GB2228219A - A surface cleaning machine - Google Patents

Abstract

A mobile surface cleaning machine for horizontal surfaces comprises an opening (6) through which a particulate material can be propelled to impact against a surface. An upwardly extending conduit (5) can receive spent material rebounding from the surface along with surface debris. To assist in the recovery of the spent material and debris, a means (19, 20) for inducing a flow of air upwardly through the conduit (5) is provided. Located beneath the upper end of the conduit (5) is a hopper (17) for spent materials. A baffle plate (25) is positioned near the upper end of the conduit (5) to direct the spent material downwardly into the hopper (17) and a means is provided for inducing a flow of air across a separator region (9) located beneath the baffle plate (25) to entrain the surface debris therewith for removal from the machine. The battle plate (25) is movable towards or away from the end of the conduit (5) to decrease or increase the air pressure difference across the separator region (9) in order to optimize the separation of the particulate material form the surface debris according to the type of material being used and the type and the quantity of debris. <IMAGE>

Description

A SURFACE CLEANING MACHINE The present invention relates to a mobile surface cleaning machine suitable for use on horizontal or near horizontal surfaces.

The machine is of the type in which a particulate material, usually a form of abrasive such as steel shot, grit or sand, is propelled at a high velocity to impact against the surface to be cleaned. The rebounding material is then collected and any surface debris mixed with it is removed therefrom so that the material can be re-used again during the same cleaning operation.

The separation of the surface debris from the particulate material is an essential aspect of mashines of this type in order to keep the quantity of blasting material required in a cleaning operation down to a reasonable level both as regards cost and in terms of the volume of material required. It is important, therefore, for the removal of the surface debris from the spent material to be accomplished as successfully as is possible. However, this is often dependent on the type of particulate material being used and the quantity and type of debris mixed therewith. Conventional machines tend to be constructed for use with a particular type of blasting material and the successful separation of surface debris therefrom usually depends on the type and quantity of debris mixed therewith.

The object of the present invention is to provide a surface cleaning machine in which the successful separation of surface debris from the spent blasting material can be optimized for any given type of blasting material and type and quantity of surface debris ini':ea.

therewith.

According to the present invention there is provided a surface cleaning machine comprising an opening in an enclosure through which a particulate material can be propelled at a high velocity to impact against a surface to be cleaned, an upwardly extending conduit which is in communication with the opening and which can receive spent material rebounding from the surface along with surface debris, means for drawing air into the machine and inducing a flow of air upwardly through the conduit, a hopper for the particulate material which is located beneath the upper end of the conduit and into which the spent material can fall, a baffle plate located near the upper end of the conduit to direct the spent material downwardly into the hopper, and means for inducing a flow of air across a separator region located above the hopper and beneath the baffle plate to entrain the surface debris therewith for removal from the machine, the baffle plate being movable towards or away from the end of the conduit to decrease or increase respectively the air pressure difference across the separator region as desired in order to optimize the separation of the particulate material from the surface debris according to the type of particulate material being used and the type and the quantity of surface debris to be separated therefrom.

Preferably, the means for inducing a flow of air across the separator region comprises an air inlet located in the separator region on the opposite side of the baffle plate from an air outlet communicating with said means for drawing air into the machine.

Preferably also, the air inlet comprises a pipe located across the separator region and in communication with the atmosphere at at least one end thereof, a series of holes being provided along the length of the pipe which is within the separator region.

Preferably also, the machine is mobile and mounted on wheels. A front wheel is preferably a caster wheel and is adjustably mounted so that it can be raised and lowered to vary the height of the opening from the surface to be cleaned.

Preferably also, the baffle plate comprises an angled plate which can be rotated and thereby moved towards or away from the end of the conduit.

Preferably also, the machine is powered by at least one hydraulic motor. A tank for the supply hydraulic fluid to the motor is preferably located above the level of the motor so that the fluid can flow to the motor under gravity.

Preferably also, the conduit is fabricated fror, a series of angled plates and has a substantially constant cross-sectional area along its length.

The present invention will now be described by way of example with reference to -the accompanying drawings, in which: Figure 1 is a schematic cross-sectional view of a surface cleaning machine according to the invention Figure 2 is a more detailed cross-sectional view of a separator region of the machine shown in Figure i; and Figure 3 is a more detailed and enlarged view of the mounting of a front wheel of the machine shown in Figure 1.

A surface cleaning machine comprises a mobile rigid structure 1 mounted on wheels 2 and 3. The front wheel 2 is a caster wheel, as is described below with reference to Figure 3, and the two back wheels 3 are driven so that the machine can be moved easily by an operator over the surface to be cleaned.

