US 2650993 A
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Description (OCR text may contain errors)
Sept. 1, 1953 E. M. BROWN ET AL ELECTRIC HAIR CLIPPER 3 Sheets-Sheet l Filed Jan. 31. 1949 m 2mm E vw v mm mv Nm m w@ n@ OM N Mv Qnunii'ii;
SCP- 1, 1953 E. M. BROWN` x-:T AL 2,650,993
ELECTRIC HAIR CLIPPER Filed Jan. 3l. 1949 5 Sheets-Sheet 2 32215 MEM@ 172725Z H5117 P51955 SePfl, 1953 E. M. BROWN ET AL 2,650,993
ELECTRIC HAIR CLIPPER SOLDER CONNECTIO Patented Sept. 1, 1 953 ELECTRIC HAIR CLIPPER Ellis M. Brown and Ernest Harry Forss, Racine, Wis., assignors to John Oster Manufacturing Company, Racine, Wis., a corporation of Wisconsin Application January 31, 1949, Serial No. 73,832
(Cl. S-50) 1 Claim. l
This invention relates to certain new and useful improvements in electric hair clippers and has as its general object to provide a hair clipper which is less costly to manufacture but nevertheless entirely satisfactory in service and -performance.
With this general objective in view it is a furthei object oi this invention to provide an eleotric hair clipper so designed and constructed that its motor may be fully assembled and tested before the housing, which also serves as a handle for the clipper, is applied.
In this connection it is another object of this invention to provide an electric hair clipper wherein the motor housing consists of two complementary substantially cup-like sections telescoped endwise over the opposite ends of the motor.
Another object of this invention is to provide an improved electric motor especially adapted for use in a hair clipper or similar tool.
Another object of this invention is to so arrange and construct the motor switch that the applcation of the rear housing section to the motor automatically brings the switch `contactor into proper cooperative relation with the stationary contacts of the switch.
Another object of this invention is to provide l'an inexpensive sturdy drive transmission for translating rotation of the motor shaft into reciprocation of the movable cutter blade,
To this end the drive transmission comprises essentially a pinion on the armature shaft of the motor meshing with a gear fixed to a cam shaft inside a gear case formed of inexpensive stampngs, and to assure smooth, quiet operation notwithstanding the relatively wide tolerances such construction entails, an unusual tooth design is combined with a deliberately short center-tocenter distance.
Still another object of this invention is to obviate the usual threaded securement of the plugliiie retainers for the motor brushes by having these retainers held in place by the walls of one of the housing sections.
With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination yand arrangement of parts substantially as hereinafter described, and more particularly dened by the appended claim, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claim.
The accompanying drawings illustrate onecomplete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:
Figure 1 is a longitudinal sectional View through an electric hair clipper embodying this invention;
Figure 2 is a longitudinal sectional view through Figure l substantially on the plane of the line 2 2;
Figure 3 is a perspective view of the motor and the two complementary housing sections shown disassembled;
Figure 4 is a back end view of the clipper with a part of the housing broken away and in section;
Figure 5 is a perspective view of the iront end portion of the motor and the drive transmission shown detached therefrom but with the parts in their proper order of assembly;
Figure 6 is a perspective view of the cradlelike frame of the electric motor;
Figure 7 is a detail view, on an enlarged scale, of the pinion and a portion of the gear oi the drive transmission;
Figure 8 is a detail sectional view taken through Figure l on the plane of the line 8 8 and showing the switch construction; and
Figure 9 is a diagram illustrating the electrical connections of the motor.
Referring now particularly to the accompanying drawings in which like numerals indicate like parts throughout the several views, the numeral 5 designates generally the electric motor of the hair clipper of this invention which, as will be hereinafter more fully brought out, is a unit entirely independent of its housing indicated generally by the numeral 6.
The housing 6 comprises two complementary substantially cup-like sections, namely a front section 'I preferably formed as a die casting and a back section 8 drawn and stamped from sheet metal, The open ends of the housing sections meet` substantially at the middle of the housing and preferably have a telescopng interengagement as at 9. The iront housing section has the cutter head I0 of the clipper removably mounted thereon and the back housing section carries the contactor II of the motor controlling switch and has an electric cord I2 entering the same through a gromet I3 anchored in its rear end.
The cutter head I0, which is of the conventional type having superimposed stationary and movable blades I4 and I5 respectively, is attached to the front housing section 'I by screws i6. These screws are threaded into tapped holes in bosses iT formed on the inside of the housing section 1.
