US2976436A - Multi-speed drill - Google Patents

Description

March 21, 1961 ANTON 2,976,436

v MULTI-SPEED DRILL Filed July 12, 1957 3 Sheets-Sheet 1 INVENTOR.

36 NICHOLAS ANTON FIG. 2 BY m Maw ATTORNEYS March 21, 1961 NQANTON MULTISPEED DRILL 3 Sheets-Sheet 2 Filed July-l2. 1957 INVENTOR. NICHOLAS ANTON BY mam/f ATTORNEYS March 21, 1961 N. ANTON MULTI-SPEED DRILL a Sheets-Shet 3 Filed July 12; 1957 FIG. l4

INVENTOR. NICHOLAS ANTON ATTORNEYS United States Patent 1 MULTI-SPEED DRELL Nicholas Anton, 460 Dec Road, Park Ridge, Ill.

Filed July 12, B57, Ser. No. 671,635

Claims. (Cl. 310-50) This invention relates to a new and improved multipurpose electrically powered hand tool; more particularly, the invention relates to a new and improved multiple speed power tool suitable for drilling, grinding, polishing, and like operations.

More and more power tools are being sold for use by relatively unskilled personnel, primarily in the home workshop and do-it-yourself market but also in other fields. In many instances the purchaser, who frequently is the user, requires a versatile tool readily adaptable to a wide variety of jobs rather than a single-purpose or therwise relatively specialized device. This demand has been met to some extent by small hand-type power tools which may be used for several different operations, including drilling, grinding, sawing, and the like. Virtually all of these tools now on the market, however, are substantially limited with respect to practical applications, since they are capable of operation at only one speed regardless of the job on which they are employed.

Multiple speed tools, on the other hand, have been employed in the past but have not been particularly successful in the field of small, inexpensive multi-purpose devices. Many of these previously known multiple speed power tools have employed relatively complex speedehange devices which render the tools economically impractical for the home workshop and other similar markets. Other known devices, while less complex and expensive from a structural standpoint, require substantial skill on the part of the operator in order to obtain, the desired operating speed or require a substantial amount of time and effort to effect the desired speed change. I

A primary object of the invention, therefore, is a new and improved multi-speed hand power tool suitable for drilling, grinding, polishing and like operations.

A more specific object of the invention is a new and improved multi-speed multi-purpose hand power tool which permits the operator to change speeds easily and conveniently and with a minimum of skill required.

Another important object of the invention is a new and improved multi-speed multi-purpose hand power tool which aifords substantially unchanged balance and feel regardless of the speed used.

A further important object of the invention is a new and improved multi-speed multi-purpose hand power tool having corresponding handle arrangements for alternate speeds, thereby affording maximum ease and convenience in the use of the tool.

An additional object of the invention is a new and improved multi-speed multi-purpose hand power tool which is simple and economical in construction and subject to a minimum of maintenance difficulties.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principles thereof and what is now considered to be the best mode for applying those 2,976,436 Patented Mar. 21, 1961 principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. 1 is a perspective view of a multi-speed electrically powered hand tool constructed in accordance with a preferred embodiment of the invention;

Fig. 2 is a plan view of the tool of Fig. 1;

Fig. 3 is a front view of the electrical hand tool;

Fig. 4 is a sectional view taken along line'4-4 in Fig. 1;

Fig. 5 is a rear View of the multi-speed electrically powered hand tool of Fig. 1;

Fig. 6 is a sectional elevation view of the hand tool of Fig. 1;

Fig. 7 is a sectional plan view taken along line 7-7 in Fig. 6;

Fig. 8 is a sectional view of the output portion of the hand tool taken along line 8-8 in Fig. 6;

Fig. 9 is a sectional view of the speed-changing apparatus taken along line 9-9 in Fig. 6;

Fig. 10 is a further sectional view taken along line 10-10 in Fig. 6;

Fig. 11 is a sectional view illustrating the mechanical driving connection to the motor and is taken along line 11-11 in Fig. 6;

Fig. 12 is a further sectional view of the device taken along line 12-12 in Fig. 6;

Fig. 13 is a sectional view taken along line 13-13 in Fig. 10;

Fig. 14 is a detail view of a part of the tool;

Fig. 15 is a detail view, on an enlarged scale, of a thrust bearing employed in the preferred embodiment of the invention; I

Fig. 16 is a detail view of the switch employed in the preferred embodiment of the invention showing the switch in actuated and latched position;

Fig. 17 is a sectional view of the tool handle taken along line 17-17 in Fig. 16; and

Fig. 18 is a further sectional view of the handle showing the switch latching mechanism and is taken along line 18-18 in Fig. 16.

