GB1601456A - Apparatus for cleaning floors carpets and the like - Google Patents

Description

(54) APPARATUS FOR CLEANING FLOORS, CARPETS AND THE LIKE (71) We, ABRA INVESTMENTS LI MITED, a British Company of 21, Hall Street, Birmingham B18 6BS, West Midlands. formerly of Weatheroak, Alvechurch, Birmingham B48 7EG, West Midlands, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to apparatus for cleaning floors, walls, carpets, curtains, upholstery and the like. It is an object of the invention to provide a dual purpose apparatus suitable for both dry suction cleaning and water extraction cleaning.

Many types of dry suction cleaning apparatus ("vacuum cleaners") are known and there have been a few proposals for combining such apparatus with shampooing apparatus, that is to say apparatus for generating a cleansing foam which is essentially dry in nature in that it requires only a relatively small quantity of water so that a carpet or the like treated in this way is scarcely wetted, but only dampened, the foam being sucked up by the vacuum cleaner which is then adapted to collect the relatively small quantity of liquid incorporated in the foam instead of the normal dry dust.

However, a more thorough cleaning process is that known as water extraction cleaning, in which a carpet or the like is thoroughly wetted by a solution containing a suitable cleansing agent, such as a nonfoaming detergent, and the carpet or the like is then substantially dried by uptake of the solution by suitable suction apparatus.

According to the invention we provide a suction cleaning apparatus comprising a container adapted for the collection of both solids and liquids and having an inlet for connection with a cleaning head, a motordriven air suction unit with an air exhaust outlet and an air inlet which communicates with said container to apply section thereto, a detachable dust retaining member for retaining dry dust within the container, and a detachable reservoir for storing cleaning liquid with a liquid delivery duct for connection to a liquid delivery outlet for applying the cleaning liquid to a surface to be cleaned, the arrangement being such that the detachable filter is used in the absence of the reservoir and vice-versa so as to enable the apparatus selectively to prform either dry suction cleaning with the filter in place or wet cleaning with the reservoir in place, wherein said reservoir incorporates an air passageway which, when the reservoir is in use, communicates at one end with the air inlet of said suction unit and at the other end with the interior of said container, a shut-off valve is provided in association with said passageway to close the latter in response to the level of liquid collected in said container, and an air flow director separate from said passageway is provided for either directing air from the exhaust outlet of said suction unit to atmosphere when said filter is in use or allowing the exhaust air to flow 10 the interior of said reservoir when the latter is in use so as to displace said cleaning liquid therefrom through said delivery duct, while in either case suction from said suction unit is applied simultaneously to said container.

Thus, when the detachable reservoir is in position, the cleaner can be used for water extraction cleaning, the cleaning liquid being delivered to the cleaning head, which is preferably a separate member coupled to the container by means of the suction hose, and through which the cleaning liquid is extracted from the carpet or other material being cleaned immediately after its application thereto.

Alternatively, the apparatus can be used for dry suction cleaning by removing the reservoir and fitting the detachable dust retaining member, which may comprise either a filter unit so that dry dust is collected directly in the container, or a dust bag placed in the container and in which the dust is collected.

The air flow director preferably includes a valve member biased into a first position in which exhaust air from the suction unit is allowed to flow to atmosphere, the valve member being so arranged as to be engaged by a part carried by the reservoir when the latter is in use so that the valve member is then moved to a second position in which the exhaust air flow from the suction unit is diverted to the interior of the reservoir so as to apply a positive pressure therein.

If desired, a foam generating unit could be provided as an alternative to the liquid reservoir so that the apparatus could then perform the additional function of shampooing as well as dry vacuuming and water extraction cleaning.

