Note: Descriptions are shown in the official language in which they were submitted.
~Z73551
This invention relates to an electromotively
operated kitchen appliance including a drive shaft
arranged in a housing body and a tool shaft which
is engageable with the drive shaft via a coupling,
is coupled in a non-rotatable relationship to a
tool operated to process food, and is operatively
engageable with the drive shaft only when the tool
shaft experiences an axial-displacement motion in
its longitudinal direction in opposition to the
force of a spring element.
An electromotively operated kitchen appliance of
this type is already known from German prior published
patent application DE-A1 2,813,168. This kitchen
appliance, which is configured as a shredder, in-
corporates a motor body, a container adapted to be
secured to the motor body for shredding food, and a
cover adapted to close the container. In the motor
body, the electric motor is connected with a gear
drive including a claw coupling whose output coupling
half has a drive shaft secured thereto through a pin,
the drive shaft extending through the motor body and
projecting into the container of the shredder. The
drive shaft is rotatably carried in the motor body,
its free end which extends outside of the motor body
being connected with a drive member in a non-rotatable
relationship thereto via a tooth system. The drive
member is also rotatably mounted in the motor body and
has at its free end a carrier device formed by a hexagon
and engaged by a tool in a non-rotatable relationship
thereto, the tool incorporating a tool disc and a
supporting disc, with the supporting disc providing
the relatively non-rotatable connection with the drive
member.
2 ~.
~73551
In this kitchen appliance, it is to be considered as
less advantageous that koth the drive shaft and the
drive member are rotatably carried in the motor body
independently of each other. This renders the bearing
of these parts complex and costly, in addition to
making the shredder more susceptible to trouble.
Further, in order to avoid that the drive member
and the drive shaft are carried in the container on one
side only, an additional bearing is provided for these
parts which consists in that the drive shaft takes
support, via the drive member and via the supporting
disc, in a bore provided in a partition wall of the
container. In view of the tolerances occurring in the
manufacture of the motor body and the container which
may easily add up when these parts are assembled, a
relatively large radial clearance is provided between
the bore and the cylindrical shank of the supporting
disc. As a result of the transverse forces occurring
in operation, this may cause premature wear of this
bearing, whereby a failure of the shredder is ultimate-
ly bound to occur. Also the other bearings may be
affected thereby, in such a manner that also a break-
-down of the drive unit may occur.
It is, therefore, an object of this invention to
provide an electromotively operated kitchen appliance
with an integrated safety device, which incorporates
a simple and easy-to-manufacture drive unit and has a
long life.
This object is accomplished according to this in-
vention in that the tool is directly mounted on the
tool shaft and that a displacement of the tool shaft
:
1;~73551
involves its displacement in conjunction with the tool.
sy mounting the tool directly on the tool shaft, addi-
tional bearing points are avoided, thereby making the
kitchen appliance last longer. Because the tool dis-
placement occurs simultaneously with the tool shaft
during the engagement procesS, material wear between
these parts is avoided and the bearing clearance in
the tooth system remains substantially unchanged.
To ensure that the tool remains fixed in place on
the tool shaft with the kitchen appliance in operation,
an improvement of the invention provides for the dis-
placement of the tool shaft to ke initiated by the tool.
In the operation of the kitchen appliance, a relative
movement between the tool and the tool shaft is thus
avoided, so that the relatively non-rotatable connection
is not subject to wear. The tolerance clearance between
these parts which existed when the kitchen appliance was
new is thereby maintained, so that the tool is prevented
from wobbling on the tool shaft. The tool is firmly and
securely fixed in place on the tool shaft by providing
for the tool to be slipped on the tool shaft until its
abutment with a stop. The stop may be a circlip secured
to the tool shaft or an annular collar formed on the
tool shaft, for example.
