Transmission system for selectively transmitting a rotational motion of a primary member to a secondary member

Abstract

: In the field of transmission of a rotational motion from one member to another, an adjustable transmission system (1) is provided which is configured to selectively transmit a rotational motion of a primary member (10) about a rotational axis (R) to a secondary member (20), to cause the secondary member (20) to selectively rotate about the rotational axis (R). The transmission system (1) comprises a coupling member (30) which is configured to selectively be in first and second axial positions relative to the primary member (10), for decoupling from and coupling to the secondary member (20), respectively, wherein the primary member (10) is configured to enable displacement of the coupling member (30) in axial direction on the basis of changes of the direction of the rotational motion, and wherein use is made of a pattern of guiding channels (12) which are engaged by a guided element (31).

Description

[0001] TRANSMISSION SYSTEM FOR SELECTIVELY TRANSMITTING A ROTATIONAL MOTION OF

[0002] A PRIMARY MEMBER TO A SECONDARY MEMBER

[0003] FIELD OF THE INVENTION

[0004] The invention relates to an adjustable transmission system comprising a primary member and a secondary member and being configured to selectively transmit a rotational motion of the primary member about a rotational axis to the secondary member, to cause the secondary member to selectively rotate about the rotational axis.

[0005] Further, the invention relates to a personal care appliance comprising a motor and the transmission system as mentioned here before, wherein the primary member of the transmission system is coupled to an output shaft of the motor.

[0006] BACKGROUND OF THE INVENTION

[0007] Appliances which can be operated in more than one particular mode are well known in the art. For example, personal care appliances are often configured to be operated in one of a number of preprogrammed modes of operation, so that a user of a personal care appliance is provided with a possibility to set a mode of operation according to her / his preference prior to or during use of the appliance. In practical cases, a personal care appliance is equipped with a user interface enabling the user to indicate desired operation of the appliance and to thereby directly influence control of components of the appliance.

[0008] A personal care appliance usually comprises a motor, particularly an electric motor, and one or more components driven by the motor. In case it is desired to have one or more modes of operation in which a component which is normally driven by the motor is decoupled from the motor, this can be realized by means of a suitable type of adjustable transmission system arranged between the component and the motor.

[0009] An example of a personal care appliance is an electric shaver which typically comprises at least one hair-cutting unit having an internal cutting member and an external cutting member. In conventional cases, the internal cutting member is driven by the motor of the shaver so as to rotate during operation of the shaver, while the external cutting member is a stationary component of the shaver. Further, a type of shaver has been developed in which the external cutting member is also rotated during operation of the shaver. For example, WO 2023 / 247194 Al discloses an electric shaver in which the internal cutting member and the external cutting member are rotated about a central axis of the haircutting unit, respectively, at a first rotational speed and at a second rotational speed and such that the internal and external cutting members are rotated relative to each other. A reason for rotating the internal and external cutting members at respective rotational speeds is that this is beneficial to the hair-catching efficiency, i.e., the degree at which hairs are able to penetrate into hair-entry openings of the external cutting member during a shaving action, and thereby to the overall performance of the shaver. In a practical embodiment of the known shaver, a drive system of the shaver including the motor is configured to rotate the internal cutting member about the central axis of the hair-cutting unit at the first rotational speed and in a first rotational direction, and to rotate the external cutting member about the central axis of the hair-cutting unit at the second rotational speed and in a second rotational direction, wherein the second rotational speed is lower than the first rotational speed and the second rotational direction is opposite to the first rotational direction. For this purpose, the drive system comprises a transmission system via which the motor is able to rotate both the internal cutting member and the external cutting member.

[0010] In view of the foregoing, there is a need for a practical way of implementing a switching feature in an electric shaver in which both the internal cutting member and the external cutting member of the at least one hair-cutting unit of the shaver are rotatable, that is to say, a possibility to set a first mode of operation involving rotation of the internal and external cutting members and a second mode of operation involving rotation of the internal cutting member only. In general, there is a need for a practical way of enabling and disabling coupling of a member in a personal care appliance to a motor of the appliance according to desire, possibly combined with continuously maintaining a coupling between the motor and at least one other member of the appliance. In this respect, it is an object of the invention to provide an adjustable transmission system which is designed to selectively transmit a motion, particularly a rotational motion, of one member to another member.

