EP4218525B1

EP4218525B1 - Floor treatment machine

Info

Publication number: EP4218525B1
Application number: EP23153298.7A
Authority: EP
Inventors: Piotr BUKOWSKI; Matthew Bright; Lewis WARREY
Original assignee: Numatic International Ltd
Current assignee: Numatic International Ltd
Priority date: 2022-01-26
Filing date: 2023-01-25
Publication date: 2024-08-07
Anticipated expiration: 2043-01-25
Also published as: EP4218525A1; EP4218525C0; GB2615080A; GB202200990D0

Description

The present invention concerns the field of floor treatment and finishing machines such as scrubbers, sanders or polishers. Floor scrubbers typically have rotating work heads equipped with bristles for working the floor to remove dirt. Finishers may have stiffer bristles with which to smooth or pare down a floor surface, such as a wooden surface. Polishers are typically equipped with relatively soft cleaning pads for polishing floor surfaces such as wooden, polymer coverings, or concrete/ceramic surfaces.
The present invention in particular concerns treatment machines having at least two floor-facing generally disc shaped work heads. These work heads typically have vertical, or near vertical, axes of rotation. Where there are two work heads, they are typically arranged to be counter rotating so as to balance out any tendency for generating torque reaction which results in a net force parallel to the floor, causing unintended travel or drift of the machine which carries the work heads. One example of a machine having counter-rotating balanced work heads is described in US8,887,348B2 (2014 ). This machine is especially prone to torque induced drift because the weight of the machine is taken entirely by the two work heads, with no support wheels to provide directional stability. Thus, the machine has a tendency to drift if asymmetries arise, such as in brush wear or in slight variations in the respective axes of rotation. US9,826,874B2 discloses a similar machine have a base portion or deck supported by two counter-rotating work heads. However, in this case the work heads have axes of rotation that are deliberately inclined slightly from the vertical so as to be convergent in a transverse direction. In this way the work heads have slightly lifted transverse outer edge regions and correspondingly depressed inter transverse inner edge regions. Because the friction of the work head brushes is higher in the inner edge regions, a permanent linear propulsion effect arises in a working direction perpendicular to the transverse direction.
US4,457,036A discloses a walk-behind floor sweep/scrubbing machine provided with two floor facing scrubbing/sweeping discs which are disposed side-by-side with one disc slightly in advance of the other. The discs are drive to co-rotate so that debris from the floor is thrown by the discs to one side of the machine into a common channel where it is collected and deposited in a hopper. US2,318,960 discloses a hand-guided floor polishing machine with two side-by-side floor polishing discs driven by a belt so as to co-rotate in one direction or another. The handle of the machine may be lifted to tilt the discs forward and dropped to tilt them back. This causes the machine to move left or right as a reaction to the local pressure exerted on the underside front or rear tilted regions of the discs. US2,220,224 also discloses a floor wax-polishing machine with two floor facing side-by-side polishing discs in which floor dust removal is aided by the use of internal guide walls which feed a suction portion. In driving the work heads of floor treatment machines, a work head chuck is typically driven by a motor and transmission combination. There may be one motor per work head, or a single motor which drives two work heads using a suitable transmission arrangement, such as by the use of pulleys, gears or chains. A floor treatment machine is also known from e.g. US-A-2019223667 .
The present invention seeks to provide a floor treatment machine which uses co-rotating work heads (i.e. which rotate in the same direction; clockwise or anti-clockwise), but which avoids the tendency to drift under torque steer, or can provide propulsion in a preferred direction so as to assist travel of the machine over floor surface.
In accordance with one aspect of the present invention there is provided a floor treatment machine comprising a base portion provided with two or more rotatable generally disc-shaped floor-facing work heads which are arranged side-by-side and define therebetween a sagittal plane which is vertical with respect to the floor, wherein each work head has a generally vertical axis of rotation, the machine being provided with drive means for rotating the work heads about the generally vertical axis of rotation, wherein in the drive means is/are arranged to rotate both work heads in the same rotational direction around each generally vertical axis of rotation. Thus the at least two work heads can be said to co-rotate during use.
The side-by-side disposition of the work heads may be perpendicular to a floor treatment working direction, or one work head may be disposed slightly ahead of the other (but still substantially side-by-side.
By 'generally vertical' the applicant means (and includes) vertical (within manufacturing tolerances) or slightly off vertical so as to cause the work heads to be tilted with respect the floor when the base portion sits on the floor. The tilt may be sufficient to modify the pressure applied to the floor by a work head so as to invoke a torque reaction.
The invention may be characterised in that a corrective measure is applied to at least one of the work heads. In one option the corrective measure acts to neutralize any net force generated by the co-rotation of the work heads so as to prevent drift of the machine.
