Abstract
A guard element (4) for use in a hair cutting unit as a guard of a movable hair cutting element of the hair cutting unit has a disc-shaped base (10) and an annular wall (20) comprising a main part (21) extending from the periphery of the base (10), and a flange-shaped part (22) comprising an outwardly bent section (24). The annular wall (20) is reinforced on the basis of at least one of a design where a smallest inner periphery of the flange-shaped part (22) has a diameter which is smaller than a diameter of a largest inner periphery of a straight section (23) of the main part (21) connected to the periphery of the base (10), and a design where a free end section (25) of the flange-shaped part (22) is at least partially bent. In an embodiment, at least a portion of the main wall part (21) of the guard element (4) tapers inwardly in a direction along a central axis (11) of the disc-shaped base (10), from the disc-shaped base (10) to the flange-shaped wall part (22), such that the flange-shaped wall part (22) is enlarged with respect to a flange-shaped wall part (22) of a guard element (5) not having the tapered shape of the main wall part (21), resulting in increased stiffness and an increased resonant frequency of the guard element (4).
Claims
1. Guard element for use in a hair cutting unit as a guard for a movable hair cutting element of the hair cutting unit, which guard element is generally cup-shaped and comprises a disc-shaped base and an annular wall, wherein the disc-shaped base comprises a central axis and a peripheral section which is curved when seen in a central cross-section of the guard element comprising the central axis; and the annular wall comprises a main part and a flange-shaped part; and wherein the main part of the annular wall has a substantially upright orientation with respect to the disc-shaped base and comprises a straight section, which is uncurved when seen in the central cross-section and which is connected to the peripheral section of the disc-shaped base; and the flange-shaped part of the annular wall comprises an outwardly bent section, which is bent outwardly relative to the central axis when seen in the central cross-section, and a free end section; wherein the outwardly bent section of the flange-shaped part of the annular wall interconnects the main part of the annular wall and the free end section of the flange-shaped part of the annular wall; and wherein the annular wall is reinforced on the basis of at least one of a design where a smallest inner periphery of the flange-shaped part of the annular wall has a diameter which is smaller than a diameter of a largest inner periphery of the straight section of the main part of the annular wall, and a design where the free end section of the flange-shaped part of the annular wall is bent upwards towards the disc-shaped base, such that the flange-shaped part is U-shaped when seen in the central cross-section.
2. Guard element according to claim 1, wherein at least a portion of the main part of the annular wall tapers inwardly in a direction along the central axis from the disc-shaped base to the flange-shaped part of the annular wall.
3. Guard element according to claim 1, wherein the main part of the annular wall is partially bent when seen in the central cross-section.
4. Guard element according to claim 3, wherein the main part of the annular wall has an inward annular bulge at a transition to the outwardly bent section of the flange-shaped part of the annular wall.
5. Guard element according to claim 1, wherein the free end section of the flange-shaped of the annular wall is bent inwardly towards the central axis.
6. (canceled)
7. Hair cutting unit, comprising a guard element according to claim 1 and a movable hair cutting element rotatably arranged in an inner space of the guard element which is surrounded by the main part of the annular wall.
8. Hair cutting appliance, comprising a main body for a user of the hair cutting appliance to take hold of and a head including at least one hair cutting unit according to claim 7.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will now be explained in greater detail with reference to the figures, in which equal or similar parts are indicated by the same reference signs, and in which:
[0017] FIGS. 1a and 1b show a top view and a sectional view of a cap having a conventional design;
[0018] FIGS. 2a and 2b show a top view and a sectional view of a cap according to a first embodiment of the invention;
[0019] FIGS. 3a and 3b show a top view and a sectional view of a cap according to a second embodiment of the invention;
[0020] FIGS. 4a and 4b show a top view and a sectional view of a cap according to a third embodiment of the invention;
[0021] FIGS. 5a and 5b show a top view and a sectional view of a cap according to a fourth embodiment of the invention; and
[0022] FIG. 6 illustrates the difference between the cap according to the fourth embodiment of the invention and a cap having a conventional design.
DETAILED DESCRIPTION OF EMBODIMENTS
[0023] FIGS. 1a and 1b show a guard element or cap having a conventional design, which is suitable to be used in a shaving appliance (not shown) as a guard of a movable hair cutting element of the appliance, which will hereinafter be referred to as known cap 5. A shaving appliance comprising such a cap is generally known, and therefore, the particulars of such appliance will not be further explained. For the sake of completeness, it is noted that an example of such appliance can be found in U.S. Pat. No. 4,168,570, as mentioned earlier. Generally speaking, a shaving appliance comprises a main body for a user of the shaving appliance to take hold of and a head including at least one shaving unit, wherein a shaving unit is defined as a unit comprising a combination of a cap and a movable hair cutting element. The cap is normally made of metal.
