Motion transducer and drive unit equipped with motion transducer

Abstract

Motion transducers (5A, 5B, 5C, 5D, 8C) configured to convert rotational motion provided by motor shafts (31A, 31B, 31, 3) into linear reciprocating motion of drive shafts (70A, 70B, 70D). The motion transducers (5A, 5B, 5C, 5D, 8C) consist of a deformable part (50A, 50B, 50C, 50D, 8C), a mounting part (60A, 60B, 60D) connected to the deformable part (50A, 50B, 50C, 50D, 8C), and a coupling part (59A, 59B, 59C, 59D, 8A) connected to the deformable part (50A, 50B, 50C, 50D, 8C), and drive shafts (70A, 70B, A coupling portion (59A, 59B, 59C, 59D, 8A) configured to receive a 70D) or comprising a drive shaft (70A, 70B, 70D), and a connector portion (8A, 8B, 8C, 8D) connected to a deformable portion (50A, 50B, 50C, 50D, 8C), which receives the first eccentric shaft element (41A, 41B, 41D) of the motor shaft (31A, 31B, 31, 3) A first essentially U-shaped receiving part (90E) having a U-shaped base and two U-shaped legs that together define a first elongated hole (804B, 805B, 814B, 902E) having a length (l), width and height, and the first elongated hole (804B, 805B, 814B, 902E) having a U-shaped base and two U-shaped legs configured to allow the first elongated hole (804B, 805B, 814B, 902E) to be extended over the width and height of the first elongated hole (804B, 805B, 814B, 902E The connector portion (8A, 8B, 8C, 8D) comprises a first reinforcing element (903E) that connects two U-shaped legs of a first essentially U-shaped receiving portion (90E) at their free ends, so as to provide access to the first reinforcing element (903E), preferably the first reinforcing element (903E) being bar-shaped, U-shaped, or O-shaped, and its length (l) being measured from the inner surface of the U-shaped base to the free end of the U-shaped leg.

Description

Technical Field

[0001] The present disclosure relates to a motion converter and a drive unit including the motion converter. The motion converter is intended to receive the rotational motion of a motor shaft and provide a linear reciprocating motion in a drive shaft, and the drive unit including a motor and a drive shaft can be disposed within a handle section of a personal care device and can be used to drive a head of the personal care device.

Background Art

[0002] Converting the rotational motion provided by the shaft of a DC motor into an oscillating motion using a suitable gear mechanism, such as a four-bar linkage, is generally known and is described in German Patent Application Publication No. 3937854 (A1). German Patent No. 3430562 (C1) describes a device for converting the rotational motion of an eccentric body driven by a motor shaft into a reciprocating motion of a working tool of a small electric appliance driven electrically. The described conversion mechanism includes an eccentric body and a connecting rod connected to a first lever arm of a double-arm rocker lever. The connecting rod includes a film hinge, and the central axis of the film hinge intersects the longitudinal axis of the first lever arm. The first lever arm is designed to be elastically twisted about its longitudinal axis. The double-arm rocker lever is pivotally attached to the housing of the electric appliance and further includes a shaft pin coupled to the working tool. During operation, the shaft pin moves in a rocking wiping motion with respect to the pivot mount of the double-arm rocker lever.

[0003] A drive unit for converting the rotational motion of a motor shaft into a reciprocating linear motion of a drive shaft of the drive unit may include a motion converter. A drive unit including a motion converter is described in co-pending European Patent Application Publications No. 21158962.7 and No. 22156286.1.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] German Patent Application Publication No. 3937854(A1) [Patent Document 2] German Patent No. 3430562 (C1) [Patent Document 3] European Patent Application Publication No. 21158962.7 [Patent Document 4] European Patent Application Publication No. 22156286.1 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of this disclosure is to provide a motion transducer and a drive unit equipped with the motion transducer, specifically a plastic injection-molded motion transducer, the motion transducer having a structure that allows for easy manufacturing. The object of this disclosure is also to provide a method for manufacturing a motion transducer for a drive unit by plastic injection molding. [Means for solving the problem]

[0006] According to at least one embodiment, a motion transducer is provided configured to convert rotational motion provided by a motor shaft into linear reciprocating motion of a drive shaft, the motion transducer comprising: a deformable portion; a mounting portion connected to the deformable portion; a coupling portion connected to the deformable portion, configured to receive or comprising a drive shaft; a connector portion connected to the deformable portion, configured to receive a first eccentric shaft element of a motor shaft, and having a U-shaped base and two U-shaped legs that together define a first elongated hole having length, width and height; and a first reinforcing element connecting the two U-shaped legs of the first essentially U-shaped receiver at their free ends so as to provide access to the first elongated hole across the width and height of the first elongated hole; preferably, the first reinforcing element is bar-shaped, U-shaped, or O-shaped, and its length is measured from the inner surface of the U-shaped base to the free ends of the U-shaped legs; and a connector portion.

