Rotary work head assembly
The invention relates to a rotary work head assembly suitable for linking together a drive hub and a working tool. In particular, the invention relates to an assembly for coupling a drive hub to the working head of a rotary floor cleaning or treatment machine.
This invention relates particularly to the field of rotary floor maintenance machines, of a type having a circular or annular rotating treatment head, provided on an underside thereof with a working surface comprising, for example, a brush or a polishing pad, which rotates parallel and juxtaposed the surface to be cleaned. Treatments may range from polishing, through cleaning, to aggressive treatments such as sanding, grinding, scouring or scarifying.
Floor treatment machines typically comprise one or more rotatable treatment heads, driven by for example an electric motor. Typical machines are described in WO 92/10128 (Numatic International Limited) and WO 93/14684 (Numatic International Limited). The working surface is formed on an annular ring or circular disc. The working surface may be formed by brushes, which may be soft and pliable, such as for use in polishing, or stiff and wiry such as for use in scarifying or scouring. The working surface alternatively may be formed by sanding or grinding pads, for example formed of abrasive material. The working surface may also be formed by absorbent material such as felt or pads suitable for cleaning with the aid of a cleaning liquid applied to the floor.
Typically the working heads are demountable for replacement or cleaning.
Examples of known working heads are available from Numatic International Limited, of Chard, Somerset in the United Kingdom. These include accessories for the Twintec® range and Nuspeed® ranges of floor treatment machines.
Other manufacturers have similar products that will also be well known to the person skilled in the art.
The working head (or pad) of such cleaning machines is typically releaseably attached to the drive shaft of a machine via a drive hub or chuck. Known working heads have a variety of mechanisms to help with the engagement/disengagement of the working head to the cleaning machine. For example, JP-A-2002065538 discloses a radially directed spring-loaded plunger carried on a hub collar, wherein the plunger engages with a circumferential depression in a rotor hub. US-A-5243727 discloses a similar plunger arrangement.
US- A-5, 421,053 discloses a coupling between a hub and a work head in which an hexagonal spring bar carried by the work head retains an hexagonal hub. The spring bar has crossed over end regions which may be drawn together to allow detachment of the work head from the hub.
US-A-5,513,409 discloses a gimbaling connection between a work head and a hub which relies upon a domed hexagonal-section hub member and corresponding female seat in the work head. This allows the axis of rotation of the work head to shift
slightly relative to the axis of rotation of the hub and drive rotor. The means by which the work head is attached to the hub is not disclosed, other than with reference to conventional means such as a retention spring or locking collar.
With the prior art arrangements, when it is desired to remove or replace a working head it may be difficult to access the head as it is typically floor facing and located on the base of the machine. Thus the manual fitting of the working pads can require rather awkward manipulation. Correct alignment and orientation of the pad and drive hub is required to ensure correct mating. Further, in order to ensure that the pad remains connected to the drive hub during operation, a locking mechanism is usually employed, which is frequently difficult to access and operate due to the physical location. Incorporation of a locking mechanism, such as a spring bar or plunger, into the working head of the machine also increases the weight and cost of the working head.
The present invention seeks to provide a coupling mechanism for connecting a tool to a hub which ameliorates the above problems and facilitates the easy removal and remounting of tools, without reducing the effectiveness and integrity of the mechanical coupling.
A further problem which remains to be solved is the provision of a coupling mechanism for connecting a tool to a hub not requiring complex connection mechanisms on the tool.
The present invention addresses these and other problems of the prior art.
According to one aspect of the invention there is provided a rotary work head (tool) assembly comprising a hub carried by a drive shaft and a working head coupled to the hub for co-axial rotation therewith, the coupling comprising latching features associated with the hub and working head respectively, which latching features inter- engage to retain the working head on the hub, the coupling being adapted to permit tilting of the working head out of coaxial alignment with the hub, and the latching features being configured so that sufficient tilt serves to disengage a latching feature associated with the hub from a corresponding latching feature associated with working head so as to permit demounting of the working head from the hub.
In this way simple rocking or tilting of the work head may be used to detach the work head from the hub (and any associated floor treatment machine). This is useful where the work head is situated in an inaccessible location, such as under a floor treatment machine. One handed manipulation is typically all that is necessary to effect the required tilting for detachment of the work head.
The tilting may be achieved by the provision in the coupling of gimbal means operative between the hub and work head.
The coaxial coupling between the hub and work head may involve location of the hub in a corresponding female seat provided in an upper surface of the work head. The hub is preferably provided with a shaft end and a distal end, the distal end being formed with a domed or partially-domed surface portion which facilitates tilting of the work head on the hub for demounting.
An outer circumferential surface of the hub may be provided with tangentially extending facets so that the hub has a polygonal cross-section. A female seat in the work head preferably has a corresponding polygonal perimeter in which the hub can nest, thereby to permit rotation of the working head by the hub. One or more of the work head facets may be provided with a recess into which a latching spigot provided on a corresponding hub facet may be seated.
