Background to the Invention A combined washing and drying machine is described in GB Patent Specification No.

2,348,213. In that machine the washed articles are dried by creating a vacuum or partial vacuum in the chamber containing the washed articles, to assist in evaporation of moisture from the articles.

It is an object of the present invention to provide an improved machine and method of operation thereof.

It is a second object of the present invention to provide an improved door arrangement for giving access to the article containing chamber of such a machine.

It is a third object of the present invention to provide an improved seal for such an access door.

A washing machine of the type described in GB Patent Specification No. 2,348,213 will be referred to as apparatus of the type described.

Summary of the Invention According to a first aspect of the present invention in a washing and drying method in which articles which have been washed are then dried in the same chamber in which washing has taken place and in which during the drying step a vacuum or partial vacuum is created in the chamber containing the articles, to assist in the drying, by evaporation, heat is supplied to the chamber during the drying step to reduce the time required for drying the articles.

The vacuum assisted evaporative drying step may be followed by the step of introducing heat into the chamber for a period of time, to complete the drying step.

The pressure in the chamber during the heating step may be maintained at or above atmospheric pressure.

In a preferred method the drying step comprises an alternating sequence of vacuum assisted evaporative drying, and heat assisted drying, steps.

In such a sequence each step lasts for a predetermined duration in the range 30 seconds to 4 minutes. Preferably each step lasts for 2 minutes.

Heat may be supplied by introducing hot air into the chamber.

The air pressure in the chamber may be increased above atmospheric during some of the heat assisted drying steps in the sequence.

In another preferred method there is a single vacuum assisted evaporative drying step which is not interrupted and heat is supplied to the chamber for at least part of the time for which the vacuum or partial vacuum is applied.

Where there is a single vacuum assisted step the heat may be supplied for the whole of the vacuum assisted drying step, or during a plurality of separate spaced apart periods of time during the single vacuum assisted drying step.

Typically the heat may be supplied for periods of 30 seconds, separated by 60-second periods when no heat is supplied.

In a modification of this method heat is supplied for 2-minute periods separated by 2- minute intervals when no heat is supplied.

Heat may be supplied to the articles by heating at least part of the wall of the chamber containing the articles.

Alternatively infra-red heating is employed to heat the chamber interior.

Where infra-red radiation is employed, it is preferably directed at the chamber wall from externally of the chamber, so that the articles are heated indirectly.

Where infra-red radiation is directed at the chamber wall the latter preferably includes one or more infra-red transmittive windows to enable the radiation to enter the interior, so that the articles are heated directly by the radiation.

In another method a jacket surrounds the chamber and heated air is supplied to the space between the jacket and the chamber wall, to warm the chamber wall externally.

Whatever heating method is employed, preferably a temperature sensitive control is provided to reduce or stop the heating if the temperature within the chamber exceeds a predetermined value.

Where the articles are clothing or soft furnishings the predetermined temperature value will typically lie in the range 40 to 45 degrees centigrade.

The air may be heated by an electric heating element and a fan is employed to force air through the heating element and into the chamber.

It has been found advantageous to ionise the air supplied to the chamber. This further reduces the time required to achieve a given dryness of the articles. The ions in the air flow are believed to break down moisture molecules in the fabric from which the articles are made.

It has been found that the quantity of heat energy needed to dry a given load of wet articles to a given level of dryness can be significantly reduced if the warm air is ionised.

It has been found that the time required to achieve the given level of dryness of a given load of wet articles is significantly reduced if the warm air is ionised.

In practice, ionising the warm air flow has resulted in up to 50% reduction in heat energy needed if no ionisation is employed, and the drying time to a given level of dryness has been reduced by up to 50% of the time needed to achieve a given level of dryness if no ionisation is employed.

Ionisation may be achieved by forcing the heated air through a jet orifice, and/or by exposing the air flow to an electric field.

Ionisation may be performed before or after the air is heated, or both.

Where the chamber is non-cylindrical but is generally elliptical, and has longer and shorter axes, and is rotated about an orthogonal axis which extends through the intersection of its longer and shorter axes, one or more openings through which air can pass, are provided in a region of the chamber wall at one end of the longer chamber axis.

Preferably at the end of the or each vacuum assisted drying step, the rotation of the chamber is stopped, with the end of the chamber from which air is being drawn at or near the lowest point on the circle about which the chamber rotates, to assist in drainage of water from the chamber whilst it is stationary.

Stopping the chamber with the apertured end lowermost is also for the purpose of enabling articles therein to be readily visible to someone looking diagonally downwards through aligned openings in the front wall of the chamber and in the front wall of a housing containing the chamber.

The invention also lies in apparatus adapted to perform any of the above methods.

The invention also lies in apparatus which also includes a control system for controlling the rotation of the chamber, the creation of vacuum or partial vacuum in or the supply of positive pressure air to the interior thereof, the operation of heating means for heating the chamber, or air entering the chamber, and the operation of ionisation means (if fitted).

The invention also lies in apparatus of the type described wherein the chamber containing the articles to be washed and dried has differing length and breadth dimensions when viewed along its axis of rotation, and includes apertures in the wall thereof through which air is drawn to establish a vacuum or partial vacuum in the chamber during the or each vacuum assisted evaporative drying step, and through which heated air can be introduced during the or each heat assisted drying step, wherein the apertures are located in a region of the chamber wall located at one end of the longer dimension thereof.