The preferred embodiment of the invention shown in the several views of Figs. l-S comprises a multi-speed multi-purpose electrically powered hand tool 20 comprising a mounting structure 21 at the forward end of the tool and a main handle structure 22 which is secured to the mounting structure and extends therefrom in substantially symmetrical relation to the longitudinal axis 23 of the device. The power tool 20 includes two separate output shafts, as will be described more fully hereinafter. In Figs. 1-3, a chuck 24 is shown connected to one of these output shafts, whereas the other shaft is covered by a cap 25. The two output shafts of the device are syrinmetrically located with respect to each other, being equally spaced from the axis 23.

The power tool 20 further includes an auxiliary handle 26 which is illustrated as being mounted on the lower portion of the mounting structure 21 in Fig. l but which may be removed and re-mounted in an alternate position on the opposite side of the mounting structure as indicated by the dash outline 26A. Accordingly, the auxiliary handle 26 may be fitted to the tool to aiford, together with the main handle 22, corresponding handle facilities for each of the two separate output shafts of the device. The main handle 22 comprises the rear portion of :a casing including two casing members 27 .and 28. The casing members 27 and 28 are secured to the mounting structure 21 by suitable means such as a plurality of bolts 30 which extend through the mounting structure and are threaded into the forward ends of the two casing members. The casing members are preferably provided with suitable apertures 31 and 32 to afford adequate ventilation for the electrical motor mounted within the casing as explained more fully hereinafter in connection with Figs. 6 and 7 and are secured to each other as by a plurality of bolts 33. A power cord 34 is connected to the device and is employed to connect the tool to a suitable electrical supply source such as a conventional 115 volt A.C. line.

The operating characteristics of the electrically powered hand tool may be-considered in connection with Figs. 1-5 before consideration of the internal construction of the device. The chuck 24 may bethreaded into either of the two output shafts of the device to be driven thereby. The chuck itself is of standard construction and may comprise any relatively simple but effective tool holder. A typical chuck which may be employed is manufactured by the Jacobs Company of Hartford, Connecticut, and is designated as their model No.-MC4, having a capacity of A to inch, although anyother suitable tool holder may be utilized. The chuck 24in Fig. l is shown in the low speed position for the tool as will be explained more fully in connection with Fig. 6. For operation with the tool holder in this position, the removable auxiliary handle 26 is mounted in the position shown in Fig. l. A suitable drill, polishing wheel, screw driver, paint mixing device, or other low speed operating tool may be installed in the chuck 24 and the tool is then ready for operation.

To change the power tool 20 to highspeed operation, it is only necessary to remove the cap 25 covering the high speed shaft and to re-mount the chuck 24 in the high speed shaft opening. Preferably, the connection between the chuck and the shafts is a threaded one, thereby facilitating rapid removal and replacement of the chuck. This completes the changeover from low speed to high speed operation of the tool except that, with the chuck connected to the high speed shaft, the auxiliary handle 26 is preferably removed and re-mounted at its alternate position 26A. In this manner, the handle facilities for high speed operation of the tool are made essentially identical with the low speed arrangement. With the chuck and auxiliary handle in their alternate positions, a drill, rotary sanding wheel, rotary saw, grinding wheel, or other working tool may be installed in the chuck for high speed operation. Accordingly, it is seen that speed changes may be efiected in'the power tool 20 without shifting of gears and without dismantling any of the working parts of the tool. It is only necessary to change the chuck 24 from connection to one output shaft to the other and to mount the auxiliary handle 26 at the proper location.

