Reduction of vibration noise in a hair cutting unit for a rotary electric shaver

Abstract

In the field of rotary electric shavers, a hair-cutting unit is provided, which comprises a generally cup-shaped outer cutting member 10 with a circumferential annular flange 11, a rotatably arranged inner cutting member covered by the outer cutting member 10, and a support member 30 configured to support the outer cutting member 10 in an assembled state of the hair-cutting unit. In the assembled state of the hair-cutting unit, in the direction in which the central axis of the hair-cutting unit extends, the support member 30 only locally supports the flange 11 of the external cutting member 10 by exclusively contacting the flange 11 at a position of the flange that is a vibration node area of ​​the flange 11. In this way, a reduction in vibration-induced noise in the hair-cutting unit is obtained.

Description

[Technical Field]

[0001] The present invention relates to a hair-cutting unit for a rotary electric shaver, which comprises: a generally cup-shaped outer cutting member having an annular hair-cutting region with a hair entry opening and a circumferential annular flange; an inner cutting member covered by the outer cutting member and rotatable relative to the outer cutting member about a central axis of the hair-cutting unit; a support member configured to support the external cutting member in an assembled state of the hair-cutting unit.

[0002] Furthermore, the invention relates to a shaving unit comprising at least one hair-cutting unit as described above, and to a rotary electric shaver comprising a shaving unit as described above. [Background technology]

[0003] Rotary electric shavers, as well as shaving and hair-cutting units for rotary electric shavers, are well known. Rotary electric shavers are typically used to shave body hair, such as facial hair, and are powered from a mains power source and / or an electrical energy storage device, such as a battery.

[0004] In a commonly known setup, a rotary electric shaver has a body configured to be held by a user's hand, and the body and a shaving unit including at least one hair-cutting unit are coupled together in the assembled state of the shaver. Conventionally, a hair-cutting unit has a combination of an external cutting member having an annular hair-cutting area with a hair entry opening as a non-driven element and an internal cutting member as a driven element, at least the internal cutting member having one or more cutting edges. In such a case, using a hair-cutting unit incorporated in a shaving unit of a rotary electric shaver involves placing the hair-cutting unit in an operating mode in which the internal cutting member of the hair-cutting unit is actually rotated, and moving the shaving unit over the skin in such a manner that the hair-cutting area of ​​the external cutting member of the hair-cutting unit faces and contacts the skin. In the process, hairs protruding from the skin are trapped in the internal space of the hair-cutting unit, where they are forced to strike the external cutting member at the hair entry opening and are cut when they encounter the cutting edge of the rotating internal cutting member.

[0005] EP3643460A1 discloses a hair-cutting unit for a shaving head of a rotary electric shaver. The hair-cutting unit has a holder including a first holding mechanism, a second holding mechanism, and a third holding mechanism. When the hair-cutting unit is in a shaving-ready assembled state, the three holding mechanisms hold the inner and outer cutting members of the hair-cutting unit and the skin support member of the shaving head, respectively. When the hair-cutting unit is in a cuttable assembled state, the third holding mechanism is disengaged compared to the shaving-ready assembled state. When the hair-cutting unit is in a ready-to-cut assembled state, the second holding mechanism is disengaged compared to the cuttable assembled state. The first holding mechanism has an elastic snap connection mechanism that holds the holder and the inner cutting member together. The second holding mechanism has a holder snap connection portion for snap-connecting to a flange of the outer cutting member. The third holding mechanism has a holder snap connection portion for snap-connecting to a flange of the skin support member. Summary of the Invention [Problem to be solved by the invention]

[0006] To reduce manufacturing costs and ecological footprint, it is common for the external cutting member to be made from a thin sheet material. A practical example in this regard is a sheet thickness of 0.1 mm. However, the thinner the sheet material, the higher the sound level generated by the external cutting member when the hair-cutting unit is not on the skin during the operation mode of the hair-cutting unit. This sound is caused by the excitation of the resonant frequency of the external cutting member by the rotating internal cutting member. Vibrations are transmitted via the annular flange of the external cutting member to the support member of the hair-cutting unit on which the external cutting member is supported. Due to the vibrations causing the excitation of the resonant frequency of the support member, the overall sound generated by the hair-cutting unit and the shaving unit comprising the hair-cutting unit is increased.

