GB2239700A - Spin control in combination washing and drying machines - Google Patents

Abstract

A combined clothes washing, spin drying and tumble drying machine includes two user selectable wash programmes the first of which is selected to end in spin drying and provides a first spinning operation having a sequence of spins at increasing speeds followed by a final high speed spin, and the second of which is selected to end in tumble drying and automatically provides a modified spinning operation consisting of the first spinning operation preceded by an additional sequence of spins over a lower range of speeds. This modified, extended, spinning operation helps to ensure that the clothes are not left clinging to the clothes drum at the end of spinning and that the clothes are evenly dried and uncreased at the end of tumble drying.

Description

Combination washing and drying machine This invention relates to a combined clothes washing, spin drying and tumble drying machine having a clothes drum rotatable about a horizontal axis.

In operation of such a machine, clothes and other textile articles are placed in the drum, into which wash liquid is also fed.

In accordance with a wash programme set by the user of the machine a series of washing and rinsing operations for the clothes occurs, followed by a spinning operation which ends in a final high speed spin. The wash programme may be set to end with the clothes as dried by this spinning operation, or otherwise it may be set to continue after the spinning operation with a tumble drying operation in which the drum is rotated at a low speed to produce a tumbling motion of the clothes while a current of heated air is fed through the drum to carry away moisture from the clothes.

A problem encountered with these combination machines is that at the end of the spinning operation the clothes tend to form a compacted mass or ring clinging to the inner periphery of the clothes drum. This ring of clothes can relatively easily be removed by the user if the wash programme is set to end with the spinning operation. However, if the wash programme is set to continue after the spinning operation with a tumble drying continue after the spinning operation with a tumble drying operation, then at least some of the clothes may fail to tumble and remain in a compacted ring in which the outer layer of clothes tends to become over-dried while the inner layer its often left only partially dried. Furthermore; the clothes may become badly creased.

Various arrangements have been proposed in an endeavour to ensure that at the end of the spin drying operation the clothes are left resting loosely in the bottom of the drum, leaving them to move freely in the heated air stream during a subsequent tumble drying operation. One such arrangement, according to published Patent Application EP 0,083,302, comprises the use of resilient (i.e.

compressible) lifter bars within the clothes drum so that initially the clothes are less likely to adhere to'the drum wall and even if they do are finally 'sprung off' when the lifter bar reverts to its uncompressed state once the drum comes to rest. Provision of additional mechanical components is undesirable. Another such arrangement, according to Patent Specification GB 1,469,023, involves admission of water into the drum behind the compacted ring of clothes to push them off when the drum comes to rest. However, such an arrangement is somewhat counter-productive in a function which is setting out to remove water from the clothes in the drum.

In the specification of our own Patent GB 2,172,977 relating to a combined clothes washing, spin drying and tumble drying machine, a spinning operation is described in the form of a pulsed sping sequence, which consists of a series of operations viz., distribute - the clothes drum being rotated at some 85 revs/min; slow spin at some 500 revs/min; pause; distribute; pause; distribute; and slow spin, the sequence being repeated for some settings of the wash programme, e.g. cottons. The pulsed spin sequence is followed by a final spin at a speed, and for a duration, according to the wash programme setting.This pulsed spin sequence is primarily to ensure as far as possible that no clothes are left clinging to the walls of the drum when the tumble drying programme commences, but its function is said to be also of use if the user wishes to terminate the washing/spin drying operation at the end of the pulsed spin sequence. In such an event the clothes are much easier to remove from the drum.

We have found that in practice the particular spinning operation described in our Patent GB 2,172,977 does not produce entirely satisfactory results. Often the amount of moisture left in the clothes after the spinning operation is such that a following tumble drying operation is less efficient than desirable in that too long a period of heated drying is required. Furthermore it has been found that at least some of the clothes are left clinging to the drum at the end of the spinning operation more often than had been hoped. The desired pulsed spin sequence may, as stated, be repeated for some wash programmes, e.g. for cottons. This decreases the chance of clothes being left clinging to the drum at the end of the spinning operation, but at the expense of significantly increasing the total time of the wash programme.In particular, the increased time for this repeated spin sequence is undesirable to a significant degree where the wash programme for those particular clothes is set to end with the spinning operation without being set to go on to the much longer period of time which would be required for a tumble drying operation. In practice this pulsed spin sequence has been used in a spinning operation in which the final spin speed which precedes the tumble drying operation is 1000 r.p.m. It is now considered desirable for more efficient moisture removal in the spinning operation to have a higher final spin speed which may be up to 1400 r.p.m. Such a higher final spin speed makes it more likely that the pulsed spin sequence as described in our Patent GB 2,172,977 would leave at least some clothes clinging to the drum.