[0011] SUMMARY OF THE INVENTION

[0012] The invention provides an adjustable transmission system comprising a primary member and a secondary member and being configured to selectively transmit a rotational motion of the primary member about a rotational axis to the secondary member, to cause the secondary member to selectively rotate about the rotational axis, wherein: the transmission system further comprises a coupling member which is configured to selectively be in first and second axial positions relative to the primary member, seen in a direction in which the rotational axis extends, when the rotational motion of the primary member is in a main direction about the rotational axis; in the first and second axial positions of the coupling member, the coupling member is, respectively, decoupled from and coupled to the secondary member to, respectively, prevent and allow transmission of a rotational motion of the coupling member about the rotational axis to the secondary member; one of the primary member and the coupling member has a pattern of guiding channels which are engaged by a guided element provided on the other of the primary member and the coupling member; the pattern of guiding channels is configured to maintain the guided element in a first end position and a second end position within the pattern of guiding channels under the influence of the rotational motion of the primary member in the main direction when the coupling member is in, respectively, the first axial position and the second axial position, so as to enable transmission of rotation of the primary member to the coupling member by engagement of the guided element with the pattern of guiding channels; to cause movement of the coupling member relative to the primary member from the first axial position to the second axial position, the guided element is displaceable within the pattern of guiding channels from the first end position to a first intermediate position within the pattern of guiding channels by a temporary rotational motion of the primary member about the rotational axis in a direction opposite to the main direction, and the guided element is subsequently displaceable within the pattern of guiding channels from the first intermediate position to the second end position by a resumed rotational motion of the primary member in the main direction; and to cause movement of the coupling member relative to the primary member from the second axial position to the first axial position, the guided element is displaceable within the pattern of guiding channels from the second end position to a second intermediate position within the pattern of guiding channels by a temporary rotational motion of the primary member about the rotational axis in the direction opposite to the main direction, and the guided element is subsequently displaceable within the pattern of guiding channels from the second intermediate position to the first end position by a resumed rotational motion of the primary member in the main direction.

[0013] It follows from the definition of the adjustable transmission system according to the invention that the transmission system comprises a primary member, a secondary member and a coupling member, wherein the coupling member is functional to selectively decouple from or couple to the secondary member. All of the members are rotatable about a rotational axis, and the coupling member is also movable in a direction in which the rotational axis extends, which will hereinafter also be referred to as axial direction. Varying a coupling status of the coupling member is done through varying a position of the coupling member in the axial direction. A specific aspect of the invention is that actuating the coupling member to move from one coupling status to another is done by temporarily reversing the direction of the rotational motion of the primary member about the rotational axis, i.e. reversing the direction of the rotational motion of the primary member for only a short period of time, as a short pulse or kickback of the rotational motion of the primary member. This specific aspect of the invention is most advantageous, because having the functionality to change the coupling status of the coupling member through changing the direction of the rotational motion of the primary member implies that the coupling status of the coupling member can be changed simply by temporarily (shortly) reversing the driving direction in which a motor, associated with the transmission system, drives the primary member. As a result, there is no need for additional actuators and / or adjustment mechanisms actuated by an additional actuator to perform the functionality. In the context of personal care appliances, particularly handheld personal care appliances such as shavers comprising a handle accommodating the motor and a shaving unit accommodating driven components, this means that there is no need for an additional connection in the form of a shaft, electric wiring or the like on the interface between the handle and the shaving unit where space is limited. As a further advantageous consequence, the invention is easily applicable in existing appliances, wherein the design of the interface between the handle and the shaving unit can be left unchanged.