The structure comprises a housing 1 defining a pair of conduits 4 and 5, which extend upwardly at divergent angles from a common opening 6 located at ground level.

At the upper end of the conduit 4 is positioned a means 7 for propelling particulate material at a high velocity down the conduit 4 and through the opening 6 to impact the surface to be cleaned. The conduit 5 is fabricated from a series of angled plates 8 and has a substantially constant cross-sectional area along its length. It extends curvilinearly upwards from the opening 6 to a separator region 9 located above the opening 6. The conduit 5 receives spent particulate material rebounding from the surface being cleaned along with surface debris.

The means 7 for propelling the particulate material is preferably a centrifugal blasting wheel 10 which is driven by an electric motor 11, preferably, as shown, via drive belts 12 and pulleys 13 connected to the axle 14 of the wheel 10. The wheel 10 has a series of radially extending blades 15 and when it is rotated at high speed the blades 15 propel particulate material, fed thereto via a spout and cage arrangement 16 at the centre of the wheel 10, down the conduit 4.

The particulate material can be any suitable blasting material such as shot, grit or sand and it is stored in a hopper 17, which feeds by gravity the arrangement 16 and thereby the wheel 10.

The hopper 17 is located beneath the upper end 18 of the conduit 5 so that spent particulate material can fall into it after passing through the conduit 5. Between the end 18 of the conduit 5 and the hopper 17 is the separator region 9 where the surface debris exiting from the conduit 5 is air washed out of the spent material, which is returned to the hopper 17 for re-use.

To assist in the recovery of the spent particulate material and the collection of surface debris, a means is provided for drawing air into the machine and inducing a flow of air upwardly through the conduit '. This means comprises a pump (not shown) with a flexible duct i9 attached to an outlet 29 situated at the top of the structure 1 to communicate with the separator region 9 above the hopper 17. Air is extracted fro the separator region 9 and the conduit 5 along the duct 19 and this induces an air flow, as indicated by the broken arrows in Figures 1 and 2, through the opening 6, along the conduit 5 and through the separator region 9. The opening 6 of the machine is, however, enclosed by means of seals 21, which extend completely around its periphery apart from along the edge 22 at the back of the machine. This edge 22 is provided with a brush 23. The seals 21 are preferably made from polyurethane or other resilient plastics material and prevent any significant flow of air td occur between them and the surface being cleaned. The air flowing through the opening 6 is, therefore, mainly drawn through the brush 23 at the back of the machine and the suction thereby produced within the enclosure 24 around the opening 6 assists in the dislodgement and passage of surface debris through the opening 6 and into the conduit 5.

With particular reference to Figure 2, at the upper end of the conduit 5 and located within the separator region 9 is a baffle plate 25. The plate 25 is angled and rotationally mounted to the structure 1 by means of a bracket 26 and a hinge 27. The plate 25 can be rotated towards or away from the end 18 of the conduit 5 and fixed in any position so that the area of the gap between the plate 25 and the end 18 of the conduit 5 forming the outlet of the conduit into the separator region 9 can be controlled. As air is being drawn through the conduit 5 and the separator region 9 past the baffle plate 25, the area of the gap helps to control the air pressure difference which is set up across the separator region 9.

This enables the separation of the spent material and the surface debris to be optimized for any given material and type and quantity of debris.

The air washing of the blasting material is aided by inducing a further flow of air across the separator region 9 below the baffle plate 25 and immediately above the hopper 17. This is done by the provision of an air inlet 29 in the form of a pipe 30, which is located on the opposite side of the baffle plate 25 from the duct outlet 20 so that air is drawn across the whole of the separator region 9 above the hopper 17. The pipe 30 spans the separator region 9 and passes through the housing 1 so that it is in communication with the atmosphere outside the machine at both of its ends. Along its length within the separator region 9, it is provided with a series of holes so that air is drawn from the atmosphere down the pipe 30 and through the holes to form a curtain of air passing across the region 9 which entrains the surface debris.

In use, the spent material and the surface debris passing out of the conduit 5 strikes the angled baffle plate 25, which directs the rebounding material downwardly into the hopper 17, as shown by the lighter unbroken arrows in Figures 1 and 2. The blasting material is usually heavier than the surface debris and after striking the baffle plate 25 loses much of its momentum and falls under gravity into the hopper 17. However, the lighter debris tends to be entrained in the flow of air passing across the separator region 9 and is removed from the machine through the outlet 20. The air inlet pipe 30 assists in this process by providing a clean flow of air, as shown by the heavy black broken arrows 31, across the top of the hopper 17 beneath the bottom edge of the baffle plate 25 and towards the outlet 20.

The level of air suction through the conduit 5 can also be altered by raising or lowering the front wheel 2 of the machine, as will now be described with reference to Figure 3.