In kitchen appliances which, to ensure safety, are
equipped with a geared coupling, the problem exists that
during the engagement process and with the motor running
the tips of the opposed teeth of the-coupling often rub
against each other too long until their final engage-
ment. This rubbing action causes noisy chatter on the
one hand and high tooth wear on the other hand which is
even speeded up particularly if the teeth are made of
~ 4 --
1'27355~
plastic material. The result is a premature coupling
failure amounting at the same time to a total breakdown
of the kitchen appliance. In an improvement of the in-
vention, these drawbacks are eliminated by providing, in
an axial direction on either side of the claw coupling,
one or several teeth which protrude relative to the
other teeth. By virtue of this arrangement of the in-
vention, first the two protruding teeth become abruptly
engaged as the two coupling halves approach each other,
so that the usual rubbing action does not occur. As
soon as the tip of the one protruding tooth of the one
coupling half engages with the opposite tooth of the
other coupling half, it will be positively engaged with
the opposite protruding tooth, causing both coupling
halves to rotate at the same speed. As the two coupling
halves continue approaching, the recessed teeth will
also become engaged with the opposite interdental spaces,
thus producing neither noise nor wear.
In a further improvement of the invention, the kitchen
appliance is composed of a driving part containing a
motor and of a working part seatable thereon such as a
juice extractor, citrus fruit press, chopper unit or
the like, wherein a gearing is arranged in the working
part between the drive shaft and the tool shaft, wherein
a coupling half is formed on the output-side driving
gear of the gearing, and wherein the driving gear is
rotatably mounted on the tool shaft. This arrangement
makes it possible to place a variety of appliances for pro-
cessing food at varying operating speeds on only one
motor body. To avoid additional and costly holding
fixtures for the tool, the coupling and the driving
gear, these parts are directly m~unted on the tool shaft.
-- 5 --
1;~73551
In order to enable the tool shaft to take up the
forces of pressure acting on the tool during the pro-
cessing of food without appreciable friction losses,
in a further improvement of the invention an axial
bearing is arranged on the tool shaft on either side
of the driving gear, the axial bearing formed inter-
mediate the coupling halves establishes an abutment
stop with the tool shaft after the claw coupling is
engaged, and the other axial bearing supports these
parts relative to the housing body. The forces im-
parted from the tool to the tool shaft are trans-
ferred by the coupling half connected with the tool
shaft in a non-rotatable relationship thereto to
the axial bearing resting on the driving gear whence
they are directed, via the driving gear, to the second
axial bearing taking support on the housing body and
onwards to the housing body. Accordingly, in view of
the low number and low friction of the axial bearings,
the drive unit has a high degree of efficiency enabling
the drive motor to be built to smaller dimensions.
In particular with appliances having sharp and
easily accessible blades such as shredders, in which
access to the blades has to be prevented during their
operation to avoid injury, the invention provides for
the displacement of the tool shaft to be initiated by
the cover and to be transferred via the tool to the
tool shaft. Thus, with the motor running, the tool
connected with the tool shaft is not allowed to turn
until the cover has safely closed the housing body.
To enable the cover to be readily secured to the
housing body and to ensure that during the operation of
the working part the cover remains firmly connected with
1;~7355~
the housing body whereby the coupling is invariably kept
engaged by the cover, in a further improvement of the
invention the means securing the cover to the housing
body are resilient locking elements adapted for engage-
ment with the housing body by seating the cover thereon
axially. Advantageously, the locking elements can be
unlocked manually from outside for ~uick disengagement
of the cover from the housing body in order to permit
removal and, where applicable, exchange of the tool disc
or cleaning of the working part.
It is an advantage to arrange on the cover, con-
centrically with the tool shaft, an abutment on which
the tool and/or the tool shaft take support in the
direction of the force of the spring, when the cover
is in the seated condition. With the cover seated in
place, the abutment formed on the cover holds the drive
shaft invariably in coupling engagement. The abutment
can be obtained by particularly simple means using a
cup-shaped cap forming a snap-on connection with the cover
by means of hooks. Should the cup become damaged, it can
be easily exchanged simply by releasing the snap connection
from the cap.-
For the contact pressure produced during rotation ofthe tool and the tool shaft to be absorbed by the cap
without damage, the invention provides for the abutment
to be made of a wear-resistant and low-friction material.