In another option, the corrective measure acts to modify a net force created by the co-rotation so as to provide a net propulsive force in a working direction of use.
Preferably there are only two work heads. Each work head may be driven by an associated electric motor, with an optional reduction transmission acting between motor and work head.
The corrective measure preferably introduces a bilateral asymmetry as between the orientation of the rotational axes of the work heads. The bilateral asymmetry may be in the orientation of the rotational axis of one work head with respect to the other. In some prior art symmetric configurations of work heads, the work heads counter-rotate, so as to balance out any net torque. In other prior art configurations both work heads have vertical axes that are inclined inwards by a few degrees, so that the planes in which the work heads rotate adopt a dihedral configuration when viewed from the front (or rear) of the machine (i.e. along the Z axis). This locally increases friction in the down-tilted region which provides a net force in a cleaning direction. Thus, machine propulsion results.
In the present invention a sagittal plane may be defined between two side-by-side work heads. In a preferred arrangement of the present invention the rotational axis of one work head is inclined towards (or away from) the sagittal plane more than the axis of the other work head. The other work head may have a vertical axis of rotation, or may be tilted.
Preferably the rotational axis of one work head is essentially vertical (i.e. vertical within manufacturing tolerances) and the rotational axis of the other work head is inclined towards or away from the sagittal plane. The inclined work head typically acts to reduce or prevent machine drift.
For improved cleaning effect it is preferred that both work head rotational axes are inclined rearwardly in a minus Z direction. In this way the rear edge region of the rotating work heads is biased into closer contact with the floor. This rear edge region tends to receive or collect more cleaning liquid, and the biasing helps retain the liquid under the warhead in the scrubbing brushes. The work heads are preferably inclined rearwardly by the same amount.
The machine is preferably a hand-guided, walk-behind machine. It typically includes a generally upright handle portion which is reclinable up/down with respect to the base portion. The handle portion is may also be pivotable transversely (from side to side) with respect to the base portion. Furthermore, the two pivots may be configured as a universal (Cardan) joint, by which torque is transferred to the base portion so as to aid maneuverability of the machine during, so as to facilitate tight turns of the machine left or right by the user twisting the handle.
So, the machine may be provided at a lower end region thereof with a longitudinal pivot and a transverse pivot.
The machine may be provided with one or more floor-engaging wheels for supporting at least part of the weight of the machine when in use. The wheel or wheels may be provided to the rear of the work heads. The wheels may be connected to a lower region of the handle portion, so that the wheels support at least part of the weight of the handle portion.
The connection to the lower region of the handle portion may be via a universal joint, which permits longitudinal and transverse pivoting of the handle and permits torque to be applied to the handle portion to be applied to the wheels for the purpose of steering the machine on the floor.
The wheel or wheels may be connected to the base portion via a linkage which substantially decouples the weight of the base portion from the wheels. Thus, the weight of the base portion is essentially supported by the work heads. The weight of the motor(s) and any transmission is taken by work heads which are thereby kept in intimate contact with the underlying floor being cleaned.
In a preferred configuration the co-rotating work heads as hereinbefore described are arranged so that in use no net drift of the machine occurs due to the rotating work heads. One work head may have an essentially vertical axis of rotation, and the other work head is tilted inwards towards the sagittal plane and away from the vertical.
In an alternative configuration the co-rotating work heads as hereinbefore described are arranged so that in use a net forwards propulsion (most preferably in the plus Z-direction) is provided by the rotating work heads. In this case, the co-rotating work heads may have axes which are both tilted, with one work head axis tilted away from the sagittal plane and the other tilted towards the sagittal plane. The degree of tilt of one work head may be greater than the other, so as to produce a net propulsive force which induces travel in the desired working direction of use.
In another aspect of the invention, the machine is configured as a wet scrubbing machine, comprising a cleaning liquid reservoir and a conduit for delivering cleaning fluid to the region of the work heads so as to permit wet cleaning. The machine may be provided with a squeegee collector with an associated suction drive for entraining waste liquid from the floor surface behind the work heads. There may be a waste liquid collection tank in fluid communication with the suction drive, into which tank waste liquid is drawn from the squeegee collector by means of the suction drive. The reservoir and tank may each be mounted on the handle portion, or elsewhere on the machine, such as the base portion. The squeegee collector is typically trailed behind the work heads, spanning the width (cleaning/scrubbing path) of the work heads.
Following is a description by way of example only and with reference to the figures of the drawings of modes for putting the present invention into effect.