[0007] In view of the above, it is an object of the present invention to design a hair-cutting unit such that the overall level of sound produced by the hair-cutting unit and the shaving unit comprising the hair-cutting unit in the operating mode is reduced without the need to increase the thickness of the external cutting member. [Means for solving the problem]

[0008] The present invention provides a hair-cutting unit for a rotary electric shaver, comprising: a generally cup-shaped outer cutting member having an annular hair-cutting region with a hair entry opening and a circumferential annular flange; an inner cutting member covered by the outer cutting member and rotatable relative to the outer cutting member about a central axis of the hair-cutting unit; a support member configured to support the external cutting member in an assembled state of the hair-cutting unit.

[0009] To achieve the object of the present invention, the hair cutting unit according to the present invention comprises: the support member is configured to support the flange of the external cutting member only locally in the direction of extension of the central axis in the assembled state of the hair-cutting unit by exclusively contacting the flange at a location of a region of the flange that is a vibration node region of the flange of the external cutting member, and the value of the amplitude of vibration of the external cutting member at a resonant frequency that occurs during operation of the hair-cutting unit as a result of rotation of the internal cutting member is minimum; In an assembled state of the hair cutting unit, at a position different from the position of the flange area, which is the vibration node area, The flange of the external cutting member is characterized in that it is at a distance of at least 0.2 mm from the support member when viewed in the direction in which the central axis extends.

[0010] Therefore, the hair-cutting unit according to the present invention has a special measure at the interface between the flange of the external cutting member and the support member. The design of the hair-cutting unit is such that, in the assembled state of the hair-cutting unit, the flange of the external cutting member is supported by the support member only locally, i.e., exclusively at the location of the vibration node area of ​​the flange, in the direction of extension of the central axis. The measure of the present invention includes not only minimizing the contact between the external cutting member and the support member, but also a more intelligent positioning of the minimized contact. The exclusive contact of the flange of the external cutting member at the location of the vibration node area of ​​this flange minimizes the degree to which vibrations are transmitted from the external cutting member to the support member, thereby minimizing the overall level of sound generated by the hair-cutting unit and the shaving unit comprising the hair-cutting unit during operation. Advantageously, in order to achieve a significant sound-reducing effect, the vibration node area is actually the vibration node area of ​​the first resonant frequency of the external cutting member.

[0011] In view of the above, it is practical if the support member has at least three bearing elements spaced apart in a direction around the central axis and protruding from the annular inner surface of the support member. Advantageously, the contact area between the flange of the external cutting member and the inner surface of the support member is as small as possible. In this respect, it is practical if the bearing elements of the support member are generally ridge-shaped. Taking into account the typical dimensions of hair-cutting units, it is practical if the flange of the external cutting member is at a distance of at least 0.2 mm from the inner surface of the support member, as viewed in the direction of extension of the central axis, at a position different from the position of the bearing elements of the support member, in the assembled state of the hair-cutting unit, to ensure that the flange of the external cutting member does not come into contact with the inner surface of the support member in an area outside the bearing elements, especially when the flange is vibrating.

[0012] The present invention covers any suitable number of bearing elements on the support member, for example, three and four. Generally, it is suitable to select the number of bearing elements on the support member in relation to the number of vibration node areas on the flange of the external cutting member, and the number of bearing elements may be the same as or less than the number of vibration node areas. In this regard, it is noted that simulations and / or tests are useful to determine the number and locations of vibration node areas on the flange of the external cutting member for any given hair-cutting unit and external cutting member. The bearing elements may be arranged at positions on the support member that correspond to the locations of the vibration node areas on the flange of the external cutting member.

[0013] In the context of the present invention, the bearing elements of the support member can be provided in any suitable manner. Practical options in this regard include bearing elements having locally raised areas on the inner surface of the support member, and bearing elements provided as appendages on the inner surface of the support member.