The internal structure of the multi-speed power tool 20 is illustrated in detail in the several views of Figs. 6-18. As indicated in Figs. 6 and 7, the mounting structure 21 comprises a pair of castings 36 and 37 which are secured to each other and to the casing members 27 and 28 by the bolts 30. In addition, a further pair of screws 38 may be provided to hold the two mounting structure members 36 and 37 together and also to mount a cover plate 39 on the rear internal surface of the mounting structure as described more fully hereinafter.

A motor 40 is mounted within the power tool and is secured to a mounting bracket 41 aflixed to the rear wall of the mounting member 37. As indicated in Fig. 13, the shaft 43 of the motor is journalled in a boss 44 on the mounting structure member 37, the extreme end of the shaft 43 comprising a pinion gear 45. The motor 40 is preferably provided with a fan 46 which draws air in through the slots 32 in the tool casing, over the motor, and out through the slots 31 in the front thereof (see Fig. 1).

The motor 40 is not mounted on the longitudinal axis 23 of the device; rather, as indicated in Fig. 6, the motor is displaced vertically by a relatively small distance from 4 the axis but extends parallel thereto. By thus disposing the motor 40 in a somewhat .asymmetrical relation with respect to the axis 23, the multi-speed power tool may in some instances be made substantially smaller in size than would otherwise be necessary depending upon the motor speed relative to the desired output speeds. The asymmetry introduced into the structure by this location of the motor, however, does not materially alter the overall symmetry and balance, nor does it detract substantially from the balanced feel of the tool, so long as the spacing between the motor shaft and the axis is held to a The pinion gear is disposed in meshing engagement with a spur gear 48 on the rear end of the high speed output shaft 49 of the tool. The shaft 49 is journalled in suitable bearings 50 and 51 mounted in the support members 36 and 37 respectively (see Figs. 6 and 12). The forward end of the high speed shaft 49 is shown, in Fig. 6, as being covered by the cap 25 to protect the output shaft from dirt and other foreign matter which might otherwise damage the bearing or clog the threaded opening 52 at the forward end of the shaft. The threaded opening 52 is provided to receive the shaft of the chuck 24 (Fig. 1) when it is desired to use the tool for high speed operation. A second spur gear 54 is affixed to the high speed output shaft 49 and is in mesh with an idler gear 55 mounted upon a shaft which is also supported in each of the two mounting members 36 and 37 as best indicated in Fig. 12, the shaft being journalled in suitable bearing members 56 and 57. The idler gear 55, in turn, is disposed in meshing engagement with a driven spur gear 61 which is affixed to the second or low speed output shaft 62 of the tool. Like the first output shaft 49, the low speed output shaft 62 is journalled in suitable bearings 63 and 64 in the two mounting members 36 and 37 respectively as best indicated in Figs. 6 and 13. Moreover, the low speed output shaft 62 is provided with a threaded socket 66 which correspondes to the socket 52 in the shaft 49 to afford complete interchangeability with respect to mounting of the chuck 24 in the device. It is of course preferred that socket 66 and the exposed end of the bearing for shaft 62 be covered by the cap 25 whenever the chuck is mounted on the high speed shaft 49. The lower rear portion of the mounting structure 21 is covered by the cover plate 70 (Fig. 14), which also serves as a bearing plate for the high speed output shaft 49. Thus, as best shown in Fig. 15, a steel ball 71 is disposed in a suitable socket 72 at the rear of the high speed output shaft 49, the ball further engaging a hardened steel bearing plate 73 afiixed to the cover plate 70. This simple construction affords a ball-type thrust bearing for this shaft and effectively transmits the thrust from the shaft to the mounting structure member 37. Similarly, and as shown in Fig. 13, a second steel ball 75 is mounted in a suitable socket 76 at the rear of the low speed output shaft 62 and engages a hardened steel hearing plate 77 at the rear of the bearing member 64 to afford an antifriction thrust bearing for the second output shaft. The bearing plates 73 and 77 are preferably fabricated from tempered steel; tempered clock spring steel is suitable. By using hardened steel plates at these locations, the useful working life of the device is materially prolonged, since thrust bearing wear is minimized. For convenience of assembly, the spur gear 48 is not pinned or otherwise rigidly fixed tothe low speed output shaft 49. Rather; the shaft and gear are provided with a mating key structure as indicated in Fig. ll by reference numeral 78. In this way, the gear 48 may be engaged with the shaft by inserting the shaft through the mounting member 37 from the fiont side thereof, thereby permitting the use of a shaft which is journalled in both of the mounting structures 36 and 37 instead of in only one of these members. Similarly, the spur gear 61 may be keyed onto the shaft 62'rather than being rigidly affixed thereto for convenience in assembly.