A U-shaped spring i8 having the ends of its arms secured to the movable cutter blade and its closed end anchored to a bracket i9 which is xed to the back of the stationary cutter blade idiprovides spring tension to hold the blades in cooperative engagement and also serves as part of the driving connection between the movable blade and the motor. This feature of the cutter head, however, forms no part of the instant invention, being covered in a copending application, Serial No. 73,831, led January Sl, 1949, now Patent No. 2,611,955, dated September 30, 1952.
To accommodate the U-shaped spring iii and its mounting upon the back of the cutter head, the front of the housing l is open, and through this opening access may be had (when the cutter head is removed) to the front end of the motor and more speoically to a drive transmission 2i) mounted on the front end of the motor frame.
The electric motor is of the universal A. C.D. C. type and comprises a eld core 2i upon which field coils 22 are mounted and the customary armature 23 with its commutator Fifi mounted upon a shaft 25. These stator and rotor elements are mounted in a cradle-like frame 2%? preferably formed as a die casting and having diametrically opposite longitudinal side arms 2l' connected by a crosspiece 2t and by a ring 2Q integral with the side arms and situated substantially medially of the length thereof. Longitudinal circumferentially spaced ribs @il are formed on the inside of the ring 22 to receive the iield core 2i with a drive t. This construction not only provides an exceptionally facile manner of assembling the field core with the frame but also provides air passages 3i across the outside of the eld core. f
Mounted on the inside face of the crosspiece or end wall 23 is a bearing 32 to receive the adjacent end of the armature shaft. A cup 33 secured to the inner face of the crosspiece or end wall 28 by rivets passing through ears on the edge of the cup coacts with the edge of a bearing socket 34 in the wall 23 to hold the bearing in a manner allowing limited rocking movement. rPhe cup 33 also contains packing to hold a supply of lubricant.
The stationary contacts Bti-3e of the motor switch are riveted to an insulated switch base :il which is secured to the outer face of the crosspiece or end wall 2S by screws 38. The contacts 35-35 are spring blades the outer end portions of which are spaced apart a distance to receive a lug 39 of the bridging contacter therebetween.
The contacter, designated generally by the numeral i i, comprises the lug '3S and an integral actuating button GG of insulating material with a metal cross pin or rivet 4l extending through the lug 3S with its ends exposed to engage and electrically bridge the contacts 35-35. The lug 39 projects through and is guided in an elongated hole :i2 in the housing section 8, so located that upon proper application of the housing section 8 over the rear end of the motor the contacter is operatively associated with the switch blades i5-35. A spring clip 43 snapped into grooves in the opposite sides of the lug 3% holds the contactor assembled with the housing section in a manner allowing the same to be slid back and forth to open and close the motor circuit.
It is, of course, understood that before the housing section 8 is applied the supply cord i2 is threaded through the gromet i3 and one wire l5 thereof is soldered to the rivet by which one of the switch contacts, i. e. the contact 35, is anchored to the base 31, and the other wire 56 of the cord is connected to one side of the field as at 4'1 (see Figure 9).
Inasmuch as the other switch contact 3c is connected to the other side of the iield through a lead 48, bridging of the contacts 35i-36 closes the circuit for the motor.
The front end of the armature shaft is journalled in a bearing 49 carried by a transmission head indicated generally by the numeral 5c. This transmission head is secured to the front ends of the two side yarms 2i of the motor frame by screws 5i threaded into lugs 52 which in turn are secured to the inner faces of the arms 2l at their extreme front ends.
It is, of course, understood that the lugs 52 are secured in place after the field core 2i is shoved down into the motor frame and driven into the ring 29. The lugs 52, however, do not interfere with the insertion of the armature.
The transmission head iii) consists of two stampings 53 and 54 riveted together to form a hollow gear case 55. The stamping E3 is substantially cup-shaped with its side wall 5t interrupted at opposite sides as at 5'? to accommodate the side arms 2i. Its bottom wall i553 has the bearing i9 mounted thereon, which like the bearing 32 is held in place by a cup-shaped stamping 33 riveted to the wall 5S. Though theoretically the bearings 31. and i9 are coaxial, some misalignment may be encountered in production but this is compensated by the self-alignment inherent in the bearings.
The wall 58 of the stamping d3 also mounts a bearing 59 which coacts with a bearing S9 mounted on the front wall iii of the stamping 5@ to support a cam shaft 62. The front end of this cam shaft projects beyond the bearing @i and has an eccentric $3 fixed thereon by being threaded against a shoulder on the shaft. The shaft is held against axial displacement by having the bearing @ii interposed between the eccentric 63 and a gear tti driven onto a serrated portion 65 of the shaft inside the gear The eccentric (53 is of a diameter to fit snugly between the arms of the U-shaped spring i3 so that upon rotation of the cam shaft these arms will be oscillated to reciprocate movable cutter blade i5. Entry of the eccentric between the arms or the Ushaped spring during the application of the cutter facilitated by having the extreme front end of the eccentric chamfered.