[0014] In a practical embodiment of the hair-cutting unit according to the invention, the flange of the external cutting member has a pair of blocking recesses arranged at diametrically opposite positions relative to the central axis, and the support member has a pair of blocking notches configured to engage with the pair of blocking recesses in the flange of the external cutting member to block rotation of the external cutting member about the central axis in the assembled state of the hair-cutting unit. The blocking notches are suitable to be used as reference directions for determining the positions of the bearing elements in combination with simulated or measured positions of the vibration node areas. For example, four vibration node areas can be found at such positions relative to the blocking notches, and the number of bearing elements of the support member is suitably four, and these four bearing elements are suitably arranged in a pattern such that, as viewed in a direction around the central axis, the bearing elements are at a mutual angular distance of 90° and there is an angular distance of 45° between the bearing elements and the blocking notches.

[0015] In a practical embodiment of the hair-cutting unit according to the invention, the support member is of the type having an opening through which part of the outer cutting member other than the flange extends in the assembled state of the hair-cutting unit, and such support member may further have an annular outer surface on the side facing the skin of the hair-cutting unit.

[0016] The present invention further relates to a shaving unit comprising a base member and at least one hair-cutting unit as defined and described above, supported by the base member, and also to a rotary electric shaver comprising such a shaving unit. In a practical embodiment, the rotary electric shaver according to the invention comprises a body adapted to be held in the hand of a user, the shaving unit and the body being coupled to each other in the assembled state of the shaver.

[0017] These and other aspects of the present invention will become apparent from and elucidated with reference to the following detailed description of an embodiment of a hair-cutting unit in which the support member has four bearing elements arranged and configured to achieve contact between the support member and the flange of the external cutting member only at a minimum extent and location of vibration node areas on the flange. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 shows a schematic perspective view of a rotary electric shaver according to an embodiment of the present invention, the shaver having a main body and a shaving unit with three hair-cutting units. [Figure 2] FIG. 2 is a diagrammatic exploded perspective view of the external and internal cutting members of the hair-cutting unit; [Figure 3] FIG. 2 is a diagrammatic illustration of an exploded perspective view of several elements of a hair-cutting unit, including an external cutting member and a support member, but excluding an internal cutting member. [Figure 4] FIG. 10 is a diagram showing a perspective view of a support member. [Figure 5] FIG. 2 is a diagrammatic view of a longitudinal cross section of a support member. [Figure 6] FIG. 10 is a diagrammatic top view of an external cutting member. [Figure 7] FIG. 10 is a diagrammatic detail of the support member and the external cutting member in a supported position on the support member; DETAILED DESCRIPTION OF THE INVENTION

[0019] The invention will now be explained in more detail with reference to the figures, in which like or similar parts are designated with the same reference numerals.

[0020] 1 shows a rotary electric shaver suitable for use in shaving as a practical example of a rotary electric shaver 1 according to an embodiment of the present invention. The shaver 1 has a main body 2 and a shaving unit 3 on which three hair-cutting units 4 are arranged, the hair-cutting units 4 being supported by a base member 5 of the shaving unit 3. The main body 2 is designed to enable a user of the shaver 1 to hold and handle the shaver 1, and the shaving units 3 constitute the part of the shaver 1 that is placed on and moved over the skin for hair removal.

[0021] When the shaver 1 is actually applied for the purpose of performing a shaving operation, the actual cutting process of the hairs protruding from the skin takes place at the location of the hair-cutting units 4. In the context of the present invention, the number of hair-cutting units 4 arranged in the shaving unit 3 can be freely selected and does not necessarily have to be three. The main body 2 can accommodate at least one electric motor for driving the elements of the individual hair-cutting units 4. The main body 2 can further comprise means, such as a rechargeable battery, for supplying power to the at least one electric motor. As is known per se in the field of rotary electric shavers, it is practical if the shaving unit 3 and the main body 2 are releasably connectable to each other.