The latching means may comprise one or more spigots. Each spigot may be biased into a latching engagement configuration when the working head is coupled to the hub. Each spigot is typically provided on the hub and may project radially on the hub.
The latching means may comprise, or further comprise, one or more lip feature which constrains a corresponding spigot. The said one or more lip feature is provided on the working head.
In a preferred arrangement the latching means comprises one or more spigots associated with the hub and one or more lip features associated with the work head, the spigots and lip features being arranged so that coupling of the hub with the work head involves sliding travel of each spigot past a corresponding lip feature into an engaged configuration in which the lip retains the spigot.
The spigot is preferably formed with a cammed surface profile which facilitates sliding travel of each spigot past the lip. In particular an upper edge region of each lip may be tapered to facilitate travel of the spigot past the lip during entry into the facet
recess. One or more of the spigots may be biased so as to permit retraction of the spigot so as to allow travel of the spigot past the corresponding lip.
In a preferred configuration, the hub nests in a hub seat provided in the working head and each lip feature is provided on a respective upper inner wall portion of the hub seat.
hi a particular embodiment there are two retractable spigots, each one provided on a respective hub and two corresponding recesses each one formed in the inner wall of the seat, each recess having a upper edge portion which defines an associated lip feature. The hub may be polygonal in cross section so that the perimeter of the hub comprises a plurality of facets and wherein the two spigots are located on opposite facets of the hub, so that tilting of the work head for demounting thereof causes one spigot to be displaced past out of the recess and past the corresponding lip feature in the work head seat wall, while the other spigot is retained hooked in its associated recess until further tilting allows complete release of the work head.
A portion of the hub preferably has an octagonal cross-section which defines eight circumferential facets on the hub.
The work head is typically a generally disc shaped floor treatment tool which has a lower working face adapted to treat a floor surface when the work head is rotated.
Thus the work head may be adapted be for scrubbing, scarifying, polishing or any other like treatment.
In another aspect of the invention there is provided a floor treatment machine comprising one or more a rotary work head assemblies as hereinbefore described. A typical machine has means such as wheels for translation movement over a floor surface and a drive motor for driving a demountable work head. The machines may be walk-behind or ride-on, in which case a seta in provided. The machines may also be provided with a wet cleaning apparatus which delivers a liquid to the floor surface in and lifts the liquid off the floor after treatment. Machines of this type will be well known to the person skilled in the art. Examples are described in WO 92/10128 (Numatic International Limited) and WO 93/14684 (Numatic International Limited).
According to a further aspect of the invention there is provided a work head as hereinbefore described but, in particular, a work head for a floor treatment machines comprising a generally annular or disc shaped member having an underside provided with a floor treatment surface an upper side provided with a polygonal hub seat for coupling with a corresponding drive hub of a treatment machine, the hub seat having a polygonal inner wall surface comprising a plurality of facets, each facet being formed with a recess for receiving a hub spigot.
An upper edge region of each recess may be provided with a lip feature which constrains the spigot against travel out of the seat recess. In a preferred embodiment the hub seat has a generally octagonal form.
Following is a description by way of example only and with reference to the drawings of one embodiment for putting the present invention into effect.
In the drawings :-
Figures Ia, Ib and Ic are respectively a side view, plan view from above and perspective view of a drive hub used in implementing invention;
Figure 2 is a cross-sectional view of the drive hub of figure 1 ;
Figures 3a and 3b are respectively a plan view from above and a diametric cross- sectional view of a rotary cleaning head of a floor cleaning machine;
Figure 4 is a cross-sectional view of the drive hub immediately prior to engagement with the cleaning head;
Figure 5 is a cross-sectional view of the drive hub during engagement with a the cleaning head;
Figure 6 is a cross-sectional view of the drive hub engaged with the cleaning head;
Figure 7 is a cross-sectional view of the drive hub during disengagement from the cleaning head;
Figure 8 is a perspective view of the hub and cleaning head arrangement shown in figure 4.
Figure 9 is a perspective view of the arrangement shown in figure 5.;
Figure 10 is a perspective view the arrangement shown in figure 6;
Figure 11 is a perspective view of the arrangement shown in figure 7.
Figure 12 is a floor cleaning machine according to the invention.
The drive hub (1) is shown generally as (1) in figures Ia to Ic. The hub is formed from a single piece of machined metal. The hub has an upper portion (2) (configured as a tubular collar). The tubular collar defines a bore for receiving a motor driven drive shaft (not shown). Locking means (not shown) are provided securely to affix the hub to the drive shaft for rotation therewith. Suitable means will be known to the person skilled in the art and might include, for example, a dog stub (not shown). A lower portion (3) of the hub is formed as a generally domed cap. Side regions of the cap are machined with eight vertical facets 5 which provide an octagonal plan form. The cap thus has an upper shoulder surface of generally octagonal annular plan extending around the upstanding tubular element. A lower surface of the cap is formed as a flat circular surface (6). The surface (6) tapers away its outer circumferential region following a domed profile which extends until intersecting with the octagonal vertical facets (5) on the side regions of the hub. The operational axis of the hub (i.e. the axis about which it rotates in normal operation) is indicated as arrow A in figure 1.
