US3122765A

US3122765A - Centrifugal speed regulator for a surface working device

Info

Publication number: US3122765A
Application number: US192499A
Authority: US
Inventors: Gerald M Magarian
Original assignee: Preco LLC
Current assignee: Preco LLC
Priority date: 1962-05-04
Filing date: 1962-05-04
Publication date: 1964-03-03
Anticipated expiration: 1981-03-03

Description

March 3, 1964 e. M. MAGARIAN 3,122,765

CENTRIFUGAL SPEED REGULATOR FOR A SURFACE WORKING DEVICE Filed May 4, 1962 4 Sheets-Sheet l IN VEN TOR.

March 3, 1964 Filed May 4, 1962 G. M. MAGARIAN CENTRIFUGAL. SPEED REGULATOR FOR A SURFACE WORKING DEVICE 4 Sheets-Sheet 2 Gama JV. MAGARIAAQ w I INVENTOR.

25AM V6444;

March 3, 1964 e. M. MAGARIAN 3,122,765

CENTRIFUGAL SPEED REGULATOR FOR A SURFACE WORKING DEVICE Filed May 4, 1962 4 Shee ts-Sheet s 6"EQA 1. U M. MAGAQ/AM,

IN V EN TOR.

BY bi),

March 3, 1964 G. M. MAGARIAN 3,122,765

CENTRIFUGAL SPEED REGULATOR FOR A SURFACE WORKING DEVICE Filed May 4, 1962 '4 Sheets-Sheet 4 '1 I "4 I l 4/ 4 47 46 4&4 5;

/ l-n g I fl/ I i 5' 4 4 9 INVENTOR.

6524 0 M. MAAE/A/V,

United States Patent Mail 3,122,765 CENTRIFUGAZL SEEED REGULATQR FOR A SURFACE WUPEQNG DEVICE Gerald M. Magarian, Long Beach, Calif, assignor to Preco, Incorporated, lies Angeles, Qalif, a corporation of California Filed May 4, 1962, Ser. No. 192,499 6 Claims. (Q1. 15-49) The present invention relates generally to a surface Working machine designed to polish, scrub, or otherwise work on a plane surface; and, illustratively, the invention relates to a device, such as a floor polisher, which is driven by an air motor and which is connectible to the suction wand of an ordinary vacuum cleaner in order to induce a current of air through the air motor of the surface working device. Such an air motor is illustrative of a power source whose speed varies Widely under varying load or varying power supply.

Since the present invention has been embodied in a device which is particularly suited to floor polishing, the invention is illustrated and described in this aspect; but it will be realized that other surface working implements can replace the polishing brush. For example, the polishing brush or buffer can be replaced by a brush for scrubbing, and abrasive element for sanding, or other suitable element for working on the plane surface.

The familiar vacuum cleaner for household use has a fan or blower which is driven by an electric motor. The air stream is drawn into the cleaner through the wand and flexible hose. The air stream is a convenient source of power for an accessory, such as a floor polisher, connected to the suction wand of the vacuum cleaner equ pment. The floor polisher, or other surface working device when driven by an air turbine operates most effectively within a relatively limited speed range since the turbine is adapted to operate most efiiciently at a given revolutionary speed. Although the optimum speed for the air turbine is determined in general by the design of the particular unit, it will also differ for a given unit at different rates of air flow; but for a given unit operating on a particular air flow there is an optimum speed of rotation and for best performance the unit should be operated relatively close to that optimum speed. Obviously, this indicates that a generally constant speed of the surface working member, the polishing brush in the case of a floor polisher, is desirable, as long as the air flow is constant. For higher or lower air flows, as produced by vacuum cleaners of high or low power, the generally constant speed should be somewhat higher or lower, respectively.

Obtaining a relatively constant speed of rotation of the working element, particularly in the case of a floor polisher which operates on surfaces having different coefficients of fiiction, presents some problems. The drag or frictional load on the Working unit varies greatly depending upon the characteristics of the surface being worked on. This is true not only of different surfaces on which the unit may be operated but also it is true of the same surface with the passage of time, as for example, a floor being waxed has a much lower coefficient of friction and consequently much less drag on the working ele ment when the wax applied to the floor is hardened and is polished than at the beginning of the operation.