[0007] According to at least one embodiment, a drive unit is provided comprising a proposed motion transducer, the drive unit comprising: a drive shaft connected to a coupling and providing linear reciprocating motion during operation; a motor having a motor shaft and providing rotational motion about a longitudinal central axis of the motor shaft during operation; and a motor shaft extension coupled to or connected to the motor shaft, the motor shaft extension comprising at least a first eccentric shaft element positioned eccentrically with respect to the longitudinal central axis so as to move along a circular path about the longitudinal central axis during operation, wherein the first eccentric shaft element extends through the first elongated hole along the height direction of the first elongated hole, the first eccentric shaft element has a diameter that fits tightly into the first elongated hole in the width direction of the first elongated hole, and the first eccentric shaft element is able to move freely within the first elongated hole in the length direction of the first elongated hole during operation.

[0008] According to at least one embodiment, a personal care device is provided comprising a proposed drive unit, wherein the head section is coupled to a drive shaft, and the head section or a driven element of the head section is driven to a forward-backward motion such as a rocking motion or a reciprocating motion during operation, optionally, the mounting portion of the motion transducer is fixedly mounted to the motor, and further optionally, during operation, the circular motion of at least a first eccentric shaft element causes a periodic force to be transmitted to a deformable portion to at least a first essentially U-shaped receiving portion, thereby causing the deformable portion to deform periodically, preferably, the periodic deformation means periodic deformation in the z direction and periodic deformation in the y direction perpendicular to the z direction with a 180-degree phase shift. [Brief explanation of the drawing]

[0009] This disclosure will be further clarified by a detailed description of exemplary embodiments and reference to the figures. [Figure 1] This is a diagram of a personal care device implemented as an electric toothbrush, comprising a handle section and a head section, the head section comprising a driven element that is implemented as a personal care head. [Figure 2] This is a cutaway, open upper view of the handle section of a personal care device having an exemplary drive unit as described herein. [Figure 3] This is a diagram of an exemplary drive unit according to the present disclosure, in which the deformable portion may be made from a bent sheet metal at least partially. [Figure 4A] This is a perspective view of an exemplary motion transducer implemented according to this proposal. [Figure 4B] Figure 4A is a side view of the motion transducer shown. [Figure 5] Figures 4A and 4B are enlarged views of the central part of the motion transducer. [Figure 6A] This is an exemplary side view of a drive unit relating to the present disclosure, which comprises a proposed motion transducer. [Figure 6B] Figure 6A is a cross-sectional view of the drive unit. [Figure 6C]This is an enlarged view of section A of the cross-sectional view in Figure 6B. [Figure 7] This is a detailed diagram of an exemplary receiving portion of the connection part relating to this disclosure. [Modes for carrying out the invention]

[0010] In the context of this specification, “personal care” means the grooming (or care) of the skin and its appendages (i.e., hair and nails) and the teeth and oral cavity (including the tongue, gums, etc.), aiming, on the one hand, to prevent disease and maintain and enhance health, and on the other hand, to provide cosmetic treatment and improve the appearance of the skin and its appendages. This includes maintaining and enhancing well-being. This includes skin care, hair care, oral care, and nail care. This further includes grooming procedures such as beard care, shaving, and hair removal. Accordingly, “personal care device” means any device for performing such grooming or grooming procedures, e.g., (cosmetic) skin treatment devices such as skin massage devices or skin brushes; wet razors; electric shavers or trimmers; electric hair removal devices; and oral care devices such as manual or electric toothbrushes, (electric) flossers, (electric) scrubbers, (electric) tongue cleaners, or (electric) gum massagers. The terms in parentheses indicate that this is an optional feature. This does not preclude the proposed personal care device from having a more significant advantage in one or more of these growth or device areas than in one or more other areas. In this specification, an electric toothbrush has been chosen to represent a personal care device. Unless the details are specific to an electric toothbrush, the proposed techniques and concepts can be used in any other personal care device.

[0011] This disclosure relates to a motion transducer, a drive unit having such a motion transducer, and a personal care device equipped with such a drive unit.

