US 3902284 A
A portable belt sander having a frame carrying an electric motor which drives a cluster gear through a timing belt to rotate the rear drum of a pair of drums on which the endless sanding belt is mounted. A blower assembly is exteriorly mounted on the frame to be driven by the cluster gear to draw dust from a suction chamber formed at the rear of the rear drum through the blower to be discharged into a collection chamber. The blower has an axial line which projects to intersect the area enclosed by the endless sanding belt to insure the low profile assembly.
Description (OCR text may contain errors)
United States Patent [1 1 Hestily [4 1 Sept. 2, 1975 LOW PROFILE BLOWER ASSENIBLY FOR PORTABLE BELT SANDERS FOREIGN PATENTS OR APPLICATIONS 1,055,527 10/1953 France 51/170 EB Primary Examiner--James L. Jones, Jr. Attorney, Agent, or Firm-Robert E. Smith; Edward L. Bell; Harold Weinstein ABSTRACT A portable belt sander having a frame carrying an electric motor which drives a cluster gear through a timing belt to rotate the rear drum of a pair of drums on which the endless sanding belt is mounted. A blower assembly is exteriorly mounted on the frame to be driven by the cluster gear to draw dust from a suction chamber formed at the rear of the rear drum through the blower to be discharged into a collection chamber. The blower has an axial line which projects to intersect the area enclosed by the endless sanding belt to insure the low profile assembly.
5 Claims, 3 Drawing Figures 3,9022% SHEET 1M2 PATENTED SEP 2 I975 LOW PROFILE BLOWER ASSEMBLY FOR PORTABLE BELT SANDERS BACKGROUND OF THE INVENTION In the prior art, it is common for belt sanders to have a top mounted electric motor to drive a rear sanding belt drum through .a timing belt. When a blower assembly is attached, it is mounted at the level of the motor or substantially above the sanding belt drum. This is disadvantageous because it requires a long conduit from the suction chamber behind one of the drums to the blower, so as to require a more powerful blower which, results in a lesser pickup rate of the dust deposited in the chamber from the sanding operation. The elongated conduit is susceptible to leaks and requires extra material and complicates the general assembly of the tool. The high location of the blower makes the tool more bulky and interferes with the balance of the tool and the visibility of the operator.
SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved low profile blower assembly for portable belt sanders which overcomes the prior art disadvantages; which is simple, economical and reliable; which offers a low profile for the blower; which uses short conduits to interconnect the blower assembly with the suction chamber and the collection chamber; which has the axis of the blower intersect within the area enclosed by the endless sanding belt; which uses a cluster gear to drive the drum and the blower simultaneously; which uses parallel shafts for the cluster gear, the blower, and the drum; which uses a frame having a motor housing and a drum housing with the drum internally mounted, and the blower externally mounted, and the cluster gear connected to simultaneously engage and drive both the drum and the blower.
Other objects and advantages will be apparent from the following description of one embodiment of the invention, and the novel features will be particularly pointed out hereinafter in the claims.
I BRIEF DESCRIPTION OF THE DRAWINGS This invention is illustrated in the accompanying drawings in which:
FIG. 1 is a side elevational view, partly broken away, of a portable belt sander embodying the present invention.
FIG. 2 is a top plan view of the sander of FIG. 1, showing sectional views of the motor, rear drum, cluster gear and blower assembly.
FIG. 3 is an exploded perspective view showing the cluster gear and blower assembly of the present invention.
DESCRIPTION OF THE INVENTION 7 In the illustrated embodiment of the invention, a portable belt sander, designated generally as 10, is shown in FIGS. 1 and 2. and has a main frame 12 including a motor housing 14 and a drum housing 16. The drum housing 16 has a side wall 18, an end wall 20 and an upper wall 22, which the motor housing 14 is carried. The main frame 12 is of clamshell construction having frame portions 12a and 12b interconnected by a plurality of bolts 24, threadedly engaging either nuts 26,
,shown in FIG, 1, or tapped inserts 28, as seen in FIG. 2.
An electric driving motor 30 is mounted in the motor housing 14 and has an armature shaft 32 extending from one end of the motor housing 14 transversely of the frame 12, as illustrated in FIG. 2.
The frame 12 supports a pair of revolvable drums or pulleys 34 and 36, located adjacent the longitudinal ends thereof, and an endless flexible sanding belt 38 is trained over the drums. The front drum 34 is the idler drum, while the rear drum 36 is the driving drum, and is operatively connected to and driven by the electric motor 30.
A handle 40 is cast integrally with the main frame 12 to provide forward and aft grip portions 42 and 44 for convenient manipulation of the tool, as illustrated in FIG. 1. A switch having a trigger 46 is mounted in the handle 40 and an electrically conducting cable 48 extends from the bottom rear of the aft grip portion 44 of a the handle 40 for connection to a conventional source of electrical power.
