US3432703A

US3432703A - Portable electric drill

Info

Publication number: US3432703A
Application number: US601143A
Authority: US
Inventors: Martin I Sheps; Jacobus J Beckering; Thaddeus E Bednarski
Original assignee: Black and Decker Manufacturing Co
Current assignee: Black and Decker Corp
Priority date: 1966-12-12
Filing date: 1966-12-12
Publication date: 1969-03-11
Anticipated expiration: 1986-03-11

Description

Marh l1, 1969 M. sHEPs ETAL L 3,432,703

PORTABLE ELECTRIC DRILL J BY ATTORNEY March 11, 1969 M. l. sHEPs ETAL 3,432,703

PORTABLE ELECTRI C DRILL Filed DeC. l2l 1966 Sheet of 3 `4g INVENTORS MARTIN I. SHEPS JACOBUS J. BECKERING THADDEUS E. BEDNARSKI March 1l, 1969 M. sHEPs ETAL PORTABLE ELECTRIC DRILL 3 ors Sheet Filed Deo. 12, 1966 FIG. 6

INVENT ORS MARTIN l. SHEPS JACOBUS d. BECKERING THADDEUS E. BEDNARSKI BKM www United States Patent Ofiice 3,432,703 Patented Mar. l1, 1969 3,432,703 PORTABLE ELECTRIC DRILL Martin I. Sheps, Baltimore, Jacobus J. Beckering, Bel Air, and Thaddeus E. Bednarski, Timonium, Md., assignors to The Black and Decker Manufacturing Company, Towson, Md., a corporation of Maryland Filed Dec. 12, 1966, Ser. No. 601,143 U.S. Cl. 310-50 38 Claims Int. Cl. H02k 7/14 This invention relates generally to portable electric devices, andparticularly to an improved housing and motor frame -construction for portable electric tools.

Important objects of the present invention are to provide an improved housing and motor frame construction for portable electric tools which construction provides snugly interitting component parts and facilitates formation of the housing from a variety of non-metallic, moldable materials having different physical characteristics using a substantially uniform molding die.

Additional important objects of the present invention are to provide an improved housing and motor frame construction of the above character which provides builtin, novel motor and motor component support features and insulating techniques adapted to satisfy high insulating requirements.

Other important objects of the present invention are to provide an improved housing and motor frame construction of the above character which comprises a minimum of separate parts and eliminates the need for special motor supports and fasteners, which is adapted to rapid and easy assembly and disassembly and which provides an overall compact and well balanced device.

Further important objects include the provision of a housing and motor frame construction of the above character which is adapted for use with a variety of different tools, which is neat and aesthetically pleasing in appearance and which is relatively inexpensive to manufacture, rugged in construction and reliable in use.

Other objects and advantages of the present invention will become more apparent from a consideration of the following detailed description taken in conjunction with the drawings in which:

FIG. 1 is a side elevational view, partly in section, illustrating a portable electric tool embodying the present invention and shown with a housing constructed from a preferred material;

FIG. 2 is a sectional view of FIG. 1 taken along the line 2-2 thereof;

FIG. 3 is an enlarged sectional View of FIG. 1 taken along the line 3--3 thereof and showing one part of the motor frame;

FIG. 3A is an enlarged sectional view of FIG. 1 taken along the line 3A-3A thereof and showing one part of the motor frame;

FIG. 4 is a view similar to FIG. 3 illustrating the assembled motor frame;

FIG. 5 is an exploded perspective view illustrating the motor frame of the present invention and showing the drive motor parts in place therein;

FIG. 6 is a sectional view of FIG. 1 taken along the line 6 6 thereof;

FIG. 7 is a sectional view of FIG. 1 taken along the line 7 7 thereof;

FIG. 8 is a fragmentary view, similar to FIG. l, showing a housing constructed from another material having different physical characteristics;

FIG. 9 is a fragmentary view (to an enlarged scale) similar to FIG. 7, showing the relation of the housing and frame when using the housing material of FIG. 8; and

FIG. l()` is an end view of the assembled motor frame of the present invention.

