Missing pad detector for a floor polishing tool

#This invention relates to the field of surface treating tools such as floor polishers. More specifically, it is directed to methods and apparatus for automatically detecting the absence of a surface treating member such as a floor pad on such tools and operating the tool according to avoid damaging the floor or other surface.

#In surface treating tools such as floor polishers, the surface treating member (e.g., floor pad) is typically rotated about an axis to polish or otherwise treat a surface such as a floor. The tool commonly includes a frame which has a rotatable support to which the pad is removably attached. In operation, the pad is mounted on the support wherein the support and pad are rotated at relatively high speeds about an axis as the tool is moved across the floor. The pad and its support are often adjustable so that the pad can be vertically lowered and raised relative to the floor to selectively increase and decrease the pad pressure on it. In more sophisticated models, such pad pressure on the floor is monitored and the pad automatically raised or lowered to maintain a desired pressure or range of pressures.

#One problem that can and does often arise with such tools is that the operator may neglect to check to see that a pad is mounted on the tool before operating it. In this regard, the support for the pad is not intended to contact the floor as it will grind or otherwise damage it. Consequently, if the operator neglects to make sure a pad is present, the tool may end up lowering the padless support into engagement with the floor potentially resulting in significant damage to the floor as well as to the tool itself.

#FIG. 1 illustrates a floor polishing tool incorporating the present invention.

#FIG. 2 is a side elevational view of the tool.

#FIG. 3 is a plan view of the tool.

#The method and apparatus of the present invention are primarily intended for use with surface treating such as the floor polishing tool 1 of FIGS. 1-3. As shown, the tool includes a frame 3 and surface treating member 5 (e.g., floor polishing pad). The pad 5 (see FIG. 4) is removably mounted at 7 to the pad support 9 wherein operation of the electric motor 11 will then serve to rotate the pad support 9 and attached pad 5 at a relatively high speed (e.g., 1500-2000 rpm's) about the axis 13.

#In operation, the height of the pad support 9 and attached pad 5 is adjustable relative to the surface 15 (e.g., floor) to be treated. This adjustability can be accomplished in any number of manners such as vertically moving the pad support 9 relative to the main body of the frame 3. Additionally, as illustrated in FIGS. 4 and 5, it can be done by moving the main body of the frame 3 up and down relative to the floor caster 17. More specifically, the illustrated height adjustment is accomplished (see FIG. 5) by selectively rotating the horizontal shaft 19 clockwise or counterclockwise to rotate, in turn, the bevel gears 21 and 23. The bevel gear 23 as best illustrated in FIG. 6 is attached to the vertically extending, threaded shaft 25 of the floor caster 17. Rotation of the shaft 19 clockwise or counterclockwise by the servo motor 27 (see FIG. 5) will selectively move the main body of the frame 3 up or down relative to the caster 17. This, in turn, will serve to raise or lower the pad support 9 and attached pad 5 relative to the floor 15.

#The method and apparatus of the present invention involve automatically operating the servo motor 27 to control the mechanism for raising and lowering the pad support 9 during the start-up sequence of the tool 1 in response to detecting whether or not there is a pad 5 on the pad support 9. That is, as discussed above, a problem currently exists with surface treating tools such as the floor polisher 1 that the operator may neglect to inspect the tool 1 to make sure a pad 5 is mounted on the pad support 9 before operating it. This is particularly true with tools that have exterior skirts or shrouds about the pad 5 or other surface treating member so that the pad 5 is not readily visible. With such tools, they generally must be tipped or otherwise manipulated in order to see whether or not a pad 5 is present. In the worse case, the operator may simply turn on the tool 1 without inspecting it wherein the pad support 9 (without a pad 5 attached to it) will be automatically lowered into engagement with the floor possibly resulting in significant damage to the floor 15 as well as to the pad support 9.