Thus it is a general object of the invention to provide a surface working machine powered by a variable speed motor such as an air turbine which operates best at a generally constant rotational speed.

More particularly, it is an object of the present invention to provide a surface working machine of this character having novel means for varying the downward pressure on the working element in a manner to compensate for changes in the coefficient of the friction of the surface being worked upon, for the purpose of maintaining a generally constant torque load on the surface working element.

These objects of the invention are achieved in a surface working machine of this character by providing in combination: a variable speed motor; a drive member rotatably mounted on a supporting frame and driven by the motor; a surface working member rotatably connected with the drive member and mounted concentrically thereof to rotate therewith and also for limited angular and axial movement relative to the drive member; centrifugally responsive means rotatably connected with the drive member and tending to move to different positions relative thereto in response to both the torque load on the brush and different centrifugal forces at different rotational speeds of the drive member; means connecting the centrifugally responsive means to the surface working member to rotate the surface working member and the drive member in unison and also to rotate the surface working member relative to the drive member in response to movement of the centrifugally responsive means, which is responsive as above; and means including cooperating element on the drive member and the surface working member acting to press the surface working member toward a working surface with more or less force as a result of said relative rotational movement of the surface working member and the drive member. As a result of this arrangement, a generally constant rotational speed of the surface working member and motor is maintained with varying coeflicients of friction between the surface and the surface working member.

How the above objects and advantages of the present invention, as well as others not specifically mentioned herein are attained will be more readily understood by reference to the following description and to the annexed drawings, in which;

FIG. 1 is a small-scale plan view of a surface working machine embodying the present invention.

FIG. 2 is an enlarged vertical section thereof on line 2-2 of FIG. 1; FIG. 2 being at full scale of a present embodiment.

FIG. 2a is an enlarged portion of FIG. 2 but differing in that the surface working member is shown at its tippermost position.

FIG. 3 is a fragmentary horizontal section on line 3-3 of FIG. 2 showing the bearing sleeve and the centrifugal weights in the positions occupied at the inward end of the range of movement of the weights.

FIG. 4 is a diagrammatic developed view of the cooperating cam surfaces pressing the surface working member down, showing the relative positions these members occupy when the working member is in an upper position.

FIG. 5 is an exploded view showing the hub carrying the drive member, the sleeve mounted thereon for carrying the surface working member, and the connection between the sleeve and the centrifugally responsive members, the parts being separated for purposes of illustration.

FIG. 6 is a fragmentary horizontal section similar to FIG. 3 but showing the centrifugal weights at the outward end of their range of movement.

FIG. 7 is a diagrammatic View similar to FIG. 4 but showing the cam surfaces at the opposite end of their range of relative movement, when the surface working element is pressed down.

FIG. 8 is a bottom plan of the surface working machine, viewed on line 38 of FIG. 2.

Referring now to the drawing, there is shown a preferred embodiment of the present invention in the form of a floor polisher, seen in plan in FIG. 1. FIG. 2 is a median section through the device taken on a vertical 'dirt under the polisher' from entering the turbine. hollow flexible bumper 14. is preferably mounted around the lower periphery of cover 12 in order to prevent dam V the floor Polisher.

3 plane, showing a normal or median position of the sur face working member when the device is resting on the floor in the usual operational position.

The major assemblies. of the device seen in FIG. 2 are the frame A which serves as a support structure for the various moving parts; the air turbine B which drives the surface working member C which is rotatably mounted upon the underside of a frame A to engage thefloor surface, as illustrated; and a drive member D, rotatable on the frame concentrically with the surface working memher. The drive member D transmits power to the surface working member through means that includes centrifugaily and brush torque responsive means E seen best in FIGS. 3 and 6, these centrifugal means being rotatatable with the drive member as will be further described. Cooperating elements, typically inclined cam surfaces, on hub 46 of the drive member D and sleeve 55 of the surface working member C cooperate to press the latter downwardly against the floor surface with a variable force, as a result of the relative rotational movement of .the surface working and drive members, caused by the centrifugal means and in such a way as to compensate for changes in the coefficient of friction encountered by the surface working member and variable driving torque available from the air motor. Thus there is maintained a generally constant load on the motor, assuming constant air flow power applied to it.

