# US 10,864,644 B2 · Electric appliance for personal care

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- Number: US 10,864,644 B2
- Document ID: US10864644B2
- Status: Granted
- Kind: B2
- Application number: 15/950,597
- Filed: 2018-04-11
- Published: 2018-11-01
- Granted: 2020-12-15
- Earliest claimed: 2017-04-27
- Assignees: Braun GmbH
- Applicants: Braun GmbH
- Inventors: Bernhard Kraus; Thomas Verstege; Uwe Schober; Frank Ziegler
- Web page: https://patentgrep.com/patent/US10864644B2

## CPC

- B26B 19/048: {Complete cutting head being movable}
- B26B 19/288: {Balance by opposing oscillation}
- H02K 33/18: with coil systems moving upon intermittent or reversed energisation thereof by interaction with a fixed field system, e.g. permanent magnets
- B26B 19/282: {Motors without a rotating central drive shaft, e.g. linear motors}
- B26B 19/38: Details of, or accessories for, hair clippers, or dry shavers, e.g. housings, casings, grips, guards (cutters, cutting heads B26B19/04, B26B19/12, B26B19/14; cleaning or disinfecting devices A45D27/46; drying devices A45D27/48; casings for electric apparatus in general H05K)
- B62D 11/14: differential power outputs being effected by additional power supply to one side, e.g. power originating from secondary power source
- F16F 1/185: {characterised by shape or design of individual leaves (F16F1/22 takes precedence)}
- H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information
- B26B: HAND-HELD CUTTING TOOLS NOT OTHERWISE PROVIDED FOR (for harvesting A01D; for horticulture, for forestry A01G; for butchering or meat treatment A22; for manufactering or repairing footwear A43D; nail clippers or cutters A45D29/02; kitchen equipment A47J; {vegetable slicers, julienne cutters and similar devices and holders therefor, B26D3/28}; for surgical purposes A61B; for metal B23D; cutting by abrasive fluid jets B24C5/02; plier-like tools with cutting edges B25B7/22; pincers B25C11/02; handles for hand implements, in general B25G; guillotine-type cutters B26D; {perforating by non-mechanical means, e.g. by fluid jet, B26F1/26}; for erasing B43L19/00; for textile materials D06H)
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION

## Abstract

The present invention relates to electric appliances for personal care, in particular electric shavers, comprising a magnetic linear drive unit having first and second drive components supported for linear displacement relative to each other by a spring device and adapted to magnetically interact with each other. The spring device includes at least one leaf spring having a constricted section in a central region of the leaf spring, wherein surfaces of the at least one leaf spring neighboring the constricted section are shaped convex. Such convex surfaces may have a parabolic contour.

## Claims

### Claim 1

An electric appliance for personal care comprising a magnetic linear drive unit having first and second drive components connected to each other by a spring device for linear oscillation relative to each other and adapted to magnetically interact with each other, wherein said spring device includes a leaf spring comprising a pair of opposing main surfaces and a constricted section in a central region of the leaf spring, wherein each of the opposing main surfaces of said leaf spring has a convex shape such that the convex shape starts at the constricted section and extends outwardly, and wherein said convex shape of each of said convex main surfaces is a parabolic shape.

### Claim 2 (depends on 1)

The electric appliance according to claim 1, wherein said pair of convex main surfaces of the leaf spring comprises a first pair of convex main surfaces and further comprising a second pair of convex main surfaces, wherein said first and second pairs of convex main surfaces extend from said constricted section to opposite ends of said leaf spring on opposite sides thereof, so that, when considering a cross-section taken in a plane perpendicular to a neutral axis of the leaf spring, said leaf spring has a thickness increasing from said constricted section towards opposite ends of the leaf spring.

### Claim 3 (depends on 2)

The electric appliance according to claim 2, wherein more than ⅔ of an entire length of a side of the leaf spring has convex main surfaces.

### Claim 4 (depends on 1)

The electric appliance according to claim 1, wherein said pair of convex main surfaces of the leaf spring comprises a first pair of convex main surfaces and further comprising a second pair of convex main surfaces, wherein the first and second pairs of convex main surfaces are defined by portions of a pair of parabolas facing each other.

### Claim 5 (depends on 1)

The electric appliance according to claim 1, wherein said pair of convex main surfaces of the leaf spring comprises a first pair of convex main surfaces and further comprising a second pair of convex main surfaces, said first and second pairs of convex main surfaces of said leaf spring, when considering a cross-section taken in a plane perpendicular to a neutral axis of said leaf spring, are defined by portions of a pair of parabolas facing each other.