These and other features of the invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 shows a preferred embodiment of suction cleaning apparatus in front view and with a removable clean water reservoir in position; Figure 2 shows a transverse section on the line A-A of Figure 1; Figure 3 shows a horizontal section on the line B-B of Figure 2 through an air suction unit with aparts of a motor base plate and a valve plate broken away to show the internal construction of a valve assembly; Figure 4 shows a horizontal section on the line C-C of Figure 2 with part of the reservoir broken away to show a liquid filter assembly; Figure 5 is a fragmentary transverse section in a vertical plane perpendicular to that of Figure 2 showing a dust filter assembly in place of the reservoir and the exhaust air flow directed to atmosphere; Figure 6 shows a horizontal section on the line D-D of Figure 5 (omitting the clips) with certain parts broken away to show the structure more clearly; Figure 7 is a half sectional front elevational view of a preferred embodiment of cleaning head; Figure 8 is a section on the line X-X of Figure 7; Figure 9 is a section on the line Y-Y of Figure 7; Figure 10 is an underneath plan view corresponding to Figure 7; Figure 11 shows a modified embodiment of the suction cleaner with a manual exhaust air flow valve in the air suction unit in fragmentary transverse section similar to Figure 5 but in a plane perpendicular thereto; and Figure 12 shows a horizontal section on the line E-E of Figure 11.

The suction cleaner illustrated in the accompanying drawings includes a main container 10 having an open top closed by a top cover assembly 20 with the interposition of either a reservoir 60 if the cleaner is to be used for water extraction cleaning, or a dust filter assembly 90 if it is to be used for dry suction cleaning. An impeller driven by an electric motor for creating the suction is housed in the top cover assembly 20, together with a valve assembly whereby exhaust air from the impeller is directed to the interior of the reservoir when the latter is in use or alternatively allowed to escape to atmosphere when the reservoir is not in use.

The main container 10 is formed with a lateral protruberance 11 for the reception of an end fitting (not shown) of a suction hose.

The protuberance 11 is formed, for this purpose, with a circular aperture 12 with recesses 13, and an opening 14 is formed opposite thereto in the upper portion of the side wall of the container 10 so that air, together with any dust or water entrained therein, enters from the hose directly into the interior of the container in a generally radial direction.

The main container 10 also carries a pair of dimetrally spaced lugs 15 to which are pivoted retaining clips 16 each havkng a respective lip 17 for the purpose of securing the top cover assembly 20 and either the reservoir 60 as shown in Figures 1 to 4 or the dust filter assembly 90 as shown in Figures 5 and 6.

The main container 10 is provided with a mobile base 18 equipped with castors 19.

The top cover assembly 20 includes a main outer casing 21 having a carrying handle 22 centrally disposed thereon, and a switch 23 is mounted with the handle. A housing 24 beneath the handle 22 encloses the electric motor 25 and is covered by a ventilated top plate 26. The motor 25 is coupled to an impeller 27 which is located in a circular housing defined in combination by an annular wall 28 formed integrally with the man casing 21, and a similar annular wall 29 carried by a mounting plate 30. The latter is supported from a base plate 32 of the top cover assembly by means of studs 31 and an annular wall 47. The base plate 32, mounting plate 30 and annular wall 47 in combination define a valve chamber of a valve assembly indicated generally at 40 in Figure 2.

The base plate 32 is itself supported by a peripheral downwardly directed rib 33 which seats within the upper peripheral edge of the outer wall of the reservoir 60 or the dust filter assembly 90 as can be seen particularly in Figures 2 and 5 respectively.

The plate 32 affords a central aperture 34 (Figures 3 and 5) which forms the outlet from the valve chamber, and a central ring 35 is formed beneath the mounting plate 30.

A plurality of holes 36 within the central region of the plate 30 form an inlet to an inlet chamber 43 which is bounded by an inner wall 42 and in which the intake of the impeller 27 is disposed, a sealing ring 41 surrounding the impeller intake.

A valve plate 37 is disposed within the valve chamber and is slidable over the studs 31 and carries a central ring 38 which is slidable over the ring 35.