Broadly described, the present invention includes an elongated motor frame, electric motor means supported by said motor frame, a hollow, elongated, insulating housing encompassing said motor and at least a portion of said frame, and having an end portion engageable with a shoulder on said frame, means removably interconnecting said housing and said frame and drawing said housing end portion against said shoulder, said housing having an inner surface portion adapted to overlay an outer surface portion of said frame, said housing and frame having cooperable, longitudinally extending abutment means, said outer and inner surface portions on said frame and said housing respectively, being adapted to be closely engaged when a housing of a first predetermined size is positioned on said frame, said longitudinal abutment means on said housing and frame being adapted to be closely engaged when a housing of a second predeterp mined size greater than said first predetermined size is positioned on said frame.

In another aspect, the present invention broadly includes a frame and housing construction for portable electric devices comprising a pair of elongated, metal frame members detachably secured together to form an elongated frame, said frame members including cooperable, generally C-shaped first portions and hollow second portions integral with said first portions, an electric motor disposed within said rst portions of said frame lmembers and trapped therebetween, a gear transmission encased within said second frame member portions and in driven relation with said motor, a hollow housing encompassing said frame member rst portions and said motor and cooperating with said frame member second portions to completely enclose said motor, longitudinally extending holt means engaging said housing and received in nut means trapped between said frame member rst portions and adapted to draw said housing into close cooperation with said frame member second portions, said housing including a dependent handle adapted to carry a control switch for said motor.

In still another aspect, the present invention includes a pair of metallic frame members detachably secured together along a common longitudinal plane, each of said frame members comprising a first portion and a second portion, said second portion being formed integrally with said first portion and extending axially forwardly therefrom, and having a continuous outer wall, whereby said respective walls of the second portions of said frame members form a gear case for the tool, a first set of bearings trapped between the respective frame members, an electric motor including a field trapped between the respective first portions of said frame members, said motor further including an armature having a shaft journaled in said first set of bearings, a second set of bearings trapped between the respective second portions of said frame members, a spindle journaled in said second set of bearings, a tool element driven by said spindle, gearing means in said gear case connecting said spindle to said armature shaft, plastic housing means fitted over the respective first portions of said frame members thereby enclosing said motor, means securing said plastic housing means to at least one of said frame members, said plastic housing means being disposed axially rearwardly of said gear case, thereby forming with said gear case an outer housing for the tool, a handle rigid with said plastic housing means, and a control switch mounted in said handle.

In still other aspects, the present invention includes: elongated iframe means having a first, open portion and a second, hollow, closed portion, an electric motor supported by said frame means first portion, hollow housing means encompassing said motor and said frame first portion and having an end portion engageable with a shoulder on said frame means, said housing means having an inner surface portion overlaying and closely engaging an outer surface portion on said frame means, cooperating lug and recess means on said housing means and frame means adjacent said end portion and said shoulder, and means removably interconnecting said housing means and said frame means and drawing said housing end portion against said shoulder; and/or elongated frame means having a first, open portion and a second, hollow, closed portion, an electric motor supported by said frame first portion, hollow housing means encompassing said motor and said frame first portion and having an end portion engageable with a shoulder on said frame means, said housing means having inwardly projecting longitudinally extending rib means closely engaging longitudinally extending abutment means on said frame means, cooperating lug and recess means on said housing means and frame means adjacent said end portion and said shoulder, and means removably interconnecting said housing means and said frame means and drawing said housing end portion against said shoulder.

The construction of the present invention may be employed with that class of hand held, portable tools which includes electric drills, impact wrenches, rotary hammers, and the like. With this in mind, reference is now made to the drawings, FIGS. 1 and 2, where a portable electric drill, illustrated generally at 11, is shown embodying the present invention. The drill 11 is seen to include a motor and gear case frame 13 having a motor and handle housing 15 secured thereto by

bolts

17, 19 and

nuts

21, 23. A conventional universal electric motor is disposed within and supported by the frame 13 and rotatably drives a tool bit chuck 27 through a gear transmission 29. Electric current is supplied to the motor 25 through a conventional line cord 31 secured within the end of the housing 15 and a trigger switch 33 controls energization of the motor 25'.

