US2041442A - Floor polishing machine - Google Patents

Description

May 19, 1936. E. s. STINSMAN FLOOR POLISHING MACHINE Original Filed Sept. 9, 1930 INVENTOR Edya Jtaale fitimsman ATTORNEY Patented May 19, 1936 UNETE STATES PATENT OFFICE signor of one-half to Harry M.

Seattle, Wash.

Madden,

Original application September 9, 1930, Serial No. 480,646. Divided and this application June 19, 1934, Serial No. 731,228

9 Claims.

This invention relates to direct drive floor polishing machines of the type set forth in my copending application, Serial No. 480,646, filed Sept. 9, 1930, which has matured into Patent No. 1,973,915, of which this is a division pertaining to means for ventilating and cooling the electric motor elements.

In polishing waxed floors and other waxed surfaces with a machine incorporating a rotating brush, it is found that when air for cooling the driving motor is obtained from the vicinity of the brush, small particles of the excess wax and dust are drawn into the interior of the motor where a portion thereof lodge on the walls of the ventilating ducts, and on the surfaces of the windings and on other interior parts. As the layer of wax and dust increases in thickness, it interferes with the proper functioning of the moving parts, with the circulation of the air, and with the effective cooling of the heated parts. This necessitates relatively frequent cleaning of the interior surfaces in order to prevent serious damage to the windings. It is difficult, however, to induce the users of such machines to have said cleaning done often enough because. of the time required and expense entailed.

An object of my invention is to provide improved means for ventilating the motor elements of floor polishing machines.

Another object is to provide means for obtaining the ventilating and cooling air for floor polishing machines from a region removed a considerable distance from the vicinity of the rotating polishing brush.

A further object is to provide removable means in a device of the kind described for screening the dust and wax particles from the ventilating air before it enters the interior cavities of the motor portion of the machine.

Other objects and advantages will be apparent from the following detailed description of a preferred form of the invention, which consists of certain parts and combination of parts, hereinafter described, illustrated in the accompanying drawing and embraced in the appended claims.

In the drawing:

Figure 1 is a side elevation of the complete. machine.

Fig. 2 is a longitudinal mid-section of the operating mechanism to a larger scale on broken line 4-4 of Fig. 1.

Fig. 3 is an end elevation of the operating mechanism to the same scale as in Fig. 2.

Fig. 4 is a view in perspective of the polishing ring pad to a smaller scale.

Like reference numerals are used to indicate like parts throughout the drawing wherein a frame casting 5, preferably of an aluminum alloy, is shown provided with a split socket 6 in which a tubular metal handle l of suitable length is removably secured against rotational or axial displacement by means of a notch 8 in the handle and a snug fitting clamp bolt 9. The upper end of the tubular handle may be enlarged and bent through a suitable angle to form a handle grip It) for the convenient operation of the machine.

The downwardly projecting portion of frame 5 terminates in a hollow conical end piece ll having an axial cylindrical aperture l2 adapted to receive the threaded projecting end [3 of stationary spindle M of motor unit l 5. This end piece also forms a guard covering the adjacent end of the rotating member, and is adapted to prevent clothing and the like from being caught and wound about said spindle. The larger end of spindle I4 is hollow as at E3 and has radial connecting apertures I4 and M" which are used as hereinafter described.

This spindle is the nucleus around which the motor is assembled. First, pressed steel starting switch support It is mounted upon the spindle so it bears against shoulder ii and projects slightly past shoulder l8. Stamped sheet steel laminations I9 each having a central circular aperture 26 adapted to fit over portion 2| of the spindle are assembled thereon with their partly closed slots 22 and ventilating duct apertures 23 in assured alignment by reason of key 24 in the spindle and registering key-way notches, not shown, in the laminations. End discs of insulating material 25 having slot and ventilating duct apertures registering with those of the laminations are assembled therewith in the order shown. Shoulder l8, sleeve 26 and the inner race of self aligning ball bearing 21 in combination with the threaded end 28 of spindle l4 and nut 29, provided with a set screw 29, serve to clamp the laminations securely in position to form the stator core of the motor. Sleeve 26 is preferably a press fit on the spindle.

