A ROTARY CLEANING BRUSH DEVICE FOR CLEANERS OF PAVED SURFACES

Abstract: The invention relates to a rotary cleaning brush device for cleaners of paved surfaces, whose brushes (2) are aligned perpendicularly to the straight travel direction of the cleaner and have peripheral regions which are formed of an orderly succession of projections (8) and recesses (9), the projections (8) of each brush (2) fitting into the recesses (9) of another brush (2), and having at least one pair of brushes (2) arranged with their respective axes of rotation (4) convergent together in a direction away from a surface (7) to be swept, the brushes (2) being rotated in a direction which produces, in the areas of least mutual distance between the brushes (2), tangent velocities which are on the average oppositely directed with respect to the straight travel direction of such cleaners.

Description: This invention relates to a rotary cleaning brush device of the kind disclosed in US-A-3 286 289, for cleaners of paved surfaces. As is known, machines and equipment for cleaning floors and the like surfaces have long been available on the market. Such machines range from very simple designs to comparatively sophisticated designs for professional application. In each case, they include devices having two or more cleaning brushes which are set for rotation close together to perform at least a substantial proportion of the cleaning operation. Many cleaners have, for example, a brush head comprising two circular brushes mounted side-by-side for counter-rotation. The two brushes are close to each other but, of course, not tangent, and a sufficiently wide gap is left therebetween to avoid any interference and assembly problems. The two brushes of such brush heads are aligned in a transverse direction but not in a perpendicular direction to the straight direction of advance of the heads, which would be coincident with the longitudinal centerline of such machines. It has been found, in fact, that if the two brushes are aligned perpendicularly to the straight direction of advance, during the forward movement of the brush head in a straight line there is formed an unswept continuous thin stripe on a paved surface at the linear gap between the brushes. In order to overcome this drawback, the two brushes are set obliquely to said longitudinal centerline. Thus, each brush is caused to act over an area which partly overlaps that of the other brush, thereby avoiding formation of an unswept stripe. That arrangement has the disadvantage that it confers an irregular outline on the cleaner, increases the machine length dimension, and makes cleaning close against a wall, or in any case along edges of floors, more difficult. In fact, the cited brush head stands in many istances proud of such cleaners, on which it usually forms the foremost portion, and is to take an oblique attitude much like that of the brushes themselves. In this condition, it is the very forward working end of the machine which becomes asymmetrical relatively to the machine main extension. These problems have led to the manufacture and sale of other cleaners provided with a brush head having three brushes, wherein two brushes are laid along a perpendicular direction to the machine longitudinal centerline and the third brush extends in an intermediate, either forward or rearward, set position, so as to form a triangular set of brushes. It may be appreciated that the approach just described has good operational features, but involves a more complex and expensive construction that that using two brushes only and is significantly bulky. In general, this approach only becomes viable with cleaners of higher price and size. These problems have also led to cleaners like that shown in the US Patent n. 3 286 289, where the brushes have peripheral regions formed with an orderly succession of projections or tufts of bristles and recesses. The brushes are aligned side-by-side and driven rotatively in opposite directions and the line of communication between the two brushes is perpendicular to the travel direction envisaged for the cleaner. During the forward movement these known cleaners create a partial overlap of the brushes and do not form a continuous unswept strip. The arrangement just described appears to be the most viable with cleaners of simple design and of minimal bulk in lengthwise. But not even this arrangement gives a solution to a drawback which is typical of the cleaners of simple design, having no arrangements of self-propulsion: there is no facilitation for the operator in driving a cleaner and the brushes do not exert any useful effect of traction or propulsive force in the straight direction of travel. On the contrary, in many cases, particularly if the paved surface or the brushes are irregular, the frictional engagement of the brushes with the surface to be swept generates reaction thrusts applied to the brushes causing the cleaner to move along a curved or oblique path to the linear direction of travel. Moreover, particular positions of the brushes may worsen the situation. For instance, the CH patent n. 536 105 shows the use of a single and very large brush having a rotation axes inclined backwards with respect to the direction of advance of the device. So a reaction thrust is generated by the floor on the brush in a transversal direction to the linear path of advance. In the light of the above-outlined situation, the technical aim which underlies this invention is to provide a rotary brush device which affords both optimum cleaning operation conditions and a significant traction or propulsive stabilizing force along the straight direction of advance of the cleaner. This technical aim is substantially achieved by a rotary brush device for cleaners of paved surfaces comprising brushes having peripheral regions formed with an orderly succession of projections and recesses and laid side-by-side such that said projections of each said brush fit at least partway into said recesses of another such brush, the side-by-side brushes in each pair being driven rotatively in opposite directions and being aligned perpendicularly to the straight travel direction envisaged for said cleaners incorporating the device, - characterized in that at least one pair of said brushes are provided wherein the brushes have mutually convergent rotation axis in a direction away from a surface to be swept, and in that said brushes are rotated in suitable directions to produce, in the areas of least distance of the brushes from each other, tangent velocities directed on the average in a substantially opposite direction to the straight travel direction envisaged for said cleaners. The advantages of this invention will become apparent from the following description of the rotary brush device shown in the accompanying drawings, where: Figure 1 shows schematically in perspective two brushes of the inventive device isolated from the remainder; Figure 2 is a plan view of the brushes of Figure 1 showing their action on a surface; and Figure 3 shows the brushes of Figure 1 as fitted to the brush holder head of a floor washer. With reference to the drawing figures, the device of this invention is comprehensively designated 1. It comprises two side-by-side brushes 2 which are shown in Figure 3 as assembled to a brush holder head 3 e.g. of the kind of those used on cleaners commonly referred to as "auto-scrubbers". These machines have relatively compact dimensions and are for washing and drying the floor areas of sheds, warehouses, commercial establishments, and more generally large area paved surfaces. The brush holder head 3 is located, on these machines, as the forward end of the machines. The brushes 2 are rotatable about axes 4 and driven rotatively by specially provided drive members 5 such that they can act on a surface 7 with respective working sides 6. As shown in Figures 1 and 2, the brushes 2 have, across perpendicular planes or sections to the axes 4, peripheral regions formed with an orderly succession of projections 8 and recesses 9. Provision is made for the brushes 2 interleaving with each other, thereby the projections 8 fit into the recesses 9, and for same to turn in opposite directions of rotation at concurrent tangent velocities in the area of mutual interleave. In the instance shown, angular velocities would be the same because the brushes are identical to each other. In the embodiment shown, the brushes have three tooth-like projections 8 and three wide recesses 9. The recesses 9 have a larger width than the projections 8 to provide ample clearance between the brushes and no interference and assembly problems. Furthermore, the projections 8 are caused to fit with a major portion thereof into the recesses 9, thereby ensuring in all cases loose fit interpenetration even with low-precision constructions. The brushes 2 are laid side-by-side and aligned perpendicularly to the straight direction of advance envisaged for the device 1, as shown in Figure 2. The axes 4 are arranged to converge together in a direction away from the surface 7 so as to bring the working sides 6 closer to the surface 7 in the area of interpenetration of the brushes. Furthermore, the directions of rotation of the brushes are selected to have, in that same area of interpenetration, oppositely directed tangent velocities with respect to the envisaged straight direction of advance of the device. The planes of lay of each brush, perpendicular to the axes 4, are contemplated to be slanted by an angle alpha of at least one degree over the surface 7. The magnitude of the angle alpha should be selected each time according to the type of brush being used and its pliability so as to achieve substantially maximum inclination of the brushes compatibly with even and homogeneous cleaning throughout the surface 7. The device 1 operates as follows. As shown in Figure 2, the brushes 3, being aligned perpendicularly to the straight travel direction of the device 1, will interleave with each other and act on lanes across the surface 7 which are not separated by unswept stripes. Indeed, the lanes would partly overlap each other. The slanted setting of the brushes 2 by the angle alpha also results in increased frictional engagement of the working sides 6 with the surface 7 in the very area of partial overlap. This increased friction reflects in a reaction thrust being applied to the brushes 2 in the opposite direction to the directions of their tangent velocities in that same area. It follows that the brushes will exert a significant traction or propulsive force along the straight direction of advance of the device, thereby greatly facilitating the action of an operator where the cleaner or apparatus equipped with these brushes happens to have no self-propelling features. Otherwise, these brushes would serve to minimize the power requirements of any self-propulsion provisions. What may be even more important is that these brushes exert a stabilizing effect on the machine by tending to keep truly on a straight line or to straighten it up when negotiating bends. Thus, the machine operator has a valuable steering aid afforded to him/her because the machine travel path can be straightened nearly automatically and is made significantly more stable in its straight-line travel. Different embodiments of the invention from the one discussed hereinabove are possible, such as incorporating more than two brushes. In the latter instance, a set of brushes, all laid side-by-side and interacting, may be arranged without increasing, contrarywise to the prior art, the longitudinal dimension of the machine mounting them and to greatly expand the overall area being swept. Where more than two brushes are provided, any brush pair would be driven in opposite directions of rotation. Accordingly, with three interacting brushes, the middle brush would turn in an opposite direction to the side brushes. In order to secure the aforesaid tractive and straightening effect it is expedient that an even number of brushes be used, or that the third brush be set true flat. The invention affords important advantages. In fact, this device is quite simple and readly adapted for fitting to a cleaner. In addition, the brushes can provide accurate traction or propulsive force in the straight direction of travel to partly make the use of a propulsion motor unnecessary, especially with small size cleaners. It should be noted that if this traction feature were incorporated to prior design devices having their brushes aligned obliquely to the machine, the resulting thrust would be also directed obliquely and, accordingly, detrimental more than beneficial to the machine steering performance.