An object of the present invention is to provide a combination machine with spinning operations which enable the set of criteria consisting of (i) efficient removal of moisture by the spinning, (ii) avoidance of leaving clothes clinging to the drum, and (iii) good overall time for the wash programme both when it ends in spinning and when it ends in tumble drying to be more nearly met than with the spinning operations described in our Patent GB 2,172,977.

According to the invention there is provided a combined clothes washing, spin drying and tumble drying machine having a clothes drum rotatable about a horizontal axis and including wash programme selection means operable by a user of the machine and drum control means responsive to operation of the wash programme selection means, in which the drum control means is arranged, responsive to user selection of a first predetermined wash programme ending in spin drying, to provide a first spinning operation comprising a sequence of spins at increasing drum speeds over a first range of speeds followed by a final high speed spin, and in which the drum control means is arranged, responsive to user selection of a second predetermined wash programme consisting of said first wash programme followed by tumble drying, to provide a modified spinning operation which has a sequence of spins over the same range of speeds and a final spin at the same high speed as said first spinning operation but in which said sequence of spins over said first range of speeds is preceded by an additional sequence of spins over a second range of drum speeds lower than said first range.

Automatic introduction by the drum control means of the additional sequence of spins over the lower speed range only when tumble drying is required means that (a) the possibility is reduced of clothes clinging to the drum before tumble drying such that a higher final spin speed may be used than would otherwise be the case, with the extra time for the extended spin being offset by a reduction in the time needed for tumble drying, while (b) when the wash programme is to end in spinning such that the user may remove any clothes clinging to the drum, the non-extended spinning operation enables a usefully shorter overall time for the wash programme to be achieved while retaining the advantage of the degree of moisture removal achieved by the chosen high speed final spin.

The wash programme selection means may include another predetermined wash programme ending in spin drying, and in which the drum control means is arranged, responsive to user selection of this other wash programme to provide a spinning operation which is the same as said modified spinning operation. Thus, although the machine will normally not perform the extended spinning operation when the wash programme is to end in spin drying, the user may have the facility to select the extended spinning operation for a programme ending in spin drying when the clothes require the final high speed spin for maximum moisture extraction while the user is nevertheless concerned to minimise creasing of the clothes and to leave them more easily removable from the drum.

The wash programme selection means may include two other predetermined wash programmes, one ending in spin drying and the other ending in tumble drying, and in which the drum control means is arranged, responsive to user selection of either of these two other wash programmes, to provide a spinning operation comprising a sequence of spins at increasing drum speeds over said second range of drum speeds followed by a sequence of spins at increasing drum speeds higher than said second range and ending in a spin at a speed lower than the final spin speed of said first spinning operation.

Thus, for delicate fabrics where wash programmes ending either in spin drying or tumble drying are required to have a suitably low maximum drum speed in the spinning operation, it is of advantage also to use the lower speed range extension of spinning in order to minimise the clothes being creased and clinging to the drum.

The final spin speed of said first spinning operation may be in the range 1100 r.p.m. to 1400 r.p.m. and the highest speed in said second range of drum speeds may be less than 500 r.p.m.

Spinning speeds lower than 500 r.p.m. might not hitherto have been thought to be of value, but we have found them to be of advantage as part of the automatically introduced lower speed range extension as now proposed.

Each said sequence of spins may comprise discrete spins, the drum coming to a halt and then being rotated at a low clothes distribution speed between each discrete spin.

An example of a combination clothes washing, spin drying and tumble drying machine according to the invention will now be described, including reference to the accompanying drawing which shows the control system of the machine in outline, diagrammatic form.

The combination clothes washing, spin drying and tumble drying machine in this example comprises an open-fronted perforated clothes drum rotatable about a horizontal axis within a stationary outer container mounted within an enclosing cabinet. Both the container and cabinet have access openings which register with an open front of the drum and through which clothes may be loaded into, or removed from, the drum. The cabinet is provided with a door which closes the cabinet access opening and which, in the closed position, engages a flexible gasket forming a seal between the cabinet and the container openings.

The clothes drum is arranged to be driven in use of the machine, by a series-wound motor 1 energised via a power board 2 controlled by a control board 3. The power board 2 carries electromechanical relays and solid state power switches such as triacs, the control board 3 carries a microprocessor, and a multi-way ribbon cable connects the boards 2 and 3. Control of the motor speed is achieved by a comparative feed-back system, the motor speed signal being derived from a tachogenerator 1A driven by the motor. The microprocessor on the control board 3 also serves to control, via the power board 2, operation of the valves 4, 5 and 6 admitting cold or hot water into the container via detergent or fabric conditioner dispensers, and a pump 7 for removing liquid from the container at appropriate times during a washing or spin drying cycle.Heater 8 for the washing operation and heaters 9 and 10 for the tumble drying operation are energised by the power board 2 under control of the microprocessor, a thermistor 12 being used to monitor the water temperature and feed back information to the microprocessor. Thermostats 13, 14 and 15 are used to control, via the microprocessor, the tumble drying temperatures.

