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1. WO2020109094 - HAIR-CUTTING UNIT WITH CUTTER BLOCKING PREVENTION

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS:

1. A hair-cutting unit (5) for use in a shaving device (1), said hair-cutting unit comprising an external cutting member (6) and an internal cutting member (7) which is rotatable relative to the external cutting member in a rotational direction (8) about an axis of rotation (9), wherein:

the internal cutting member comprises a plurality of cutting elements (10), each having a cutting edge (11) with a respective main direction of extension in a radial direction relative to the axis of rotation;

the external cutting member comprises an annular wall portion (12) having an outer surface (14) facing away from the internal cutting member and a plurality of hair-entry openings (15) which are mutually separated by hair-guiding elements (16), each hair-entry opening and each hair-guiding element having a respective main direction of extension in a radial direction relative to the axis of rotation, and each hair-guiding element having a counter-cutting edge (17) for co-operation with the cutting edges of the internal cutting member during rotation of the internal cutting member in said rotational direction;

each cutting element has a top surface (18) facing the hair- guiding elements and a front surface (19) facing in the rotational direction, wherein said top surface and said front surface mutually connect at the cutting edge of the respective cutting element, and wherein, in a cross-section of the respective cutting element taken perpendicularly to the radial direction, a normal vector (20) at the front surface is defined with a direction facing away from the cutting element;

each hair- guiding element has an inner surface (21) facing the cutting elements and a side surface (22) facing in a direction opposite to the rotational direction, wherein said inner surface and said side surface mutually connect at the counter-cutting edge of the respective hair-guiding element, and wherein, in a cross-section of the respective hair-guiding element taken perpendicularly to the radial direction, a normal vector (23) at the side surface is defined with a direction facing away from the hair-guiding element;

during rotation of the internal cutting member in said rotational direction, seen in an axial direction relative to the axis of rotation, the cutting edges pass the counter-cutting edges, the cutting edges and the counter-cutting edges enclosing a shearing angle (24) during said passing, and each said passing starting at a radial initial-passing position (R0) relative to the axis of rotation, said radial initial-passing position being defined as a radial position at which a respective cutting edge first meets a respective counter-cutting edge as compared to other radial positions along the respective cutting edge;

characterized in that, in a cross-section at said radial initial-passing position (R0) and taken perpendicularly to the radial direction, only one of the internal cutting member and the external cutting member is provided with an abutment geometry (25; 27) according to which, at each position on an abutment segment (25; 27), said normal vector (20; 23) has a non-zero axial component being parallel to the axis of rotation and being directed towards the other one of the internal cutting member and the external cutting member such that:

in case the internal cutting member is provided with said abutment geometry, said abutment segment (25) is a segment of the front surface extending from the cutting edge (11) until an end point (26) of said segment of the front surface, said axial component being directed towards the outer surface (14) of the annular wall portion of the external cutting member at each position on said abutment segment; and

in case the external cutting member is provided with said abutment geometry, said abutment segment (27) is a segment of the side surface extending from the counter cutting edge (17) until an end point (28) of said segment of the side surface, said axial component being directed away from said outer surface (14) at each position on said abutment segment.

2. A hair-cutting unit as claimed in claim 1, wherein:

a first angle al between the axis of rotation (9) and said normal vector (20) at the front surface of the cutting element (10) is defined in the acute angular range 0° < al < 90° as opposed to the obtuse angular range 90° < al < 180°;

a second angle a2 between the axis of rotation (9) and said normal vector (23) at the side surface of the hair-guiding element (16) is defined in the acute angular range 0° < a2 < 90° as opposed to the obtuse angular range 90° < a2 < 180°;

in case the internal cutting member is provided with said abutment geometry, said first angle al between the axis of rotation and said normal vector (20) at said abutment segment (25) of the front surface of the cutting element (10) is within the range 45° < al < 90°, preferably 50° < al < 80°; and

in case the external cutting member is provided with said abutment geometry,

said second angle a2 between the axis of rotation and said normal vector (23) at said abutment segment (27) of the side surface of the hair-guiding element (16) is within the range 45° < a2 < 90°, preferably 50° < a2 < 80°.

3. A hair-cutting unit as claimed in claim 1 or claim 2, wherein said abutment segment of, respectively, the front surface and the side surface is straight.