After insulating the slots, insulated copper magnet wire is wound therein in the usual manner to form what is known in the art as a split phase Winding, which fills the slots and occupies approximately the space 30 at the ends of the stator core. The tops of the slots are closed in the usual way after winding by means of fibre insulating strips 3 The stationary part of the centrifugally operated starting switch consists of two nearly semicircular bronze segments 32 having terminal lugs and screws 33 which are mounted on starting switch support I6 over a strip of suitable insulating material 34 and secured thereto by means of insulated rivets 35, thus electrically insulating the segments from the support and from each other. These switch segments are connected in series with the starting winding and insulated flexible stator leads 36 which pass through aperture I4 into space I3 of the spindle. The terminal ends of the running winding are connected directly to the two stator leads, thus forming the usual parallel arrangement of the two windings so long as segments 32 are connected by the usual contact members 31 which are electrically connected and mounted within the cylindrical flange portion of pressed steel end piece 38, on a strip of insulating material 39, and secured thereto by means of insulated screws 40 and nuts M.

The rotating elment, or rotor, of the motor consists of a plurality of annular sheet steel laminations 42 having partly closed slots 43 carrying bare copper wire bars 44 that are riveted over and soldered to copper end rings 45 to form the usual squirrel-cage type of rotor winding.

With the squirrel-cage rotor in position over the stator as shown and the ball bearings 21 and 21' removed from the spindle, the rotor assembly is built up by fitting the flange edges of rotor end pieces 38 and 38' into notches 45 in the periphery of the rotor end rings and clamping the end pieces firmly in position by means of bolts 46 which pass through equally spaced holes, not shown, in the rotor assembly and nuts 41 in re cesses 48 of the end pieces.

The self aligning ball bearings 21 and 21', properly packed with grease, may next be placed in position with their inner races on the spindle and outer races within the accurately ground cylindrical recesses provided therefore in their respective end pieces. Nut 29 is used to secure the inner race of bearing 21 to the spindle as previously described, and a threaded ring 52, adapted to fit with threads in the recess of end piece 38, and a leather ring of triangular cross section 53 are used to secure the outer race of bearing 21' to the end piece. A flanged sleeve 54 is next fitted over end I3 of spindle I4 and, with flexible stator leads 36 projecting axially from space I 3', end I3 of the spindle is fitted into aperture I2 of the frame and removably secured therein by means of lock washer 55 and nut 56, thus forcing sleeve 54 against the inner race of bearing 21 which is thus firmly gripped between the sleeve and shoulder 51 of the spindle. The registration of frame and spindle apertures I I and I4 respectively is assured by means of a suitable alignment pin 55' positioned in grooves in the spindle and frame.

It will be noted that the fastening arrangements for the inner and outer races of bearing 21' provide means whereby the rotor and stator elements are definitely positioned axially of the spindle; yet provision is made for the unequal axial expansion and contraction of these elements by providing adequate end clearances for bearing 21 in the bearing recess of end piece 38. The ball bearings are considerably over size for the requirements of the machine, hence assure a constant air gap 58 between rotor and stator cores for along period of time. The bearings are sealed against the entrance of dust particles by means of felt rings 59 secured to the rotor elements and a taper-threaded closure cap 60, as clearly shown in Fig. 2 of the drawing.

The flexible stator leads 36 next may be passed through registering apertures II' and I4 and cored space I I for joining to insulated flexible conductors 36' by means of connectors BI, after which the connectors are taped and plug I32 screwed into position to close the threaded convenience opening 63 in frame 5. A pressed metal cap 64, fitting tightly into recess 55, closes the exposed end of the spindle and its fastenings. A snap switch 66 of standard design adapted to be removably secured in the end of handle grip III by means of screws 61, is connected to one of the insulated conductors 36 which pass from tubular handle 1 through an insulating bushing 68 to a suitable terminal plug connection, not shown, and to one of the wires connected to the motor windings.