As seen best in FIGS. l, 2 and 5, the frame 13 includes a pair of clam-

shell frame members

35, 37 removably secured together by screws 39 positioned in aligned openings 41. Each of the

frame members

35, 37 is constructed of cast metal, preferably aluminum, and includes mating, generally C-shaped, open motor support portions 43, formed integral with generally concave

gear case portions

47, 49 respectively. The

motor support portions

43, 45 are formed at their rear ends with cooperating recesses 51, 53, preferably semi-spherical in configuration, which, when the

frame members

35, 27 are secured together, form a spherical cavity adapted to receive and trap a spherical bearing rotatably supporting one end of an armature shaft 57 forming a part of the motor 25. Of course, if another type of bearing is employed in place of the spherical bearing 55, the recesses 51, 53 can be modified or a liner employed. A fiber and spring washer assembly 59 is carried upon the armature shaft 57 to locate the motor 25 and shaft 57 relative to the bearing 55.

The other end of the armature shaft 57 extends through and is rotatably supported by another bearing 61, preferably of the spherical type also, trapped between cooperating, semi-spherical, concave recesses 63, formed in the gear case Iframe

portions

47, 49, respectively. An insulating plastic sleeve 67 is molded directly on the armature shaft 57 and within armature windings 26 of the motor 25 and abuts a motor cooling fan 69 pressed on the shaft 57 and rotatable therewith. A fiber washer 71 is positioned between the fan 69 and the bearing 61 to reduce friction therebetween.

The forward end of the armature shaft 57 is formed with a spiral pinion 73 which rotatably drives a gear 75 pressed on a spindle 77. The spindle 77 is rotatably supported at its rear end by a spherical bearing 79 trapped h1 generally semi-spherical,

concave recesses

81, 85

formed in the gear case portions 47 49, and at an intermediate portion by a spherical needle bearing trapped in generally

semi-spherical recesses

87, 89 in the outer ends of the

gear case portions

47, 49, respectively. The spindle 77 extends outwardly of the

gear case portions

47, 49 and has the tool chuck 27 secured thereto in the usual manner so that when the motor 25 is energized, it rotates the armature shaft 57 and through the gear transmission 29 rotates the spindle 77 and the tool chuck 27.

Electric current is transmitted to the motor 25 from a pair of leads 95, 97 connected to a pair of

brushes

91, 93 respectively. One of the leads 95, 97 stems directly from the line cord 31 and the other is connected to the motor field. Another lead (not shown) connects the field to the trigger switch 33 and still another lead (not shown) stemming from the line cord 31 is connected to the switch 33 in the usual manner. The pair `of

electrical brushes

91, 93, are carried by insulating

brush holders

101, 103, respectively, and are biased by a pair of

metallic compression springs

133, 135 into contact with a commutator 99 carried by the larmature shaft 57 and electrically connected to the armature windings 26. The

springs

133, 135 are trapped within the

brush holders

101, 103 by insulating caps 102, 104 adapted to snap over one end of the

brush holders

101, 103, respectively. In addition to holding the

brushes

91, 93 in contact with the commutator 99, the

springs

133, 135 electrically connect the power leads 95, 97 with the

brushes

91, 93, the leads 95, 97 having terminal ends trapped in engagement with the

springs

133, 135 by the caps 102, 104. For a more detailed illustration and description of the brush assembly components, reference may be made to the copending application of Carl J. Amrein et al., Ser. No. 589,716, filed October 26, 1966 and owned by the assignee of the present application.

The

brush holders

101, 103 are trapped in place by and between the assembled clam

shell frame members

35, 27. Thus, for example, the brush holder 101 is provided with a pair of laterally extending arms 105', 107 integral therewith and projecting from opposite sides thereof and which are trapped in aligned

recesses

113, and 117, 119 formed in the adjoining faces of the motor support frame portions v43, 45, respectively. Similarly, the brush holder 103 has a pair of

arms

121, 123 trapped in recesses 125, `127 and 129, 131 formed in adjoining faces of the motor support frame portions 43, `45 at the lower side thereof.

The motor

support frame portions

43, 45 are formed with

offset arms

114, 116 and 118, 120 adjacent the

brush holders

101, 103 so that when the clam

shell frame members

13, 15 are assembled with the

brush holders

101, 103 trapped in place, an air gap is yformed around the brush holders. This air gap, together with the wall thickness of the

brush holders

101, 103 themselves, provides the insulation required between the

brushes

91, 93 and the metal frame members to satisfy industry requirements such as, for example, Underwriters Laboratories double insulation standards. In addition, the trapped relation of the

brush holders

101, 103 within the

frame members

35, 27 provides a safe and secure assembly free of separate, special connectors and one which is relatively easy to assemble and disassemble for service and/or part replacement.