[0014] The functionality to change the coupling status of the coupling member through changing direction of motion is achieved on the basis of a specific design of the primary member and the coupling member. The fact is that one of the primary member and the coupling member has a pattern of guiding channels which are engaged by a guided element provided on the other of the primary member and the coupling member. The pattern of guiding channels is designed in such a way that the guided element is held at one of two end positions when the rotational motion is in a main direction, wherein a first end position is a decoupling end position which is associated with an axial position of the coupling member at which the coupling member is decoupled from the secondary member, and wherein a second end position is a coupling end position which is associated with an axial position of the coupling member at which the coupling member is coupled to the secondary member. Further, the pattern of guiding channels is designed such that when the direction of the rotational motion is reversed, the guided element is caused to move away from a respective end position and to reach an intermediate position, which is in fact a temporary end position. As soon as the direction of the rotational motion is reversed back to the main direction, the pattern of guiding channels causes movement of the guided element from the intermediate position to the other end position.

[0015] In order to enable a cycle in which the guided element moves from the first end position to the second end position via the first intermediate position, and back from the second end position to the first end position via the second intermediate position, it is practical if the guiding channels of the pattern of guiding channels are arranged to form a closed guiding track with curved guiding channel portions respectively defining the first end position, the first intermediate position, the second end position, and the second intermediate position.

[0016] In a practical embodiment, the transmission system further comprises an input member which is arranged to be jointly rotatable about the rotational axis with the primary member, wherein: the primary member comprises a cylindrical body provided with the pattern of guiding channels on its outer cylindrical surface; the input member comprises a hollow cylindrical shaft which is arranged coaxially with the cylindrical body, circumvents the cylindrical body and has a longitudinal guiding slot extending in the direction in which the rotational axis extends; the coupling member is arranged to coaxially circumvent the input member; and the guided element is provided on an inner surface of the coupling member and extends through the guiding slot of the input member into engagement with the pattern of guiding channels on the outer cylindrical surface of the cylindrical body.

[0017] In this embodiment, by engagement of the guided element with the guiding slot of the input member, the coupling member is jointly rotatable about the rotational axis with the input member and is guided relative to the input member in the axial direction. Thereby the input member may provide a stable support of the coupling member in any axial position of the coupling member. At the same time, the input member and the primary member are mutually coupled to be jointly rotatable about the rotational axis by engagement of the guided element with the guiding slot of the input member and the pattern of guiding channels in the cylindrical body of the primary member. Thereby, the input member may be configured to be directly connected to a motor for driving the transmission system, e.g., for arrangement on an output shaft of the motor, and the rotation of the input member may be transferred to both the coupling member and the primary member via the guided element. Effective functioning of the embodiment of the transmission system comprising the input member is obtained if a position of the primary member relative to a position of the input member is fixed in the axial direction. The guided element may comprise a cylindrical pin extending inwardly from the inner surface of the coupling member and engaging the guiding slot of the input member with substantially no mechanical play seen in the rotational direction of the input member. It is noted that, in alternative embodiments of the transmission system according to the invention, the input member as described here before may be absent. In such alternative embodiments, the coupling member may be arranged directly around the primary member, and the primary member may be directly connected to a motor for driving the transmission system.

[0018] In the context of the invention, the ability of the coupling member to couple to the secondary member may be realized in any suitable way. For example, it is possible that the coupling member comprises teeth at a side facing the secondary member, and that the secondary member comprises slots at a side facing the coupling member for receiving and accommodating the teeth of the coupling member when the coupling member is in the second axial position.

[0019] A practical design of the secondary member, in which the secondary member is suitable to be used to transmit a rotational motion to one or more further components to be coupled to the transmission system, is a design in which the secondary member comprises a gear wheel.

[0020] It follows from the foregoing that the invention provides an adjustable transmission system comprising a primary member, a secondary member, and a coupling member, wherein the coupling member is configured to selectively be in first and second axial positions relative to the primary member. It is to be noted that the invention includes embodiments of the transmission system in which at least one further axial position of the coupling member relative to the primary member can be set, and in which this can be done on the basis of the mechanism defined and explained in the foregoing, i.e., the mechanism which is actuated by temporary reversal of the direction of the rotational motion of the primary member about the rotational axis. For example, starting from the principle of setting the first and second axial positions of the coupling member relative to the primary member by relying on engagement of the guided element with the pattern of guiding channels as described here before, it is possible to have an extended design of the pattern of guiding channels enabling at least one further intermediate position and at least one further end position of the guided element within the pattern of guiding channels.