After assembly with the rotor core, the peripheral surfaces of end pieces 38 and 38 are accurately ground to a suitable taper with the smaller diameter at the fan end of the rotor. Metal ring 69, in which the brush bristles 10 are mounted in the usual way, is taper bored to fit over the tapered rotor end pieces and is secured in position against axial and rotational displacement by means of a pin H in end piece 38 and an L shaped slot 12 in the ring. In addition to the ring brush, each machine is preferably supplied with a polishing ring pad, shown in Fig. 4, adapted to be used interchangeably with the ring brush. This ring pad consists of a metal ring similar to ring 69 on which is secured a suitable polishing pad material 10 such as wool felt that occupies approximately the same space as brush bristles 10.

A sheet metal guard 13, having fastening ears 14 adapted to fit over the lower edges 15 of frame 5, protects the operator from flying particles projected from the rotating brush or pad while the machine is in use. Edges 15 are preferably tapered toward the open end of the frame to facilitate the installation and removal of the guard which can be done without interference with the brush or pad rings, which likewise can be installed and removed without interfering with the guard.

To operate the machine the terminal plug at the end of conductors 36 is inserted in a convenient receptacle connected to the source of electrical supply. With the left hand grasping handle grip IIJ switch 6'6 is turned to the on position, thus completing the circuit to the two stator windings of the motor. ing element reaches the speed for which the starting winding switch is set, the centrifugal force causes contact members 31 to overcome the tension of the closing springs, not shown, and open the switch thus breaking the flow of current to the starting winding. The machine then operates as a single phase, squirrel cage, induction motor with the interior member of the motor stationary, and with the exterior member rotating about the interior member on ball bearings 21 and 21 preferably in the direction indicated by the arrow in Fig. l of the drawing.

By turning switch 66 to the oil position the flow of current to the running winding is interrupted and the rotating element comes to rest, 5

thus, allowing the tension of the starting switch springs to actuate contact members 31 to again close the circuit through the starting winding.

It will be seen by the foregoing description that the construction of the exterior rotating element When the rotat- 5 provides two comparatively large interior air chambers within the respective end pieces, and that said air chambers are connected by a plurality of ventilating ducts 23, air gap 58 between the stator and rotor cores, and by the shallow ducts formed at the tops of the slots above fibre strips 3| and copper bars 44.

The air chamber within end piece 38 is connected also with the space within frame 5 by means of the hollow portion I3 of the spindle and a plurality of radially disposed apertures l4 and II. The space within frame 5 in turn is connected with tubular handle 1 in which a plurality of apertures 8| are provided near handle grip H].

The upper portion of the frame of the machine preferably is fitted with an air straining unit consisting of a fine mesh wire screen envelope [6, to one end of which a head 11 is fixedly attached by soldering, and in like manner a plain sleeve 18 is attached to its opposite end. When in position, as shown in the drawing, sleeve 18 fits in aperture 19 of wall 80, and head 11 closes the end opening of the frame.

Flanged end piece 38 carries a centrifugal fan assembly consisting of an annulus 49 to which a plurality of radial impellers 50 are fixedly attached, preferably by spot welding. Screws 5| serve to removably secure the fan assembly in position.

When the machine is in operation the rotation of impellers 50 forces the air within end piece 38' outwardly through a plurality of apertures 83, thereby inducing a flow of cooling air through iinlet apertures 8| into tubular handle I, then down the same to space 82 exterior of air strainer screen 76, thence through the mesh of said screen to the interior thereof and out of end sleeve 18, then through apertures II, M, l3 and M, respectively, to the air chamber within end piece 38, thence through the air gap, ventilating ducts and slot spaces to the air chamber within end piece 38', from which it enters the intake of the fan assembly, and in turn is forced outwardly through said apertures 83, thus maintaining a continuous flow of air that removes the heat resulting from various losses within the motor elements, as will be explained.