The impeller 27 thus draws air in from beneath the top cover assembly 20 through the apertures 36 so as to create a partial vacuum beneath the cover assembly. The exhaust air from the impeller 27 is discharged into an annular chamber 44 defined by the walls 28 and 29 in combination. A ring of apertures 45 in the mounting plate 30 between the annular walls 29 and 42 allows the exhaust air to escape into the valve chamber through a corresponding ring of apertures 46 in the valve plate 37, the apertures 45 and 46 being in register with one another as can most clearly be seen in Figure 3. When the valve plate 37 is in its raised position as illustrated in Figure 2, the exhaust air from the fan is directed through the central aperture 34 of the base plate 32 and thus into the interior of the reservoir 60 as shown in Figure 2when 2.

On the other hand, when the valve plate 37 is in its lower position with the filter assembly 90 in place of the reservoir 60 as illustrated in Figure 5, the aperture 34 is closed by the valve plate 37 and air can only escape from the valve chamber through an outer ring of apertures 48 which are formed in the mounting plate 30 outside the annular wall 29. When the valve plate 37 is in its raised position, the apertures 48 are closed by the peripheral margin of the valve plate, but when the valve plate is in its lower position, exhaust air is thereby allowed to escape into the interior of the main casing 21 and thence through a gap 49 beneath the lower edge of the casing 21.

The base plate 32 of the top cover assembly includes a pair of ears 51 which are engaged by the lips 17 of the clips 16, and the outer casing 21 is formed with recess 52 to accept the retaining clips, as seen most clearly in Figures 3 and 5.

The reservoir 60 includes a mounting ring 74 which is interposed between the upper edge of the main container 10 and the lower edge of the top cover assembly 20, as shown in Figures 1 and 2. A number of vertical ribs 61 are disposed within the ring 74 to support the base plate 32 of the top cover assembly by engagement with the rib 33 thereof. The mounting ring 74 has an inwardly directly flange 73 which supports an integral annular trough 62 which is defined by a generally cylindrical outer wall 63 and a frusto-conical inner wall or cone 64. The cone 64 supports a boss 65 which as seen in Figure 2 engages the central ring 35 of the mounting plate 30 and also has at its upper edge an outer ring 66 which is so positioned as to engage beneath the ring 38 of the valve plate 37.

Thus, when the reservoir 60 is interposed between the top cover assembly 20 and the main container 10, the valve plate 37 is automatically lifted into its raised position so as to close apertures 48 and open aperture 34 and thereby direct exhaust air from the impeller 27 into the interior of the reservoir as shown in Figure 2. In this way, sufficient pressure is generated within the trough 62 to displace liquid therefrom through a liquid delivery duct in the form of a pipe 77 which is secured by means of a clip 76 in the mounting ring 74. It will be appreciated that the pressure generated within the reservoir in this way is relatively low, but it is adequate to initiate and maintain a siphoning action since this is all that will be necessary when the appliance is used for cleaning carpets or other floor coverings. However, providing leakages of air are minimised by ensuring that the various components have an accurate fit with one another, it is possible to obtain sufficient pressure to raise liquid from the reservoir through a height of 2 meters or so, sufficient for the purpose of cleaning upholstery and curtains for example.

The boss 65 defines an air passageway extending through the reservoir with one end communicating with the inlet chamber 43 of the impeller 27 and the other end communicating with the main container 10 beneath the reservoir 60. In this way, suction is applied to the main container 10 and thence a hose (not shown) connected to the main container 10 whilst simultaneously the exhaust air from the suction unit is applied to the reservoir to cause the cleaning liquid to be delivered along the pipe 77.

To facilitate separation of entrained liquid droplets from the incoming air, the air flow from the hose leading to the cleaning head is arranged to impinge directly on a flat face 86 afforded by the outer wall 63 of the trough 62. In this way, the incoming air tends to spread out in all directions and the sudden change in direction of flow when the air impinges on the flat face 86 assists in separation of the liquid droplets which collect on the outer face of the wall 63 and drain down so as to collect on a flange 79 formed at the underside of the trough and then drip into the body of the main container 10.