[0012] The motion transducer is configured to convert rotational motion provided by the motor shaft of a drive or motor, such as a DC motor, into linear reciprocating motion, preferably such that the direction of the linear reciprocating motion coincides with or is parallel to the longitudinal central axis of the motor shaft. The motion transducer is configured to receive at least a first eccentric shaft element of a motor shaft extension connected to the motor shaft, and to receive a drive shaft. The motor shaft extension may be a separate part that can be detachably attached to the motor shaft, or the motor shaft extension may be integral with the motor shaft. The motion transducer has a mounting portion for fixing the motion transducer to or to a motor in a personal care device, a coupling portion for receiving a drive shaft, a connector portion configured to receive at least a first eccentric shaft element, and a deformable portion connected to the connector portion, the mounting portion, and the coupling portion. The connector portion has a first essentially U-shaped receiving portion having a U-shaped base and two U-shaped legs that together define a first elongated hole opening at one end which is the opposite end of the U-shaped base. The first elongated hole has a length measured from the inner surface of the U-shaped base toward the free ends of the U-shaped legs, a width between the U-shaped legs, and a height, the height not having to be constant along the length of the elongated hole. See further considerations with respect to Figure 7 below. The width should be constant at least along the length of the U-shaped first elongated hole through which the eccentric shaft element moves during operation. A first reinforcing element is provided connecting the free ends of the U-shaped legs so that longitudinal access to the first elongated hole is possible across its entire width and height. The first reinforcing element may be essentially bar-shaped, U-shaped, or O-shaped, but other shapes are possible as long as they perform the function of the reinforcing element, namely connecting the free ends of the U-shaped legs of the receiving part and enabling full longitudinal access to the elongated hole. The width of the first elongated hole may be set so that the first eccentric shaft element described above fits tightly into the first elongated hole in the width direction. The first eccentric shaft element may have a cylindrical shape that extends in the height direction through the first elongated hole and has a diameter that is essentially the same as the width of the first elongated hole.The connector part includes a second substantially U-shaped receiving part for receiving the second and third eccentric shaft elements respectively, and optionally may also include a third substantially U-shaped receiving part. The above considerations regarding the first receiving part, the first elongated hole, the first reinforcing element, and the first eccentric shaft element also apply to all such elements having different numberings such as the second or third. Two, three, or more receiving parts may have a rest position where the respective elongated holes are at least aligned with each other in the width direction. The longitudinal directions of the elongated holes are parallel to each other. Each of the receiving parts may be connected to an arm element. For example, the first arm element may be connected to the first substantially U-shaped receiving part, and that arm element may subsequently be connected to the deformable part, whereby the movement transmitted from the eccentric shaft element to the receiving part is transmitted by the arm element to the deformable part. In some examples, the arm elements of two or more aligned receiving parts may be combined to transmit the movement of the two or more aligned receiving parts to the deformable part via a single joint arm element. The structure of the two joint arm elements may be essentially like a tuning fork.

[0013] The deformable part may be configured to deform such that when the drive shaft is connected to the coupling part, the periodic force applied to the deformable part by the arm element results in a linear reciprocating motion of the coupling part and thus the drive shaft. To achieve this, the deformable part may have a generally convex quadrilateral-shaped structure such as a rhombus structure having four edges and four vertices, and the mounting part and the coupling part may be provided at two opposite vertices of the convex quadrilateral-shaped structure. The connector part may be connected by at least one of the two other vertices, preferably both of the two other substantially opposite vertices, and one or more of the above-mentioned arm elements.

[0014] The above-mentioned U-shaped receiving part, and preferably the entire motion converter, can be manufactured by plastic injection molding. In this case, in order to define the U-shaped elongated hole of the receiving part, it is sufficient to provide two molds divided into halves that move together in the longitudinal direction of the receiving part because no additional core is required due to the position of the reinforcing element.

[0015] The term "U-shaped" should be understood to refer to the inner shape of the receiving portion that defines the elongated hole. The receiving portion may have an outer shape different from the U-shape.

[0016] The receiving portion can also be described with reference to a Cartesian coordinate system having an x-axis, a y-axis, and a z-axis, where the length direction is parallel to the x-axis, the width direction is parallel to the y-axis, and the height direction is parallel to the z-axis. The terms axis and direction are used synonymously in this disclosure. In this case, the reinforcing element may extend in a plane parallel to the y-z plane, but it is not excluded that the reinforcing element may be curved, specifically may have a curvature in the length direction. With respect to the directions defined by such a Cartesian coordinate system, the first and / or further eccentric shaft elements rotate along a circular path around the longitudinal central axis of the motor shaft, i.e., around the longitudinal central axis, which is parallel to the z-axis, which means that the movement of the first and further eccentric shaft elements, i.e., the circular movement, occurs essentially in the x-y plane. The elongated hole of the receiving portion is configured as described above, and thus the receiving portion is moved by the x-direction movement of each eccentric shaft element, while the y-direction movement occurs freely within the elongated hole and does not move the receiving portion. The arm element of the receiving portion may generally extend in the y-direction, and those skilled in the art will understand that each element described herein is originally a three-dimensional shape and extends in all directions, but here, the relevant extending direction means the direction in which the arm element extends to connect the receiving portion to the deformable portion. The periodic movement of the arm element in the y-direction results in the deflection of the deformable portion in the y-direction. Due to the structure of the deformable portion, the periodic movement of the arm element also results in a periodic deformation in the z-direction as a result, which results in the periodic movement of the joint in the z-direction, i.e., the linear reciprocating movement of the joint in the z-direction.