### Claim 6 (depends on 1)

The electric appliance according to claim 1, wherein the pair of convex main surfaces of the leaf spring comprises a first pair of convex main surfaces and further comprising a second pair of convex main surfaces, wherein the first and second pairs of convex main surfaces of said leaf spring are defined by portions of a pair of parabolas of higher degree defined by the equation
y
=
±
a
⁢
(

x

mm
)
b
wherein 10 mm ≤a ≤50 mm and 1 <b <4,
or by the equation
y
=
±
a
⁡
(

x

inch
)
b
wherein 0.4 inch ≤a ≤2 inch and 1 <b <4.

### Claim 7 (depends on 6)

The electric appliance according to claim 6, wherein 20 mm ≤a <40 mm and 2 ≤b ≤3, or 0.8 inch ≤a ≤1.6 inch and 2 ≤b ≤3.

### Claim 8 (depends on 6)

The electric appliance according to claim 6, wherein for an inner leaf spring, parameter a of the equation ranges from about 26 mm to about 50 mm, whereas for an outer leaf spring said parameter a ranges from about 10 mm to about 25 mm.

### Claim 9 (depends on 1)

The electric appliance according to claim 1, wherein a thickness (R) of said leaf spring in a center section thereof ranges from about 0.1 to about 0.5 mm or about 0.004 to about 0.02 inch.

### Claim 10 (depends on 1)

The electric appliance according to claim 1, wherein said spring device is formed by a ring element surrounding said drive unit and made in one piece from plastic including at least one pair of leaf springs and a pair of cross-bars extending crosswise to said leaf springs and connecting said leaf springs to each other.

### Claim 11 (depends on 10)

The electric appliance according to claim 10, wherein said cross-bars include mounting contours adapted to form-fit and press-fit with mounting contours of the first and second drive components.

### Claim 12 (depends on 10)

The electric appliance according to claim 10, wherein the spring device includes two or more leaf springs on each of opposite sides of the ring element, wherein leaf springs on the same side of the ring element have different contours.

### Claim 13 (depends on 10)

The electric appliance according to claim 10, wherein said cross-bars of the ring element are configured to be rigid and to resist stresses and forces of the drive unit in the operational status substantially without deformations of said cross-bars.

### Claim 14 (depends on 1)

The electric appliance according to claim 1, wherein said leaf spring of the spring device forms a resonance spring device helping the first and second drive components to oscillate at a natural frequency.

### Claim 15 (depends on 1)

The electric appliance according to claim 1, wherein the spring device is made of long-chained polyphenylene sulfide PPS.

### Claim 16 (depends on 1)

The electric appliance according to claim 1, further comprising a second spring device for connecting the first or the second drive component or a further component of the drive unit to a structural part of the electric appliance.

### Claim 17 (depends on 16)

The electric appliance according to claim 16, wherein said second spring device includes one or more spring elements made from metal and formed as leaf springs with a longitudinal axis thereof extending crosswise to the oscillation axis of the drive unit.

### Claim 18 (depends on 16)

The electric appliance according to claim 16, wherein the first spring device made of plastic is configured to have a spring stiffness being at least twice as large as the spring stiffness of the second spring device made of metal.

### Claim 19 (depends on 16)

The electric appliance according to claim 16, wherein the second spring device comprises two metal leaf springs whereas the first spring device includes at least four plastic leaf springs.

### Claim 20 (depends on 16)

The electric appliance according to claim 16, wherein the first spring device is decoupled from the second spring device in terms of vibrations and oscillations of the spring elements thereof by a vibration barrier arranged between said first and second spring devices, wherein said vibration barrier is formed by a rigid part of a drive transmitter structure for transmitting the oscillation of the drive unit to an appliance tool.

### Claim 21 (depends on 1)

The electric appliance according to claim 1, wherein said leaf spring further comprises a pair of narrow surfaces each of which is defined by a first dimension and a second dimension transverse to the first dimension, wherein each of said convex main surfaces is defined by a third dimension and a fourth dimension, wherein the third dimension is parallel to the first dimension and transverse to the second dimension and the fourth dimension is transverse to the first, second and third dimensions, wherein the fourth dimension is greater than the second dimension.

### Claim 22

A magnetic linear drive unit for driving a reciprocating tool of an electric appliance, said magnetic linear drive unit comprising first and second drive components connected to each other by a spring device for linear oscillation relative to each other and adapted to magnetically interact with each other, wherein said spring device includes at least one leaf spring having a constricted section in a central region of the leaf spring, wherein surfaces of said at least one leaf spring neighboring said constricted section are shaped convex, wherein said convex shape of each of said surfaces is a parabolic shape.