Any motor that, like an air turbine, changes speed with variations of the power supply or the torque load on the motor maybe considered to be a variable speed motor as the term isused herein.

Considering now the illustrative construction in greater detail, frame A comprises several individual parts which are fastened together in any suitable manner. Frame A includes a hollow domed housing 12' closed on its open underside by bottom plate which carries around its margin a narrow stationary brush 11, as seen in FIGS. 2 and 8, which engages the floor surface and normally supports the Whole device on the floor, carrying a variable fraction of the entire weight of the floor polisher as will appear. Housing 12 is spaced upwardly above the bottom plate to enclose between them the interior-space containing the other parts of the frame, more especially two 'mag'or separable frame elements 15 and 16 which'enclose and support bearings for the air turbine B and the drive member D. Frame element 16 extends forwardly at 31 to form at least in part an exhaust air duct at the forward end of which is an integral collar 45 supporting shaft 44 on which the drive member D and the surface working member C are rotatably mounted. Frame elements 15' and 16, bottom plate 10, and housing 12 are all secured together by members not shown, 'but may be 7 fastened together in any suitable way; Peripheral brush 1-1 will beseen to support the device, takinga part of the total weight as will appear. Plate 10 prevents air and A age to furniture, walls, and the like from contact with The bearing support structures 15 and 16 are verticall separable and. provide bearing supporting structure for journal bearings at team 19, as may be seen in FIG. 2.

These bearings are respectively at the upper and lower ends of the vertically disposed shaft Zil of air turbine B. Mounted on shaft Ztl is turbinewheel 22 which comprises an annular series ofblades'23 disposed concentrically around; shaft 2 9. Blades 23 terminateat their inner ends, at a positionv spaced from the hub ofjturbine wheel 22, allowing the air'after inwardly passingbetween the blades to discharge upwardly and axially of the turbine wheel. 7 7 V Surrounding moving blades 23 of the turbine wheel,

is an annular series of fixed blades 25 which are supported by frame member '15 and are positioned to direct air against the moving blades 23. Air passes between fixed blades 25 by entering the blades from the interior space between housing 12 and bottom plate 10. Admission to this'interior space from the surrounding atmosphere is through an air intake opening at 27 in cover 12.

A stationary diaphragm 23 is mounted on the bearing support structure 15 immediately beneath the turbine wheel 22 and has a small running clearance with the hub of the turbine wheel in order to confine air flow to entering only through fixed blades 25. A ring 2? mounted on the upper edges of blades 23 confines air movement after discharge from fixed blades 25 to substantially a radial direction through the moving blades 23 Air exhausted from the turbine leaves the floor polisher through an air duct. built in two sections 31 and 32;. The first section 31 is fixed in place and may be an integral portion of the bearing support structure 16 in order to provide a continuous enclosed path for air leaving the turbine to flow into the duct 31. A removable plate 31a closes the bottom of duct section 31. At the outlet'end, of duct 31 is swingingly mounted by shaft 33 a movable duct section 32 which is designed to take one end of a wand or hose connected at the other endto a vacuum cleaner to induce air flow through the floor polisher over the path described. Y

Lubrication for each of the journal bearings 18, and 19 is provided by oil saturated wicks 35 and 36 respectively which are located in wells in the bearing support structures 16 and 15 respectively. These wells are each covered over by a thin metal cap 37'which is press fitted to seal the wicks in place and prevent the entryof dirt or other foreign'matter into the well. These well spaces, are each connected to the shaft side of their respective bearings by means of pressure equalizing openings 38 so that air pressures within the wells are the same as pressures at the shaft side of the bearings to assure normal lubricant supply from'the wick to the bearings.

The hub ofturbine wheel 22 extends downwardly be low the blades. The extension is in the form of an in-' tegral drive pinion with gear teeth 46: which mesh with gear teeth 41 of a rim 54 around the periphery ofplate 52 of drive member D to drive the latter. Drive member D- is rotatably supported within the space above bottom plate 10 and'underneath housing 12 by shaft 44. While shaft 44 may be supported on the stationary frame in any suitable mannen'it is here shown as stationary and as;

7 being pressed at its upper end into stationary collar bracket 45, which is an integral part of: duct 31 at the forward end thereof.