Claims: A rotary brush device for cleaners of paved surfaces comprising brushes (2) having peripheral regions formed with an orderly succession of projections (8) and recesses (9) and laid side-by-side such that said projections (8) of each said brush (2) fit at least partway into said recesses (9) of another such brush (2), the side-by-side brushes (2) in each pair being driven rotatively in opposite directions and being aligned perpendicularly to the straight travel direction envisaged for said cleaners incorporating the device (1), -characterized in that at least one pair of said brushes (2) are provided wherein the brushes (2) have mutually convergent rotation axis (4) in a direction away from a surface (7) to be swept, and in that said brushes (2) are rotated in suitable directions to produce, in the areas of least distance of the brushes (2) from each other, tangent velocities directed on the average in a substantially opposite direction to the straight travel direction envisaged for said cleaners. A device as in Claim 1, characterized in that three such brushes (2) are provided in mutual alignment relationship which comprise two end brushes (2) having mutually convergent rotation axes (4) in a direction away from a surface (7) to be swept, and tangent velocities, in their areas of least mutual distance which are directed on the average in a substantially opposite direction to the straight travel direction of a cleaner incorporating them, and a middle brush (2) whose axis of rotation (4) extends perpendicularly to said surface (7).

Inventors: TORTA, NELLO
Applicants: IDROPLINA S.R.L.
Application year: 1987
Main classification: A47L11
IPC codes: A47L11