The cap which is made of a plastic material slides on
a tool disc made of stainless steel. According to the
invention, a particularly good friction pair is obtained
by using a material made up of about 80~ polyamide and
about 20% Teflon.
1~73~S~L
The invention is described in more detail in the
following by way of a single embodiment, reference
being had to the accompanying drawing, in which:
FIG. 1 is a longitudinal sectional view of a
shredder unit in the engaged position, shown without
the motor body;
FIG. 2 is a side elevational view of the shredder
unit of FIG. 1; and
FIG. 3 is a part sectional view of the locking
element taken along the line III-III of FIG. 2.
Referring now to FIGS. 1 and 2, there is shown a
shredder unit 1 composed of a housing body 2 and a
cover 4 secured to and centered on the housing body
2 by means of resilient locking elements 3. Formed on
the upper side 5 of the cover 4 is a feed chute 6 ex-
tending upwardly when viewing the drawing and serving
to receive and feed the food to be processed. On the
opposite side of the feed chute 6 is the outer wall 7
of the discharge chute 8 which, extending from the
uppe-r side 5 of the cover 4, initially follows a down-
ward slope to form a radial extension, then continues
ve~tically to the upper side 5. The radially inner
wall 9 of the discharge chute 8 is formed by the housing
body 2. In the drawing, the opening 10 of the discharge
chute 8 points downwards and serves to discharge the
food processed by the shredder unit 1. Extending from
the lower side 11 of the housing body 2 downwards when
viewing the drawing is a step 12 of frusto-conical
cross section which is tapered towards its free end and
is insertable into a suitable recess of a motor body not
~Z73551
shown in the drawing and holds the shredder unit 1
centered and fixed in place on the motor body.
In FIG. 1, the step 12 has a dish-shaped downwardly
open recess 13 in which a coupling half 14 is received.
Via a drive shaft 15 carried in the bottom of the recess
13, the coupling half 14 is connected in a non-rotatable
relationship to a toothed gearing 16 adjoining upwardly
when viewing the drawing and not explained in greater
detail. As required, the gearing 16 may be configured
as a step-up or step-down unit. On seating the shredder
unit 1 on a motor body, the coupling half 14 will engage
a suitable coupling half, not shown, provided on the
motor body and is thus connected with the motor drive
in a non-rotatable relationship thereto.
On the output side of the gearing 16 is a toothed
gear 17 which serves as the driving gear for the tool
shaft 18, is centered on the tool shaft 18 and is free
to rotate about the tool shaft 18. The tool shaft 18
extends parallel to the axis of, and in a laterally
offset relationship to, the drive shaft 15. The tool
shaft 18 extends through the housing body 2 from the -
bottom to the top when viewing the drawing and is
relatively non-rotatably carried in the housing body 2
via calotte bearings 21, 22 formed in the base 19 and,
respectively, the cover plate 20. The cover plate 20
is centered on the base 19 and firmly secured to the
base 19 by means of screw connections 23. Among other
things, the cover plate 20 prevents the ingress of dirt
and water in the drive chamber 2~ accommodating sub-
stantially the gearing and claw coupling arrangement
16, 24. By means of the calotte bearings 21, 22, a
minor offset-axis condition, if any, between the cover
plate 20 and the base 19 may be compensated for.
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~735~
The claw coupling 24 and the axial bearings 26, 27
are mounted on the tool shaft 18 intermediate the two
calotte bearings 21, 22, with the axial bearings 26, 27
taking the normal forces acting on the tool shaft 18
in the longitudinal direction. Adjoining the calotte
bearing 21 upwardly when viewing the drawing are the
washer 29, the axial bearing 26, the driving gear 17
with the lower coupling half, the axial bearing 27 and
the upper coupling half 28. The axial bearing 27 takes
support upon a stop 74 formed on the upper coupling half
28. The normal force which with the shredder unit 1 in
operation acts on the tool shaft 18 downwardly when viewing
the drawing is transferred, via the coupling half 28
positively engaged with the tool shaft 18, to the axial
bearing 28 whence it is directed, via the toothed gear
17, the axial bearing 26, the washer 29 and the calotte
bearing 21 formed fast with the housing body, to the
base 19.