' The drive member D comprises the circular plate 52 and-a central hub 46 containing two spaced

journal bearings

47 and 48 by which the hub 'is rotatably mounted upon the lower portion of fixed shaft 44. This construction is shown in greater detail in FIG. 2a. The lower 1 bearing sleeve43 is a press fit within hub 46, while the upper'end'of the hub at 45a is stamped or crimped'over the upper edge of bearing sleeve 47 in order to -holdthe bearing in the, hub. The hub and'bearing assembly is then. prevented from'dropping offthe lower end of shaft 44'by washer 45* which is heldfin pl-ace by screw Sill Drive. plate 52is attached tohub &6 in any suitable manher as by pins 53 integralwitha flange 51' at the top of' the hub, the pins being headed over to hold the gear plate in place. Although other suitablev constructions maymbe "used, one is'to make plate 52 froma thin sheet of steel 56 is able to. move rotationally relative to hub 46 as well as to move axially relativetothehub over a' limited range 5;

of. travel,'as will become apparent from further descrip tion. Sleeve fie-is closed at its lower end and is there attached to brush plate. 57 0f surface working member Cl Brush plate 57 is a circular sheet of steel or other metal stamped to the proper size and shape and carrying underneath a suitable polishing, or other surface working element 58 engaging the floor or other surface being worked upon, such polishing element here being shown in the form of a brush; but it will be understood that a cloth buffer, or abrasive, or other element may be used instead.

Sleeve 56 and plate 57 are non-rotatably connected to each other by an arrangement which is shown in detail in 'FIGS. 2a and 8. Sleeve 56 has a terminal boss 56a at its lower or outer end with a plurality of radial lugs 59. An opening in plate 57 has a corresponding number of radial notches (57a in FIG. 2a) to receive the lugs 59. By engagement of lugs 59 with the sides of the notches the sleeve and plate are drivingly connected. Lugs 59 are undercut near their bases to receive a spring wire clip 59b which holds the plate against downward axial movement relative to sleeve 56.

A driving inter-connection is effected between the drive member D, and the surface working member C in order to rotate the latter, by means which are shown in FIGS. 3 and 6 and will be described particularly in connection with those figures. The inter-connecting means includes the centrifugally responsive means comprising a pair of angular, weighted arms 60 pivotally mounted on the under surface of driver plate 52 by bolts 61 which are located at diametrically spaced positions on the plate. Each of the arms can move between an extreme inner position shown in FIG. 3 and an extreme outer position shown in FIG. 6 in response to the balance of forces, including centrifugal forces, as is explained later.

Rigidly attached to each of the pivoted arms 60 is a gear segment 63, connection between the two being effected by means of the bolts which provide the pivots 61 and rectangular bosses on the arms for non-rotatably connecting each gear segment 63 to the associated swinging arm so that the gear segments swing about pivots 61 in response to swinging movement of the arms.

On the exterior of sleeve 56 are gear teeth 64-. These gear teeth may extend entirely around the sleeve if desired but it is adequate to provide only a gear segment at each of two positions, as shown in FIGS. 3 and 6 in which the teeth 64 mesh with the teeth of a gear segment 63 mounted on an arm 60. It will be seen from a comparison of FIGS. 3 and 6 that as arms 60 pivot about pivots 61, gear segments 63 meshing with teeth 64 cause sleeve 56 to rotate relative to driver hub 46. This rotation of sleeve 56, indicated in FIG. 6 by arrow 65, is about the axis of shaft 44.- and is relative to the hub 46 upon which the gear plate 52 and the cent-rifugal'ly responsive elements 60 are mounted.

It will be seen from this construction that as gear plate 52 rotates, counter-clockwise, as indicated by arrow 70 in FIG. 3, the engagement of the teeth of segments 63 with teeth 64 on the outside of sleeve 56 causes sleeve 56 to be carried around the axis of shaft 44 in unison with the drive member D.