The arrangement whereby the incoming air from the suction hose enters the main container 10 substantially radially and flows in opposite directions around the side wall 63 of the trough 62 serves largely to prevent a swirling action and the establishment of a vortex in a manner which would tend to generate foam on the surface of liquid collected within the container 10.

In order to further to reduce the generation of such foam, a liquid filter assembly 80 is positioned beneath the cone 64. A ring 81 is formed with a flange 82 which fits tightly within the flange 79, and a central boss 83 is supported by radial ribs 84 which have a nylon mesh filter 85 moulded integrally. The filter 85 substantially eliminates the risk of a vortex being created as air is sucked up within the cone 64. Additionally, the size of the apertures defined by the mesh can be so chosen as to prevent the passage of foam.

For this purpose, the holes defined by the mesh may typically have a maximum dimension of about 0.15 mm and preferably as little as 0.02 mm.

In order to pevent liquid being sucked up into the impeller 27 if the capacity of the main container is exceeded, shut-off valve 70 is provided. This consists of a spherical float 69 confined between three guides 71 which extend downwardly from the centre of the cone 64 and carry at their lower ends a disc 72 which engages the central boss 83 of the filter assembly 80 to prevent the latter from being lifted by the suction applied thereto. The boss 65 carried by the cone 64 is formed with a seating 68 against which the float 69 will engage sealingly so as to prevent the passage of water upwardly into the intake chamber 43. In the illustrated embodiment, the float 69 is made of thin plastics material so as to be capable of being lifted solely by air flow. In practice, if the level of liquid in the container 10 rises to such a height that it enters the space beneath the cone 64, and thus lifts the float 69 towards the seating 68, the flow of air which continues to be drawn beneath the trough 62 will eventually lift the float up to seating 68 before the water level reaches the lower edge of the hose inlet aperture 12.

The float valve 70 also serves to pevent water from the container 10 entering the intake chamber 43 if the appliance is inadvertently tipped over.

The mounting ring 74 of the reservoir 60 is formed with an extention 75 which is aligned with the protruberance 11 of the main container 10 and supports the pipe clip 76. A rib 78 which extends around the entire periphery of the mounting ring 74 and the extension 75 is adapted to seat within the open top of the container 10 as seen in Figure 2.

When the appliance is to be used for dry suction cleaning, the reservoir 60 is removed and the dust filter assembly 90 is assembled between the main container 10 and the top cover assembly 20 and retained by means of the clips 16 as shown in Figure 5.

The dust filter assembly 90 includes a support member 91 comprising an outer mounting ring 92 with radial ribs 93 supporting a central boss 94. An L-section ring 95 is seated within the mounting ring 92 and supports the periphery of a fine mesh filter disc 96. The filter disc 96 is retained in position by means of an inner ring 97 which fits within the outer ring 92 and traps the peripheral portion of the disc as shown in Figure 5. The inner ring 97 has a central plate 98 formed integrally therewith and radial ribs extending between the ring and the plate are formed with vertical spacer members 99 which engage the lower edge of the ring 35 of the mounting plate 30 and a rib around the aperture 34 of the base plate 32 of the top cover assembly 20 so as to prevent the filter lifting under the suction applied thereto.

In the absence of the boss 65 which forms part of the reservoir 60. the valve plate 37 drops to its lower position to close the aperture 34 and open the apertures 48 so that suction is applied to the container 10 from the inlet chamber 43 of the suction unit through the filter 96, whilst exhaust air from the suction unit is diverted by the valve plate 37 to atmosphere through the apertures 48 as clearly shown in Figure 5.

In this way, dust entrained in the incoming air is filtered out and collected in the container 10. However, it will be appreciated that it would alternatively be possible for the top cover assembly 20 to be adapted for securing direct to the top of the main container 10, for example by forming on the casing 21 ears similar to the ears 51 for engagement by the lips 17 of the clips 16, a filter bag then being provided within the container 10 and having an adaptor for direct connection to the end of the hose adjacent to aperture 12.