[0021] The invention further relates to a personal care appliance comprising a motor and an embodiment of the adjustable transmission system as defined and described here before, wherein the primary member of the transmission system is coupled to an output shaft of the motor. The primary member may be directly coupled to the output shaft of the motor. In embodiments of the personal care appliance comprising an embodiment of the adjustable transmission system having the input member as described here before, the primary member is coupled to the output shaft via the input member. For the purpose of enabling variation of the coupling status of the coupling member of the transmission system according to desire of a user of the personal care appliance, it is advantageous if the personal care appliance further comprises a user interface and a controller configured to temporarily reverse a rotational motion of the output shaft of the motor in response to user input by means of the user interface representing a command to do so.

[0022] One possible application of the adjustable transmission system is an application in an electric shaver comprising at least one hair-cutting unit having an internal cutting member and an external cutting member, wherein rotation of both the internal cutting member and the external cutting member is possible, and wherein it is desirable to have an option to rotate the internal cutting member and not rotate the external cutting member. In such a case, it is practical if the secondary member of the transmission system is coupled to the external cutting member to selectively rotate the external cutting member in the hair-cutting unit. Further, in such a case, it is possible that the primary member or the optional input member of the transmission system is coupled to the internal cutting member to rotate the internal cutting member relative to the external cutting member.

[0023] The above-described and other aspects of the invention will be apparent from and elucidated with reference to the following detailed description of an embodiment of an adjustable transmission system comprising four members, namely, a primary member, a secondary member, a coupling member, and an input member.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Fig. 1 diagrammatically shows an exploded view of an adjustable transmission system according to an embodiment of the invention, comprising a primary member, a secondary member, a coupling member, and an input member; Fig. 2 diagrammatically shows an assembled status of the transmission system, with the coupling member at a first axial position relative to the primary member and the input member, in which the coupling member is decoupled from the secondary member;

[0027] Fig. 3 diagrammatically shows an assembled status of the transmission system, with the coupling member at a second axial position relative to the primary member and the input member, in which the coupling member is coupled to the secondary member;

[0028] Fig. 4 diagrammatically shows the primary member; and

[0029] Figs. 5 and 6 illustrate application of the transmission system in a shaving unit of an electric shaver, wherein Fig. 5 shows the transmission system with the coupling member decoupled from the secondary member, and wherein Fig. 6 shows the transmission system with the coupling member coupled to the secondary member.

[0030] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Figs. 1-3 show an adjustable transmission system 1 according to an embodiment of the invention, wherein Fig. 1 shows an exploded view of the transmission system 1, and Figs. 2 and 3 show an assembled status of the transmission system 1. The transmission system 1 comprises four members, namely, a primary member 10, a secondary member 20, a coupling member 30, and an input member 40. The primary member 10 is separately shown in Fig. 4. All four members 10, 20, 30, 40 are rotatable about a rotational axis R. The input member 40 is configured to be coupled to a drive system (not shown) including a motor for imposing a rotational motion on the input member 40.

[0032] The transmission system 1 is functional to selectively transmit the rotational motion of the primary member 10 about the rotational axis Rto the secondary member 20, to cause the secondary member 20 to selectively rotate about the rotational axis R. In particular, the transmission system 1 is designed to do so without the use of any actuator in addition to the motor which is used to drive the input member 40. Aspects of the functionality of the transmission system 1 and aspects of the design of the respective members 10, 20, 30, 40 will now be described and elucidated.