Cooperating cam surfaces are provided on the drive member D and the surface working member C to press the surface working member downwardly toward the floor surface with a variable force depending on the speed-induced force exerted by centrifugal weights 60 and the opposing torque from the surface working member. These cooperating elements are best understood by reference to FIGS. 2a, 4, 5 and 7. As shown particularly' in FIG. 5, driver hub 26 is provided with two recesses 66 at opposite sides of the cylindrical portion of the hub. At the upper end of each recess is a downwardly facing helically inclined surface 67. On the inside of sleeve 56 there are two inward projections 68 at diametrically spaced positions. At the upper end of each projection is an upwardly facing helically inclined surface 69. A projection 63 fits within each of the recesses 67 as indicated diagrammatically in FIG. 4 bringing the two

surfaces

67 and 69 into engagement as shown in that figure. It will be noted that the two surfaces '67 and 69 are inclined with respect to the common axis of rotation of the hub and sleeve. Such inclination is forwardly and downwardly with respect to the direction of rotation (indicated by the arrows in the figures) for reasons which will be further explained. It will be noted that a recess 66 is wider than the projection 68 in the recess, thus allowing for limited relative rotational movement of the driving hub and the surrounding sleeve, such motion be ing preferably limited in each direction by engagement of the vertical or axially extending edges of the recess and projection on these two members. The limited extent of this relative rotation is shown by comparison of FIGS. 4 and 7 from which it will be seen that, as a result of the relative rotation and the inclination of the surfaces 67 and 69', there is also an axially directed component of motion causing relative axial movement of the hub and surrounding sleeve.

When placed on a floor, brush 11 supports the whole device, typically weighing about seven or eight pounds. The surface working unit, free to drop down under its own small weight of about one pound, rests on the floor. When the device is picked up the working unit is kept from dropping off by flange 56b of sleeve 56 resting on gear segments 63.

In operation, the unit is connected to a vacuum cleaner by a conventional vacuum cleaner wand and hose, not shown in the drawing, which is inserted into the movable section 32 of the exhaust air duct. The vacuum cleaner motor is then started to create by suction a flow of air through the floor polisher. The air entering through air intake 27 passes into the space within housing 12 and then enters the turbine through the spaces between stationary vanes 25, causing turbine wheel 22 to turn at a high speed.

Rotational movement is imparted to the drive member D from the turbine by teeth 40 on the drive pinion meshing with teeth 41 on the drive member. It will be seen from the difference in the diameters of the drive pinion and the drive member D that a substantial gear reduction is obtained. In a typical design the gear ratio is approximately 18 to 1. Thus if the turbine under an average load turns with a speed in the neighborhood of 15,000 or 16,000 r.p.m., the drive member D, and also the surface working member C, are rotated at speeds in the neighborhood of 800-900 r.p.m. These figures are given merely as examples and they are not limitative on the invention since exact speeds depend upon many factors, including the load imposed upon the surface working member, the rate at which air passes through the air turbine, and many other factors of design.

As drive member D rotates about shaft 44, the surface working member C is rotated about the same axis at the same speed. A driving connection between these two members is effected by the intermeshing of the gear segments 63 with the gear teeth 64 on sleeve 56. Neglecting for the moment any rotational movement of the gear segments about pivots 61, it will be seen that, assuming a fixed position of the segments and arms 60, rotational movement of the gear plate 52 is transmitted through pins 61 and segments 63 to sleeve 56 which in turn rotates plate 57 carrying brush 58.

Superimposed upon this rotative motion is the effect of the movement of arms 60 about pivots 61, these arms being responsive to the balance of centrifugal force and the reaction force exerted through the teeth in segments 63.

When the parts are stationary, arms 66 may occupy any position, but for descriptive purposes may be assumed to occupy an inward position such as shown in FIG. 3. As the rotational speed of the drive member increases, the centrifugal force acting on these arms increases and tends to move them outwardly, reaching an equilibrium position determined by a balance between centrifugal force tending to pull them out, and brush torque and the torque reaction of the inclined cams acting through teeth in segments 63 tending to pull them in. ,The rotational movement ofarms 69 around their pivots 61 causes equalrotational movement of gear segments 63 about thesepivots. Such rota-;

tional movement ofthe gear segments causesj angular movement of sleeve 56aboutvtheaxissof shaft .44 relative to hub 46. The brush, .by the centrifugalaction, is pressed into floor contact With a working pressure, typically about five pounds, which is materially greater than the dead weight of surface working element ,C, typically about one pound.