Figures 1A, 1B and 1C are respectively side (storage), rear and side (working) views of a floor scrubbing machine in accordance with the present invention.
Figure 2 is a three-quarter perspective front view of the configuration of a deck of the scrubbing machine.
Figure 3 is a front view of the deck in which the left hand work head's axis of rotation A has been adjusted (tilted inwards towards the centre plane) in accordance with a first embodiment the present invention.
Figure 4 is a front view of the deck in which the left and right hand work heads' axes of rotation have both been adjusted (left hand axis tilted away from the centre plane, right hand axis tilted inwards towards the centre plane, in accordance with a second embodiment of the invention.
Figure 5 is a side view of the deck viewed facing the right hand side, showing the rearward tilt of the right hand work head.
Figure 6 is a side view of the deck viewed facing the left hand side of the deck, showing the rearward tilt of the right hand work head.

The scrubbing machine in accordance with the invention is shown in figure 1A. The configuration shown is a storage configuration. The machine includes a deck portion 11, a motor housing 2, a support wheel 3, a transport wheel 4 and a squeegee suction collector 5, which is shown lifted from the floor. There is an upstanding handle portion 6, with superstructure 7 in which is provided a cleaning fluid reservoir and waste liquid collection tank. An upper region of the handle portion is provided with a cross bar 8 and is provided with controls such as an on/off work head actuation lever. Figure 1C shows the machine in a use configuration, with the handle portion 6 partially reclined and the squeegee suction collector deployed so as to rest on the floor surface. The transport wheel is retracted (no longer visible) and the working direction is shown as arrow 9. Rotation of the work heads causes the brushes 20 to scrub the floor. Cleaning liquid delivered to the floor assists in the cleaning effect. The dirty cleaning fluid is then collected behind the work heads by the squeegee collector 5 and discharged into the waste tank (not shown) in the superstructure 7 supported by the handle portion.
An arrangement of work heads on a deck is shown as 10 in figure 2. The axes Y, X and Z indicate vertical, transverse and forward-backward working directions respectively (+Z being the usual working direction of travel), as indicated by arrow 9. There is a deck 11 which has a plan form in the general shape of a C as shown in the figure. An upper surface region of the deck is provided with first and second transversely spaced apart transmission units 12, 13. An upper back region of each transmission unit is provided with associated upstanding cylindrical electric motor units 14, 15. The motor units each have a depending rotor with a splined end (not visible) which engages with a corresponding recess in its transmission unit. Each transmission includes a generally vertically oriented drive shaft 16, 16' (coaxial with the axes A and B), an upper end of which is visible as 16 in figure 1. An opposite end of each drive shaft (not visible) depends from the underside of the deck and is provided with a hub unit (not visible) to which is mounted a co-axial work head unit 17, 18.
Each work head unit comprises a generally disc-shaped upper region 19 made of structural plastics material and a corresponding lower region 20 which is provided with an annular array of floor facing bristles (shown as a layer, not individually visible bristles). The motors and transmissions are arranged so as to drive both the left-hand work head 17 clockwise and the right-hand work head 18 clockwise, so that they co-rotate in a clockwise direction. The work heads support the weight of the deck 11, transmission units 12,13, motors 14,15 and the motor housings 2 or ancillary items. The handle portion 6 is attached to an axle of the pair of space apart wheels 3 (one visible in Fig. 1A). Thus, the weight of the handle portion is supported by the wheels 3. The attachment is made via a universal (or Cardan) joint 27 (figure 1C) which includes transverse and longitudinal pivots. The squeegee suction collector 5, in a work configuration, rests under its own weight on the floor 29 towed by a pair of transversely space apart trailing arms 28, behind and spanning the work heads.
In a conventional prior art floor treatment machine (such as of the type described in US2012/279010A1 ) the drive shaft axes A and B (dashed lines) would be precisely vertical and parallel to each other so that the work heads both occupy a common transverse plane parallel to the floor when lying square onto the floor. The rotational axes A, B of the work heads in the prior art machine would counter-rotate so that in use sagittal mirror symmetry between the two work heads cancels out any net propulsive or drift-causing force.
In another class of conventional floor treatment machines (such as is described in US2015/113757A1 ), the drive shaft axes are inclined slightly (a few degrees) towards the sagittal plane so that the work heads depart from the transverse plane. Thus, they become inclined down towards the floor on an inside region and inclined upwards away from the floor on an outside region. As the work heads counter rotate, the brush inside regions are effectively biased against the floor surface and draw the machine forwards as the brushes rotate due to the enhanced frictional contact in the centre (inside) regions relative to the outside regions. The result is forward propulsion of the machine over the floor surface.
However, in both of the prior art examples described above there is bilateral (or mirror) symmetry as between the geometric arrangement of the work heads either side of a vertical sagittal plane (see centre plane C in figure 3). In the present invention the work heads co-rotate, so there is a bilateral asymmetry which will cause a net force to act inducing the machine to drift (also known as torque steering). For this reason, decks which have work heads which co-rotate are typically only seen in the ride-on class. These large machines are provided with front and rear wheels which provide direction stability which prevents the machine from drifting away from a desired direction of travel. The wheels may be driven to provide conventional traction propulsion, so contra rotation and balance is not necessary. However, in the present invention, manoeuvrability is important and the ability to make tight turns is essential.