[0022] Each hair-cutting unit 4 has a combination of an external cutting member 10 and an internal cutting member 20. The combination of the external cutting member 10 and the internal cutting member 20 will now be described in detail with reference to FIG. 2. The external cutting member 10 has a generally cup-shaped design, suitable for at least partially accommodating the internal cutting member 20 therein. The external cutting member 10 has a circumferential annular flange 11 as an outwardly curved rim of the general cup shape. The external cutting member 10 has an annular hair-cutting area, also referred to as a shaving track 12, the upper surface of which faces and contacts the skin to be shaved. The shaving track 12 has lamellae 13 extending along its width in a substantially radial direction relative to the central axis Ac of the hair-cutting unit 4, which axis coincides with the axis of rotation about which the internal cutting member 20 is rotatable relative to the external cutting member 10. The openings present between the lamellae 13 constitute hair entry openings 14 of the shaving track 12. The sides of the lamellae 13 constitute hair-cutting surfaces 14 suitable for cutting hair in cooperation with the hair-cutting edges 21 of the hair-cutting elements 22 of the internal cutting member 20. The present invention also relates to cases where the shaving path 12 does not have lamellae 13 or does not only have lamellae 13, for example where the entire shaving path 12 is provided with tooth-like elements and / or a pattern of (circular) holes instead of or in addition to the lamellae 13. The present invention also relates to cases where there are multiple shaving paths 12 on the external cutting member 10. It should be noted that for clarity, the lamellae 13 and the hair entry openings 14 of the shaving path 12 are not depicted in Figure 1.

[0023] A shaving operation can be performed when the internal cutting member 20 is actuated to rotate and a portion of the skin is actually contacted by the external cutting member 10 at the location of the shaving path 12. In Figure 2, the direction of rotation about the central axis Ac is indicated by an arrow. The actuation of the internal cutting member 20 can be performed in a known manner by the drive mechanism of the rotary electric shaver 1. When the combination of the external cutting member 10 and the internal cutting member 20 is moved over the portion of skin while the internal cutting member 20 is driven to rotate, cooperation between the hair-cutting surface 15 of the shaving path 12 of the external cutting member 10 and the hair-cutting edge 21 of the hair-cutting element 22 of the rotating internal cutting member 20 results in hair protruding from the portion of skin being captured in the hair entry opening 14 of the shaving path 12 of the external cutting member 10 and cut at that location.

[0024] With reference to Figure 3, it will be noted that the external cutting member 10 is held within the hair-cutting unit 4 between a support member 30 on one side and a combination of retaining members 40, 50 on the other side. The support members are shown separately in Figures 4 and 5. The first of the retaining members 40, 50, 40, serves to fix the position of the external cutting member 10 around the central axis Ac. Indeed, the flange 11 of the external cutting member 10 has a pair of blocking recesses 16 arranged at diametrically opposite positions relative to the central axis Ac, and the support member 30 has a pair of blocking notches 31 configured to engage with the pair of blocking recesses 16 in the flange 11 of the external cutting member 10 in the assembled state of the hair-cutting unit 4. The first retaining member 40 has a pair of fixing elements 41. In the assembled state of the hair-cutting unit 4, the external cutting member 10 and the support member 30 are positioned relative to each other in such a manner that the blocking recess 16 of the flange 11 of the external cutting member 10 is aligned with the blocking notch 31 of the support member 30, and the fixing element 40 is configured to receive parts of the flange 11 of the external cutting member 10 and the support member 30 at the positions of the aligned blocking recess 16 and blocking notch 31, thereby realizing fixing of said parts relative to each other.

[0025] The external cutting member 10 has a relatively small wall thickness. As a result, when the internal cutting member 20 is rotated during operation of the hair-cutting unit 4, vibrations of the external cutting member 10 occur at a resonant frequency, which are transmitted from the external cutting member 10 to other elements of the hair-cutting unit 4, including the support member 30. In view of the sound levels generated by the hair-cutting unit 4 during operation, particularly when the hair-cutting unit 4 is not in contact with the skin, it is an insight of the present invention that it is advantageous to take measures to minimize the extent to which the vibrations of the external cutting member 10 are transmitted to the support member 30. In this regard, in this example, as best seen in Figure 4, the support member 30 is provided with four ridge-like bearing elements 32 protruding from an annular inner surface 33 of the support member 30. Due to the presence of the bearing elements 32 on the support member 30, a minimum contact area between the flange 11 of the external cutting member 10 and the support member 30 is achieved. The positioning of the bearing element 32 is adapted to position the area of ​​the flange 11 that is the vibration node area 17 of the flange 11, where the amplitude of vibration of the external cutting member 10 at its resonant frequency has a minimum value. In this way, sound reduction is achieved based on the dual effect of having a minimum contact area and having said minimum contact area at a location where the amplitude of vibration of the flange 11 is minimum. The location of the vibration node area 17 associated with the first resonant frequency of the external cutting member 10 is indicated by a circle in Figure 6.