[0033] In the present example, the input member 40 comprises a hollow cylindrical shaft 41 which is connectable to an output shaft of the motor of the drive system. The input member 40 and the primary member 10 are both axially journaled by means of a bearing member (not shown), so that they can each rotate about the rotational axis R and cannot mutually move in axial direction. The primary member 10 and the coupling member 30 are rotationally connected to the input member 40, so that the primary member 10 and the coupling member 30 can jointly rotate with the input member 40 when the input member 40 is connected to the output shaft of the motor and the motor is running. The coupling member 30 is arranged to coaxially circumvent the input member 40 and to be axially shifted over the hollow cylindrical shaft 41 of the input member 40 for the purpose of being coupled to and decoupled from the secondary member 20, so that the secondary member 20 can be selectively driven by the motor and is thereby suitable to be used for selectively driving a function. For the purpose of enabling the coupling member 30 to be selectively coupled to and decoupled from the secondary member 20, the primary member 10 and the coupling member 30 comprise a mechanism resembling a pen-click mechanism. The primary member 10 comprises a cylindrical body 11, and a particular pattern of guiding channels 12 is provided on an outer cylindrical surface of the cylindrical body 11 of the primary member 10, as can be seen in Fig. 4. The cylindrical body 11 is arranged coaxially with the hollow cylindrical shaft 41 of the input member 40 and is circumvented by the hollow cylindrical shaft 41. The pattern of guiding channels 12 is engaged by a guided element 31 in the form of a pin which is provided on an inner surface of the coupling member 30. The position of the guided element 31 is indicated in Fig. 1. The guided element 31 extends through an axially extending longitudinal guiding slot 42 which is provided in the hollow cylindrical shaft 41 of the input member 40. The coupling member 30 is rotationally coupled to the input member 40 by engagement of the guided element 31 and the guiding slot 42. With reference to Fig. 4, it is noted that when the guided element 31 engages the pattern of guiding channels 12 in a first end position A on the primary member 10, the coupling member 30 is at a first axial position with respect to the primary member 10 in the transmission system 1, which is below and at an axial distance from the secondary member 20. In this first axial position, the coupling member 30 is decoupled from the secondary member 20, as shown in Fig. 2. When the guided element 31 engages the pattern of guiding channels 12 in a second end position B on the primary member 10, the coupling member 30 is at a second axial position with respect to the primary member 10 in the transmission system 1, at which position the coupling member 30 is coupled to the secondary member 20, as shown in Fig. 3, and thereby continuously transmits the rotational motion of the input member 40 and the primary member 10 to the secondary member 20. In this respect it is noted that, in each of the first and second end positions A and B of the guided element 31, the primary member 10 and coupling member 30 are rotationally coupled by the engagement of the guided element 31 with the pattern of guiding channels 12. In the present example, the coupling member 30 engages the secondary member 20 by means of teeth 32 which are provided at a side of the coupling member 30 facing the secondary member 20. In the coupled condition the teeth 32 of the coupling member 30 are received and accommodated by slots 21 which are provided at a side of the secondary member 20 facing the coupling member 30.

[0034] When the input member 40 is rotated in a main rotational direction as indicated in Figs. 2 and 3 by means of a curved arrow, the guided element 31 of the coupling member 30 is held either in the first end position A or the second end position B within the pattern of guiding channels 12 on the primary member 10. With the guided element 31 at one of those end positions A, B, the rotational motion of the input member 40 is transmitted to the primary member 10 by the engagement of the guided element 31 with the pattern of guided channels 12. For the purpose of moving the guided element 31 from one of the end positions A, B on the primary member 10 to the other, the direction of the rotational motion of the input member 40 and the primary member 10 is shortly reversed, as a result of which the guided element 31 is released to move to one of two intermediate positions C, D in the pattern of guiding channels 12. After having reached a respective intermediate position C, D, the guided element 31 is released to move to a respective end position A, B by resuming the main rotational direction of the input member 40 and the primary member 10, which is another end position A, B than the initial one. Movement of the guided element 31 in the pattern of guiding channels 12 is stopped as soon as the guided element 31 reaches the respective end position A, B and is caught there.

[0035] A path via which the guided element 31 moves in the pattern of guiding channels 12 on the primary member 10 is indicated by means of arrows in Fig. 4. Movement of the guided element 31 from the first end position A via the first intermediate position C to the second end position B corresponds with an axial displacement of the coupling member 30 over the hollow cylindrical shaft 41 of the input member 40 from the first axial position relative to the primary member 10 as shown in Fig. 2 to the second axial position relative to the primary member 10 as shown in Fig. 3. Movement of the guided element 31 from the second end position B via the second intermediate position D to the first end position A corresponds with an axial displacement of the coupling member 30 over the hollow cylindrical shaft 41 of the input member 40 from the second axial position relative to the primary member 10 as shown in Fig. 3 to the first axial position relative to the primary member 10 as shown in Fig. 2. As shown in Fig. 4, to enable a cyclic transition of the guided element 31 between the first and second end positions A and B, the guiding channels of the pattern of guiding channels 12 form a closed guiding track, and the pattern of guiding channels comprises a respective curved guiding channel portion at each of the first end position A, the first intermediate position C, the second end position B and the second intermediate position D. It follows from the above explanation that to selectively activate or deactivate the function driven by the secondary member 20 by engaging or disengaging the coupling member 30 with or from the secondary member 20, the motor driving the input member 40 of the transmission system 1 needs only to be shortly rotated in the direction opposite to the main rotational direction indicated by the arrows in Figs. 2 and 3, as an advantageous result of which no further actuator is required to enable this coupling and decoupling.