The invention also lies in apparatus of the type described, which includes a housing within which the chamber rotates, an opening in the housing wall which gives access to an opening in the chamber wall, and a door for closing at least the opening in the chamber wall, wherein either two seals are provided one adapted to prevent ingress of fluid (air or liquid) via any gap between the door and the opening in the chamber wall closed by the door, and the other adapted to prevent egress of fluid (air or liquid) from the chamber when a positive pressure exists therein relative to ambient, or a single bi-directional seal is provided, adapted to resist both ingress and egress of fluid (air or liquid) between the door and the opening.

The invention also lies in apparatus of the type described, which includes a housing within which the chamber rotates, an opening in the housing wall which gives access to an opening in the chamber wall, and a door for closing at least the opening in the chamber wall, wherein the chamber has a generally cylindrical axial extension at least at one end, the axis of the cylindrical extension comprising the axis of rotation of the chamber, and the outer end thereof is open, and the open end comprises the opening giving access to the chamber, wherein a bearing assembly rotatably supports the extension, and the door has a frusto conical dished central region and is hinged to the housing and in its closed position the dished region protrudes into the housing and aligns with and enters the open end of the chamber extension, and a seal is provided between the external frusto conical surface of the internally extending dished region of the door and the internal surface of the chamber extension, which seal is bi-directional and resists the ingress or egress of fluid (air or liquid) whilst permitting rotation of the chamber relative to the stationary door.

Typically the external surface of the chamber extension is generally cylindrical and the interior is generally frusto conical and is complementary to the frusto conical shape of the dished region of the door.

The chamber may be generally cylindrical and is rotatable about the axis of the cylinder.

Alternatively the chamber may be non-cylindrical and have a generally elliptical configuration, and be mounted for rotation about an axis perpendicular to and passing through the point of intersection of the longer and shorter axes of the generally elliptical shape.

For a typical domestic washing machine a 2KW electric heating element is probably sufficient to raise the temperature of the air to be introduced during the drying step, where a fan is employed to force air through the heating element and into the chamber into contact with the articles therein.

The invention will now be described by way of example with reference to the accompanying drawings in which: Fig 1 is a schematic diagram of a combined washing and drying machine embodying some of the aspects of the invention disclosed herein, and Fig 2 is a cross-sectional elevation of the access opening and door closure such as may be employed in a combined washing and drying machine of the type disclosed in GB Patent Specification No. 2,348,213, or in such a machine when modified as disclosed herein.

Fig 1 of the drawings is a modification of Fig 19 of GB Patent Specification No.

2,348,213 and the same reference numerals have been used where appropriate. Reference is made to the description of the drawings in Specification 2,348,213 for a description of any parts of the drawing not described herein.

In Fig 1 the washing machine drum/capsule 102 (comprising the article containing chamber) is shown provided with a plurality of wall openings 176 at one radial end of the capsule, instead of at an axial end the drum as shown in Fig 19 of the earlier Application.

This ensures that air drawn out of the drum/capsule during vacuum assisted drying will cause articles in the drum to migrate to that end. The drum is arranged to stop with that end (containing openings 176) lowermost, to facilitate drainage when stationary and visibility and removal of the washed and dried articles.

The three valve unit 112 of Fig 19 of the earlier Application is now replaced by a four valve unit to allow for the supply of hot air to the interior of the drum/capsule 102 via the openings 176 (shown in Fig 1), before or after a vacuum assisted evaporative drying step, in accordance with the improved drying method described herein.

Hot air is blown into the capsule by blower 162 and the air may be heated before, during or after it passes through the blower by a heating element 163. A thermostat switch (not shown) regulates the power to the heating element to regulate the temperature to which the air is heated.

An ionising device 165 is provided for ionising the air passing from the blower 162 into the drum.

The ionising device may comprise a passive device in the form of a jet orifice or may comprise an electrically powered electric field generator.

The control system 100 for the machine is modified so as to control the supply of power to the blower 162, heating element 163, as required, and to operate the appropriate solenoid operated valve in 112, to enable this additional function to be performed, and to operate the ionising device 165 (if required).

Fig 2 is a cross-section through an alternative access port and door closure for a machine such as for example disclosed in Figs 9-11 of GB2,348,213.

The drum 10 includes two aligned cylindrical axial extensions at opposite ends for mounting it in bearings which define the axis about which it is to rotate. The two extensions correspond to the extensions 106,108, of the drum 102 of Fig 19 of GB 2,348,213. One such extension is shown in Fig 2 and is denoted by reference numeral 12.

The supporting bearing assembly has inner and outer shells 14 and 16, and the circular opening in 12 gives access to the interior of the drum 10. The opening is closed by a conventional washing machine door 18 which includes an inwardly directed frusto conical dished central region, the external surface 20 of which is smooth A heavy duty seal 22 surrounds the surface 20 and seals the gap between it and the internal surface 24 of the drum extension 12. The seal 22 is a bi-directional seal and acts to resist ingress and egress of fluid (air or liquids) through the gap.

The door 18 is hinged at 26 to the front wall 28 of the machine housing such as shown in Fig 9 of GB2,348,213, and a catch 30 is provided to engage a diametrically opposite edge region of the door surround 32. The latter is secured to the edge of the dished central region of the door 18 by screws such as 34.

The seal 22 is formed from a material which permits relative rotational movement between the frusto conical surface 20 and the seal, to permit the drum 10 to rotate in use, whilst the door remains closed and stationary.

Typically the central region of the door 18 is formed from glass or perspex or other suitable transparent material, to allow the interior of the drum 10 to be viewed by the operator.

As shown in Fig 1 the 2-way solenoid operated valve 138 serves to deliver water to 132, or via 144 to operate the venturi pump. The unit 132 is as described in Specification 2,348,213