[0024] The known cap 5 is generally cup-shaped, comprising a disc-shaped base 10 and an annular wall 20. The disc-shaped base 10 has a circular periphery, comprising a central axis 11 and a peripheral section 12 which is curved when seen in a central cross-section of the cap 5 comprising the central axis 11, as illustrated in FIG. 1b. The annular wall 20 comprises a main part 21 extending from the outer periphery of the base 10, wherein the wall 20 is bent outwardly at a free end thereof, so that the wall 20 has a flange-shaped part 22 besides the main part 21. An important function of the flange-shaped wall part 22 is to constitute a rim for locking the cap 5 in a radially outward direction in a shaving appliance having a hole in a plate or the like for accommodating the cap 5. In the following, for the sake of clarity, words like “top”, “underneath” and “downwards” are used in the explanation of the particulars of the cap 5, wherein these words should be understood to be related to the orientation of the cap 5 as shown in FIG. 1b, i.e. a functional orientation in which the disc-shaped base 10 is at a top side and the annular wall 20 extends downwards from the base 10.
[0025] As can be seen in FIG. 1a, the disc-shaped base 10 includes an annular shaving track 13 with a plurality of radially extending hair-entry apertures 14 between which lamellae 15 are present. During a shaving operation in which the cap 5 is applied, the hair-entry apertures 14 allow hairs to be cut off to extend through the cap 5 at the position of the shaving track 13 and encounter cutters of a rotating cutting element (not shown) which is arranged in an inner space 16 of the cap 5 as present underneath the base 10 and surrounded by the main part 21 of the annular wall 20.
[0026] The main part 21 of the annular wall 20 has a substantially upright orientation with respect to the disc-shaped base 10 and comprises a straight section 23, which is uncurved (i.e. free from curves) when seen in the central cross-section, as illustrated in FIG. 1b. The straight section 23 is connected to the peripheral section 12 of the disc-shaped base 10. Furthermore, the flange-shaped part 22 of the annular wall 20 comprises an outwardly bent section 24 and a free end section 25. The outwardly bent section 24 is bent outwardly relative to the central axis 11 when seen in the central cross-section, as illustrated in FIG. 1b, and interconnects the main part 21 of the annular wall 20 and the free end section 25 of the flange-shaped part 22.
[0027] According to the invention, a guard element or cap is provided which has another design than the known cap 5, in particular a design involving an increased stiffness of the cap, more in particular a design involving increased stiffness of the annular wall 20, most in particular a design involving increased stiffness of the flange-shaped part 22 of the annular wall 20. In the following, particulars of four embodiments of such a cap according to the invention will be elucidated. In particular, it will be pointed out how the design of the cap according to the invention deviates from the conventional design. The general features of the known cap 5, especially the cup shape with the disc-shaped base 10 including a shaving track 13 and the annular wall 20 comprising a main part 21 and a flange-shaped part 22, the main part 21 having a straight section 23 and the flange-shaped part 22 having an outwardly bent section 24 and a free end section 25, are also applicable to the embodiments of the cap according to the invention. Therefore, like elements to those of FIGS. 1a and 1b will be designated with like numerals, even though FIGS. 1a and 1b relate to a conventional situation whereas the other figures relate to the invention. On the basis of the increased stiffness of the cap, the resonant frequency of the cap is increased, such that it is ensured that the resonant frequency of the cap is high enough to avoid a situation of resonance when the shaving appliance in which the cap is to be applied is in operation and a cutting element of the shaving appliance rotates in the inner space 16 of the cap.
[0028] FIGS. 2a and 2b show a cap according to a first embodiment of the invention, which will hereinafter be referred to as first cap 1. Contrary to the known cap 5, in which the flange-shaped part 22 has the general appearance of a planar ring, the first cap 1 comprises a bent flange-shaped part 22, particularly a flange-shaped part 22 having a U-shaped cross-section as seen in the central cross-section of the first cap 1 shown in FIG. 2b. In particular, said U-shaped cross-section is achieved by the fact that the free end section 25 of the flange-shaped part 22 is bent upwards towards the disc-shaped base 10. On the basis of the curved appearance of the flange-shaped part 22, the stiffness of the first cap 1 is higher than the stiffness of the known cap 5.