The armature shaft 32 rotates about a fixed axis 50 and carries a toothed pulley 52 mounted externally of the motor housing 14. A cluster gear 54 having a stub shaft 56 journaled in spaced bushings 58 carried by the side wall 18 rotates about a fixed axis 60, as shown in FIGS. 2 and 3. The cluster gear 54 includes a cogwheel 62 that threadedly receives and is affixed to the exterior end of the stub shaft 56, and has an annular toothed gear 64 affixed thereto by a plurality of screws 66, as shown in FIGS. 2 and 3. Intermediate the journal bushings 58, a pinion 68 of the cluster gear 54 is affixed to the stub shaft 56 to drivingly engage a drum gear 70 affixed to one end of the rear drum shaft 72, the other end of which carries the rear driving drum 36. The drum shaft 72 is journaled into the side wall 18 to rotate about a fixed axis 74.
A timing belt 76 illustrated in FIGS. 1 and 2, drivingly connect the toothed pulley 52 and the cogwheel 62 of the cluster gear 54. On operation of the motor 30, the rear driving drum 36 is caused to rotate counterclockwise,'thereby moving the lower ply of the sandpaper belt 38 rearwardly along the base of the frame 12. A sole plate 78 provides a backing support for the belt 38 as the abrasive surface thereof is pressed against the surface of a workpiece.
A belt cover 80 is detachably affixed to the frame 12, as by screws (not shown), to completely enclose the timing belt 76 as shown in FIGS. 1 and 3. A volute blower housing 82 is suitably affixed to the belt cover 80. The belt cover 80 has an aperture 84 that is aligned to an aperture 86 on the rear wall of the blower housing 82. An enlarged front aperture 88 of the blower housing 82 serves the dual function of providing access for assembling and disassembling a blower 90, and of serving as a fitting for a conduit 92. A blower assembly 93 includes the blower housing 82 and the blower 90 operatively disposed therein.
The conduit 92 is connected to the volute blower housing 82 by two diametrically spaced self-tapping screws 94. The conduit 92 is substantially U shaped as illustrated in FIG. 2 with the short front side connected into the aperture 88, and the longer rear side connected to the outer end of a nozzle 96 that is connected to the end wall 20, at its slotted inlet 98 by a self-fitting recess 100 which engages an opening in the wall 20. The bottom of the inlet end 98 has an inclined sweeper step 102 which aids in collecting and delivering the dust into the inlet 98 and nozzle 96.
A suction chamber 104 shown in FIGS. 1 and 2, is formed behind the rear sanding drum 36, and is an integral part of the drum housing 16, and runs behind the drum 36 from the open side to the interior of the side wall 18. The end wall 20 serves as a rear boundary for the suction chamber 104 and extends vertically downwardly very close to the work surface to terminate just slightly above or equal to the lower reaches of the sweeper step 102.
A journal shaft 106 shown in FIGS. 2 and 3, has one end threadedly connected to the side wall 18 to extend exteriorly thereof in cantilevered fashion. A hollow shaft 108 is journaled upon the shaft 106 by a pair of spaced needle bearings 110 as illustrated in FIG. 2. A blower gear 112 is integrally formed on the end of the shaft 108 adjacent the side wall 18 with the opposite end thereof of reduced diameter to define a hub 114 upon which the blower 90 will be affixed. Prior to connecting the blower 90 to the hub 114, the conduit 92 will have first been removed to provide access for the connection through the aperture 88 which is also used to introduce the blower into the housing 82. The blower gear 112 will engage the tooth gear 64 and be rotated thereby.
The power transmission means of the preferred embodiment includes a gear train 115 made up of the cluster gear 54 and its components cogwheel 62, toothed gear 64 and pinion 68; and drum gear 70; and the blower gear 112. The gear train 115 combined with the timing belt 76 and the toothed pulley 52 to form a drive mechanism 117 which is powered by the electric motor 30 and functions to provide rotative power to operate the belt sander and produce the dust pickup by blower 90 as described more fully hereinafter.
The nozzle 96 from its inlet 98 to the connection to the conduit 92, and the conduit 92 define a passage 116 which communicates the suction chamber 104 to the axial opening 118 of the blower 90, as shown in FIGS 2 and 3, so that on operation of the blower the blades 120 will produce a suction pressure to draw the dust from the suction chamber 104 through the passage 116 into the axial opening 118. Once in the blower 90, the dust will be radially discharged through the opening between the adjacent blades 120 into the discharge open ing 122 of the volute blower housing 82 to be collected in the collection chamber 124 which is formed by a suitable dust bag 126 having one end sealingly connected about the discharge opening 122.