[0036] Figs. 5 and 6 illustrate one of many possible applications of the adjustable transmission system 1 according to the invention, namely an application in a shaving unit 2 of an electric shaver in which hair-cutting units 3 including a functional assembly of an internal cutting member 4 and an external cutting member 5 are present. In each of the hair-cutting units 3, both the internal cutting member 4 and the external cutting member 5 are rotatable about a rotation axis R’ of the hair-cutting unit 3, wherein the transmission system 1 is used to selectively rotate the external cutting member 5 of each hair-cutting unit 3. For this purpose, the secondary member 20 of the transmission system 1 is coupled to the external cutting member 5 of each hair-cutting unit 3. In the present example, the secondary member 20 of the transmission system 1 comprises a gear wheel 22 and the external cutting member 5 of each hair-cutting unit 3 comprises a toothed rim 6, wherein the gear wheel 22 of the secondary member 20 of the transmission system 1 is coupled to the toothed rim 6 of the external cutting member 5 of each haircutting unit 3 through a compound gear 7. When the transmission system 1 is in a configuration in which the coupling member 30 is decoupled from the secondary member 20, as illustrated in Fig. 5, the secondary member 20 including the gear wheel 22 is in an idle state, as a result of which the external cutting members 5 of the hair-cutting units 3 are stationary. If the transmission system 1 is in a configuration in which the coupling member 30 is coupled to the secondary member 20, as illustrated in Fig. 6, the secondary member 20 including the gear wheel 22 is rotated about the rotational axis R, so that the external cutting members 5 of the hair-cutting units 3 are each rotated about the rotational axis R’ of the respective hair-cutting unit 3. Changing the configuration of the transmission system 1 is done through realizing a short pulse of reversed input rotational motion to the transmission system 1, based on the functionality of the transmission system 1 as explained in the foregoing with reference to Figs. 1-4.

[0037] Further, in the present example, the input member 40 of the transmission system 1 comprises a gear wheel 43, and the gear wheel 43 of the input member 40 of the transmission system 1 is coupled to the internal cutting member 4 of each hair-cutting unit 3 through a respective gear wheel 8 which is arranged on a respective shaft 9 for supporting and rotating the respective internal cutting member 4. Thereby, the internal cutting members 4 of the hair-cutting units 3 are automatically driven to rotate about the rotation axes R’ when the input member 40 of the transmission system 1 is driven to rotate about the rotation axis R. All in all, application of the transmission system 1 in the shaving unit 2 of the electric shaver enables setting of a first condition of the hair-cutting units 3 in which both the internal cutting member 4 and the external cutting member 5 of each hair-cutting unit 3 are rotated, and a second condition of the hair-cutting units 3 in which only the internal cutting member 4 of each hair-cutting unit 3 is rotated. In Figs. 5 and 6, components of two hair-cutting units 3 are shown, which does not alter the fact that more than two hair-cutting units 3 may be present in the shaving unit 2. It is advantageous if the transmission system 1 is at a central position in the shaving unit 2, i.e. in a position in which the transmission system 1 is coupled to all of the respective hair-cutting units 3 to transmit rotational motion to the hair-cutting units 3, so that it suffices to apply a single transmission system 1 in the shaving unit 2.