The motor 25 includes field windings 137 and laminations 139 having a pair of

insulating caps

141, 143 snapped over axial projections thereon. The motor support frame portions y43, 45 are formed with cooperating

recesses

145, 147 and 149, 151 adjacent their adjoining surfaces which receive and trap the insulating caps 1-41, 143, respectively, and support the laminations 139. The

caps

141, 143 are constructed from a suitable, rigid, plastic insulating material, and have a thickness dimension selected to satisfy double insulation requirements between the laminations 139 and the

frame members

35, 37. Alternatively, the laminations 139 could be supported upon and insulated from the

frame portions

43, 45 by pins (not shown) extending axially of and fixed to the laminations and having insulating caps or sleeves thereon which are trapped between the frame portions.

In similar fashion, the molded sleeve 67 on the armature shaft 57 and within the armature windings 26 is constructed of a suitable insulating material and fully in sulates the armature windings 26 and the commutator 99 from the armature shaft 57. The

brush holders

101, 103 are suspended between and spaced from the motor

support frame portions

43, 45, as described above so that the Wall thickness of the holders together with the air gap around the holders serves to insulate them from the metal frames 35, 37. Both the

brush holders

101, 103 and the

caps

141, 143 are trapped between the clam-

shell frame members

35, 37 and the sleeve 67 is molded directly on the armature shaft 57 and within the armature windings 26 so that the motor parts are both securely located within the frame 13 and are insulated therefrom. Furthermore, the motor and the

brush holders

101, 103 are assembled within and removed from the frame 13 simply by assembling and disassembling the

frame members

35, 37 and this is accomplished by inserting and removing the screws 39 so that no special fasteners, supports or the like are required and the time and skill required therefore is minimized.

As shown in the dra-wings, the motor

support frame portions

43, 45 are open throughout their entire lateral extent so that the material required therefore and the Weight thereof is minimized. The .-motor 25 is covered and protected by the motor and handle housing 15 which is constructed from an insulating, non-metallic material, preferably plastic, and includes a tubular motor housing portion 153 and a dependent hollow handle portion 154 rigid therewith. The motor housing portion 153 and the handle portion 154 are preferably integral but could be of clam shell construction secured together by suitable fastener means. In any event, a handle cover 155 is detachably secured to the handle portion 154 by bolts 156 and nuts 158 and carries the trigger 33 along with serving to trap the line cord 31 in place. The motor housing portion 153 fits neatly over the motor

support frame members

43, 45 and seats against a generally annular shoulder 157 formed at the rear end of the gear

case frame members

47, 49. The motor and handle housing 15 is secured to the frame 13 by the

axially extending bolts

17, 19, preferably, but not necessarily, located at the rear end of the motor housing portion 153` and adapted to seat in

recesses

163, 165 therein and threadedly received by the nuts 21, 23 which are trapped in

recesses

167, 169, and 171, 173 formed in the adjoining faces of the motor

support frame members

43, 45, respectively. When the

bolts

17, 19 are tightened in the nuts 21, 23, the motor housing portion 153 is pressed tightly against the shoulder 157 on the gear

case frame portion

47, 49, and

bosses

146, 148` opposite the

recesses

163, 165 seat against abutment surfaces 150, 152 on the frame 13. In addition, a projection 142 on the housing 15 is received in a recess 144 formed in the adjacent faces of the motor frame portions 43, 45 (see FIG. 1). A radially projecting lug 160 and an axially extending tab 162 are formed adjacent the forward end of the motor housing portion 153 and are received in a radial recess 164 and an axial recess 166 formed at the adjoining faces of the motor

support frame members

43, 45 and the gear

case frame members

47, 49, respectively to help locate the housing 15 on the frame 13.

It is desirable that the motor housing portion 153 snugly engage the motor

support frame members

43, 45 so as to eliminate play therebetween transversely of the motor axis. In addition, it has become desirable to use different, moldable plastic materials to form the motor and handle housing 15 for reasons of durability, appearance and ease of forming, on the one hand, as compared withf cost on the other hand. For example, a number of long life, relatively expensive electrical tools desirably will employ motor and handle housings constructed from one of a group of materials known as polyamides and generally known as nylon. This material has excellent electrical and mechanical properties, processes the necessary resistance to thermal distortion, and is easy to mold. In other tools, a less expensive material such as, for example, a thermoplastic resin including part acrylonitrilebutadiene-styrene (ABS), may be desirable. In addition to nylon and part ABS, other materials may be used to form the motor and handle housings. For example, materials selected from the groups consisting of polycarbonates, polyphenylene, oxides, phenylenes, acetals, rigid vinyls and Fiberglas reinforces polyesters or thermoplas tics may be used.