The hollow shaft 108 and consequently the blower 90, rotate about a fixed axis 128 which is coincident to the axis of the journal shaft 106.
On operation of the motor 30, the pulley 52 will rotate the cluster gear 54 through its connection by the timing belt 76 with the cogwheel 62 so as to simultaneously rotate the drum 36 and the blower 90 through their gear connections at 68, 70 and 64, 112, respectively, to produce the rotation of the drum 36 for the sanding operation which results in dust being collected in the suction chamber 104 to be subsequently withdrawn therefrom through the passage 116 by the operation of the blower 90 for final collection in the collection chamber 124 as described herein. Once the dust is collected in the collection chamber 124, it may be conveniently removed by disconnecting the dust bag 126 from the blower housing 82 or alternately, by providing a reclosable zipper opening or the like (not shown) for dust removal.
All of the axes 50, 60, 74 and 128, are parallel to each other as shown in FIG. 2, and especially the latter three for the cluster gear 54, the drum 36 and the blower 90, so as to provide a most compact and effi-. cient power transmittal from the cluster gear 54 to the other two.
The axis 128 of the blower 90 as is best seen in FIG. 1, lies within the area enclosed by the endless sandpaper belt 38, so as to insure the low profile of the blower assembly.
The side wall 18 serves to divide the interior of the frame 12 and drum housing 16 from the exterior thereof, wherein the drum 36 is disposed wholly within the interior of the drum housing 16. The cluster gear 54 has its pinion 68 disposed internally of the side wall 18 so as to lie within the drum housing 16 wherein it powers the rear driving drum 36 through the drum gear 70. Also, the cluster gear 54 is disposed exteriorly of the side wall 18 with the toothed gear 64 powering the blower 90 that is disposed wholly exteriorly of the side wall 18 to lie outside of the drum housing 16. The timing belt 76 drivingly connects the toothed pulley 52 and the cog wheel 62 on the exterior side of the side wall 18.
The blower 90 is disposed outwardly of the timing belt 76 and its belt cover adjacent the rear portion of the drum housing 16 near the bottom of the aft portion 44 of the handle 40, so as to be clear of the operators line of sight in order to provide maximum operator visibility during his operation of the tool, while providing for the shortest possible suction paths between the suction chamber 104 and the collection chamber 124 through the passage 116, and still have a convenient power take-off from the cluster gear 54.
It will be understood that various changes in the details, materials, arrangements of parts and operating conditions which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention.
1. A portable electric belt sander having a low profile blower assembly comprising:
a. a frame,
b. a pair of longitudinally spaced laterally extending drums rotatively mounted within the frame and supporting an endless sanding belt thereon,
c. an electric motor mounted on the frame having a drive shaft extending exteriorly of the frame,
d. a cluster gearjournaled in the frame and having an interiorly disposed pinion and at least one exteriorly disposed gear,
e. a timing belt means drivingly connecting the drive shaft and the cluster gear,
f. the pinion drivingly engaged to drive one of the drums,
g. a journal shaft connected to extend exteriorly of the frame,
h. a hollow shaft journaled on the journal shaft,
. a blower affixed to the outer end of the hollow shaft,
j. a gear formed on the hollow shaft to be drivingly engaged by the exterior gear of the cluster gear, whereby the blower is driven to produce a suction pressure,
k. a suction chamber means formed rearwardly of the driven drum within the frame,
l. a blower housing disposed about the blower,
m. a conduit means connecting the suction chamber means and the blower housing,
n. a collection chamber means connected to the blower housing exteriorly of the frame whereby dust will be drawn from the suction chamber by the blower into the blower housing to be discharged into the collection chamber, and
o. the blower having an axis, the projection of which intersects the area enclosed by the endless sanding belt.
2. The combination claimed in claim 1 wherein:
a. the pair of drums include a front drum and a rear drum,
b. the drum gear affixed to the rear drum,
0. the pinion engaging the drum gear to drive the rear drum, and
d. the blower connected to the frame adjacent to the rear drum.
3. The combination claimed in claim 2 wherein:
a. the cluster gear laterally extending,
b. the hollow shaft carrying the blower laterally extending, and
c. the axes of rotation of the cluster gear, the hollow shaft and the drum disposed parallel to each other.
4. The combination claimed in claim 3 wherein:
a. the drum mounted interiorly of the frame,
b. the blower mounted exteriorly of the frame, and
c. the cluster gear having the pinion interiorly disposed to drive the drum and an exterior gear disposed to drive the blow exteriorly of the frame.
5. The combination claimed in claim 4 wherein:
a. the suction chamber formed rearwardly of the rear drum,
b. the conduit means having a nozzle affixed to the frame in communication with the suction chamber,
c. an inclined sweeper step formed on the bottom edge of the nozzle to aid the dust in entering the