[0038] In respect of Figs. 5 and 6 and the application of the transmission system 1 illustrated in the figures, it is noted that electric shavers comprising hair-cutting units 3 having an internal cutting member 4 and an external cutting member 5 are generally known, and that the skilled person has a full understanding of further components of such a type of electric shaver and shaving unit apart from the ones shown in the figures, such as a holder for the hair-cutting units 3 and the respective rotating parts, and a motor and other components making up a drive system, and is familiar with the fact that the shaving unit 2 is normally combined with a handle accommodating at least the motor.

[0039] Instead of the selective rotation of the external cutting members 5 of the hair-cutting units 3, other possible applications of the transmission system 1 in the context of an electric shaver are applications relating to: exposure adjustment of an external cutting member 5 in a hair-cutting unit 3, in which case the exposure can be varied by displacing the external cutting member 5 in a direction parallel to the rotational axis R’ of the internal cutting member 4, contour following, in which case the contour following can be enabled and disabled by releasing components which are functional in the contour following and retaining those components, respectively, and operation of an arrangement for performing an additional function, such as a beard styler, in which case the arrangement can be turned on and off.

[0040] 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, and that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. It is intended that the invention be construed as including all such amendments and modifications insofar they come within the scope of the claims or the equivalents thereof. 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. The drawings are schematic, wherein details which are not required for understanding the invention may have been omitted, and not necessarily to scale.

[0041] 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. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0042] Elements and aspects discussed for or in relation with a particular embodiment may be suitably combined with elements and aspects of other embodiments, unless explicitly stated otherwise. 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.

[0043] The terms “comprise” and “include” as used in the present text will be understood by a person skilled in the art as covering the term “consist of’. Hence, the term “comprise” or “include” may in respect of an embodiment mean “consist of’, but may in another embodiment mean “contain / have / be equipped with at least the defined species and optionally one or more other species”.

[0044] Use in the present text of terms indicating a coupling between two items is to be understood so as to cover both direct engagement of the one item on the other and coupling of the items through at least one intermediate item in appropriate instances.

[0045] Notable aspects of the invention are summarized as follows. In the field of transmission of a rotational motion from one member to another, an adjustable transmission system 1 is provided which is configured to selectively transmit a rotational motion of a primary member 10 about a rotational axis R to a secondary member 20, to cause the secondary member 20 to selectively rotate about the rotational axis R. The transmission system 1 comprises a coupling member 30 which is configured to selectively be in first and second axial positions relative to the primary member 10, for decoupling from and coupling to the secondary member 20, respectively, wherein the primary member 10 is configured to enable displacement of the coupling member 30 in axial direction on the basis of changes of the direction of the rotational motion, and wherein use is made of a pattern of guiding channels 12 which are engaged by a guided element 31.