First embodiment - co-rotating work heads with no net propulsion or drift

In a first embodiment of the invention, co-rotating work heads are used in a configuration in which there is no net propulsive force causing drifting or unintended propulsion of the machine. The two work heads are arranged to rotate clockwise, as shown in figure 2 by the circular arrows. There is a mid-sagittal plane C (dot-dashed vertical line) between the two sides of the deck, as shown in figure 3. Right hand work head 19 rotation axis B is parallel to the sagittal plane C, so is precisely vertical and perpendicular to the floor. Thus, the right-hand work head 19 exerts essentially uniform brush pressure on the underlying floor.
Left hand axis A of the work head 21 is angled with respect to the sagittal plane C (and thus with respect to the vertical rotation axis B) in an amount of 0.5° so as to converge slightly towards with the upper end of plane C. The left-hand work head 21 is thus inclined so as to be raised slightly at an outside edge region and depressed slightly at its opposite inner edge region. In this way the inner edge of the work head (with associated brush bristles) urges more strongly against the floor, producing in use a reaction which counters the torque steer provoked by co-rotation of both work heads. Thus, the co-rotating work heads are effectively balanced to produce no unwanted drift. Although precise values for axis angles are given here (and below) a certain amount of trial and error may be necessary to achieve the desired effects, as these may depend upon variables such as the floor finish and materials, base portion weight, the work head treatment brush stiffness and the rotational speed of the brushes.

Second embodiment - co-rotating work heads with forward propulsion.

In a second embodiment of the invention (see figure 4) co-rotating work heads are shown either side of a vertical mid-sagittal plane C. In this case the right hand work head 19 rotation axis B is inwards tilted by 2.0° to 2.5° to converge towards an upper end region of the sagittal plane C. Left hand work head 21 rotation Axis A is tilted away from the upper end region of plane C by 0.5° to 1.0°. This results in the work head 19 and its associated scrubbing face being tilted up at the outer edge region thereof, and the inner edge of the work head being correspondingly depressed (and biased against the underlying floor). Conversely, the outer edge region of the other work head 21 is depressed so as to be biased against the floor. The inner edge region of the work head is correspondingly tilted up. The tilt of axis B from the vertical is greater than that of axis A, typically by +1.5°. Both work heads (with associated brushes) are tilted in such a way as to invoke a propulsive reaction in the plus Z direction, by the biasing of the regions of the work head which draws the brush backward over the floor surface. The difference in the amount of biasing ensures that the net force is forwards, and not skewed left or right (plus or minus X).
As shown in figures 5 and 6 the axes A and B are both also rearwardly tilted away from the vertical Y axis in the minus Z direction, so that respective front-end regions of the work heads 19, 21 are raised and the rear end regions of the work heads are correspondingly depressed. The amount of rearward tilt is the same for both axes and is typically 4.5° to 5.0°. The work head bristles are thus urged and compressed onto the floor surface at the rear end regions of both work heads. Thus, both work heads 19, 21 have bristles occupying the rear half of the work head undersides that are urged against the floor and thus produce an enhanced reaction force. This ensures a good scrubbing effect across the complete span of the two work head brushes.
The use of one or two the support wheels and self-supporting work heads to share the weight of the machine ensures that directional stability is good, while excellent manoeuvrability is maintained so that the machine can be steered to make sharp turns 'on a sixpence' about the support wheels.