One of the problem areas which exists when employing two different materials, such as nylon and a thermoplastic resin including part ABS, to form the motor and handle housings is that these materials have different physical properties, and will react differently during the forming stages. Particularly, Du Ponts Zytel 101, which is one type of nylon, found particularly useful for purposes of the present invention, has a considerably higher coeflicient of expansion than Borg-Warners combination ABS and rigid vinyl material Cycovin and will, therefore, shrink to a greater extent than the latter upon cooling out of the molding die. The coeicient of expansion for Zytel 101 is about 0.016 inch per inch while that for Cycovin is about 0.005 inch per inch so that if the motor and handle housings 15 formed from both materials were to fit snugly on a standard motor Iand gear case frame 13, different molding dies would need be employed to form these housings. This practice, however, is objectionable primarily because of the relatively high cost of these molding dies and since to do so would considerably add to the cost of the tools 11.

To overcome this problem, and make possible the use of a single molding die to form the motor and handle housings 15, the motor and gear case frame 13 and the housing 15 of the present invention are constructed in a novel manner calculated to provide a snug and secure fit therebetween for housings constructed from at least two different materials having correspondingly different coeicients of expansion. Thus, as seen best in FIGS. 6 and 7, the tubular motor housing portion 153 is provided with at least one and preferably a pair of vertically spaced, axially extending

ribs

173, 174 formed integral with and internally of one side of the housing portion 153. Similarly, at least one and preferably another pair of

ribs

175, 176 are formed internally of the other side of the housing portion 153 and opposite the

iirst pair

173, 174 and together, these ribs form abutment means on the housing portion 153. The motor

support frame portions

43, 45 are provided with abutment means in the form of pairs of arcuately shaped

arms

177, 178 and 179, 180, respectively, which are adapted to be closely received in the motor housing portion 153 and the ends of which are also present axial or longitudinal surfaces and are disposed adjacent the

ribs

173, 174 and 175, 176, respectively. The motor housing portion 153 together with the ribs 173-176 thereon and the frame arms 177-180l are dimensioned so that for housings 15 constructed from materials having a greater coefficient of expansion and therefore greater shrinkage upon cooling out of the molding die, the motor housing portion 153 will shrink sufficiently to closely encase the outer dimensional surfaces of the arms 177-180 (FIG. 7) and bear radially thereagainst as seen in FIGS. 6 and 7. This procedure is employed, for example, when forming the housings 15 from Zytel 101 which, as described above, has a coecient of expansion of about 0.016 inch per inch. On the other hand, in housings made from materials, such as, for example, Cycovin which has a coeicient of expansion of about 0.005 inch per inch, less shrinkage occurs upon cooling and some radial clearance exists between the outer surfaces of the arms 177-180 and the inner surface of the motor housing portion 153 (FIG. 9). However, because of this lesser amount of shrinkage, the

ribs

173, 174 are spaced farther apart in an arcuate direction as are the

ribs

175, 176 and fit snugly between and engage the ends of the

arms

177, 178 and 179, 180, respectively (FIGS. 8 and 9). This abutting engagement between the ribs and arms precludes relative movement between the housing and frame 13 transversely of the motor axis and importantly permits the use of a single molding die to form housings 15 constructed from either material thereby substantially reducing manufacturing costs and cost to the consumer. It should be noted here that the different shrinkage factors do not affect the thickness dimension of the ribs 173-176 sufficiently to be of importance.