The drive hub may be made of any suitable material, for example metal (e.g. brass, steel, or aluminium, preferably aluminium), or an engineering plastics material.
Two opposite facets provided with radially oriented stub bores (7) as shown in figure 2. These bores accommodate spring-biased dogs (8). The dogs are biased by means of respective spiral compression springs (9). Springs (9) bias dogs (8) to project radially outwards, and permit inward retraction of the dogs (8) on application of appropriate force.
Figures 3a and 3b illustrate the upper face and cross-section respectively of a rotary cleaning head (10) of a floor cleaning machine (not shown). This cleaning head is suitable for engagement with the hub described above. The cleaning head is in the form of a generally annular disc. A central portion of the head is formed with an octagonal plan recess (11) in the upper face. Surrounding the recess is an annular groove (17).
The periphery of the recess (11) is defined by eight contiguous vertical facets (12). Each of the facets is formed with a depression (13).
An uppermost portion of each depression (13) is formed with an inwardly overhanging lip feature (14). An upper side of each lip is provided with a cammed (or inwardly and downwardly tapering) surface. The underside of the lip forms a retaining latch as will be explained hereinafter. The recess features a flat floor portion (15) which in the embodiment illustrated includes a central circular hole. An underside (16) of the cleaning head is substantially planar and annular.
Although not shown in the present figures, the underside would in a floor scrubbing embodiment be provided with a covering of downward facing bristles formed from a
plastics material (e.g. nylon or polypropylene). Naturally in alternative applications the underside could be provided with other features such as a sanding disk, polishing pad or any other working tool of types known in the art.
To connect the drive hub to the cleaning head, the head portion (3) of drive hub is inserted into the recess (11) provided in the upper face of the cleaning head, as shown in figure 4. Figure 8 presents a perspective view of this step.
Two of the cammed surfaces (14) come into sliding contact with the two opposite spring-loaded dogs (8), causing the spring-loaded dogs to retract, compressing springs (9) (figure 5, figure 9), and permitting head portion (3) of the drive hub to progress into the recess (11).
When in the fully engaged position (figure 6, figure 10), the spring loaded dogs (8) snap outwards under the bias of the compressed springs, causing the dogs (8) to engage with the corresponding depressions (13) provided in the facet walls (12) of the recess (11). The engagement of the spring loaded dogs (8) in depressions (13) retains the working head in position on the hub. The nesting of the hub facets with the corresponding working head facets locks the working head for axial rotation with the hub when in use. Thus, turning driveshaft (18) and hub results in the tool being rotationally driven.
To detach the cleaning head from the hub, the cleaning head is tilted out of the plane normal to the axis of rotation (A) by rocking over the lower domed surface of the hub. This causes one of the engaged spring loaded dogs (8) to travel up in the depression
and come into contact (figure 7) with the shoulder (13a) of the depression (13). This causes the dog to retract into the recess (7) and thus enables the dog to travel past the Hp of the depression and out of latching engagement. In the embodiment shown, it is the domed profile of the base of the drive hub (6) which facilitates this tilting movement of the lower working face (16) of the tool out of the plane normal to the axis of the drive hub. As the retracting dog travels past the lip of the depression, the opposite dog is remains in latched engagement until the cleaning head as rocked sufficiently to allow the trailing dog to be unhooked from its depression.
In practice the cleaning head will lie under a cleaning or scrubbing machine, with the working face in intimate contact with a floor surface. To detach the cleaning head the operator manually locates the cleaning head with one hand and tilts one edge of the head upwards slightly. This causes the working head to rock on the hub and detachment of the cleaning head from the hub as described in the foregoing. The cleaning head may then be replaced by snapping a cleaning head back onto the hub, and floor cleaning can be resumed. In contrast to prior art engagement mechanisms, where complex engagements such as stub screws or detents are used, two handed access is not required to the remove a cleaning head. The cleaning machine itself need not be lifted for access to its underside. As the primary essential features of the disengagement mechanism are carried by the hub, the cost, complexity and weight of the cleaning head is kept to a minimum, hi prior art devices metal locking spigots and springs are carried by the working head which makes them expensive as spare part items.
The working head may then be attached to a floor-cleaning machine (50) of a type shown in figure 12. The machine has a motor housing (51), two spaced-apart transport rollers (52) and an articulated arm (53). The rollers are spaced apart from the floor surface when the working head is located flat on the floor, but engage with the floor when the working head and motor housing assembly are rotated from the floor surface. The machine may thereby be conveniently roller-transported across a surface when not in use. The arm is articulated at a lower end (54) to permit height adjustment. At an upper end of the arm, there is provided a handlebar (55) and control panel assembly (56). The operator (57) grasps the handle to direct and move the machine over a surface to be cleaned.