The front wheel 2 is a caster wheel with a bearing hub 32 attached to a plate 33, which is rotationally mounted at 34 to the structure 1. A screw-threaded bolt 25, which is attached to the structure 1 via a bracket 36 and locking nut 37, has its lower end rotationally mounted to the plate 33 so that by altering the position of the nut 37 on the bolt 35 the wheel 2 can be raised or lowered in relation to the bracket 36 and the rest of the structure 1. This, in turn, raises or lowers the whole structure 1 and either decreases or increases respectively the pressure on the seals 21 and the brush 23 thus permitting more or less air to be drawn into the machine in a given time.

In addition to varying the level of air suction through the conduit 5, the height of the wheel 2 can also be adjusted to suit the surface to be cleaned. If the surface is rough, the wheel 2 can be raised to permit the seals 21 to run over it more easily, whereas if the surface is pitted the wheel 2 can be lowered to force the seals 21 to follow closely the contours of the surface.

The rear drive wheels 3 of the machine are powered by at least one and preferably two hydraulic motors (not shown), which receive hydraulic fluid pumped from a tank 38 located above the conduit 5. The position of the tank 38 is such that when the pump (not shown) has Deen switched off, the hydraulic fluid can still flow to the motors under gravity to lubricate the system. This reduces the risk of aeration of the fluid.

Before using the machine, the position cf the baffle plate 25 and the height of the front wheel 2 are present according the the type of surface to be cleaned and the particulate material to be used. In this way, the pressure difference created by the air flow within the conduit 5 and the separator region 9 can be carefuily controlled to optimize the separation of the surface debris from spent blasting material to be re-cycled. If the surface has little debris on it to be removed, for example if it is a newly laid concrete floor, the baffle plate 25 is fixed in a position close to the end 18 of the conduit 5 to reduce the air pressure difference across the separator region 9 and prevent the blasting material itself from being entrained in the air flow and thereby removed from the machine. However, if the surface has a large quantity of debris to be removed, for example if it is a steel plate covered in rust scale, then a greater air pressure difference is required to remove all the debris from the spent blasting material and the baffle plate 25 would be fixed in a position further away from the end 18 of the conduit 5. Hence, unlike conventional machines, the efficiency of the separation of the debris from the blasting material can be optimized.

Claims (10)

1. A surface cleaning machine comprising an opening in an enclosure through which a particulate material can be propelled at a high velocity to impact against a surface to be cleaned, an upwardly extending conduit which is in communication with the opening and which can receive spent material rebounding from the surface along with surface debris, means for drawing air into the machine and inducing a flow of air upwardly through the conduit, a hopper for the particulate material which is located beneath the upper end of the conduit and into which the spent material can fall, a baffle plate located near the upper end of the conduit to direct the spent material downwardly into the hopper, and means for inducing a flow of air across a separator region located above the hopper and beneath the baffle plate to entrain the surface debris therewith for removal from the machine, the baffle plate being movable towards or away from the end of the conduit to decrease or increase respectively the air pressure difference across the separator region as desired in order to optimize the separation of the particulate material from the surface debris according to the type of particulate material being used and the type and the quantity of surface debris to be separated therefrom.

2. A machine as claimed in Claim 1, wherein the means for inducing a flow of air across the separator region comprises an air inlet located in the separator region on the opposite side of the baffle plate from an air outlet communicating with said means for drawing air into the machine.

3. A machine as claimed in Claim 2, wherein the air inlet comprises a pipe located across the separator region and in communication with the atmosphere at at least one end thereof, a series of holes being provided along the length of the pipe which is within the separator region.

4. A machine as claimed in Claim 3, wherein the pipe spans the separator region and is in communication with the atmosphere at both ends.

5. A machine as claimed in any one of Claims 1 to 4, wherein the machine is mobile and mounted on wheels, a front wheel of which is a caster wheel.

6. A machine as claimed in Claim 5, wherein the caster wheel is adjustably mounted se that it can be raised and lowered to vary the height of the opening .r. the enclosure from the surface to be cleaned.

7. A machine as claimed in any one of Claims 1 to 6, wherein the baffle plate comprises an angled plate which can be rotated and thereby moved towards or away from the end of the conduit.

8. A machine as claimed in any one of Claims 1 to 7, wherein the machine is powered by at least one hydraulic motor and a tank for the supply of hydraulic fluid to the motor is located above the level of the motor so that the fluid can flow to the motor under gravity.

9.. A machine as claimed in any one of Claims 1 to 8, wherein the conduit is fabricated from a series of angled plates and has a substantially constant cross-sectional area along its length.

10. A surface cleaning machine substantially as described herein with reference to the accompanying drawings.