Note: Descriptions are shown in the official language in which they were submitted.
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FIELD O~ rHE_NVENTION__
This invention relates to an electric shaver.
PRIOR ART
It is generally known in the field of electric motors
per se, to fabricate the stationary parts of the motor as an
integrated structure with the casing of the motor. For
example, in German Specification No. 2433770, it is proposed
to mould the motor body as an integral structure having an
outer cup-shaped wall in which a magnetisable shell is
embedded and ha~ing a hollow central core upstanding within
the cup from the base to support an annular permanent magnet
surrounding the core, the structure also being integrated
with bearings for a rotor shaft which extends through the
core and supports a rotor rotating in an annular space
defined between the permanent magnet and the magnetisable
shell. The open-end of the moulded structure is closed by
a member carrying the motor brushes internally and the
motor terminals externally.
British Specification No. 1116466 discloses a motor
construction adapted for use in a portable appliance such
as a cine-camera, wherein an attempt is made to reduce the 1 -
transverse dimensions of the motor by using an outer seg-
mented magnetisable shell as the motor casing. The shell
is formed of elongated arcuate pole pieces which extend --
longitudinally from around a permanent magnet past and
around ar, armature positioned in end-on arrangement to the
permanen~ magnet and beyond the armature to surround a
brush-holder and centrifugal regulator. The extensions of -
the pole pieces beyond the armature are used to facilitate
the mclnting of the brush-holder and regulator on the axis
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of the armature. The casing is completed by sealing strips
applied along the longitudinal gaps between the adjacent
edges of the elongated pole pieces.
However, this prior art is not directly of interest
or value in the construction of electric shavers. It is a
constant endeavour in the field of electric shavers to reduce
the size and bulk of the appliance, so as to facilitate
holding and manipulation thereof by the user. A major fac-
tor which limits reduction in the size of the appliance, in
conventional practice, is the requirement to include a
separately fabricated motor within the casing. The proposals
made in the prior art may assist to a very limited extent
in reducing the overall size of the motor, but it is not
practicable, at least without very substantially increasing
production costs and decreasing electrical efficiency of the
motor, sufficiently to reduce the size of the motor
materially to reduce the size and bulk of the appliance,
because of the power output required to drive the cutter
head under all possible conditions of use.
OBJECT OF THE INVENTION
It is an object of the present invention to provide
an improved electric shaver of reduced size and bulk, without - -
placing disadvantageous limitations on the motor construction.
It is a further object of the invention to provide an
improved shaver construction which enables the various
operational parts of the shaver to be readily mounted in
correc~ predetermined positional relationship to the driving
motor.
BRIEF STATEMENT OF THE INVENTION
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According to the invention there is provided an
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electric shaver comprising a cutting head having at least
one movable cutter, an electric motor for driving the movable
cutter and electric circuit means for the motor, character-
ised in that the motor has a stator/rotor assembly of which
at least part of the stator is integrated with a frame or
housing for the shaver, which frame or housing serves as a
reference mounting member for the cutting head, electric
motor and electric circuit means.
FURTHER FEATURES OF THE INVENTION
Preferably, the width of the shaver in at least one
direction does not substantially exceed the width of the
motor in the said direction. In the context of this inven-
tion, this means that the overall width of the shaver does
not exceed the width of the motor by more than about 10%
(of the width of the motor). In comparison, in a conventional
shaver, the width of the shaver is at least about 1.25 times
the width of the motor. In one arrangement, the motor
occupies the entire width of the shaver in the said direc-
tion. For example, the stator of the motor may be generally
of cylindrical shape about an axis perpendicular to the said
direction, being formed with two opposed parallel flats on
its external cylindrical surface to reduce the width of the
stator in the said direction.
In preferred embodiments, the stator comprises a
magnetisable shell integrated with the frame or housing.
Permanent magnet means may also be integrated with the frame
or housing. Alternatively the permanent magnet means may
be carried by the magnetisable shell.
The frame or housing is preferably integrally formed
with at least one internal support for the shaft of an
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internai .otor of the electric motor. This internal support
may also support the permanent magnet means. In addition,
the electric circuit means preferably comprises a printed
circuit board mounted on the frame or housing, and a brush-
holder for the motor brushes is preferably mounted on the
printed circuit board to be positioned in accurate relation-
ship to a collector forming part of the rotor.
The frame or housing may constitute the visible
external structure of the shaver. ~lternatively, the shaver
may include a thin-walled external casing covering the frame
or housing, the entire width of the shaver covered by said
easing not substantially exceeding the width of the frame
or housing. -
The frame or housing may be injection moulded of
plastics material. Alternatively, the frame or housing may
be east or moulde~ of metallie alloy. It is necessary, of
eourse, that the stator should eomprise a soft-iron shell
having magnetisable properties not damaged by the temperature
of moulding or casting. Where the stator also comprises a -
permanent magnet surrounded by a soft-iron shell, it is also
neeessary that the magnet should be made of magnetic
material the magnetic properties of which are not damaged
by the temperature of the moulding or casting.