[0029] FIGS. 3a and 3b show a cap according to a second embodiment of the invention, which will hereinafter be referred to as second cap 2. Contrary to the known cap 5, in which the main part 21 of the annular wall 20 has a generally continuous appearance without any irregularities, the annular wall 20 of the second cap 2 comprises a main part 21 which is partially bent when seen in the central cross-section of the second cap 2 shown in FIG. 3b, particularly a main part 21 which is provided with an inward annular bulge 26, as illustrated in FIG. 3b. In particular, the bulge 26 is present at the transition of the main part 21 of the annular wall 20 to the outwardly bent section 24 of the flange-shaped part 22 of the annular wall 20, so that the presence of the bulge 26 results in an increased width of the flange-shaped part 22, obtained on the basis of a decreased inner diameter of a smallest inner periphery of the flange-shaped part 22 as compared to the smallest inner periphery of the flange-shaped part 22 of the known cap 5. In particular, in the known cap 5 the diameter of the smallest inner periphery of the flange-shaped part 22 is equal to the diameter of a largest inner periphery of the straight section 23 of the main part 21 of the annular wall 20, while in the second cap 2 the diameter of the smallest inner periphery of the flange-shaped part 22 is smaller than the diameter of a largest inner periphery of the straight section 23 of the main part 21 of the annular wall 20. Said decreased inner diameter of the flange-shaped part 22 of the second cap 2 involves an increased difference between the outer diameter and the inner diameter of the flange-shaped part 22. For example, the inner diameter of the flange-shaped part 22 may be decreased by 0.6 mm on the basis of the presence of the bulge 26. All in all, on the basis of the curved appearance of the main part 21 at the transition to the flange-shaped part 22, the stiffness of the second cap 2 is higher than the stiffness of the known cap 5.
[0030] FIGS. 4a and 4b show a cap according to a third embodiment of the invention, which will hereinafter be referred to as third cap 3. Contrary to the known cap 5, in which the flange-shaped part 22 of the annular wall 20 has the general appearance of a planar ring, the third cap 3 comprises a partially bent free end section 25 of the flange-shaped part 22, particularly a free end section 25 which is bent inwardly towards the central axis 11 as can be seen in FIG. 4b, wherein an increased difference between the outer diameter and the inner diameter of the flange-shaped part 22 is obtained. All in all, on the basis of the bent appearance of the free end section 25 of the flange-shaped wall part 22, the stiffness of the third cap 3 is higher than the stiffness of the known cap 5.
[0031] FIGS. 5a and 5b show a cap according to a fourth embodiment of the invention, which will hereinafter be referred to as fourth cap 4. Contrary to the known cap 5, in which the main part 21 of the annular wall 20 has a constant diameter along its height, the annular wall 20 of the fourth cap 4 comprises a main part 21 which tapers inwardly in a downward direction as can be seen in FIG. 5b, i.e. tapers inwardly in a direction along the central axis 11 from the disc-shaped base 10 to the flange-shaped part 22. In particular, the tapered shape of the main part 21 of the annular wall 20 results in an increased width of the flange-shaped part 22, obtained on the basis of a decreased inner diameter of the smallest inner periphery of the flange-shaped wall part 22 as compared to the smallest inner periphery of the flange-shaped part 22 of the known cap 5. In particular, in the fourth cap 4 the diameter of the smallest inner periphery of the flange-shaped part 22 is smaller than the diameter of a largest inner periphery of the straight section 23 of the main part 21 of the annular wall 20, wherein said largest inner periphery of the straight section 23 is present at the location where the straight section 23 connects to the peripheral section 12 of the disc-shaped base 10. Said decreased inner diameter of the flange-shaped part 22 of the fourth cap 4 involves an increased difference between the outer diameter and the inner diameter of the flange-shaped part 22. All in all, on the basis of the tapered appearance of the main part 21 of the annular wall 20, the stiffness of the fourth cap 4 is higher than the stiffness of the known cap 5.
[0032] FIG. 6 illustrates the difference between the fourth cap 4 and the known cap 5 by showing sectional views of both caps 4, 5, with the disc-shaped bases 10 of both caps 4, 5 being in an overlapping position. The basic outline of the sectional view of the fourth cap 4 is indicated by means of a black line, whereas the basic outline of the sectional view of the known cap 5 is indicated by means of a white line cased in black. In this way, it can clearly be seen that the main part 21 of the annular wall 20 of the fourth cap 4 has a tapered shape with respect to the main part 21 of the annular wall 20 of the known cap 5, and that the flange-shaped part 22 of the fourth cap 4 extends more inwardly towards the central axis 11 than the flange-shaped part 22 of the known cap 5 while having a similar outer diameter as the flange-shaped part 22 of the known cap 5, as a result of which the flange-shaped part 22 of the fourth cap 4 has a larger width than the flange-shaped part 22 of the known cap 5.
[0033] It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The invention is not limited to the disclosed embodiments.
[0034] Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached 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. 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. Any reference signs in the claims should not be construed as limiting the scope of the invention.
[0035] Summarizing, when the invention is applied, the flange-shaped part 22 of the annular wall 20 of a guard element 1, 2, 3, 4 is provided with a certain bent shape and/or is enlarged with respect to the flange-shaped part 22 of the annular wall 20 of a known guard element 5 not having an adapted design of the wall 20. In this way, the annular wall 20 is reinforced, on the basis of which an increased stiffness and an increased resonant frequency of the guard element 1, 2, 3, 4 according to the invention are obtained with respect to the known guard element 5, which is advantageous because noise associated with the operation of a hair cutting appliance including the guard element can thereby be reduced.