A closed-air circulating system for the tumble drying operation of the machine includes an electrically driven blower 19 conveniently arranged to feed air around the closed path, the air being arranged to be passed over the heaters 9 and 10 and then fed into the perforated drum through an access opening at the front of the drum and onto clothes tumbling in the drum, moisture from the clothes being taken up in the air flow. The system includes a condenser for removing moisture from the air passing around the system, water for condensing purposes being fed to the condenser and controlled from the microprocessor operating through the power board and condenser valve 21.

Manually operable controls, shown as touch buttons 24 on the control board 3, for selecting various washing, drying or washing and drying programmes are used to cause appropriate information to be fed to the microprocessor enabling selected programmes to be introduced. Thus, in a programme involving a washing operation the required amount of cold and hot water are fed into the drum until the required temperature is reached. Pressure switches 16 are used to control the wash liquid levels within the container and a door switch 22 and interlock 23 of any known kind are provided. The rinsing and spin drying operations are also controlled by the microprocessor in accordance with programme settings selected by the user. In a tumble drying operation the closed air circulating system is enabled and the condenser brought into operation.The tumble drying operation continues until terminated either by the drying temperatures reaching an appropriate level or by the user ending the programme.

The above-mentioned manually operable controls 24 may be described as wash programme selection means and a spinning operation may be described as being provided by drum control means responsive to selection of a wash programme, the drum control means comprising the motor 1, the speed controls on the power board 2 and those parts of the microprocessor arrangement which control the motor speed controls.

Considering in more detail the spinning operations, these comprise set functions for cottons, synthetics and wool programmes, each function comprising a sequence of spins at increasing drum speeds followed by a final high speed spin, at a speed and for a duration according to the wash programme setting, and ending with a short period of tumble. Furthermore, the wash programme setting may be such that the spinning operation is followed immediately by a tumble drying operation, clothes being left in the drum and not removed until the end of the tumble drying operation. It is desirable that at the end of any spin drying operation the clothes should be left resting loosely in the bottom of the drum. For a wash programme ending in spin drying it is inconvenient for the user if clothes are left clinging to the drum walls and have to be removed from the drum in this condition. For a wash programme ending in tumble drying the consequences are more serious if the tumble drying operation starts with the clothes having been left clinging to the drum walls at the end of the spin drying operation.

In this case there is a significant likelihood of clothes being over-dried or left in varying degrees of dryness, or even creased at the end of the tumble drying operation.

Included in the various wash programmes which may be selected by the user of the above-described combination machine are two particular programmes which differ only in that one of them, a first programme, is intended to end in spin drying and the other, a second programme, consists of the first programme followed by tumble drying. These two programmes are intended for use with cotton articles, which is the worst case for the above-described problems of clothes being left clinging to the drum at the end of the spin drying operation with the effect of uneven drying and creasing during subsequent tumble drying. Responsive to user selection of the first programme the drum control means is arranged to provide a first spinning operation comprising a sequence of spins over a first range of speeds followed by a final high speed spin.The sequence of spins is a pulsed spin sequence, that is to say that it comprises discrete spins, the drum coming to a halt and then being rotated at a low clothes distribution speed between each discrete spin. In detail, the sequence has three discrete periods of spinning consisting of 45 seconds at 500 revs/min (r.p.m.), 40 seconds at 700 r.p.m. and 180 seconds at 1000 r.p.m., with 32 second distribution periods of drum rotation at 92 r.p.m. preceding each spin. This sequence is immediately followed by a 30 second spin at 1400 r.p.m. The total time taken for this first spinning operation is 9 minutes.Responsive to user selection of the second programme the drum control means is arranged to provide a modified spinning operation which has a sequence of spins over the same range of speeds and a final spin at the same high speed as the first spinning operation but in which the sequence of spins over the first range of speeds is preceded by an additional sequence of spins over a second range of drum speeds lower than the first range. The sequence of spins over the first range of speeds in this case, has four discrete periods of spinning consisting of 45 seconds at 500 r.p.m., 40 seconds a 700 r.p.m., 20 seconds at 1000 r.p.m. and 90 seconds at 1000 r.p.m. with 32 second distribution periods at 92 r.p.m.

preceding each spin. This sequence is immediately followed by a 30 second spin at 1400 r.p.m. The preceding additional sequence of spins in the second, lower, range of drum speeds consists of two discrete periods of spinning consisting of 20 seconds at 250 r.p.m.

and 30 seconds at 350 r.p.m. again with 32 second distribution periods preceding each spin. The total time taken for this modified spinning operation is 13 minutes 25 seconds.