The claw coupling 24 is composed of the upper and
lower ~upling half 28, 17, with the lower coupling half
17 forming at the same time the driving gear. Pro-
truding from the end faces 30, 31 close to the respective
coupling halves 17, 28 are several circumferentially
spaced and radially outwardly extending teeth 32, 33,
34, etc. which in the operating position of the shredder
unit 1 shown are in relatively non-rotatable engagement.
On the upper coupling half 28, one tooth 34 protrudes
relative to the other teeth 33, etc. provided on this
coupling half 28. The end face 31 of the coupling half
28 has preferably four teeth, while the end face 30 of
the other coupling half 17 has preferably twelve teeth.
Radially within the teeth 32, 33, 34, etc., a compression
spring 35 biased by these parts bears against the two
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1~7~355~
coupling halves 17, 28, the spring urging the coupling
half 28 together with the tool shaft 18 upwardly when
viewing the drawing as the cover 4 is lifted, thereby
producing an automatic disengagement action.
The lower side of the cover plate 20 has a friction
ring 36 fastened thereto which, following disengagement
of the claw coupling 24, becomes frictionally engaged
by the upper side 73 of the coupling half 28 as a result
of the force of the compression spring 35. The tool
shaft 18 extends through the cover plate 20 upwardly
when viewing the drawing, through a bore 37 provided in
the cover plate 20. The calotte bearing 22 is received
in the bore 37. The bore 37 has at its upper end a lip
seal 38 sealed to and bearing against the surface of
the tool shaft 18. This prevents dirt and water from
entering the working chamber 25.
The free end of the tool shaft 18 above the cover
plate 20 when viewing the drawing has on its surface a
tooth system 39 extending longitudinally of the tool
shaft 18, starting at the free end of the tool shaft
18 and extending downwards to an annular collar 40
whose outside diameter is slightly greater than the
outside diameter of the tooth system 39. The annular
collar 40 is provided above the cover plate 20 on the
tool shaft 18. Seated on the tooth system 39 is a
hub 41 bearing with its lower edge, when viewing the
drawing, against the annular collar 40. The hub 41
is integrally formed with the supporting disc 42 ex-
tending substantially plane~parallel and at a small
distance above the cover plate 20. Through an upwardly
extending tubular neck 43, the supporting disc 42 is
connected with the hub 41. From the neck 43, ribs 45
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~ ;~735~
extending radially towards the outer edge of the
supporting disc 42 are formed on the upper side 44 of
the supporting disc 42. The function of the ribs 45
is to improve the circulation of the already shredded
food on the supporting disc 42 so that the centrifugal
forces acting thereon can convey the food bettér into
the discharge chute 8.
Where the neck 43 blends into the hub 41, an annular
collar 46 extends radially inwardly on the supporting
disc 42, continuing upwardly in a further section of the
hub 41. Provided on the outside diameter of this
section of the hub 41 is a tooth system 47 which extends
parallel to the tooth system 39 and is engagéd by the
tool disc 48 through a suitable gearing in a non-rotatable
relationship thereto. The tool disc 48 is slipped on
the tooth system 47 from above and pushed downwards until
it rests against the annular collar 46. The tool disc
48 includes cutting elements not shown in the drawing
for cutting the food filled into the feed chute 6 as
the tool disc 48 rotates.
