- contacts the device -7- on a periphery corresponding to a progressively greater diameter. In the limiting position the components -18- and -19make mutual contact, at which stage the belt is at its maximum developped useful length as shown in Fig. 2 by the solid lines, the diameter of contact being maximum as well as the velocity of rotation.

It should-be observed, in examining Fig. 6 that the cycle of rotation of the drum -2-, clockwise and anti-clockwise, at a low speed; of the order of 60 revolutions per minute take place with a period of increase of speed which is very short, being of the order of 2 to 4 seconds, with intervals of stopping of the order of 8 seconds, the total cycle of the wash being in the region of some 90 minutes.

For the draining of the clothes the spinning operation, as may be seen in the diagram in Fig. 7, is carried out in cycles of 2 minutes duration followed by a high speed 6 minute cycle of approximately 800 revolutions per minute, or such other value as may be suitable.

Another benefit to be derived from the invention herein described is the self-centering effect of the transmission belt, between the variable diameter pulley in the form of the device -7- fitted to the motor shaft and the pulley -5- which is fixed to the machine drum shaft. A displacement of one of these pulleys with respect to the other may occur for a variety of reasons, making them no longer co-planar with the result that the belt will be under a stress which will produce a continuous abrasion on one of its flanks and a loss of contact between the other flank with the leading pulley. This can give rise to a premature wear on the belt and to an eventual breakage.The movable characteristic of the components -18- and -19- in an axial direction along the motor shaft results that in the event of there occurring an undesirable displacement of the belt, so that it lies on two non coincident planes, this effect is automatically corrected by a compensating movement which neutralizes the said displacement.

The passage from the low speed stage corresponding to the washing phase to the high speed stage corresponding to the spindrying phase is obtained automatically by altering the speed of the motor by modifying the number of poles in the motor coils; from 12 poles corresponding to 490 revolutions per minute of the motor shaft to 2 poles, corresponding to a speed of 2,900 revolutions per minute, or similar values.

As an example; in the washing phase, for a drum pulley diameter of 300 mm., a motor pulley diameter of 36,5 mm. (minimum) and a motor speed of 490 revolutions per minute, a speed of 60 revolutions per minute is obtained for the driven pulley.

In the spin-dry stage for a diameter of 82,75 mm. in the device -7- and a speed of 2,900 revolutions per minute of the motor we obtain for the same pulley -5- of 300 mm.

diameter, a speed of 800 revolutions per minute.

The corresponding values of the starting torque are, respectively, 1 5 kg.cm. and 10 kg.cm. while the running torque values in operation are 12 and 7 kg.cm. respectively.

The start-up or tensile stress induced in the belt -6- is, at starting; 8,4 kg for the washing phase and 5,5 kg. for the drying phase, while during the working part of the cycle the stresses are 6,6 kg. and 1,7 kg. respectively.

These values are obtained by dividing the respective torque values by the radius of the circle in contact with the belt during the time under consideration.

Claims

1. In, or for use in, a clothes washing machine, a mechanism for driving the rotatable drum of the clothes washing machine, wherein the mechanism is provided with a mechanical means for the continuous variation, between two limits, of the speed of rotation of a pulley fitted to the drum shaft and driven, by means of a a transmission belt, from a device in the form of a variable diameter pulley fitted to the operating motor shaft, the mechanical means comprising two adjacent annuli components fitted symmetrically and each having the possibility of axial movement over a predetermined distance, the transmission belt being held between the two adjacent annuli.

2. A mechanism according to Claim 1, wherein the device, which functions as a pulley with a variable daimeter at its groove, comprises a pair of identical components in the form of an annulus and with a cross section in the shape of a "C", each component provided with longitudinal splines in the central bore, which engage with the longitudinal serrations of an axial sleeve fitted on to the motor shaft of the washing machine, to two adjacent annuli being able to move axially, but with their travel limited in either axial direction by means of two pieces each in the shape of an annulus fixed to the axial sleeve.

3. A mechanism according to Claim 1 or 2, wherein the means for varying the distance which separates axially the two adjacent annuli which hold the belt, comprises cylindrical elements, covered on the side and end face of their extremities, and situated inside radial slots having a rectangular configuration which is defined by ribs formed on the outer faces of the two adjacent annuli.

4. A mechanism, substantially as hereinbefore described with reference to, or as illustrated in, Figs. 1 to 10 of the accompanying drawing.

5. A clothes washing machine, substantially as hereinbefore described with reference to, or as illsutrated in, Figs. 1 to 10 of the accompanying drawings.