The preferred form of cleaning head 100 for use with the appliance includes a tubular spigot 101 for attachment to the suction hose (not shown) and a transverse housing 102 with an internal transverse rib 103 and a central hollow boss 104 for reception of a nozzle 105 at the end of the pipe 77 through which liquid is supplied from the reservoir 60. A hole 106 is formed at the lower end of the boss and communicates with a channel 107 which extends along the underside of the transverse rib 103. A pair of mouldings 108 are located within the housing 102 by engaging at their ends in slots 109 formed in the ends of the housing. Additionally, the two mouldings in combination are shaped to afford a pair of vertical lugs 110 which fit within apertures 111 formed in the top wall of the housing adjacent the ends thereof.

The two mouldings in combination also define a channel 112 which together with the channel 107 defines a transversely extending duct 113 whereby liquid received from the nozzle 105 through the hole 106 is distributed along the whole length of the housing 102.

Calibrated apertures 114 are provided at spaced intervals along the length of the head in order to regulate the flow of liquid so as to cause it to be delivered uniformly and continuously at an appropriate rate. Typically, the aperture 114 have a diameter of 0.4 mm and are spaced on 4 mm centres. Liquid then drops through these apertures and enters an inner compartment 115 defined between a pair of transversely extending walls 116 formed on the mouldings 108. The inner compartment 115 is disposed centrally of an outer compartment 117 defined by the casing 102, and the end faces 118 of the walls 116 are arranged so as to be flush with the mouth of the housing 102 as defined by a rounded bead 119. The bead is of continuous and uninterrupted form so that when passed over a pile fabric, the pile is not separated or combed. In this way the outer chamber 117 can be effectively sealed from the outside atmosphere so that a strong suction is applied to the fabric being cleaned. The arrangement of the end faces 118 of the walls 116 in the same plane as the mouth of the outer compartment 17 ensures that the inner compartment 115 is likewise effectively sealed against the fabric being treated and there is virtually no possibility of liquid being drawn from the inner compartment 115 directly to the outer compartment 117 by virtue of the air flow established within the head. Instead, the liquid is constrained to drip onto the fabric being cleaned. In this way, a thorough wetting of the fabric is ensured without spraying. This in turn, makes it possible for the appliance to operate with only a low pressure within the reservoir, and without any pump for the delivery of cleaning liquid to the head.

A shut-off valve (not shown) may be incorporated in the pipe 77 so as to enable the flow of cleaning liquid to the head to be interrupted.

A similar control of liquid delivery can be achieved by the use of a manually operable valve for control of the exhaust air flow from the impeller 27, so as to enable such air to be directed to atmosphere when the reservoir is in position if it is desired to interrupt the supply of cleaning liquid. A modified valve assembly 140 for this purpose is illustrated in Figures 11 and 12 of the accompanying drawings.

The valve assembly 140 is incorporated at the underside of the top cover assembly 20 in place of the valve assembly 40 which is illustrated in Figures 2, 3 and 5. In this case, the cover assembly includes a base plate 141 having a peripheral rib 142 which engages within the mounting ring 74 of the reservoir 60 or within the mounting ring 92 of the dust filter assembly 90. The base plate 141 is formed with an annular wall 144 which in combination with the wall 28 of the casing 21 defines the exhaust outlet chamber 44 around the impeller 27. The base plate 141 is provided with reinforcing ribs 143 and 145 and a central boss 146 which affords the seating 68 for the float valve 70.

The annular wall 144 is formed as a series of tongues 147 spaced apart circumferentially by openings 148, with an elongated opening 149. A shutter 150 is provided within the annular wall 44 and this is formed as a cylinder 151 affording a series of tongues 152 separated circumferentially by openings 153, with an elongated tongue 154 to which a radial arm 155 is attached. The cylinder 151 also includes a number of inwardly projecting horizontal tongues 156, and the base plate 141 is formed with a ring of apertures 157 arranged between the annular wall 144 and an inner wall 158 which defines the intake chamber 43.