[0017] The drive unit of this disclosure is available as a commercially available component and can therefore utilize a standard motor, such as a DC motor, which typically has a low-cost profile. To achieve the conversion described, the motor shaft comprises a motor shaft extension comprising at least a first eccentric shaft element positioned eccentrically with respect to the longitudinal central axis of the motor shaft, so that during operation, the first eccentric shaft element moves along a circular path around the longitudinal central axis of the motor shaft, the circle extending in a plane being perpendicular to the longitudinal central axis. The motor shaft extension may be integral with the motor shaft or may be a separate component detachably or indetachably connected to the motor shaft. The motor shaft extension may comprise two, three, or more eccentric shaft elements positioned behind each other with respect to the direction defined by the longitudinal central axis, i.e., behind each other in the z-direction. The first eccentric shaft element is intended to extend through a first elongated hole in a first essentially U-shaped receiving portion, while the second eccentric shaft element is intended to extend through a second elongated hole in a second essentially U-shaped receiving portion, and so on. In the drive unit, the first eccentric shaft element extends through the first elongated hole in the height direction, i.e., the z direction, which coincides with the direction defined by the longitudinal central axis; optionally, the second eccentric shaft element similarly extends through a second elongated hole; and optionally, the third eccentric shaft element extends through a third elongated hole.

[0018] The first and second eccentric shaft elements may be arranged to rotate around a longitudinal central axis with a 180-degree angular offset during operation. A third eccentric shaft element may subsequently be arranged to move in alignment with the first eccentric shaft element. The first arm connecting the first essentially U-shaped receiving portion to the deformable portion and the third arm connecting the third essentially U-shaped receiving portion to the deformable portion may be joined in front of the point where the joining arms connect to the deformable portion.

[0019] The disclosure also relates to a personal care device comprising a drive unit as described above. The personal care device may comprise a head section coupled to a drive shaft, the head section or a driven element of the head section being driven to a forward-backward motion such as a rocking motion or a reciprocating motion during operation, optionally, a mounting portion of the motion transducer being fixedly mounted to the motor, and further optionally, during operation, the circular motion of at least a first eccentric shaft element causes a periodic force to be transmitted to a deformable portion to at least a first essentially U-shaped receiving portion, thereby causing the deformable portion to deform periodically, preferably, the periodic deformation means periodic deformation in the z direction and periodic deformation in the y direction perpendicular to the z direction with a 180-degree phase shift. This means that if the deformation in the z direction results in an extension of the deformable portion in the z direction, the deformation of the deformable portion causes a contraction of the deformable portion in the y direction.

[0020] Figure 1 shows an exemplary personal care device 1 implemented as an electric toothbrush, the personal care device 1 comprising a head section 10 and a handle section 20, the head section 10 may comprise a driven element 11, which is here implemented as a brush head, or the head section may alternatively comprise a driven element, i.e., in this case, not only the driven element of the head section but the entire head section is driven and moves. If the head section 10 comprises a driven element 11, the head section 10 may comprise a connector element for releasably attaching the head section 10 to the handle section 20 such that at least the mounting portion of the head section 10 is fixed to the handle section 20. The head section 10 may be repeatedly detachable from and reattachable from the handle section 20 to allow cleaning of the head section 10, or to replace a worn head section with a new head section, or to replace a first type of head section with a different type of head section. The handle section 20 may comprise a drive unit, as considered herein, for driving and moving the driven element 11.

[0021] Figure 2 is a cutaway and open top view of the handle section 20A of a personal care device, which may be used as the handle section of a personal care device 1 as shown in Figure 1. The bottom of the handle section 20A is not shown. The handle section 20A comprises a handle housing 21A to which a motor carrier 22A is attached, and a mounting shaft 23A for detachably attaching the head section, as schematically shown in Figure 1. The handle section 20A also comprises a drive unit 25A, which is described below. The drive unit 25A comprises a motor 30A having a motor shaft 31A and a motor shaft extension 40A, a drive shaft 70A, and a motion transducer 5A. The motion transducer 5A comprises a deformable part 50A, a mounting part 60A, a coupling part 59A, and a connector part 8A. The motion transducer 5A may be a single, integrated element made, for example, by plastic injection molding, or the motion transducer 5A may comprise several elements fixed to one another, as considered in relation to Figure 3. It should be understood that some of the features shown in Figure 2 are optional and not mandatory according to this disclosure, as will be obvious to those skilled in the art. For example, the motor carrier 22A is optional, and the drive unit 25A may be directly attached to the handle housing 21A.