. 7 When the floor polisher is in operation, the drive, member D and the surface working member Care rotated;

together in a counter-clockwise direction when viewed from above as in FIGS. 3 and 6. In FIGS. 4 and.7 the rotation is to the right. It will ,be seen from comparison of FIGS. 3 and 6 that the outward swinging movement of c'entrifugally responsive arms 66 causes sleeve 56 to.

advance v(arrow 65) in thevdirection of rotation relative to hub 46. ,Presuming FIG. 4 represents the relative. p0si-.

tionof the hub and sleeve when the parts are stationary and brush 58 is merely resting on the floor and is raising the surface working member towardthe limit of its upplay no part in the driving connection between driver 'D j and surface working member .C.

It will ,be seen that the driving force. .advancing the cause of the inclination of the engaging

surfaces

67 and 69 relative to the axis of rotation. As thecentrifugallyresponsive arms 60 cause the sleeve to advance angularly sleeve. with respectto the hubalso forces the surface, working member downwardly with respect to the hub be.

with respect to the hubon which the sleevevis, mounted,

the twocamfaces 67 and 690m. these members at the same time cause the axial movement of the surface work? ing member in a downward direction.

The operative mode of the described device may b est be understood by first assuming it to be operating ata given fixed rotational speed with the centrifugal fly weights at equilibrium in some intermediate position. The mounting sleeve and the brush will then be in equilibrium under the following forces:

(1) Axial upward force on the, brush;

'(2) Drag torque'on the brush opposing rotation;

(3) Torque from the centrifugally actuated fly weights in thedirection of rotation;

4) Axial downward forcecomponent from the cam that inter-relates the driving hub and the brush sleeve; (5) The torque tion.

Assume that the coeificient of friction between the component from that cam Opposing rotabrushand floor increases substantially. Torque (3) from the centrifugalfly weights will remain constant at the constantly maintained speed. Torque '(2)the drag torque on the brush-will increase with the increased c0- efiicient of friction. Consequently torque '(5) the cam componenfopposing relative forward rotation of the sleeve on the driver-must decrease to maintain equilibrium of moments. Torque (5) is a tangential component of the'cam force. Thus the total cam force, including component (4) the downward force on the brush that pushes the brush againstthe floor, has been reduced by an. 1 increase in coeflicient of friction between brush and floor even thoughthe speed has been assumed to be constant. 7 It can be seen that this reduction in downward force on the brush is a direct result of coefiicient of friction increase andiis not a result .of speedLreductioh, Because of this reduction in downward force on the brush, the torque increase is: less than efiicient of frictionv. V I

Consider nowthat the actual polisher is driven by an air turbine, a type of motor that has inherently poor speed regulation. Theneven the limited torque increase resulting from a substantial coeflicieutof friction increase will result in a significant reduction inrotational speed. However, any reduction in rotational speedrapidlyreduces thecentrifugal force acting on the flyweights, and this reduction in force further reduces the downward force on 1 the brush. Thus the force with which the brush contacts 3 the floor is responsive to both-changes in coeflicient of friction and rotational speed. Because ofthis combined action, a relatively large increase in'coefiicient of friction requires a very small reduction in rotational speed to re- 7 establish equilibrium conditions. 1

Also, the centrifugal portion-of the brush control takes care of variations in the air motor'powe-r due e.g., to varying vacuum cleaner conditions. If, for instance, that air motor power -is reduced, the speed reduction, through the action of the centrifugal control, reduces torque (2) the drag torque on the brushand thus reduces the required driving torque, preventing the device from slowing excessively orstalling.