As can be seen from Figure 12, the elongated tongue 154 is arranged in register with the elongated opening 149 so that the arm 155 projects outwardly through the elongated opening and terminates at a position outside the casing 21. In the position as shown in Figure 12, the tongues 147 are in register with the openings 153 and the tongues 152 are in register with the openings 148, whilst the horizontal tongues 156 are disposed between the apertures 157. Thus, the exhaust air flow from the impeller 27 is confined within the chamber 44 and allowed to escape only through the apertures 157 to the underside of the base plate 141 so as to pressurise the interior of the reservoir 60 when this is assembled with the top cover assembly 20.

However, when the operating arm 155 is moved to the other end of the slot from which it protrudes through the casing 21, the tongues 147 and 152 are brought into register with one another so that the openings 148 and 153 are similarly brought into register with one another. This allows exhaust air to escape from the chamber 44 to the interior of the casing 21 and thence to the external atmosphere. At the same time the horizontal tongues 156 are brought into register with the apertures 157, and the air flow is prevented from entering the reservoir 60. Thus, the flow of liquid can be interrupted by operation of the arm 155, and indeed a degree of regulation may be obtained by intermediate settings of the operating arm 155.

Whilst the float 69 of the float valve 70 is shown in Figure 2 as constrained by guides 71, it is alternatively possible to provide three or more internal vanes beneath the cone 64 of the reservoir 60, such vanes being of generally triangular shape so that their vertical edges serve as guides for the float 69. This arrangement has the advantage of further restricting the possibility of the establishment of a vortex beneath the cone 64, to such an extent that the filter assembly 80 could be omitted, although it is preferable to retain it because of its function as a screen substantially impervious to the passage of foam.

The cleaning head shown in Figures 7 to 10 of the accompanying drawings is the subject of our co-pending application no.

20151/77 cognate 46145/77. Serial No.

1601455.

WHAT WE CLAIM IS: 1. Suction cleaning apparatus comprising a container adapted for the collection of both solids and liquids and having an inlet for connection with a cleaning head, a motor-driven air suction unit with an air exhaust outlet and an air inlet which communicates with said container to apply suction thereto, a detachable dust retaining member for retaining dry dust within the container, and a detachable reservoir for storing cleaning liquid with a liquid delivery duct for connection to a liquid delivery outlet for applying the cleaning liquid to a surface to be cleaned, thearrangement being such that the detachable filter is used in the absence of the reservoir and vice-versa so as to enable the apparatus selectively to perform either dry suction cleaning with the filter in place or wet cleaning with the reservoir in place, wherein said reservoir incorporates an air passageway which, when the reservoir is in use, communicates at one end with the air inlet of said suction unit and at the other end with the interior of said container, a shut-off valve is provided in association with said passageway to close the latter in response to the Ivel of liquid collected in said container, and an air flow director separate from said passageway is provided for either directing air from the exhaust outlet of said suction unit to atmosphere when said filter is in use or allowing the exhaust air to flow to the interior of said reservoir when the latter is in use so as to displace said cleaning liquid therefrom through said delivery duct, while in either case suction from said suction unit is applied simultaneously to said container.

2. Suction cleaning apparatus according to Claim 1 wherein the air flow director includes a valve member biased into a first position in which exhaust air from the suction unit is allowed to flow to atmosphere, the valve member being so arranged as to be engaged by a part carried by the reservoir when the latter is in use so that the valve member is then moved to a second position in which the exhaust air flow from the suction unit is directed to the interior of the reservoir so as to apply a positive pressure thereto.