Claims

CLAIMS:Claim 1. An adjustable transmission system (1) comprising a primary member (10) and a secondary member (20) and being configured to selectively transmit a rotational motion of the primary member (10) about a rotational axis (R) to the secondary member (20), to cause the secondary member (20) to selectively rotate about the rotational axis (R), wherein: the transmission system (1) further comprises a coupling member (30) which is configured to selectively be in first and second axial positions relative to the primary member (10), seen in a direction in which the rotational axis (R) extends, when the rotational motion of the primary member (10) is in a main direction about the rotational axis (R); in the first and second axial positions of the coupling member (30), the coupling member (30) is, respectively, decoupled from and coupled to the secondary member (20) to, respectively, prevent and allow transmission of a rotational motion of the coupling member (30) about the rotational axis (R) to the secondary member (20); one of the primary member (10) and the coupling member (30) has a pattern of guiding channels (12) which are engaged by a guided element (31) provided on the other of the primary member (10) and the coupling member (30); the pattern of guiding channels (12) is configured to maintain the guided element (31) in a first end position (A) and a second end position (B) within the pattern of guiding channels (12) under the influence of the rotational motion of the primary member (10) in the main direction when the coupling member (30) is in, respectively, the first axial position and the second axial position, so as to enable transmission of rotation of the primary member (10) to the coupling member (30) by engagement of the guided element (31) with the pattern of guiding channels (12); to cause movement of the coupling member (30) relative to the primary member (10) from the first axial position to the second axial position, the guided element (31) is displaceable within the pattern of guiding channels (12) from the first end position (A) to a first intermediate position (C) within the pattern of guiding channels (12) by a temporary rotational motion of the primary member (10) about the rotational axis (R) in a direction opposite to the main direction, and the guided element (31) is subsequently displaceable within the pattern of guiding channels (12) from the first intermediate position(C) to the second end position (B) by a resumed rotational motion of the primary member (10) in the main direction; and to cause movement of the coupling member (30) relative to the primary member (10) from the second axial position to the first axial position, the guided element (31) is displaceable within the pattern of guiding channels (12) from the second end position (B) to a second intermediate position(D) within the pattern of guiding channels (12) by a temporary rotational motion of the primary member(10) about the rotational axis (R) in the direction opposite to the main direction, and the guided element (31) is subsequently displaceable within the pattern of guiding channels (12) from the second intermediate position (D) to the first end position (A) by a resumed rotational motion of the primary member (10) in the main direction.Claim 2. The transmission system (1) as claimed in claim 1, wherein the guiding channels of the pattern of guiding channels (12) are arranged to form a closed guiding track with curved guiding channel portions respectively defining the first end position (A), the first intermediate position (C), the second end position (B), and the second intermediate position (D).Claim 3. The transmission system (1) as claimed in claim 1 or 2, further comprising an input member (40) which is arranged to be jointly rotatable about the rotational axis (R) with the primary member (10), wherein: the primary member (10) comprises a cylindrical body (11) provided with the pattern of guiding channels (12) on its outer cylindrical surface; the input member (40) comprises a hollow cylindrical shaft (41) which is arranged coaxially with the cylindrical body (11), circumvents the cylindrical body (11) and has a longitudinal guiding slot (42) extending in the direction in which the rotational axis (R) extends; the coupling member (30) is arranged to coaxially circumvent the input member (40); and the guided element (31) is provided on an inner surface of the coupling member (30) and extends through the guiding slot (42) of the input member (40) into engagement with the pattern of guiding channels (12) on the outer cylindrical surface of the cylindrical body (11).Claim 4. The transmission system (1) as claimed in claim 3, wherein a position of the primary member (10) relative to a position of the input member (40) is fixed in the direction in which the rotational axis (R) extends.Claim 5. The transmission system (1) as claimed in any of claims 1-4, wherein the coupling member (30) comprises teeth (32) at a side facing the secondary member (20), and wherein the secondary member (20) comprises slots (21) at a side facing the coupling member (30) for receiving and accommodating the teeth (32) of the coupling member (30) when the coupling member (30) is in the second axial position.Claim 6. The transmission system (1) as claimed in any of claims 1-5, wherein the secondary member (20) comprises a gear wheel (22).15Claim 7. A personal care appliance comprising a motor and the transmission system (1) as claimed in any of claims 1-6, wherein the primary member (10) of the transmission system (1) is coupled to an output shaft of the motor.Claim 8. The personal care appliance as claimed in claim 7, further comprising a user interface and a controller configured to temporarily reverse a rotational motion of the output shaft of the motor in response to user input by means of the user interface representing a command to do so.Claim 9. The personal care appliance as claimed in claim 7 or 8, being an electric shaver comprising at least one hair-cutting unit (3) having an internal cutting member (4) and an external cutting member (5), wherein the secondary member (20) of the transmission system (1) is coupled to the external cutting member (5) to selectively rotate the external cutting member (5) in the hair-cutting unit (3).Claim 10. The personal care appliance as claimed in claim 9, wherein the primary member (10) of the transmission system (1) is coupled to the internal cutting member (4) to rotate the internal cutting member (4) relative to the external cutting member (5).Claim 11. The personal care appliance as claimed in claim 7 or 8, wherein the transmission system (1) is as claimed in claim 3 or 4, and wherein the personal care appliance is an electric shaver comprising at least one hair-cutting unit (3) having an internal cutting member (4) and an external cutting member (5), wherein the secondary member (20) of the transmission system (1) is coupled to the external cutting member (5) to selectively rotate the external cutting member (5) in the hair-cutting unit (3), and wherein the input member (40) of the transmission system (1) is coupled to the internal cutting member (4) to rotate the internal cutting member (4) relative to the external cutting member (5).

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