Considering the over-all functioning of the device it" may be noted, disregarding frictional-and other losses, that in general the drag torque on the brush equals the driving torque from the motor. The downward pressure applied to the brush, and by it to the'fioor in addition to its own light or effectively non-existent weight, is a function-of the centrifugal force developed by thecentrifugal fly weights, which in turn is a function of the rotary speed and the brush drag'torque. If, for any reason such as decreaseof torque from the motor or increase of torque drag on the brush, the rotating speed is lowered, the can tn'fugally developed down pressure on the brush decreases and puts the ,whole system in equilibrium 'as above'fexplained. The opposite action occurs to equilibratethe system if for any reason the rotating speed increases.

Seeing that the brush is only pressed downwardly into working pressure by operation of the device as'above explained, it. does not have to initially contact the floor ,at

all, but can normally be held up to'its highest position (FIG. 2a). clear of the floor, by e.g., a light spring that preferably just supports the weight of the brush unit.

I claim: A 1. In a surface working machine, the combination comprising:

a frame adapted to be supported at substantially fixed distance from a surface-to be Worked; a variable speed motor mounted on the frame; a drive member rotatably mounted on the frame on 'anaxis perpendicular to the surface and driven in a'- forward direction b the motor; a

a surface working member rotatably mounted coaxially of the drive member for limited axial movement rela--- j tive thereto through a continuous series of-working positions between a relieved position not more than V lightly engaging the'surface and a fully engaged posi- 7 tion forcibly engagingvthe surface; meanscoupling the surface working member rotatively tothe drive member, said coupling means permitting limited relative rotation of said two members; 7 means including cooperating elements on the drive member and on the surface working member and acting tomove thesurf ace working member axially to-' ward said fullyengaged position in response to forward rotationof thesurface working member relative to the drive member, and centrifugally responsive mechanism interconnecting said members and acting to produce a torque between said members in a direction to produce forward rotation of the surface working member relative to the proportional to the increase in so drive member, said torque increasing with increasing rotational speed of said members,

whereby the surface working member is pressed on the surface to be worked with a force that increases with increasing rotational speed of the members.

2. In a surface working machine, the combination defined by claim 1, and wherein said centrifugally responsive mechanism comprises a plurality of centrifugal masses pivotally mounted at angularly spaced positions on one of said members for swinging movement relative to said one member in a radially outward direction with respect to said axis in response to increasing member rotation,

and linkage means interconnecting said masses and the other member and acting to produce forward rotation of the surface working member relative to the drive member in response to radially outward swinging movement of the masses.

3. In a surface Working machine, the combination de fined by claim '1, and wherein said centrifugally responsive mechanism comprises a plurality of gear segments pivotally mounted on one of said members at 'angularly spaced positions and engaging gear teeth mounted coaxially on the other member,

an equal plurality of centrifugal means mounted on said one member for radially outward movement relative thereto in response to increasing member rotation,

and means interconnecting the centrifugal means with respective gear segments to drive the gear segments in a direction to produce forward rotation of the surface working member relative to the drive member in response to said outward movement of the centrifugal means.

4. In a surface working machine, the combination defined by claim 1, and wherein said centrifugally responsive mechanism exerts substantially zero torque between the members at zero rotational speed thereof,

and the only force then pressing the surface working member on the surface to be worked corresponds substantially to the weight of the surface working member.

5. In a surface working machine having a frame, the

combination comprising:

a variable speed motor mounted on the frame;

a drive member rotatably mounted on the frame and driven by the motor;

a surface working member rotatively connected with the drive member concentrically thereof to rotate therewith and for limited rotative and axial movements relative to the drive member, said axial movement in one direction being toward the working surface;

centrifugally responsive elements mounted on the drive member for rotation therewith and for movement to different positions relative thereto in response to different centrifugal forces at different rotational speeds of the drive member,

the centrifugally responsive elements comprising arms pivoted near one end to the drive member at angularly spaced positions, said arms being weighted at their free ends to tend to swing outwardly as the speed of the drive member increases;

means connecting the centrifugally responsive elements to the surface working member to rotate the surface working member and the drive member in unison and also to rotate the surface working member relative to the drive member in response to speed induced movements of the centrifugally responsive elements relative to the drive member,

the connecting means interconnecting said swinging arms directly with the surface working member and including a sleeve connected to the surface working member and journaled on the drive member and a gear segment on the inner end of each arm meshing with gear teeth on said sleeve;

and means including cooperating elements on the drive member and surface working member acting to move the surface working member axially toward the working surface as a result of said relative rotational movement of the surface working member caused by movement of the centrifugally responsive element due to higher rotational speeds.

whereby the surface working member is pressed on the working surface with a force generated by said centrifugally responsive elements and varying with the rotational speed of the drive member.