Referring to Fig. 2 of the drawing, it will be apparent that a portion of the heat losses are conducted away from the exterior or rotor element of the motor through the cylindrical flanges of end pieces 38 and 38 to their head portions, and to the annulus and impeller elements of the fan assembly mounted within end piece 38'. Likewise some of the heat losses are conducted away from the stator element of the motor through stationary spindle M to frame 5, which provides relatively large interior and exterior cooling surfaces that effectively dissipate the heat thus conducted to it. Heat also is conducted from said stator element through conical flange member l6 which provides cooling surfaces of considerable area in the path of air flow through the inclosing air chamber of the machine.

I make use of these additional cooling surfaces by causing the cooling air to first traverse the interior of the aforesaid frame 5, and then directing its flow over the interior surface of conical flange member l6 upon entering the air chamber within end piece 38, as previously described.

Said cooling air then sweeps over the interior surface of said end piece, the exposed end surfaces of the motor elements and the exterior surface of said conical flange member before entering the ducts connecting with the air chamber within end piece 38'; where it traverses the opposite end surfaces pf the motor elements, the interior surface of end piece 38' and the various surfaces of the fan assembly, before being discharged from apertures 83. In this way the cooling effect of the flow of air through the machine is greatly increased.

It will be noted that the ventilating and cooling air entering the tubular handle through apertures 8!, is drawn from a region removed a considerable distance from the rotating polishing brushand the fioor or other surface being polished, hence contains fewer dust and wax particles than the air in the immediate vicinity of said brush.

The removable air straining unit provides a relatively large area of fine mesh screen through which the air from the tubular handle readily passes inwardly to the interior of the screen structure and then flows out through the large opening provided by sleeve 18. Said screen is effective in catching a large portion of the dust and wax particles carried by the ventilating air, thus preventing their entering the interior of the rotating member of the machine. By thus cleaning the cooling air, the ventilating ducts and interior surfaces of the motor elements remain clean and effective in cooling the heated parts for a long period of time without attention.

When the accumulation of dust and wax particles interferes with the free passage of air through the aforesaid screen, the air straining unit may be removed easily from the machine and cleaned, preferably by immersing it in a vessel containing a cleaning fluid, such as benzine, which will dissolve the wax that acts as a binder for the dust particles. The air straining unit is then removed from the cleaning fluid, dried and replaced in the machine. A similar procedure may be used to advantage in cleaning the ring brush and ring pad. By using a container with a tight fitting cover, the cleaning fluid may be saved and used several times.

Although I have illustrated and described my invention in a preferred form as applied to a direct drive floor polishing machine, it will be apparent to those skilled in the art that the combination of coacting elements constituting the invention may be adapted and applied to other devices, such as surface finishing machines employing a rotating drum on which sandpaper or other abrasive materials may be mounted.

What I claim as new and desire to protect by Letters Patent is:

1. In a machine for polishing waxed surfaces, the combination of a hollow L shaped frame, a tubular handle providing an air duct connection with one leg of said hollow frame, screen means in said leg of said frame, a stationary spindle having one end mounted in and providing an air' duct connection with the other leg of said hollow frame, a motor stator element fixedly mounted on said spindle and having air ducts therethrough parallel with said spindle; an enclosed motor rotor element having interior cavities at the ends thereof connected by the air ducts in said stator, rotatably mounted on said spindle exterior of said stator, and adapted to peripherally mount a polishing ring; fan means in the interior of said rotor element adapted to induce a flow of air through said tubular handle, said screen, said hollow frame and connecting air ducts and said interior cavities and adapted to discharge said air through apertures in an end of said rotor, whereby the dust and wax particles may be strained from said air used to cool said motor elements.

2. In a machine of the class described, the combination of a hollow frame, an air straining unit removably mounted in said frame, a spindle having one end fixedly secured to said frame and providing air duct means connecting with the air space within said frame, a wound stator element containing a plurality of longitudinal air ducts fixedly mounted on said spindle, a rotor member exterior of said stator element rotatively mounted on said spindle and providing an air chamber at either end thereof one of which connects with the air duct means of said spindle, fan means secured to said rotor member in the other said air chamber, whereby cooling air is forced outwardly therefrom and is induced to fiow through said air straining unit mounted in said frame, through the aforesaid air duct means into the first said chamber and through the air ducts in said stator element into the second said chamber when said rotor member is rotating.