antenna The driving motor 40, which is preferably of the universal type, is energized through a pair of leads .80 and 81 which are introduced into the casing of the tool from the power cord 34 (Fig. The one conductor 80 is connected directly to the field Winding of the motor, whereas the other conductor is connected to one fixed contact 82 of a switch 83. Contact 82 is mounted on an insulator block 84 which in turn is secured to a mounting plate 85, and a second fixed contact 86 is mounted on the block 84 closely adjacent contact 82. This second contact 86 is connected back to the motor winding by a further conductor 87.

The switch 83 further includes a movable contact member comprising a second insulator block 91 which is mounted within the switch adjacent the fixed contact block 84 and which is slidably movable with respect to the block 84 (see Fig. 17). This second insulator block 91 includes a lug 90 which extends downwardly from the switch as seen in Fig. 6. As best indicated in Fig. 17,

the second insulator block 91 carries a contact element 92 which is effective to bridge the two contacts 82 and 86 and complete an electrical connection between the conductors 81 and 87. The switch 83- also includes a substantially U-shaped biasing spring 94 which is affixed to the mounting plate 85 and which engages the lug 90 to urge the lug and the movable contact member 91 toward their normal or unactu-ated position as illustrated in Fig. 6. A switch actuator 96 is included in the switch assembly; this actuating member comprises an insulator block which is disposed partly within the handle but extends externally thereof. The insulator block 96 is aligned with the movable contact member 91 and engages the movable contact member to move that member to its actuated position, as shown in Fig. 16, in response to inward movement of the block 96. The switch assembly is maintained in position within the handle 22 of the tool by engagement of the mounting plate 85 with suitable bosses 99 (Figs. 16 and 17) in the handle portions of the two casing members 27 and 28.

The control switch for the tool further includes a latching member comprising a rod 100 which is mounted within the handle portion of the tool in alignment with the insulator lug 90 onthe movable contact member 91. A first washer 102 is mounted in fixed position on the rod 100 and a second washer 103 is slidably mounted on the rod. A biasing spring 104 is mounted in encompassing relation to the rod 100 and in engagement with the two washers 102 and 103. The washers 102 and 103 engage spaced bosses 106 and 107 within the handle of the tool as best shown in Fig. 17; the bosses 107 retain the washer 103 on the rod 100. One end 101. of the rod is knurled to afford a means for maintaining the rod in engagement with switch lug, 90 as explained more fully hereinafter, and prevent slippage therebetween due to vibration of the tool when in use.

