Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF TH INUENTI~N
This inuention rslates tD a knife sharpener and more particularly,
tu a knife ~harpener of the typa having a grinding wheel driven by
an electric motor, as cnmmonly used in homes.
~ACKGROUND OF THE INVENTION
; In the electric knife sharpener~ of the type that have been
prOpC18ed 80 far, the slot or alots ~or the knife, and the grinding
............. ........ wheel are relatively arranged with the r~ult that the quality of tha
sharpening very much dependQ on the skill o~ the u~erO In practics,
this leads to uneven sharpening, fastsr grinding out of th~ knive3
to correct unevenly grounded ~pots or portion~ of the blade, and to
a skill requirement that i8 beyond the pos~ibilities of many people.
More particularly, the electric knife sharpenere that havs b~en
'~ prOp'08ed 90 far include at lea~t one of the following dieadvantage3:
their 810t9 are arranged such that tha kni~e i8 not positively guided --
all the way at the ~ame angla relative to ths grinding ~acs; the
pr~s~ure of the blade against th~ grindlng wheal i9 not positivsly
contrslled and i8 entirely dependent on th~ sklll of the u~er; the
; s3me slot ia u~d for tha l~t ~ide and the right eide o~ the blads
~ 2U and th~re i3 thu~ ~ probl~m to hold tho blede at th~ ~ame angle
- ~or both 0ide~; thu grlnding wheel rotat~ in ths fr~nt to roar
diréction againRt the blad~ end thi~ prcduce~ a rough cùtting sdge
~: with graininga on it.
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A general ob~ect of the pre~0nt lnv~n~lon i9 to provide an ~lectric
knife 3harpener o~ the abnv~ type that ~8 conctructed and arranged to
~ ~ubstantially evold tha 3bove montioned disedvQntageeO
; A more partlcular 90nsr~1 ob~ect of tha presont invention ie toprovld0 an elactric kni~e ~h~rpener of th~ abov~ type that i9 adapted
-. 30 to providu even sharpening of kniv~D subat~ntially irrespactivs of
the skill o~ tha u3~r.
A mor~ aper-i~ic ob~act of the pre~ent invention ia to provide
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an electric kniYe eh&rpener of tha aho~e type th~t produces svan
biasing o~ ~ kni~e and grinding wheel operativaly againat aach -
oth0r .
Anothor ob~act of the ~rs~ent in~ention i9 to providR an el0ctric
knife harpaner o~ the above type whHrein the knife is adapted to be
poRitively held angularly and poeitionally relative to a grinding
whHel for even grlnding all the way along the blada of tha kni~e.
A further object o~ th~ present 1nvention ia to pro~ide an
eleotric knife sharpensr of the sbova type wherein ther~ i8 a slQt
on e3ch side of th~ grinding wheel to seFarately and accurately
grind both sides o~ a knife in thoae elots respectively.
A still ~urther ob~ec~ o~ tha pressnt invention i8 to provide sn
electric knl~e eharpener of the above typ~ wherein ths motor and the
alote are arrangsd to rotate the grinding wheel againAt the blade
of a knife in the ~orward dir~ction o~ diapl~csm~nt c~ the kni~e
and ther~by produce ~ minimum o~ grainings on the blade.
Still another ob~ct ot th~ pras3nt in~ention ie to prouide an
electric knif0 sharpener o~ th~ abo~a type wherein the biae of the
grinding wheel relatlvo to the blad~ ot a kni~e i8 achi~ved by
magnetic axial bi~e ef the orinding wheal by the magnetic field of
ths motor winding.
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The above ~nd other ob3eota ~nd ~d~ant~ges o~ tha pr0ssnt
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lnvention w111 be b~tt~r unde~tood with ra~srenc~ to the ~ollowing
~ dat0ilad daecrlption o~ a pr0farred embodi~ent thersof which ie
;~ illuatr~ted by woy oP exa~ple in the acco~panying drawings, in whioh:
Figure a tep plan viaw of an eleGtric knife ~harpener
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according to the pr~ent lnv~ntion9
Figure 2 i8 ~ front el~vation vlew o~ the ~am0 ~lectric knife
aharp0ner;
Figure 3 i~ a croa~ s~ctionAl view, ae ~een along lina 3-3 in
v Figure l;
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~ igure 4 i~ a crpss-3ectional vi~w as aeen along lins 4-4
in Figur0 1;
Figurs 5 i9 a par~p~cti~s view of the 3ame electric knife
~hsrpanar with a knifa operativaly associated with it in sharpening
position; and
Figure 6 i~ a view of R grinding whaal fnrming part of the
alactric knif~ sharpenar o~ the other figur0~ of drawings~
The illu~trated elsctric knif0 sharpener comprises a housing
fermad of an upper portion 1 and a bottom or lower portion 2. An
electric ewitoh i~ eecured to the upper po~tion 1 and outwardly
proJscts thsra~rom to energize an electric moto~ driving a grinding
whsel 4. The electric motor 5 iA ~ecured to the base portion 2 and
projsct~ into the upp0r houaing portion 1.