[0022] Motor 30A is fixed to motor carrier 22A, and motor 30A comprises a motor shaft 31A, which provides rotational motion R about the central longitudinal axis A of the motor shaft 31A. Motor shaft 31A is extended by a motor shaft extension 40A comprising a first eccentric shaft element 41A, a second eccentric shaft element 42A, and a third eccentric shaft element 43A in the illustrated embodiment. Since the three eccentric shaft elements 41A, 42A, and 43A are all shown at their central positions, their relative positions with respect to the longitudinal central axis A and to each other are not clearly visible in Figure 2; refer to Figure 3, which shows a perspective view. The motor shaft extension 40A may be integral with motor shaft 31A, or it may be an additional element that is removablely or permanently attached to motor shaft 31A. The first eccentric shaft element 41A and the third eccentric shaft element 43A have the same circumferential position around the longitudinal central axis A, while the second eccentric shaft element 42A has a circumferential position offset by 180 degrees relative to the first and third eccentric shaft elements 41A and 43A. During operation, the three eccentric shaft elements 41A, 42A, and 43A move along circles around the longitudinal central axis A, and these circles extend in a plane perpendicular to the longitudinal central axis A. The first and third eccentric shaft elements 41A and 43A are coupled to a first crossbeam 80A which has a first arm element and a third arm element that are joined to each other. Each of the eccentric shaft elements 41A, 42A, and 43A is coupled to its respective arm element by an elongated hole, the relationship of which will become clear from Figure 3 and the description relating to Figure 3. The first arm element is connected to the first eccentric shaft element 41A, and the third arm element is connected to the third eccentric shaft element 43A. Thus, the first and third eccentric shaft elements 41A and 43A cooperate as a single eccentric shaft element in the illustrated embodiment to cause the first crossbeam 80A to perform a periodic linear reciprocating motion along the first crossbeam direction perpendicular to the longitudinal central axis A.The second eccentric shaft element 42A is similarly coupled to the second crossbeam or second arm element 81A, and as the second eccentric shaft element 42A rotates around the longitudinal central axis A, the second eccentric shaft element 42A causes the second crossbeam or second arm element 81A to perform a periodic linear reciprocating motion along the second crossbeam axis, which is coincident with or at least parallel to the first crossbeam axis. The periodic circular motion of the first and third shaft elements 41A and 43A and the periodic circular motion of the second shaft element 42A are offset by 180 degrees, that is, when the first crossbeam 80A moves to the right, the second crossbeam 81A moves to the left, and vice versa (where left and right are defined with respect to the plane of the paper). The arm and crossbeam, together with the elongated hole described above, form a coupling 8A connected to the deformable portion 50A.

[0023] The first and second crossbeams 80A and 81A, i.e., the first, second, and third arms, are each connected to the deformable section 50A. The deformable section 50A is realized here as a rhombic structure having four edges and four vertices, but this should not be considered limiting. The rhombic structure is a particular case from a more general class of convex quadrilateral structures representing one class of possible realizations of the deformable section. The four edges of the rhombic structure are realized here by four arm sections 51A, 52A, 53A, and 54A. The first arm section 51A has a first end fixed to a mounting structure 60A, which is fixedly mounted here to or against the motor 30A. On the opposite side of the first arm section 51A of the rhomboid structure is a third arm section 53A having a first end, which is similarly fixed to a mounting structure 60A, so that the first end of the first arm section 51A and the first end of the third arm section 53A form the first vertex 55A of the rhomboid structure of the deformable section 50A. The second end of the first arm section 51A and the connection point, which are connected to the first end of the second arm section 52A at a generally obtuse angle, are considered to be the second vertex 56A of the rhomboid structure formed by the deformable section 50A (or the “knee section” resulting from the obtuse angle at which the first and second arm sections intersect). A joint 59A is connected to the second end of the second arm section 52A. The first end of the fourth arm section 54A, opposite to the second arm section 52A, is connected at an obtuse angle to the second end of the third arm section 53A, thereby forming a third vertex 57A (or further "knee section"). The second end of the second arm section 52A and the second end of the fourth arm section 54A are fixed to each other at a connecting element 59A, thereby forming a fourth vertex 58A.

[0024] The first crossbeam 80A, i.e., the first and third arms joined together, is connected to the second vertex 56A, and the second crossbeam 81A or the second arm is fixedly connected to the third vertex 57A, which is the vertex opposite to the second vertex 56A. When both the first and second crossbeams move outward or both move inward, the deformable part 50A deforms and the coupling part 59A enters a state of linear reciprocating motion along axis A1. When the two crossbeams 80A, 81A move outward, the coupling part 59A is pulled downward toward the motor 30A, and when the two crossbeams 80A, 81A move inward, the coupling part 59A moves upward toward the motor 30A, resulting in a periodic linear reciprocating motion M as indicated by the double-headed arrow, which occurs here along axis A1 parallel to the central longitudinal axis A, and the motor shaft 31A rotates along this axis A1 as indicated by the arrow R.