3. In a machine of the class described, a hollow frame, an air straining unit remov-ably mounted in said frame, an electric motor stator structure having a spindle fixedly secured at one end to said frame and providing an air duct connecting with the air space in said frame, an exterior rotor member providing a plurality of air chambers connected by a plurality of air ducts one of said air chambers being connected with the air duct of said spindle, and fan means fixedly secured to said rotor member in the other said air chamber, whereby air flow is induced through said straining unit into the first said air chamber, through said connecting air ducts into said other air chamber from which it is forced outwardly when said rotor member is rotating.

4. In a machine of the class described, the combination of a hollow frame, a spindle having one end fixedly secured to said frame and providing air duct means connecting with the air space within said frame, a wound stator element containing a plurality of longitudinal air ducts fixedly mounted on said spindle, a rotor member exterior of said stator element rotatively mounted on said spindle and providing an air chamber at either end thereof one of which connects with the air duct means of said spindle, fan means secured to said rotor member in the other said air chamber, whereby cooling air is forced outwardly therefrom and is induced to flow into the air space within said frame, through the aforesaid air duct means into the first said chamber and through the air ducts in said stator element into the second said chamber when said rotor member is rotating.

5. In a machine of the class described, an electric motor stator structure providing a spindle having therein an air duct, a conical flange mem ber fixedly mounted on said spindle with the space within its inner surface connected with the interior end of the air duct in said spindle,

an exterior rotor member rotatively mounted on said spindle and providing air chambers at the ends thereof connected by a plurality of air ducts said conical flange member being within one of said air chambers, and fan means fixedly seemed to said rotor member in the other said air chamber, whereby air is caused to fiow through the air duct of said spindle and is directed against the interior end surface of the first said air chamber by the interior surface of said conical flange member when said rotor member is rotating.

6. In an electric motor polishing machine, a hollow frame member, a tubular handle providing an air duct connection with said frame member, removable air strainer means in said frame member, a spindle having one end mounted in and providing an air duct connection with the interior of said frame member, a motor stator element containing longitudinal air ducts fixedly mounted on said spindle, a rotor member exterior of said stator element rotatively mounted on said spindle and providing air chambers at the opposite ends thereof connected by the air ducts in said stator with one of said chambers connecting with the air duct in said spindle, and fan means in the interior of said rotor member adapted to cause cooling air to fiow through said tubular handle, said air strainer means and said air chambers, and to discharge said air through apertures in said rotor member, when said rotor member is rotating.

7. In a machine of the class described, the

combination of a stationary spindle providing air duct means at one end, a wound stator element containing a plurality of longitudinal air ducts fixedly mounted on said spindle, a rotor member exterior of said stator element rotatively mounted on said spindle and embodying end pieces having cylindrical flanges supporting an exterior ring member and providing air chambers at either end thereof one of which connectes with the air duct means of said spindle, and fan means fixedly secured to said rotor member in the other said air chamber, whereby heat produced in said stator, rotor and ring parts is removed by cooling air which is caused to flow inwardly through the air duct means in said spindle and contact the walls of the first said chamber, then to flow through the air ducts in said stator element and contact the walls of the second said chamber when said rotor member is rotating,

8. In a machine of the class described, an electric motor structure incorporating an exterior rotor member providing air chambers at the opposite ends thereof connected by air ducts, fan means in one said air chamber fixedly secured to the outer end wall thereof and utilizing the same as. a side member for said fan means,

whereby said cooling air is caused to flow adja cent said end wall when said rotor is rotating.

9. In a machine of the class described, an electric motor structure incorporating an exterior rotor member providing air chambers at the opposite ends thereof connected by air ducts, guide means within one said air chamber for directing air fiow adjacent the interior surfaces thereof, and fan means within the other said air chamber fixedly secured to said rotor member for producing said air fiow when said rotor mem ber is rotating.

EDGAR STANLEY STINSMAN.

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