~ t its upper end, the bore 49 including the longi-
tudinal tooth system terminates in an annular step 50
of reduced diameter upon which the tool shaft 18 takes
support via an annular collar 51 provided on the upper
end. Next to the annular collar 51 in upward direction
is a pin 52 which is formed on the tool shaft 18, ex-
tends through the bore 49 on the annular step 50 and
rests with its free end against the bottom 53 of the
cup-shaped sleeve 54. The sleeve 54 which is open in
downward direction extends concentrically around the
hub 41. The annular end face 55 provided on the sleeve
54 at the free end of the tubular section is in abutment
3~51
with the surface of the tool disc 48. Radially within
the sleeve 54, the tool disc 48 is provided with an
annular collar 56 extending into the annular chamber of
the sleeve 54 and having the sleeve 54 in radial out-
ward abutment therewith for the purpose of centering
the tool disc 48. The tool disc 48 is additionally
centered within certain limits by the tooth system 47.
The bottom 53 of the sleeve 54 abutting against the
lower side 58 of the cover 4 has circumferentially
spaced apertures 57 through which hooks 59 extend to bias
the bottom 53 in the interior of the sleeve 54 from
behind, thus establishing a positive-engagement connection
between the sleeve 54 and the cover 4. The hooks 59 are
formed on the lower side 58 of the cover 4.
According to FIGS. 2 and 3, the locking elements 3
diametrically opposed on the shredder unit 1 incorporate
each a spring tongue 61 formed on the outer wall 60 and
obtained by slots 62 i-n the cover plate 20 extending
upwardly from the lower edge of the wall 60, so that
only the upper end of the spring tongue 61 is connected
with the cover plate 20. The wall 60 serves at the same
time for centering the cover 4. From the wall 60,
detents 63 of peg-shaped configuration extend radially
outwardly on the spring tongue 61 for locking engagement
wlth suitable openings 64 provided in the wall 65 of
the cover 4 when the cover 4 is seated. The detent 63
has a chamfer 72 at its free upper end. On the wall 65
of the cover 4, an arched cutout 66 is provided inter-
mediate the two openings 64 for engagement by a suitable
segment 67 protruding from the spring tongue 61. The
segment 67 also has a circular projection 68 whose out-
wardly pointing annular area 69 is concave. The concave
annular area 69 serves to provide a better rest and
locating area for the operator's fingers.
- 13 -
551
For the spring force of the spring tongue 61 to be
sufficiently high and remaining high on frequent
operation, thereby ensuring at all times that the cover
4 is securely fixed to the housing body 2, FIG. 3 pro-
vides, in addition to the spring tongue 61, a leg spring
70 which is held in a slot 71 formed in the cover plate
20 and rests with its free end resiliently against the
spring tongue 61.
The operation of the shredder unit is as follows:
First, the housing body 2 is placed on a motor base
not shown in the drawing, so that the coupling half 14
becomes engaged with a motor-driven coupling half which,
however, is not shown in the drawing. Then the supporting
disc 42 is slipped on the tooth system 39 of the tool
shaft 18 and pushed down until it comes to rest against
the annular collar 40 of the tool shaft 18. The tool
disc 48 is subsequently seated on the tooth system 47
of the supporting disc 42 until it comes to rest against
the annular collar 46 of the supporting disc 42. Should
the motor be turned on inadvertently in this condition
of assembly, neither the supporting disc 42 nor the tool
disc 48 nor the tool shaft 18 will start rotating since
the two coupling halves 17, 28 are not in gear. This
prevents the possibility of personal injury.
If the cover 4 is then placed on the housing body
2, the bottom 53 of the sleeve 54 will abut the pin 52
provided on the tool.shaft 18. However, the cover 4
can be seated only if the.arched cutouts 66 engage the
segments 67 of the spring tongues 61. Further displace-
ment of the cover 4 will urge the tool disc 48 and the
supporting disc 42 downwards,.when viewing the drawing,
- 14 -
7;3551
in opposition to the force of the compression spring
35. As soon as the edge 65 of the cover 4 has reached
the detents 63, these will be initially urged radially
inwardly as the cover 4 is further displaced. The
displacement force necessary for pushing in the detents
63 on the cover 4 is kept within acceptable limits by
the chamfers 7~ provided on the detents 63, so that it
is predominantly only the displacement force necessary
for pushing the tool shaft 18 down that has to be imparted.