DESCRIPTION OF DRAWINGS
Some praetieal embodiments of eleetric shaver in
aeeordanee with the invention will now be deseribed by way
of example, with referenee to the aeeompanying drawings, in
whieh:
Figure 1 is a transverse seetional view through one
embodiment of electric shaver;
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.~igure 2 lS a section on the line A-~ of Figure l;
Figures 3 to 5 show respective modifications in sec-
tional views similar to Figure 2;
Figure 6 shows in section one possible moulding
assembly for use in manufacture of the shaver of Figures 1
and 2;
Figures 7 and 8 are sectional views transverse to the
plane of Figure 6, showing alternative modifications of the
moulding assembly;
Figure 9 is a transverse sectional view through an
alternative embodiment of electric shaver;
Figure 10 is a section on the line B-B of Figure 9;
Figure 11 shows in section a moulding assembly for
use in manufacture of the shaver of Figures 9 and 10; and
Figures 12 and 13 respectively show further modifi-
cations of shaver construction, in sectional views similar
to Figures 2 and 10.
DESCRIPTION OF EMBODIMENTS
The shaver shown in Figure 1 is generally of right
rectangular form, with a cutter head mounted at one end of
a shaver housing. The cutter head is elongated in the direc-
tion of the width of the shaver. The minimum dimension of
the shaver is a depth mutually perpendicular to the longi-
tudinal direction and the width. In accordance with this
embodiment of the invention, it is the depth of the shaver
which is minimized.
The shaver comprises a motor, generally designated 1,
having a stator which includes an external hollow cylindri-
cal shell 2 of magnetisable material, and an annular
permanent magnet 3 surrounding the shaft 4 of the motor.
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An annular space is defined between the permanent magnet 3
and the external shell 2 to accommodate a cup-shaped rotor 5, _
which drives the motor shaft 4 at its base 5a. The axis of
the motor extends across the width of the shaver transverse
to the longitudinal direction thereof.
In accordance with the invention, the external magnet-
isable shell 2 of the motor is formed as an integral structure
with the housing of the shaver. The shaver housing is
generally designated 6. The sectional webs 7a, 7_ of the
housing shown in Figure 1, which extend across the depth of
the shaver, are integrally formed with the side walls 6a
(see Figure 2) of the housing, which extend parallel to the ;
plane of the drawing above and below said plane.
~he housing includes parts 8a, 8b associated with the
mounting of the cutter head, which has a movable cutter 9.
However, the movable cutter 9 and also the transmissive
drive 10 therefore from the motor are only illustrated
diagrammatically in Figure 1, because the particular construc- ;
tion of cutter head and drive employed form no part of the
present invention. One possible construction has an arcuately
oscillating cutter for cooperation with a cylindrical foil,
the transmissive drive including means for converting the
rotary output of the motor shaft 4 into an arcuately oscil-
lating cutter motion.
In the embodiment illustrated, the end walls in the
direction of the depth of the shaver are formed by separately
moulded elements 11 fitting detachably to the housing 6, as
by means indicated at 12. Removal of these end walls 11
provides access to the interior of the housing, for example r
to replace batteries which are accommodated in the spaces
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30 or for making repairs, for example to a printed circuit
board 31 which bears electric circuitry associated with the
electric motor and its batteries. The printed circuit board
31 is also mounted on the housing 6, as indicated at 31a,
and carries a brush-holder 32 carrying brushes cooperating c
with a collector (not shown) carried by the motor shaft 4.
As can be seen from Figure 1 of the drawings, the r ~ .
housing also includes internal parts 13a, 13b which are
integrated with the external shell ~ of the stator, and
parts 14a, 14b which are not only integrated with the
permanent magnet 3 but also integrat~ed with bearings 15 for
the motor shaft 4.
With the arrangement described above, it is possible
to minimize the depth of the housing, and thus the shaver
as a whole, as more clearly appears from the sectional view
of Figure 2. In the embodiment of Figures 1 and 2, the
external stator shell 2 occupies substantially the whole
depth of the shaver, but a thin thickness of the housing 6
is present on both sides of the stator.
In the modification of Figure 3, the cylindrical
external stator shell 2 occupies the whole depth of the
housing. In the modification of Figure 4, the cylindrical
stator shell is formed with two external flats 2a and a thin
thickness of housing is present outside these external ~ -
flats. r
The modification of Figure 5 provides the maximum
minimlzation of shaver depth. In this modification the
external stator shell 2 is formed with opposed flats 2a,
and the dimension of the stator between these external flats r
corresponds to the depth of the housing 6.
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In Figures 2 to 5, the large arrow indicates the
direction of magnetization of the magnet 3.