The elsctric mutor 5 lncluds~ a stator and a rotor. The atetor
compriss~ a fixed armature 6 made of laminations, as ~hown in Figura
4~ with a winding 7 coiled around a bottom partlon o~ the ~ix~d
armatura. The rotor f.the motor compri~es an armaturs ~ rotative~y
mounted ae i~ well known for magn~tic ~nergi~atiun by the winding 7
through ths laminated ermature 50 A pair o~ bearinga 9 rotativaly
carry a ~haft 10 ~n which sre fixadly s~cur~d the arm~ture ~ snd thæ
grinding wh0~1 4 for bedily di~placement ther~with both in rotation and
axially ralatlva to the ba0rings 9. A ventil~ting fan 11 i~ securad
on th0 oppoaite end o~ th0 ~h~t 10 to vantilate th~ mctor upon lt~
rotation. The bearing~ 9 and the mounti~g Qf the ahaft lD i8 su~h
that the latter i8 ~reely axi~lly displec~able. It is well known that
the ~agnetic ~ield prnvided by the winding 7 produces 8 magnetic bi~a
on tha armature B to driv~ tha latte~. Al~o, it i~ known but to a
lesa sxt0nt that the ~ama ~gnstic ~l~ld producas an axial biaa
against axi21 displacem~nt of th~ rotary armatur~ ~ 0ithsr wày from
, 3D a næutral, intermadiat0 ~xi~l position.
The grinding wha01 4 define~ axially opposit~ flat facaa or
sid~ 12 ~ach having a circumfarsntial outar ndg0 or lina 13 and a
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circumferential outer portion adjoining the line 13. On eaoh ~ide of
~ the grinding wh~el 4, there i8 alsn providsd a circumferential Dutar
portion 14 whi~h, as ~hown in Figur0 6, i~ transversely conv~x with
a radius indicated by R to sharpen a hollow ground blada. Th0
grinding wheel 4 al~o includes a cylindrical surface 15. Washar~s
16 are mounted on the ~haft lO to ~oparate the rotary armature 8
from the bearings 9.
. The upper portion 1 of the houelng i8 provided with a palr of
~; ~lots 17 and lB ext~nding downwardly into the upp~r portion~ each
to a pradetsrmined depth snd at a prsdet3rminad angle. The slot
17 and lB are arranged on the opposit0 eide3 o~ the grinding wheel
with their plane conv0rging toward sach other and toward the grinding
whe01 such that each o~ the~e~lote intersects ths corresponding side
o~ the grinding wheel when tho latter stands ln the neutral position
oP magnetic axial biae produced by the windlng 7 on tha rotor armature
8. Thi~ relationship between the slot~ 17 and 18 and the grinding
wheel 4 i9 illustrated in Flgurss 2 and 4 wherein th~ ~ull line
illu~tration o~ the grinding wheel r~presents ita neutral poeition
. of magnetic axial bias~ ~he depth o~ the 810te 17 and 18 is such
:~ 20 that the blade ~ ot a knife K iB engagad to the bottDm thqrao~, the
~ blade will overlap the abova mentioned ~l~t c1rcu~fer0ntial outar
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portion only with ~ g~all o~erlap indlcatsd by the latter E in
Flgure 3~ The l~tt~r F indicates the dapth o~ ths ground portion
that can be made by the eircum~erential sur~ace~ 14 oP the grinding
:~ whael 4.
It must be readily und0rstood that upon operatlve 3ngagement
-; of the blada 9 o~ a kni~e K in the elot 17, the grinding whsel 4
ia sxially ~i~pl~ced a predetermined distance by tho blsd~ to the
: po~ltion indicated by th0 da~hed line~ 4' in Figure 4~ There
results the ~ame axial displacement of the armature ~ re~ulting in
the magnetic ~iold acting ther00n So produce ~ counter-acting
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magn~tic axi~l bias ot the grinding wheel 4 against the right ~ide
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of -'ha blada. Similarly, the engag0m~nt' of the blade o~ a kni~
to the bsttom o~ tha ~lot 18 prnducs~ a magnetic axial bias in the
oppositfl direction upon di~placam0nt o~ the grinding wheel to the
dashed lines po~ition 4'~. Thu~, a constant magn~tic axial blaa i9
produc0d against aither ~ide of the blade. The right ~ide and the
left side of tha blade are sharpened into the left and the right slots
regp8ctivaly. ThH 810t8 17 and lH are inclined at a predetermined
angla A, a~ sho~n in Figure 4, for optimum sharpe'ning of ths cutting
edoe o~ knif~ blades.
An intermediate alot 19 i~ ~ormed in tha top oP the hsusing
portion 1 in o~erlying regi~try w~th the cylindrical sur~ace 15 o~
the grinding whael 4. The alot 19 is in an inclined plane relative
to the plane o~ rot~tion ot the grinding wheel and hss oppoaite faces
inclined at dif~0rant angles B and C~ ahown in Figure 4. The
differently inolined opposite ~aceR are predetermined to engage the
two bladas respsctively o~ ~oissors against them.
Aa ~hown in Figure 3,~the grinding whs01 4 ha~ ito uppsr portlon
rotsting in a ~orward direction again3t the bl~de o~ the kni~ to
produce a very smooth,~harpening froe o~ grainings,elong the edge
o~ tha blade~ ~
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