The downward movement of the tool shaft 18 will also
entrain the upper coupling half 28. As soon as the tip
of the protruding tooth 34 engages with a tooth profile
of a tooth 32 provided on the lower coupling half 17,
the tool shaft 18, the supporting disc 42 and the tool
disc 48 will be entrained abruptly should the motor be
turned on. In this position, the teeth 33, etc. of the
upper coupling half 28 which are recessed relative to
the protruding tooth 34 are not yet in engagement with
the opposite teeth 32, etc. of the lower coupling half
17. Only on further displacement of the cover 4 will
the other teeth 32, 33, etc. become engaged without
producing noise. Then the detents 63 will fall into
their respective openings 64, and the cover 4 will be
in positive engagement with the housing 2. As long as
the cover 4 closes the housing body 2, the claw coupling
24 will remain engaged.
In this position, it is possible to fill the feed
chute 6 with food which, after turning the motor on,
will be shredded by the rotating tool disc 48 and
conveyed to the discharge chute 8 by means of the
supporting disc 42.
- 15 -
55~
On completion of the shredding operation, normally
the motor should be turned off first before the cover 4
is removed from the housing body 2. Failure to do so
will still permit unseating of the cover 4 from the
housing 2 without the risk of injury by the tool disc
48 existing. As the cover 4 is removed, first the
spring tongues 61 will be urged radially inwardly,
causing the detents 63 to slide out of their respective
openings 64. As a result of the force of the compression
spring 35, the tool shaft 18, in conjunction with the
supporting disc 42~ the tool disc 48 and the cover 4,
will unseat themselves upwards when viewing the drawing.
The claw coupling 24 will be off or disengaged. The
upper side 73 of the upper coupling half 28 will become
frictionally engaged with the friction ring 36. In
this position, the biasing force of the compression
spring 35 will still be sufficiently high to urge the
upper coupling half 28 against the friction ring 36,
whereby the supporting disc 42 and the tool disc 48
will be slowed down to a complete stop promptl~. Accordingly,
the tool disc 48 will have come to a complete stop
faster than it is possible for the cover 4 to become
unseated from the housing body 2.
1~7;~551
1 Shredder Unit
2 Housing Body
3 Resilient Locking Elements
4 Cover
Upper Side
6 Feed Chute
7 Wall
8 Discharge Chute
9 Inner Wall
Opening
11 Lower Side
12 Step
13 Recess
14 Coupling Half
Drive Shaft
16 Gearing
17 Toothed Gear, Coupling Half
18 Tool Shaft
19 Base
Cover Plate
21 Calotte Bearing
22 Calotte Bearing
23 Screw Connection -
24 Claw Coupling
Drive Chamber
26 Axial Bearing
27 Axial Bearing
28 Upper Coupling Half
29 Washer
End Face
31 End Face
32 Teeth
33 Tooth
34 Protruding Tooth
- 17 -
1 ~73551
Compression Spring
36 Friction Ring
37 Bore
38 Lip Seal
39 Tooth System
Annular Collar
41 Hub
42 Supporting Disc
43 Neck
44 Upper Side
Ribs
46 Annular Collar
47 Tooth System
48 Tool Disc
49 Bore
Annular Step
51 Annular Collar
52 Pin
53 Bottom
54 Cup-shaped Sleeve
End Face
56 Annular Collar
57 Aperture
58 -Lower Side
59 Snap Hook
Outer Wall
61 Spring Tongue
62 Slot
63 Detent
64 Opening
Edge
- 18 -
~'73S5~
66 Arched Cutout
67 Segment
68 Projection
69 Annular Area
Leg Spring
71 Slot
72 Chamfer
73 Upper Side
74 Stop
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