[0025] The four vertices 55A, 56A, 57A, and 58A can each be realized as an inherently rigid structure without hinge functionality. Subsequently, the arm sections 51A, 52A, 53A, and 54A must each be deformable from their inherently linear extensions, as shown in Figure 2 representing their natural or resting state, to a deformable state, for example, so that each of the arm sections 51A, 52A, 53A, and 54A can bulge inward or outward, or extend along an S-shaped curve between the respective vertices to which they connect. Since the arm sections 51A, 52A, 53A, and 54A can essentially be made from an elastic material such as spring steel or elastic plastic, the energy required to deform the arm sections 51A, 52A, 53A, and 54A is stored in the elastic material and released again when the arm sections 51A, 52A, 53A, and 54A are returned to their natural state.

[0026] The motor 30A, together with the motor shaft extension 40A, the drive shaft 70A, and the motion transducer 5A, forms the drive unit 25A according to this disclosure.

[0027] Figure 3 is a diagram of another exemplary drive unit 25B having various structural similarities to the drive unit 25A shown in Figure 2 and considered with reference to Figure 2. The drive unit 25B comprises a motion transducer 5B having a deformable portion 50B, a mounting portion 60B connected to the deformable portion, a coupling portion 59B connected to the deformable portion 50B, and a connector portion 8B connected to the deformable portion 50B. The drive unit 25B further comprises a motor 30B (partially shown) having a motor shaft 31B, a shaft extension portion 40B attached to the motor shaft 31B, and a drive shaft 70B connected to the coupling portion 59B. Here, the mounting portion 60B is fixedly attached to the motor 30B, but in other embodiments, the motor 30B and the mounting portion 60B may be attached to the same base structure (e.g., a handle of a personal care device) so as to be fixedly attached to each other. In general, the shaft extension 40B may be integrated with the motor shaft 31B, or it may be a separate element fixed to the motor shaft 31B. In the latter case, the shaft extension 40B may be snap-fitted to the motor shaft 31B, or it may be attached by friction lock, welding, bonding, or fixedly in any other way known to those skilled in the art. The drive unit 25B comprises a drive shaft 70B connected to a coupling 59B, the drive shaft 70B may be coupled to a driven element. The motor shaft 31B provides rotational motion about its longitudinal central axis, but this motion is converted by the motion transducer 5B of the drive unit 25B, and the drive shaft 70B instead provides periodic linear reciprocating motion along an axis that coincides with or is parallel to the longitudinal central axis of the motor shaft 31B (see Figure 2 for indications of each longitudinal central axis A). The shaft extension 40B also comprises first, second, and third eccentric shaft elements 41B, 42B, and 43B. The eccentric shaft elements 41B, 42B, and 43B are each offset with respect to the longitudinal central axis and therefore rotate around the longitudinal central axis along a circular path during operation, as also explained in Figure 2.Similarly, as described in Figure 2, the first and third eccentric shaft elements 41B and 43B have the same circumferential position and therefore move in alignment in position and angle, while the second eccentric shaft element 42B is positioned circumferentially with a 180-degree offset.

[0028] The first and third eccentric shaft elements 41B and 43B are connected to the deformable section 50B via a connector section 8B. The connector section 8B is here also fork-shaped and comprises a first crossbeam 80B realized by a first arm 801B and a third arm 802B that join together. The first and third arms 801B and 802B are here parallel to each other in the free end region, but this should not be understood as a limitation and any other structure can be similarly selected. The second eccentric shaft element 42B is connected to the deformable section 50B by a second crossbeam or second arm 81B of the connector section 8B. The first and second crossbeams 80B and 81B can be said to extend parallel to each other. The first crossbeam 80B is positioned to move along a first crossbeam direction perpendicular to the longitudinal central axis of the motor shaft 31B, and the second crossbeam 81B is positioned to move along a second crossbeam direction parallel to the first crossbeam direction, the second crossbeam axis of which is, in this case, naturally also perpendicular to the longitudinal central axis of the motor shaft 31B.