In considering operation of the tool, it may first be assumed that chuck 24 is threaded into the socket 66 in the low speed output shaft 62, as shown in Figs. 1 and 7, and that the auxiliary handle 26 is mounted in the position indicated in Figs. 1 and 6. Moreover, it may be assumed that a suitable drill or other working tool (not shown) is mounted in the chuck. Under these circumstances, the power tool is ready for operation and may be energized simply by pressing the switch actuating member 96 inwardly of the main handle 22 as indicated in Fig. 16; this is accomplished by finger pressure by the tool operator. This closes the electrical circuit to the motor 40 which drives the output shaft 62 through the gear train comprising the pinion #55, the spur gear 48, the second spur gear 54, the idler gear 55 and the driven spur gear 61. If it is desired to maintain the tool in continuous operation Without the necessity of holding the switch actuating member 96 in its actuated position, the switch is latched closed simply by pressing the latch rod 100 into the handle, bringing the knurled end 101 into the path of return movement of the lug as indicated in Fig. 16. With rod end 101 engaging lug 90, the switch is latched in closed position, and the power tool may be operated as long as desired. When it is desired to stop use of the device, it is only necessary to again press the actuating member 96 inwardly. As soon as the actuating member 96 is moved inwardly through a very small distance, the engagement of the lug 90 with the knurled end 101 of the latch rod is released and the latch rod is returned to its normal or uuaotuated position by spring 104 (see Fig. 6). Consequently, when the actuating member 96 is released, the spring 94- returns the movable contact member 91 of the switch to its normal or open position and breaks the electrical circuit to the motor. It is thus seen that the switch 83 affords a convenient arrangement for energizing the motor 40 either for intermittent or continuous operation. Once the switch is assembled Within the handle 22 of the tool, it is virtually impossible for it to become misaligned or to malfunction for other reasons. Moreover, the switch structure is extremely simple and economical as compared with previously known latch-type switches affording the same versatility of operation.

Changing the device from low speed to high speed operation, as described hereinabove, is a very simple operation. The chuck 24 is simply removed from the socket 66 in the low speed output shaft 62 and remounted in the socket 52 in the high speed shaft 49. The handle 26 is then removed and installed in the alternate position 26A (see Fig. 1) and the tool is ready for high-speed operation. Because the high speed shaft 49 is continuously driven, regardless of the selection of output speed for use, it is not necessary to effect any change in the driving mechanism as by replacement of gears or actuation of clutches or the like. As far as the operator is concerned, the handle facilities are identical for the two speeds and the balance and feel of the device do not change materially with changes from one output shaft to the other. This is made possible by the symmetrical location of the two output shafts with respect to the longitudinal axis 23 of the tool and the corresponding symmetry of the mounting structure 21 and the casing and handle structures of the device. The removable auxiliary handle 26 makes it possible to utilize the machine with maximum visibility using either output shaft and affords a natural gripping arrangement for the operator regardless of which output shaft is currently in use. The simple yet effective gear drive rotates both output shafts in the same direction but at substantially different speeds, thereby permitting use of a simple threaded connection as a means for securing the chuck 24 to the shafts.

In a typical commercial embodiment of the invention, the rated output speed for the armature shaft 43 of the motor 40 is approximately 25,000 rpm. and the gear ratios are selected to afford a no-load speed of approximately 3200 rpm. at the high speed shaft 49 and 1100 rpm. at the low speed shaft 62. Using a universal motor, of course, these speeds are reduced somewhat under load; with a motor rated for two amperes maximum, the output speeds of the two shafts at maximum rated load may be of the order of 1800 and 600 r.p.m. respectively. The high speed output is suitable for drilling through steel A to inch in thickness, through wood A to inch in thickness, or through relatively soft metal such as aluminum, brass, or copper of A to A inch thickness. The high speed shaft is also well suited to such other applications as rotary sanding, rotary sawing, grinding, wire brushing, and buffing. The low speed output of the device is suitable for drilling through relatively thick steel of inch to /2 inch thickness, through wood up to 2 /2 inch thickness, and through soft metals of M1 to /2 inch thickness. The low speed output of the tool. may also be used for drilling in masonry or concrete up to /2 inch in thickness. The low speed output is also suitable for such other applications as polishing, waxing, paint mixing, and the driving of screws or bolts. These specifications, are of course related to a light duty tool and may be changed substantially in a heavier and more rugged device following the same basic construction and equipped with a more powerful motor.

Hence, while I have illustrated and described the preferred embodiment of my invention, it is to be understood that this is capable of variation and modification, and I therefore do not Wish to be limited to the precise de tails set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. In an electrically powered hand tool including an electric motor mounted within a casing and a handle afiixed to said casing, a control switch comprising: a fixed contact member disposed within said handle and electrically connected to said motor; a movable contact element disposed within said handle in juxtaposition to said fixed contact member and movable between a normal position and an actuated position, said movable contact member having a lug of electrical insulating material affixed thereto; biasing means urging said movable contact element toward said normal position; a switch actuating member disposed partly within said handle and extending externally thereof, said actuating member being aligned with said movable contact memher to engage said movable contact member and move said movable contact member to its actuated position in response to inward movement of said switch actuating member with respect to said handle; a latching member, mounted within said handle and extending externally thereof, in alignment with said lug when said movable contact member is in said normal position, said latching member being movable from a normal position free of said lug to a latching position in the path of return movement of said lug to engage said lug and maintain said movable contact member in its actuated position; and biasing means for urging said latching member toward its normal position to release said latching member from engagement with said lug when said switch actuating member is moved inwardly of said handle.