4. A hair-cutting unit as claimed in claim 1 or claim 2, wherein said abutment segment of, respectively, the front surface and the side surface is convexly or concavely curved.

5. A hair-cutting unit as claimed in any one of the preceding claims, wherein said abutment segment of, respectively, the front surface and the side surface, in said cross-section at said radial initial-passing position and taken perpendicularly to the radial direction, extends in the axial direction over a distance H > 1/(500 * T), wherein T is a minimum thickness of the hair-guiding elements, and wherein H and T are expressed in mm.

6. A hair-cutting unit as claimed in any one of the claims 1-4, wherein said abutment segment of, respectively, the front surface and the side surface, in said cross-section at said radial initial-passing position and taken perpendicularly to the radial direction, extends in the axial direction over a distance H in a range between 10% and 80% of a minimum thickness of the hair-guiding elements.

7. A hair-cutting unit as claimed in any one of the preceding claims, wherein, in case the external cutting member is provided with said abutment geometry (27), said side surface, in said cross-section at said radial initial-passing position and taken perpendicularly to the radial direction, has a further segment (29) extending from the end point of said abutment segment of the side surface in a direction towards the outer surface of the annular wall portion of the external cutting member, wherein at each position on said further segment the normal vector to the side surface has no axial component or a non-zero axial component which is directed towards said outer surface.

8. A hair-cutting unit as claimed in any one of the claims 1-6, wherein, in case the internal cutting member is provided with said abutment geometry (25), said front surface, in said cross-section at said radial initial-passing position and taken perpendicularly to the radial direction, has a further segment (30) extending from the end point of said abutment segment of the front surface in a direction away from the outer surface of the annular wall portion of the external cutting member, wherein at each position on said further segment the normal vector to the front surface has a non-zero axial component which is directed away from said outer surface.

9. A hair-cutting unit as claimed in any one of the preceding claims, wherein said abutment geometry is provided in any cross-section, taken perpendicularly to the radial direction, within a range of radial positions relative to the axis of rotation including said radial initial-passing position (R0).

10. A hair-cutting unit as claimed in claim 9, wherein said abutment geometry is provided only within said range of radial positions.

11. A hair-cutting unit as claimed in claim 9 or claim 10, wherein the cutting edges extend from a radially inward cutting edge tip (31) at a first radial position (Rl) relative to the axis of rotation until a radially outward cutting edge tip (32) at a second radial position (R2) relative to the axis of rotation, and wherein said range of radial positions includes said first radial position.

12. A hair-cutting unit as claimed in claim 9 or claim 10, wherein the cutting edges extend from a radially inward cutting edge tip at a first radial position relative to the axis of rotation until a radially outward cutting edge tip at a second radial position relative to the axis of rotation, and wherein said range of radial positions includes said second radial position.

13. A hair-cutting unit as claimed in any one of the claims 9-12, wherein the cutting edges (11) extend from a radially inward cutting edge tip (31) at a first radial position (Rl) relative to the axis of rotation until a radially outward cutting edge tip (32) at a second radial position (R2) relative to the axis of rotation, and wherein said range of radial positions extends from a third radial position (R3) relative to the axis of rotation to a fourth radial position (R4) relative to the axis of rotation, and wherein a radial distance between the third and fourth radial positions (R3, R4) is between 5% and 50% of a radial distance between the

first and second radial positions (Rl, R2), preferably between 5% and 25% of the radial distance between the first and second radial positions.

14. A hair-cutting unit as claimed in claim 9 or claim 10, wherein the cutting edges extend from a radially inward cutting edge tip at a first radial position relative to the axis of rotation until a radially outward cutting edge tip at a second radial position relative to the axis of rotation, and wherein said range of radial positions includes said first and second radial positions.

15. A shaving unit (3) for use in a shaving device (1), said shaving unit comprising a supporting member (4) and at least two hair-cutting units (5) according to any one of the preceding claims.

16. A shaving device (1) comprising a shaving unit (3) according to claim 15 and a main body (2) accommodating a motor and a drive system, wherein the shaving unit is coupled to the main body such that the internal cutting members (7) of the hair-cutting units (5) are rotatable by means of the motor via the drive system.