It will be appreciated that the different expansion coefiicients of the various materials used in forming the housings 15 affects the axial location of the screw recesses 163, 165 relative to the motor housing portion 153. Thus, for example, housings 15 constructed from Zytel 101 with its relatively high coefiicient of expansion shrink in an axial direction upon cooling out of the molding die to a greater extent than housings constructed from Cycovin with its lower expansion coefficient. This condition has the result that if the molding die for the housings 15 is constructed so that the

housing bosses

146, 148 seat against the abutment surfaces 150, 152 on the frame 13 in a housing constructed from Zytel 101, the

bosses

146, 148 in the housings 15 constructed from Cycovin will not seat against the

surfaces

150, 152 since Cycovin has a lesser shrinkage factor and the distance from the

bosses

146, 148 to the forward end of the motor housing portion 153 is greater. To overcome this problem, the molding die employed to form the housings 15 simply is provided with movable pins which are adjustable to vary the axial length of the projection and of the

recesses

163, 165 and therefore the axial position of the

bosses

146, 148. Manifestly, the

bosses

146, 148 are set inwardly from the adjacent wall of the housing 15 to a greater extent for those housings constructed from Cycovin, or other material having a lesser shrinkage factor, than for those housings constructed from Zytel 101, or other material having a larger shrinkage factor.

By the present invention, there has been provided an improved electric `power device frame and housing construction calculated to fulfill the inventive objects hereinabove set forth, and while a preferred embodiment of the present invention has been illustrated and described in detail, various additions, substitutions, modifications and omissions may be made thereto without departing from the spirit of the invention as encompassed by the appended claims.

We claim:

1. A motor frame and housing construction for portable electric devices comprising an elongated motor frame, electric motor means supported by said frame, a hollow, elongated insulating housing encompassing said motor and at least a portion of said frame, and having an end portion engageable with a shoulder on said frame, means removably interconnecting said housing and said frame and drawing said housing end portion against said shoulder, said housing having an inner surface portion adapted to overlay and closely engage an outer surface portion of said frame when a housing of a first predetermined size is positioned on said frame, said housing and frame having cooperable, longitudinally extending abutment means adapted to be closely engaged when a housing of a second predetermined size greater than said first predetermined size is positioned on said frame.

2. A construction as defined in claim 1 wherein said housing has an inner arcuate surface adapted to fit adjacent spaced, arcuate outer surfaces on said frame, said housing being provided with at least two internal, arcuately spaced, radially projecting ribs, said frame having abutment means adjacent said arcuate surfaces positionable adjacent said ribs, said housing inner surface adapted to closely engage said frame outer surfaces when said first predetermined sized housing is positioned on said frame, said ribs adapted to engage said abutment means when said second predetermined sized housing is positioned on said frame.

3. A construction as defined in claim 2 wherein said housing is constructed of a molded plastic material and wherein a single molding die may be employed to form housings from materials having different coefficients of expansion, the housings formed from materials having a larger coefficient of expansion having their inner surface closelyengaged with said outer surface portions of said frame, and the housings formed from materials having a smaller coefcient of expansion having their ribs closely engaged with said abutment means on said frame.

4. A construction as defined in claim 2 wherein said lug means includes at least two arcuately spaced lugs, said abutment means being formed at the ends of arcuately shaped arms defining said arcuate surfaces, said arcuately shaped arms on said frame being adapted to receive a respective pair of said lugs therebetween.

5. A construction as defined in claim 1 wherein said frame includes first and second, detachably secured, elongated frame members.

6. A construction as defined in claim 5 wherein said removable interconnecting means includes bolt means extending through said housing and threadedly received by nut means trapped between said frame members.

7. A construction as defined in claim 5 wherein said motor means includes armature windings, an armature shaft trapped between and supported by said frame members and insulated from said armature windings, laminations surrounding said armature windings, insulating means trapped between said frame members and supporting said laminations.

8. A construction as defined in claim 7 which includes insulating ybrush holder means trapped between said frame members, brush means carried by said brush holder means and electrically interconnecting electrical lead means and a commutator on said armature shaft.

9. A construction as defined in claim 5 wherein said frame members include overlying, generally C-shaped first portions and generally semi-cylindrical second portions, said motor means positioned within said first portions and having an armature shaft carried by first and second axially spaced bearings trapped between and supported by said first and second frame portions, respectively.

10. A construction as defined in claim 9 wherein said frame members are integrally cast metal and said housing is integrally molded plastic.

11. A construction as defined in claim 9 wherein said housing surrounds said frame first portions, said shoulder means being formed between said first and second p0rtions.

12. A construction as defined in claim 1 wherein said housing is provided with projection means adjacent said end portion, and recess means in said frame adjacent said shoulder and receiving said projection means.