2. In an electrically powered hand tool including an electric motor mounted within a casing and a handle affixed to said casing, a control switch comprising: a fixed contact member disposed within said handle and electrically connected to said motor; a movable contact element disposed within said handle in juxtaposition to said fixed contact member and movable between a normal position and an actuated position; said movable contact member having a lug of electrical insulating material affixed thereto; biasing means urging said movable contact element toward said normal position; a switch actuating member comprising an insulator block disposed partly within said handle and extending externally thereof, said actuating member being aligned with said movable contact member to engage said movable contact member and move said movable contact member to its actuated position in response to inward movement of said switch actuating member with respect to said handle, a latching member comprising a rod mounted within said handle in alignment with said lug when said movable contact member is in said normal position, said latching rod being movable longitudinally from a normal position, said latching rod being movable longitudinally from a normal position free of said lug to a latching position in the path of return movement of said lug to engage said lug and maintain said movable contact member in its actuated position; and biasing means for urging said latching member toward its normal position, to release said latching member from engagement with said lug when said switch actuating member is moved inwardly of said handle.

3. A multi-speed electrically powered hand device for drilling, grinding, polishing and the like, said device comprising an elongated mounting structure of substantially symmetrical configuration with respect to the longitudinal axis thereof, a pair of output shafts journaled in said mounting structure in parallel spaced relation to said axis and being disposed substantially symmetrically on opposite sides of said axis, said shafts each including means for removably mounting a tool holder or tool on the end thereof adjacent one end of said mounting structure, a motor supported by said mounting structure, the shaft of said motor being located in parallel spaced relation to the longitudinal axis of said mounting structure, first gear means connecting said motor in mechanical driving relation to one of said output shafts for rotating said one output shaft at a predetermined speed and in a given direction, second gear means connecting said one output shaft in mechanical driving relation to the other output shaft for rotating said one output shaft at a substantially different speed as said one output shaft but in the same direction as said one output shaft, a main handle structure secured to said mounting structure and spaced a substantial distance from said tool holder mounting means and extending from the mounting structure at the end opposite to said tool holder mounting means, said handle structure being disposed substantially symmetrical with respect to the longitudinal axis of the mounting structure and including a handle portion extending substantially parallel to a line joining the axes of said output shafts, and an auxiliary handle removably mountable on opposite sides of said mounting structure adjacent either of said output shafts to extend laterally of the mounting structure in substantially parallel relationship with said handle portion whereby regardless of which output shaft is employed, the handle facilities make is possible to utilize the device with maximum visibility and provide substantially identical balance and feel of the device to an operator.

4. Apparatus as defined in claim 3, including an actuating switch electrically connected to said motor and mounted within said handle portion at the center thereof.

5. Apparatus as defined in claim 3, including a pair of steel balls, each of said balls being individually disposed in a socket in the rear surface of one of said output shafts and being in engagement with said mounting structure to afford anti-friction thrust bearings for said shafts.

References Cited in the file of this patent UNITED STATES PATENTS 781,062 Hauss et al Ian. 31, 1905 1,411,538 Sweetland Apr. 4, 1922 1,650,911 Schneider Nov. 29, 1927 1,929,662 Wappat Oct. 10, 1933 2,283,778 Wilhide May 19, 1942 2,513,271 Bluemink et al July 4, 1950 2,717,968 Lorenz Sept. 13, 1955 2,730,635 McCabe Ian. 10, 1956 2,807,732 Kurtovich Sept. 24, 1957 2,810,844 Morrill Oct. 22, 1957

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