[0026] Referring to FIG. 6 , it should be noted that in this example, where the flange 11 of the external cutting member 10 includes two blocking recesses 16 positioned at diametrically opposed positions relative to the central axis Ac, the vibration node regions 17 on the flange 11 are positioned at a 45° angular distance from the blocking recesses 16, thereby evenly distributed around the circumference of the flange 11 at a mutual angular distance of 90°. In that regard, the four bearing elements 32 on the support member 30 are arranged in a pattern that is rotated 45° relative to the blocking notches 31 when viewed in a direction about the central axis Ac. In embodiments of the external cutting member 10 in which the flange 11 has a different appearance, such as due to different positioning of the blocking recesses 16, alternative positions of the vibration node regions 17 on the flange 11 may be envisioned. The design of the support member 30 can be easily adapted to alternative positions of the vibration node regions 17 on the flange 11, since this requires no adjustment other than the position of the bearing elements 32 on the support member 30.

[0027] It is practical if, during the manufacturing process of the support member 30, the inner surface 33 of the support member 30 is molded in such a way that the bearing elements 32 are formed in the material that constitutes the surface 33. This does not change the fact that the bearing elements 32 can also be realized by suitable additions. In any case, noise reduction compared to conventional hair-cutting units can be obtained in a relatively simple manner by adapting the design of the support member 30 to a design in which the support member 30 has at least three bearing elements 32, as shown and described, in positions corresponding to the positions of the vibration node areas 17 on the flange 11 of the external cutting member 10, with spaces between said bearing elements 32. Here, contact between the support member and the flange 11 is prevented under all normal conditions of use. In this respect, it is to be noted that a practical example for the height of the bearing element 32, i.e. the dimension of the bearing element 32 in the direction in which the central axis Ac extends, is 0.2 mm, so that in the assembled state of the hair-cutting unit 4, at a position different from the position of the bearing element 32, the flange 11 is at a distance of at least 0.2 mm from the inner surface 33, as viewed in said direction.

[0028] In particular, the support member 30 comprises an opening 34 which is dimensioned to achieve that, upon assembly of the hair-cutting unit 4, only parts of the external cutting member 10 other than the flange 11 are allowed to pass through the opening 34, while the flange 11 cannot pass through, but instead becomes fixed to the bearing element 32 of the support member 30. Furthermore, the support member 30 has an annular outer surface 35 on the side facing the skin of the hair-cutting unit 4. Figure 7 helps to illustrate an arrangement in which the flange 11 of the external cutting member 10 is contacted by the bearing element 32 of the support member 30, while the other parts of the external cutting member 10 extend through the opening 34 of the support member 30.

[0029] The scope of the present invention is not limited to the above examples, and it will be apparent to those skilled in the art that several modifications and variations thereof are possible without departing from the scope of the present invention as defined in the appended claims. It is intended that the present invention be construed as including all such modifications and variations insofar as they come within the scope of the claims or their equivalents. Although the present invention has been illustrated and described in detail in the drawings and description, such illustration and description are merely explanatory or exemplary and are not restrictive. The present invention is not limited to the disclosed embodiments. The drawings are schematic, in which details not necessary for understanding the invention may be omitted and are not necessarily drawn to scale.

[0030] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the figures, the description, and the appended claims. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0031] Elements and aspects discussed for or in connection with a particular embodiment can be combined with elements and aspects of other embodiments as appropriate, unless otherwise expressly stated. Thus, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0032] The terms "having" and "including" as used herein will be understood by those skilled in the art to cover the term "consisting of." Thus, the terms "having" or "including" may mean "consisting of" in one embodiment, but may mean "including / having / comprising at least the specified species and, optionally, one or more other species" in another embodiment.

[0033] In the context of the present invention, it is not essential which side of the flange 11 of the external cutting member 10 is contacted in the manner described above, i.e., with only minimal contact and with the aim of having said minimal contact exclusively at the location of the vibration node area 17 on the flange 11.