13. A construction as defined in claim 5 wherein said housing is provided with a pair of projections adjacent said end portion, said frame members having a pair of recesses at the adjoining faces thereof and receiving said projections.

14. A construction as defined in claim 3 wherein said housings may be `formed from nylon having a coefficient of expansion of about 0.016 inch per inch, and from Cycovin having a coefficient of expansion of about 0.005 inch per inch.

15. A construction as defined in claim 1 wherein said housing is provided with internal abutment surfaces adapted to seat against said frame when said housing end portion is drawn against said shoulder.

16. A construction as defined in claim 15 wherein said housing is constructed of a molded plastic material and wherein a single molding die may `be employed to for-m housings from plastic materials having different coefficients of expansion, said internal abutment surfaces on said housings constructed from different materials being spaced from said housing end different disstances determined by said coefficients of expansion when said housings are formed.

17. A construction as defined in claim 16 wherein the positioning of said abutment surfaces relative to said housing end is adjusted by movable components on said die.

18. A construction as defined in claim wherein said abutment surfaces are internal bosses on said housing, said means removably interconnecting said housing and frame including bolts extending through said bosses and threaded into nuts carried by said frame.

19. A construction as defined in claim 1 wherein said housing has a depending handle portion integral therewith, a handle cover detachably secured to said handle and carrying a trigger switch, said handle cover cooperating with said handle to trap therebetween a line cord connected to said motor.

20. A frame and housing construction for portable electric devices comprising a pair of elongated, metal frame members detachably secured together to form an elongated frame, said frame members including cooperable, generally C-shaped lfirst portions and hollow second portions integral with said first portions, an electric motor disposed within said first portions of said frame members and trapped therebetween, a gear transmission encased within said second frame member portions and in driven relation with said motor, a hollow housing encompassing said frame member first portions and said motor and cooperating with said frame member second portions to completely enclose said motor, longitudinally extending bolt means engaging said housing and received in nut means trapped between said frame member first portions and adapted to draw said housing into close cooperation with said frame member second portions, said housing including a dependent handle adapted to carry a control switch for said motor.

21. A construction as defined in claim 20 wherein said motor includes an armature shaft, axially spaced bearing means rotatably supporting said shaft and trapped between said cooperating first and second frame member portions, respectively, said shaft extending into said frame member second portions.

22. A construction as defined in claim 20 wherein said motor is of the universal type and includes laminations supported by said frame member first portions, insulating cap means fixed to said laminations and trapped between said cooperating frame member first portions.

23. A construction as defined in claim 21 which includes a commutator fixed to said armature shaft, electrical brush means engaging said commutator and carried by insulating brush holder means, said brush holder means being trapped between and supported by said cooperating frame member first portions.

24. A construction as defined in claim 20 ywherein said housing has an end portion adapted to abuttingly engage a shoulder on said frame member second portions and held thereagainst by said bolt means, and cooperating lug and recess means on said housing and frame member second portions.

25. A construction as defined in claim 20y wherein said housing is provided with at least two bosses adapted to seat against said frame member first portions, said bolt means including at least two bolts extending through said bosses.

26. A construction as defined in claim 20 wherein said handle includes a detachable cover portion supporting said switch.

27. A portable electric tool comprising a pair of metallic frame members detachably secured together along a common longitudinal plane, each of said frame members comprising a first portion and a second portion, said second portion being formed integrally with said first portion and extending axially forwardly therefrom, and having a continuous outer wall, whereby said respective walls of the second portions of said frame members form a gear case for the tool, a first set of bearings trapped between the respective frame members, an electric motor including a field trapped between the respective first portions of said frame members, said motor further including an armature having a shaft journaled in said first set of bearings, a second set of bearings trapped between the respective second portions of said frame members, a spindle journaled in said second set of bearings, a tool element driven by said spindle, gearing means in said gear case connecting said spindle to said armature shaft, plastic housing means fitted over the respective first portions of said frame members thereby enclosing said motor, means securing said plastic housing means to yat least one of Said frame members, said plastic housing means being disposed axially rearwardly of said gear case, thereby forming with said gear case an outer housing for the tool, a handle rigid `with said plastic housing means, and a control switch mounted in said handle.

28. A construction as defined in claim 27 wherein said plastic housing and said gear case are snugly interfitted to for-m a substantially continuous outer housing for said tool.