[0029] The deformable section 50B is designed to basically have a rhombic structure having four edges and four vertices. The first edge is realized by the first arm section 51B, the second edge by the second arm section 52B, the third edge by the third arm section 53B, and the fourth edge by the fourth arm section 54B. The first arm section 51B and the third arm section 53B are each attached to the first end of a mounting structure 60B which is fixedly connected to the motor 30B. The mounting points together form the first vertex 55B of the rhombic structure, and the vertex is a so-called "extended vertex" because the mounting edges of the first ends of the first and second arm sections 51B and 53B have a certain distance between them. The first and third arm sections 51B and 53B are oriented outward with respect to the central axis of the rhombic structure. The first arm section 51B has a second end connected to the first end of the second arm section 52B, forming the second vertex 56B of the rhombic structure. As seen in Figure 3, the first and second arm sections 51B and 52B intersect at an obtuse angle, which should not be considered restrictive and depends on the design of the deformable section. In designs with arm sections as basically discussed in this context, these arm sections may intersect at an obtuse or acute angle, or the angle between both arm sections may be about 180 degrees in the resting state of the deformable section. Furthermore, the second end of the third arm section 52B and the first end of the fourth arm section 54B are connected to form the third vertex 57B. The second arm section 52B and the second end of the fourth arm section 54B are connected to form the fourth vertex 58B, and the connecting element 59B is also integrated into this slightly extended fourth vertex 58B. The drive shaft 70B is connected here to the connecting element 59B.

[0030] As can be seen from the perspective view shown in Figure 3, the arm sections 51B, 52B, 53B, and 54B are realized as “double arm sections,” that is, each arm section comprises two parallel arm elements positioned at a distance from each other, which makes the entire deformable section 50B considerably lighter on the one hand, while remaining stable against torsional deformation on the other hand. In the illustrated design, the first arm section 51B comprises two parallel arm elements 511B and 512B, the second arm section 52B comprises two parallel arm elements 521B and 522B, the third arm section 53B comprises two parallel arm elements 531B and 532B, and the fourth arm section 54B comprises two parallel arm elements 541B and 542B. At the second, third, and fourth vertices, the parallel arm elements are connected by vertical bar elements. The second vertex 56B and the third vertex 57B each comprise mounting elements 561B and 571B, respectively, which provide fixing points for the first and second crossbeams 80B and 81B of the connector section 8B.

[0031] The first crossbeam 80B comprises first and second crossbeam arms 801B and 802B, which are parallel to each other over a certain length of extension so as not to collide with the second crossbeam 81B which moves between the two crossbeam arms 801B and 802B. The first crossbeam arm 801B is coupled to the first eccentric shaft element 41B by an elongated hole 804B provided in the first crossbeam arm 801B, and the second crossbeam arm 802B is coupled to the third eccentric shaft element 43B by an elongated hole 805B provided in the second crossbeam arm 802B. The elongated holes 804B and 805B are oriented perpendicular to the longitudinal central axis of the motor shaft 31B and perpendicular to the first crossbeam axis. The first eccentric shaft element 41B extends through an elongated hole 804B, and the third eccentric shaft element 43B extends through an elongated hole 805B. The first crossbeam 80B includes a connecting portion 803B to which the first and second crossbeam arms 801B and 802B are joined together, and this connecting portion 803B is fixedly connected to the mounting element 561B of the second vertex 56B of the deformable portion 50B. The first crossbeam 80B and the mounting element 561B may be connected by overmolding, crimping, screwing, bonding, welding, or any other connection means known to those skilled in the art. The elongated holes 804B and 805B are sized such that the first and third eccentric shaft elements 41B and 43B fit essentially tightly through the elongated holes 804B and 805B, respectively, in the direction defined by the first crossbeam axis, and are able to move freely in the long direction of the elongated holes 804B and 805B when the motor shaft 31B rotates the shaft extension 40B. This design ensures that the elongated holes 804B and 805B transmit only the motion of the first and third eccentric shaft elements 41B and 43B in the direction of the first crossbeam axis to the second vertex 56B. It should be noted again that the first and second eccentric shaft elements 41B and 41C move in alignment. Similarly, the second crossbeam 81B includes a connecting portion 813B that is fixedly connected to the mounting element 571B of the third vertex 57B.The elongated hole 814B is sized such that the second eccentric shaft element 42B fits essentially tightly through the elongated hole 814B in the direction defined by the second crossbeam axis, and can move freely in the longitudinal direction of the elongated hole 814B when the motor shaft 31B rotates the shaft extension 40B. This design ensures that the elongated hole 814B transmits only the motion of the second eccentric shaft element 42B in the direction of the second crossbeam axis to the third vertex 57B. Since the second eccentric shaft element 42B is offset circumferentially by a distance of 180 degrees relative to the first and third eccentric shaft elements 41B and 43B, the first crossbeam 80B and the second crossbeam 81B move in a counter-oscillating manner, that is, when the first crossbeam moves to the right ("right" is defined with respect to the plane of the paper), the second crossbeam moves to the left, and vice versa, meaning that the direction of motion of both crossbeams periodically reverses at the same time. In this design, the deformable section 50B is first "expanded" when the first crossbeam 80B moves to the right and the second crossbeam 81B moves to the left, thereby pulling the coupling element 59B toward the motor 30B. The deformable section 50B is then "constricted together" when the first crossbeam 80B moves to the left and the second crossbeam 81B moves to the right, thereby moving the coupling element 59B upward to its maximum deflection, beyond its resting position and away from the motor 30B. This linear reciprocating motion of the coupling element 59B occurs periodically along a direction that coincides with or is parallel to the longitudinal central axis of the motor shaft 31B. It should be noted here that, in general, i.e., in all embodiments, the eccentric shaft element must have a height extension along the longitudinal axis that accommodates the deformation of the deformable section that moves the coupling up and down in accordance with the deformation.