6. In a surface working machine, the combination comprising:

a frame;

an enclosure for the frame including an upper cover and a bottom closure plate secured to the frame;

means supporting the machine on a working surface including a supporting brush extending downwardly from the closure plate;

a rotational driver rotatably mounted on the frame within the enclosure to revolve about an axis normal to the working surface and having a downwardly projecting hub;

a variable speed motor mounted on the frame within the enclosure and drivingly connected to the rotational driver,

a rotatable surface working member located below the bottom closure plate and having an upwardly projecting sleeve surrounding said driver hub for relative rotational and axial movements relative thereto and extending through the closure plate;

centrifugally responsive means comprising arms pivoted near one end to the driver at angularly spaced positions, said arms being weighted at their free ends to tend to swing outwardly as the rotational speed of the driver increases, and a gear segment on the inner end of each arm meshing with gear teeth on said sleeve;

and means moving the surface working member axially toward the working surface as a result of relative rotation of the driver and the surface working member, said last mentioned means including mutually engaging cam surfaces on the driver hub and the sleeve of the surface working member, said cam surfaces being inclined toward the working surface in the direction of rotation of the surface working member.

References Cited in the file of this patent UNITED STATES PATENTS 2,609,555 Anderson Sept. 9, 1952 2,716,724 Burian Aug. 30, 1955 2,730,219 Kitto Jan. 10, 1956 2,967,314 Kowalewski Jan. 10, 1961

Claims

1. IN A SURFACE WORKING MACHINE, THE COMBINATION COMPRISING: A FRAME ADAPTED TO BE SUPPORTED AT SUBSTANTIALLY FIXED DISTANCE FROM A SURFACE TO BE WORKED; A VARIABLE SPEED MOTOR MOUNTED ON THE FRAME; A DRIVE MEMBER ROTATABLY MOUNTED ON THE FRAME ON AN AXIS PERPENDICULAR TO THE SURFACE AND DRIVEN IN A FORWARD DIRECTION BY THE MOTOR; A SURFACE WORKING MEMBER ROTATABLY MOUNTED COAXIALLY OF THE DRIVE MEMBER FOR LIMITED AXIAL MOVEMENT RELATIVE THERETO THROUGH A CONTINUOUS SERIES OF WORKING POSITIONS BETWEEN A RELIEVED POSITION NOT MORE THAN LIGHTLY ENGAGING THE SURFACE AND A FULLY ENGAGED POSITION FORCIBLY ENGAGING THE SURFACE; MEANS COUPLING THE SURFACE WORKING MEMBER ROTATIVELY TO THE DRIVE MEMBER, SAID COUPLING MEANS PERMITTING LIMITED RELATIVE ROTATION OF SAID TWO MEMBERS; MEANS INCLUDING COOPERATING ELEMENTS ON THE DRIVE MEMBER AND ON THE SURFACE WORKING MEMBER AND ACTING TO MOVE THE SURFACE WORKING MEMBER AXIALLY TOWARD SAID FULLY ENGAGED POSITION IN RESPONSE TO FORWARD ROTATION OF THE SURFACE WORKING MEMBER RELATIVE TO THE DRIVE MEMBER, AND CENTRIFUGALLY RESPONSIVE MECHANISM INTERCONNECTING SAID MEMBERS AND ACTING TO PRODUCE A TORQUE BETWEEN SAID MEMBERS IN A DIRECTION TO PRODUCE FORWARD ROTATION OF THE SURFACE WORKING MEMBER RELATIVE TO THE DRIVE MEMBER, SAID TORQUE INCREASING WITH INCREASING ROTATIONAL SPEED OF SAID MEMBERS, WHEREBY THE SURFACE WORKING MEMBER IS PRESSED ON THE SURFACE TO BE WORKED WITH A FORCE THAT INCREASES WITH INCREASING ROTATIONAL SPEED OF THE MEMBERS.