In the construction described above, the integration
of the housing 6 with the stator of the motor ensures that
the magnetisable shell 2 and permanent magnet 3 are located
in accurate coaxial arrangement, and the motor shaft 4
carrying the rotor 5 is also located in strict coaxial '
relationship with the stator due to the integration of the
housing 6 with the shaft bearings 15. Furthermore, the
integrated housing/motor structure serves, not only as a
reference member for mounting of the parts of the motor,
but also as a reference member for mounting of the other
parts of the shaver, particularly the cutter head and the
printed circuit board 31. These other parts of the shaver
are thereby readily located in a required accurate
positional relationship to the motor. In the case of the
cutter head, this assists the achievement of a reliable,
silent transmission from the motor to the cutter head which
involves minimum power consumption. In addition, the cut-
~0 ter head may include both a short hair cutter and a long
hair trimmer, and the accurate relative positioning of said
cutter and trimmer is important to enable a simple coupling
to be provided between them. In the case of the printed
circuit board 31 which carries the brush-holder 32, the
mounting of the circuit board in a predetermined position
on the housing/motor structure ensures that the brush-holder -~
will be located in strict coaxial relationship with the
collector carried by the motor shaft.
Figures 6 and 7 illustrate a possible moulding r
3Q system for forming the integral housing and stator structure
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previously described with reference to Figures 1 and 2. In
Figure 6, a moulding assembly is proposed comprising an
external mould 20 and an internal mould 21. It is to be
noted that the core 21a of the internal mould may be very
slightly tapered to facilitate separation of the internal _
and external moulds. This separation takes place in a direc- '
tion of the arrows indicated in Figure 6.
Figure 8 indicates diagrammatically, in transverse
sectional view, the cross-section of the internal and exter- E
nal moulds appropriate to form the modification of Figure 5
referred to above.
In the construction previously described, the
integrated housing/motor structure constitutes the externally
visible structure or casing of the shaver. Figures 9 and 10
illustrate an alternative embodiment in which at least a part
of the stator of the motor is integrated with a frame which
serves as a reference member for the mounting of the o-ther
part of the shaver.
In Figures 9 and 10, the same reference numerals as
those of Figures 1 and 5 are used to identify parts not
specifically referred to. The construction mainly differs
from that shown in Figure 1 in that the axis 40 of the
motor lies transverse the longitudinal direction of the
cutter head, which has a cutter 9 mounted, for example, for
linear reciprocation along its longitudinal axis.
The magnetisable shell 2 of the stator is integrated
with a shaver frame 41 analogous to the housing 6 of the
Figure 1 embodiment. The frame 41 acts as a reference mem- ,
ber for the mounting of an interior support 42, the mounting r
screws being shown at 43, which internal support is itself
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integrated with the permanent magnet 3 and the bearings 15
of the motor shaft 4 carrying a bell or cup-shaped rotor 5.
In addition, the cutter head is mounted on the frame 41, as -
well as the printed circuit board 31, which again carries a
brush-holder 32 for brushes which cooperate with a collector
or commutator carried by the motor shaft 4.
In the embodiment of Figures 9 and 10, the shaver is
completed by a thin-walled external sleeve or casing 44,
which is slidably received over the frame 41 and the shaver
parts carried thereby. As can be seen from Figure 10, the
provision of the external casing 44 does not substantially r
increase the thickness of the shaver. ~he thickness of the
shaver remains less than 10~ more than the thickness of the
motor, as compared with a figure of about 25% in the case of
a conventional shaver construction wherein a separately
fabricated motor is mounted on a preformed frame or housing.
A moulding assembly for use in producing the shaver
construction of Figures 9 and 10 is diagrammatically illus-
trated in Figure 11, the reference numerals corresponding to
those employed in Figure 6.
Two further modifications of shaver construction
are illustrated in Figures 12 and 13. In each of these
modlfications the motor of Figures 1 and 9 is replaced by
a conventional "slotted iron" motor 50, rotating within a
stator consisting of a magnetisable shell 51 having seg- r
mented permanent magnets 52 secured, as by glueing, to the
interior surface of said shell.
In Figure 12, the magnetisable shell 51 having
opposed flats 51a is integrated with a housing 6 which r
comprises the visible external structure of the shaver and ~-
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serves d5 a reference member for the mounting of the other
parts of the shaver, in the manner previously described.
In Figure 13, the magnetisable shell 51 having opposed
flats 51a is integrated with a frame 41 on which are mounted
the other operative parts of the shaver, but the external ~,
appearance of the shaver is determined by a thin-walled
casing 44 slidably received over the frame 41.
It will be appreciated that various further modifi-
cations are possible within the scope of the invention as
defined in the appended claims. In particular the invention
may also be employed primarily to minimize the dimensions of
the shaver in the longitudinal direction and in the direc-
tion of the width, instead of or additionally to minimizing
the depth of the shaver.
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