3. Suction cleaning apparatus according to Claim 2 wherein the valve member comprises a plate which is vertically movable in a valve chamber having an upper outlet communicating with the external atmosphere and a lower outlet communicating with the reservoir, the valve plate being gravitationally biased to its first position so as to close the lower outlet unless raised to its second position by the engagement of the valve member with said part carried by the reservoir.

4. Suction cleaning apparatus according to Claim 1 wherein the air flow director comprises a manually operable shutter.

5. Suction cleaning apparatus according to Claim 4 wherein the shutter comprises a circumferentially movable ring affording apertures which may be selectively brought into register with either of two sets of outlet apertures formed in a chamber into which exhaust air from the suction unit is delivered, one set of outlet apertures allowing said exhaust air to flow to atmosphere and the other set allowing said exhaust air to flow to said reservoir.

6. Suction cleaning apparatus according to any one of the preceding claims wherein the container is an open-topped vessel and the reservoir is adapted to be mounted across the open top of the container and is itself open-topped, the suction unit being housed in a cover member which is itself adapted to be mounted across the open top of the reservoir so as to close the latter.

7. Suction cleaning

Claims (21)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   three or more internal vanes beneath the cone 64 of the reservoir 60, such vanes being of generally triangular shape so that their vertical edges serve as guides for the float 69. This arrangement has the advantage of further restricting the possibility of the establishment of a vortex beneath the cone 64, to such an extent that the filter assembly 80 could be omitted, although it is preferable to retain it because of its function as a screen substantially impervious to the passage of foam.

   The cleaning head shown in Figures 7 to 10 of the accompanying drawings is the subject of our co-pending application no.

   20151/77 cognate 46145/77. Serial No.

   1601455.

   WHAT WE CLAIM IS: 1. Suction cleaning apparatus comprising a container adapted for the collection of both solids and liquids and having an inlet for connection with a cleaning head, a motor-driven air suction unit with an air exhaust outlet and an air inlet which communicates with said container to apply suction thereto, a detachable dust retaining member for retaining dry dust within the container, and a detachable reservoir for storing cleaning liquid with a liquid delivery duct for connection to a liquid delivery outlet for applying the cleaning liquid to a surface to be cleaned, thearrangement being such that the detachable filter is used in the absence of the reservoir and vice-versa so as to enable the apparatus selectively to perform either dry suction cleaning with the filter in place or wet cleaning with the reservoir in place, wherein said reservoir incorporates an air passageway which, when the reservoir is in use, communicates at one end with the air inlet of said suction unit and at the other end with the interior of said container, a shut-off valve is provided in association with said passageway to close the latter in response to the Ivel of liquid collected in said container, and an air flow director separate from said passageway is provided for either directing air from the exhaust outlet of said suction unit to atmosphere when said filter is in use or allowing the exhaust air to flow to the interior of said reservoir when the latter is in use so as to displace said cleaning liquid therefrom through said delivery duct, while in either case suction from said suction unit is applied simultaneously to said container.
2. 2. Suction cleaning apparatus according to Claim 1 wherein the air flow director includes a valve member biased into a first position in which exhaust air from the suction unit is allowed to flow to atmosphere, the valve member being so arranged as to be engaged by a part carried by the reservoir when the latter is in use so that the valve member is then moved to a second position in which the exhaust air flow from the suction unit is directed to the interior of the reservoir so as to apply a positive pressure thereto.
3. 3. Suction cleaning apparatus according to Claim 2 wherein the valve member comprises a plate which is vertically movable in a valve chamber having an upper outlet communicating with the external atmosphere and a lower outlet communicating with the reservoir, the valve plate being gravitationally biased to its first position so as to close the lower outlet unless raised to its second position by the engagement of the valve member with said part carried by the reservoir.
4. 4. Suction cleaning apparatus according to Claim 1 wherein the air flow director comprises a manually operable shutter.
5. 5. Suction cleaning apparatus according to Claim 4 wherein the shutter comprises a circumferentially movable ring affording apertures which may be selectively brought into register with either of two sets of outlet apertures formed in a chamber into which exhaust air from the suction unit is delivered, one set of outlet apertures allowing said exhaust air to flow to atmosphere and the other set allowing said exhaust air to flow to said reservoir.
6. 6. Suction cleaning apparatus according to any one of the preceding claims wherein the container is an open-topped vessel and the reservoir is adapted to be mounted across the open top of the container and is itself open-topped, the suction unit being housed in a cover member which is itself adapted to be mounted across the open top of the reservoir so as to close the latter.
7. 7. Suction cleaning apparatus according to Claim 6 wherein the dust retaining member comprises a filter unit which is interchangeable with said reservoir and is thereby adapted to be interposed between the container and the cover member of said air suction unit.
8. 8. Suction cleaning apparatus according to claim 7 wherein the reservoir and the filter unit each include a respective mounting ring adapted to engage the upper peripheral edge of the container and the lower peripheral edge of the suction unit cover member.
9. 9. Suction cleaning apparatus according to any one of Claims 1 to 7 wherein the reservoir comprises an annular trough which is received within the container with an outer side wall of the trough disposed in spaced relation to an outer wall of the container.
10. 10. Suction cleaning apparatus according to Claim 9 wherein the inlet for connection to the cleaning head is disposed in the outer wall of the container so that incoming air flow is directed substantially radially