29. A construction as defined in claim 27 which includes a commutator rotatable with said shaft, and brush holder means trapped between the respective first portions of said frame members and carrying brush means engageable with said commutator.

30. A construction as defined in claim 27 `which includes means `accurately locating said lplastic housing relative to said frame members independent of small size variations therebetween.

31. A tool as defined in claim 27 which includes means insulating said field and said armature from said frame members.

32. A tool as defined in claim 27 wherein said plastic housing is of integral construction and is generally tubular in configuration, said handle depending integrally from said housing.

33. A frame `and housing construction for portable electric devices comprising elongated frame means having a first, open portion and a second, hollow, closed portion, an electric motor supported by said frame means first portion, hollow housing means encompassing said motor and said frame first portion and having an end portion engageable with a shoulder on said frame means, said housing means having an inner surface portion overlaying and closely engaging an outer surface portion on said frame means, cooperating lug and recess means on said housing means and frame means `adjacent said end portion and said shoulder, and means removably interconnecting said housing means and said frame means and drawing said housing end portion against said shoulder.

34. A frame and housing construction for portable electric devices comprising elongated frame `means having a first, open portion and a second, hollow, closed p0rtion, an electric motor supported by said frame first portion, hollow housing means encompassing said motor and said frame first portion and having an end portion engageable with a shoulder on said frame means, said housing means having inwardly projecting longitudinally extending rib means closely engaging longitudinally extending abutment means on said frame means, cooperating lug and recess means on said housing means and frame means adjacent said end portion and said shoulder, and means removably interconnecting said housing means and said frame means and drawing said housing end portion yagainst said shoulder.

35. A construction as defined in claim 34 wherein said rib means includes at least a pair of arcuately spaced ribs on said housing means, said abutment means including arcuately shaped pairs of arms on said frame means, one of said ribs being disposed between and engaging one pair of said arms, and the other of said ribs being disposed between and engaging the other pair of said arms.

36. A construction as defined in claim 34 wherein said rib means includes oppositely disposed, pairs of ribs, said abutment means including oppositely disposed, arcuately shaped pairs 0f arms on said frame, one pair of ribs being disposed between and engaging one pair of said arms, and the other pair of said ribs being disposed between and engaging the other pair of said arms.

37. A construction as defined in claim 33 which includes cooperating lug and recess means on said housing means and said frame means adjacent an end of the latter spaced from said second portion.

38. A construction as dened in claim 34 which includes cooperating lug and recess means on said housing means and said frame means adjacent an end of the latter spaced from said second portion.

References Cited UNITED STATES PATENTS 3,280,351 10/1966 Wolter 310-50 3,336,490 8/1967 Yelpo 310-50 3,344,291 9/ 1967 Pratt 310-50 WARREN E. RAY, Primary Examiner.

R. SKUDY, Assistant Examiner.

U.S. Cl. X.R. 310-5l, 62., 83, 43

Claims

1. A MOTOR FRAME AND HOUSING CONSTRUCTION OF PORTABLE ELECTRIC DEVICES COMPRISING AN ELONGATED MOTOR FRAME, ELECTRIC MOTOR MEANS SUPPORTED BY SAID FRAME, A HOLLOW, ELONGATED INSULATING HOUSING ENCOMPASSING SAID MOTOR AND AT LEAST A PORTION OF SAID FRAME, AND HAVING AN END PORTION ENGAGEABLE WITH A SHOULDER ON SAID FRAME, MEANS REMOVABLY INTERCONNECTING SAID HOUSING AND SAID FRAME AND DRAWING SAID HOUSING END PORTION AGAINST SAID SHOULDER SAID HOUSING HAVING AN INNER SURFACE PORTION ADAPTED TO OVERLAY AND CLOSELY ENGAGE AN OUTER SURFACE PORTION OF SAID FRAME WHEN A HOUSING OF A FIRST PREDETERMINED SIZE IS POSITIONED ON SAID FRAME, SAID HOUSING AND FRAME HAVING COOPERABLE, LONGITUDINALLY EXTENDING ABUTMENT MEANS ADAPTED TO BE CLOSELY ENGAGED WHEN A HOUSING OF A SECOND PREDETERMINED SIZE GREATER THAN SAID FIRST PREDETERMINED SIZE IS POSITIONED ON SAID FRAME.