The gear Gili meshes with a sprocket S6 formed on the front end of the armature shaft 25 and as shown in Figure '7, the teeth of the gear have very little addendum while the teeth of the pinion are all addendum. This tooth design plus the fact that the actual center-to-center distance between the shafts is slightly less than the theoretically correct distance produces a smooth running and very quiet transmission. The slight tension under which the parts are placed by the excess center-to-center distance does not affect the mechanism deleteriously.
To more clearly illustrate the nature of the transmission gearing, in one embodiment of the invention the pitch diameter of the gear is .668", its outside diameter is .683, and its root diam eter is .628; and for the pinion the pitch diameter is .1093, its outside diameter .159 and its root diameter .1033". The theoretically correct center-to-center distance is .3954 but the actual center-to-center distance is .3924.
The open front end of the housing section i, upon removal of the cutter head I0, permits ac,- cess to screws 6? by which the housing section is secured in place. These screws pass through ears 68 on the housing section and thread into tapped holes in the outer ends of the screws 5l. rI'he screws 38 by which the insulated switch base 3i is mounted on the motor frame are similarly provided with tapped holes in their outer ends to receive screws 69 by which the back housing section is held in place,
This manner of securing the housing sections to the motor frame enables them to be drawn snugly onto each other.
The motor has the customary brushes 10 mounted in bushings 'Il which in turn are carried by the side arms 21 of the motor frame but insulated therefrom. At their inner ends the bushings 'Il are grooved to receive the conventional spring clips by which the brush leads are electrically connected, and as is customary the brushes are yieldingly urged inwardly toward the commutator by springs 72, but the spring retainers 'I3 are not threaded into the bushings 1l. Instead these retainers have va sliding t in the bushings and are held in place by the adjacent wall of the housing section 8. Thus in assembling the housing section 8 over the back end of the motor the retainers 13 must be held in until the housing is applied over them.
To afford ventilation the back housing section 8 has air inlet openings 74 in its rearmost end and the front housing section and the underlying side wall 56 of the stamping 53 have slots at 15 to provide discharge ports for the Ventilating air. A fan 'I6 secured to the armature shaft draws the air into the housing through the openings 14 across the neld through the longitudinal air passages 3| and discharges the same from the housing through the discharge port 15.
From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides an electric hair clipper which is inexpensive to manufacture; and that the reduction in production costs is brought about largely by the fact that the entire motor may be completed and tested before applying the housing. In other words, the housing which consists of the two complementary front and back sections and which also provides a handle for the clipper is not essential to operation of the motor. The construction of the drive transmission with its economical use of stampings is also an important factor in reducing the cost of the entire unit.
What we claim as our invention is:
In an electric motor driven tool: a power unit comprising, a one piece motor frame having spaced opposite side arms projecting from and integral with an end wall, a stator mounted on said frame between the side arms thereof and intermediate the ends of said arms, a bearing on said end wall, a stamped sheet metal gear case fixed to the outer ends of the side arms with one wall of the gear case forming a second end wall for the motor frame, a bearing on said wall of the gear case coaxial with the stator and the bearing on the rst designated end wall of the motor frame, an armature positioned in the stator and having its shaft journaled in the bearings with one end of the shaft projecting into the gear case, a cam shaft journaled in the gear case and having one end thereof projecting outside the gear case, gears mounted within the gear case drivingly connecting the armature shaft with the cam shaft, and an eccentric Xed to the projecting end portion of the cam shaft to have a driving connection with the tool to be driven; and a combined housing and mounting for the tool to be driven comprising, complementary deep cupped sections telescoped over the opposite end portions of the power unit with their adjacent ends contiguous, means for readily removably and individually securing each of said sections to the :power unit so that either section may be removed from the power unit without disturbing the other section, and means on the housing section which covers the end of the power unit at which the gear oase is located for mounting the tool to be driven with a part of the tool disposed inside the section for engagement by the eccentric of the power unit. ELLIS M. BROWN. ERNEST HARRY FORSS.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 703,100 Wantz June 24, 1902 950,759 Weiner Mar. 1, 1910 1,461,181 Dick July 10, 1923 1,525,826v Perlman Feb. 10, 1925 1,871,700 Jepp-sson et al Aug. 16, 1932 1,974,557 Andis Sept. 25, 1934 1,987,444 Jeppsson Jan. 8, 1935 2,053,056 Whiteside Sept. 1, 1936 2,173,339 Meyers Sept. 19, 1939 2,281,641 Toop May 5, 1942 FOREIGN PATENTS Number Country Date 470,690 Great Britain Aug. 19, 1937 35,689 Holland June 15, 1935