    inwardly and directly onto the outer side wall of the trough.
11. 11. Suction cleaning apparatus according to Claim 10 wherein the outer side wall of the trough is arranged substantially vertically and is formed with a flat area in register with said inlet.
12. 12. Suction cleaning apparatus according to any one of Claims 9 to 11 wherein said trough includes a generally cone shaped inner wall with a central opening in register with said air passageway through which air is drawn from the container by said suction unit.
13. 13. Suction cleaning apparatus according to Claim 12 wherein a plurality of substantially vertical radially extending vanes are provided within the cone.
14. 14. Suction cleaning apparatus according to Claim 12 or Claim 13 wherein the reservoir is provided at its underside with a downwardly extending rib around the lower end of the con-ehshaped inner wall.
15. 15. Suction cleaning apparatus according to any one of Claims 12 to 14 wherein said shut-off valve comprises a float valve and said central opening defines a seating for the float thereof.
16. 16. Suction cleaning apparatus according to any one of the preceding claims wherein the cleaning head comprises a suction chamber connected to said inlet of the container and having an open mouth for application to the surface to be cleaned, and an inner compartment arranged substantially centrally within the suction chamber and having side walls defining an open mouth in the plane of the open mouth of the suction chamber, the inner compartment having associated therewith a cleaning liquid delivery duct connected to said liquid delivery outlet of said reservoir and formed with a plurality of closely spaced fine outlets adapted to allow cleaning liquid to flow substantially dropwise into the inner compartment at a position spaced from the mouth thereof, the arrangement being such that when the cleaning head is applied to a surface to be cleaned, cleaning liquid is applied to a part of the surface which is shielded from air flow arising from vacuous conditions within the suction chamber, but upon movement of the cleaning head in either of at least two opposed directions the area then wetted by the cleaning liquid is immediately subjected to suction drying.
17. 17. Suction cleaning apparatus according to Claim 16 wherein the end edges of the side walls of the inner compartment are free from local protrusions or recesses.
18. 18. Suction cleaning apparatus according to Claim 17 wherein the mouth of the suction chamber is free from local protrusions or recesses.
19. 19. Suction cleaning apparatus according to any one of Claims 16 to 18 wherein the end edges of the side walls defining the suction chamber are of smoothly rounded shaped in transverse section.
20. 20. Suction cleaning apparatus substantially as hereinbefore described with reference to and as shown in Figures 1 to 6 of the accompanying drawings.
21. 21. Suction cleaning apparatus according to Claim 20 modified substantially as hereinbefore described with reference to and as shown in Figures 11 and 12 of the accompanying drawings.