[0034] Notable aspects of the present invention can be summarized as follows: A hair-cutting unit 4 is provided in the field of rotary electric shaver, comprising a generally cup-shaped external cutting member 10 with a circumferential annular flange 11, a rotatably arranged internal cutting member 20 covered by the external cutting member 10, and a support member 30 configured to support the external cutting member 10 in the assembled state of the hair-cutting unit 4. In the assembled state of the hair-cutting unit 4, the support member 30 only locally supports the flange 11 of the external cutting member 10 by exclusively contacting the flange 11 in the direction in which the central axis Ac of the hair-cutting unit 4 extends, at the position of the region of the flange 11 that is the vibration node region 17 of the flange 11, so that the amplitude of vibration of the external cutting member 10 at the resonant frequency generated during operation of the hair-cutting unit 4 when the internal cutting member 20 rotates is minimized. This results in a reduction of vibration-induced noise in the hair-cutting unit 4.

Claims

1. A hair cutting unit for a rotary electric shaver, comprising: a generally cup-shaped outer cutting member having an annular hair-cutting region with a hair entry opening and a circumferential annular flange; an internal cutting member covered by the external cutting member and rotatable relative to the external cutting member about a central axis of the hair-cutting unit; a support member for supporting the external cutting member in an assembled state of the hair-cutting unit, the support member contacts the flange of the external cutting member exclusively at a position of the flange which is a vibration node area of ​​the flange of the external cutting member, thereby locally supporting the flange of the external cutting member in the direction of extension of the central axis in the assembled state of the hair-cutting unit, and the value of the amplitude of vibration of the external cutting member at a resonant frequency which occurs during operation of the hair-cutting unit as a result of rotation of the internal cutting member is minimum; a hair-cutting unit, wherein in an assembled state of the hair-cutting unit, at a position different from the position of the flange area, which is a vibration node area, the flange of the external cutting member is at a distance of at least 0.2 mm from the support member when viewed in the direction in which the central axis extends.

2. 2. The hair-cutting unit of claim 1, wherein the vibration node area is a vibration node area of ​​a first resonant frequency of the external cutting member.

3. 2. The hair-cutting unit of claim 1, wherein said support member has at least three bearing elements spaced apart in a direction around said central axis and projecting from an inner annular surface of said support member.

4. 4. The hair-cutting unit according to claim 3, wherein in an assembled state of the hair-cutting unit, at a position different from the position of the bearing element of the support member, the flange of the external cutting member is at a distance of at least 0.2 mm from the inner surface of the support member as viewed in the direction in which the central axis extends.

5. 4. A hair-cutting unit according to claim 3, wherein the number of bearing elements of the support member is three or four.

6. 4. A hair-cutting unit according to claim 3, wherein the bearing elements of said support member are generally ridge-shaped.

7. 4. A hair-cutting unit according to claim 3, wherein the bearing elements of the support member comprise locally raised areas on the inner surface of the support member.

8. 4. A hair-cutting unit according to claim 3, wherein the bearing elements of the support member are provided as appendages on an inner surface of the support member.

9. The flange of the external cutting member has a pair of blocking recesses disposed at positions diametrically opposed to the central axis, the support member has a pair of blocking notches which engage with the pair of blocking recesses in the flange of the external cutting member to prevent rotation of the external cutting member about the central axis when the hair-cutting unit is in an assembled state; the number of bearing elements of the support member is four; 4. The hair-cutting unit according to claim 3, wherein the four bearing elements of the support member are arranged in a pattern such that, when viewed in a direction around the central axis, the bearing elements are at a mutual angular distance of 90° and there is an angular distance of 45° between the bearing elements and the blocking notches.

10. 10. A hair-cutting unit according to any one of claims 1 to 9, wherein the support member comprises an opening through which a portion of the external cutting member other than a flange extends in an assembled state of the hair-cutting unit.

11. 11. The hair-cutting unit of claim 10, wherein the support member has an annular outer surface on a skin-facing side of the hair-cutting unit.

12. A shaving unit comprising a base member and at least one hair-cutting unit according to any one of claims 1 to 9 supported on said base member.

13. A rotary electric shaver comprising a shaving unit according to claim 12.

14. 14. The rotary electric shaver of claim 13, further comprising a body adapted to be gripped by a user's hand, the shaving unit and the body being coupled together in an assembled state of the shaver.

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