Claims

A floor treatment machine comprising a base portion provided with two or more rotatable generally disc-shaped floor-facing work heads which are arranged side by side and define therebetween a sagittal plane which is vertical with respect to the floor, wherein each work head has a generally vertical axis of rotation, the machine being provided with drive means for rotating the work heads about the generally vertical axis of rotation, wherein in the drive means is/are arranged to rotate both work heads in the same rotational direction around each generally vertical axis of rotation, and
wherein a corrective measure is applied to at least one of the work heads, which measure acts to neutralize any net force generated by the co-rotation of the work heads so as to prevent drift of the machine, or which measure acts to modify a net force created by the co-rotation so as to provide a net propulsive force in a direction of use.
A machine as claimed in claim 1 wherein the corrective measure introduces a bilateral asymmetry as between the orientation of the rotational axes of the work heads.
A floor treatment machine as claimed in claim 2 wherein the bilateral asymmetry is in the orientation of the rotational axis of one work head with respect to the other.
A machine as claimed in any of the preceding claims wherein a sagittal plane is defined between two side-by-side work heads and the rotational axis of one work head is inclined towards (or away from) the sagittal plane more than the other.
A machine as claimed in any of the preceding claims wherein the rotational axis of one work head is essentially vertical and the rotational axis of the other work head is inclined towards or away from the sagittal plane so as to prevent or limit machine drift.
A machine as claimed in any of claims 1 to 4 wherein both work head rotational axes are inclined rearwardly in a minus Z direction.
A machine as claimed in claim 6 wherein the work heads are inclined rearwardly by the same amount.
A machine as claimed in any of the preceding claims which is a hand-guided, walk-behind machine, and includes a generally upright handle portion which is reclinable up/down and side-to side with respect to the base portion.
A machine as claimed in claim 8 wherein the handle portion is provided at a lower end region thereof with a longitudinal pivot and a transverse pivot, such as in the form of a universal joint which permits longitudinal and transverse pivoting of the handle and permits torque to be applied to the handle portion to be applied to the wheels for the purpose of steering the machine on the floor.
A machine as claimed in any of the preceding claims provided with one or more guide wheels which are connected to the base portion via a linkage which substantially decouples the weight of the base portion from the wheels, the machine being configured so that the weight of the base portion is essentially supported by the work heads.
A machine as claimed in any of the preceding claims wherein the co-rotating work heads are arranged so that in use no net drift of the machine occurs due to the rotating work heads.
A machine as claimed in claim 11 wherein one work head has an essentially vertical axis of rotation, and the other work head is tilted inwards towards the sagittal plane and away from the vertical.
A machine as claimed in any of claims 1 to 12 wherein the co-rotating work heads are arranged so that in use a net forwards propulsion (in the plus Z-direction) is provided by the rotating work heads.
A machine as claimed in any of the preceding claims wherein the co-rotating work heads have axes which are both tilted, with one work head axis tilted away from the sagittal plane and the other tilted towards the sagittal plane, whereby the degree of tilt of one work head is greater than the other, so as to produce a net propulsive force which induces travel in the desired working direction of use.
A machine as claimed in any of the preceding claims which is configured as a wet scrubbing machine, comprising a cleaning liquid reservoir and a conduit for delivering cleaning fluid to the region of the work heads so as to permit wet cleaning;
and wherein the machine is provided with a squeegee collector with an associated suction drive for entraining waste liquid from the floor surface behind the work heads, and a waste liquid collection tank for in fluid communication with the suction drive, into which tank waste liquid is drawn from the squeegee collector by means of the suction drive.