The levels of speed and duration in the above-described modified, extended, spinning operation have been derived by experiment as providing an optimum, overall, spin function with the objective of ensuring that the clothes are not left clinging to the walls of the clothes drum at the end of the function. The experiments involved carrying out tests using loads of clothes and textile articles having different characteristics of behaviour especially in regard to a tendency to cling to the walls of the clothes drum. The tests included a measure of water extraction so as to provide a comparative extraction efficiency.The result of the experiments showed that although the extended period of pulsed spin sequence over the lower speed range was needed to ensure a satisfactory result in terms of the clothes not clinging to the drum walls at the end of the spin drying operation, the greater time involved was offset by the advantage that the subsequent time for a tumble drying operation was reduced, hence an acceptably short overall time was provided for the complete spin drying and tumble drying operation.

It is desirable for most efficient moisture removal in the spinning operation to have a high final spin speed in the range of 1100 r.p.m. to 1400 r.p.m. The lower speed range extension of the spinning operation is found to be of benefit in avoiding clothes being left clinging to the drum when the final high speed spin is in this range, and in this case the highest speed in the lower range should be less than 500 r.p.m.

The wash programme selection means includes another wash programme ending in spin drying, and the drum control means is arranged, responsive to user selection of this other wash programme to provide a spinning operation which is the same as the modified spinning operation. Thus, although the machine will not normally perform the extended spinning operation when the wash programme is to end in spin drying, the machine provides the user with the facility to select the extended spinning operation for a programme ending in spin drying when the clothes require the final high speed spin for maximum moisture extraction while the user is nevertheless concerned to minimise creasing of the clothes and to leave them more easily removable from the drum.

The wash programme selection means includes two other predetermined wash programmes, one ending in spin drying and the other ending in tumble drying, and the drum control means is arranged responsive to user selection of either of these two other wash programmes, to provide a spinning operation comprising a sequence of spins at increasing drum speeds over the second, lower, range of drum speeds followed by a sequence of spins at increasing drum speeds higher than the second range and ending in a spin at a speed lower than the final spin speed of the first spinning operation.Thus, for delicate fabrics where wash programmes ending either in spin drying or tumble drying are required to have a suitably low maximum drum speed in the spinning operation, it is of advantage also to use the lower speed range extension of spinning in order to minimise the clothes being creased and clinging to the drum.

An expample of a spinning operation provided in the above-described combination machine for use with delicate fabrics and which may be selected to end with the spin drying or to be followed without interruption by tumble drying is a sequence of two discrete periods of spinning consisting of 20 seconds at 250 r.p.m.

and 30 seconds at 250 r.p.m. each preceded by 32 second distribution periods, followed by a sequence of two discrete periods of spinning consisting of 45 seconds at 500 r.p.m. and 40 seconds at 800 r.p.m.

again with 32 second distribution periods preceding each spin. The total time taken for this spinning operation is 7 minutes 35 seconds.

Claims (6)

1. A combined clothes washing, spin drying and tumble drying machine having a clothes drum rotatable about a horizontal axis and including wash programme selection means operable by a user of the machine and drum control means responsive to operation of the wash programme selection means, in which the drum control means is arranged, responsive to user selection of a first predetermined wash programme ending in spin drying, to provide a first spinning operation comprising a sequence of spins at increasing drum speeds over a first range of speeds followed by a final high speed spin, and in which the drum control means is arranged, responsive to user selection of a second predetermined wash programme consisting of said first wash programme followed by tumble drying, to provide a modified spinning operation which has a sequence of spins over the same range of speeds and a final spin at the same high speed as said first spinning operation but in which said sequence of spins over said first range of speeds is preceded by an additional sequence of spins over a second range of drum speeds lower than said first range.

2. A machine as claimed in Claim 1, in which the wash programme selection means includes another predetermined wash programme ending in spin drying, and in which the drum control means is arranged, responsive to user selection of this other wash programme to provide a spinning operation which is the same as said modified spinning operation.

3. A machine as claimed in Claim 1 or Claim 2, in which the wash programme selection means includes two other predetermined wash programmes, one ending in spin drying and the other ending in tumble drying, and in which the drum control means is arranged, responsive to user selection of either of these two other wash programmes, to provide a spinning operation comprising a sequence of spins at increasing drum speeds over said second range of drum speeds followed by a sequence of spins at increasing drum speeds higher than said second range and ending in a spin at a speed lower than the final spin speed of said first spinning operation.

4. A machine as claimed in any one of Claims 1 to 3, in which the final spin speed of said first spinning operation is in the range 1100 r.p.m. to 1400 r.p.m. and in which the highest speed in said second range of drum speeds is less than 500 r.p.m.

5. A machine as claimed in any one of Claims 1 to 4, in which each said sequence of spins comprises discrete spins, the drum coming to a halt and then being rotated at a low clothes distribution speed between each discrete spin.

6. A combined clothes washing, spin drying and tumble drying machine substantially as described herein with reference to the accompanying drawing.