[0032] In the examples shown in Figures 2 and 3, the first crossbeam has a fork-like structure and works in cooperation with two axially displaced eccentric shaft elements, which allows the joint portion of the first crossbeam to have the same axial position as the joint portion of the second crossbeam. This makes it possible to design the first and third arm elements and the second and fourth arm elements to have the same length.

[0033] The drive unit having the hinge element shown in Figures 2 and 3 is also described in concurrently pending European Patent Application Publication No. 21158962.7 and European Patent Application Publication No. 22156286.1, the contents of which are incorporated herein by reference.

[0034] This application focuses on the modified designs of connector sections 8A and 8B discussed with reference to Figures 2 and 3, particularly the modified designs of the receiving sections that define the elongated holes 804B, 805B, and 814B. As can be seen from Figure 3, the elongated holes 804B, 805B, and 814B are defined by elements having essentially O-shaped or rhomboid notches, the notches defining the elongated holes. As can be seen with reference to Figures 4A, 4B, and 5, such O-shaped cavities require a long core within the plastic injection molding tool, for example, a core that defines all three notches. With reference to Figures 2 and 3, the design modifications discussed herein involve replacing the O-shaped receiver with a U-shaped receiver, which includes a reinforcing element positioned to allow lateral access to the inner notch of the elongated hole defined by the U-shaped receiver, i.e., by introducing a forming tool-side shaping element extending in the longitudinal direction of the elongated hole. Thus, the proposed design makes it possible to eliminate the long core required for the manufacture of the motion transducer 8A or 8B. The aforementioned reinforcing element may be bar-shaped, U-shaped, or O-shaped. All reinforcing elements discussed below are O-shaped, and such reinforcing elements provide stabilization to the free end of the U-shaped leg of the U-shaped receiver and provide geometric symmetry so that the stability is similar in all directions. If such stabilizing reinforcing elements are not used, the width of the elongated hole defined by the U-shaped receiver is not defined during operation, and noise and vibration occur because the eccentric shaft element bends and opens the U-shaped leg. Therefore, modifying the motion transducer previously discussed in the above-mentioned reference application to the design proposed herein is easy to manufacture in a plastic injection molding process and, nevertheless, serves the objective of providing a motion transducer having adequate stability of the receiving portion intended to cooperate with the eccentric shaft element, resulting in periodic deformation of the deformable portion, and thus the rotational motion of the motor shaft of a motor such as a commercially available DC motor is converted into linear reciprocating motion of the drive shaft.It should be understood that the ease of manufacturing remains the same even if the motion transducer is not entirely manufactured through a plastic injection molding process, and several inserts, such as metal sheets, are used to realize parts of the motion transducer.

[0035] Figure 4A is a perspective view of an exemplary motion transducer 5C, and Figure 4B is a side view of the motion transducer shown in Figure 4A. Figure 5 is an enlarged detail view of the connector portion 8C of the motion transducer 5C shown in Figures 4A and 4B.

[0036] The motion transducer 5C shown in Figures 4A and 4B is essentially a single, integrated part manufactured by plastic injection molding, with a metal drive shaft 70C connected to the coupling section 59C of the motion transducer 5C. In the plastic injection molding process, the metal drive shaft 70C is provided as an insert into each cavity of the molding tool. The motion transducer 5C comprises a deformable section 8C connected to a mounting section 60Cm, a coupling section 59C, and a connector section 8C, which is partially obscured by the deformable section 8C in the perspective view of Figure 4A and is better visible in the front view of Figure 4B. The basic structure of the connector section 8C is the same as that of the connector sections 8A and 8B discussed in relation to Figures 2 and 3. Therefore, please refer to the discussion in relation to Figures 2 and 3. The deformable section 50C is similarly designed to have a rhomboid structure having four edges and four vertices, and the deformable section 50C can be described as being formed from two opposingly positioned H-shaped arm structures, each of which is bent outward at the level of the vertical bar of the H. The two opposingly positioned H-shaped arm elements realize a first arm section 51C having two essentially parallel arm elements 511C and 512C, a second arm section 52C having two essentially parallel arm elements 521C and 522C, a third arm section 53C having two essentially parallel arm elements 531C and 532C, and a fourth arm section 54C having two essentially parallel arm elements 541C and 542C. As is best seen in Figure 4B, the connector section 8C comprises a first receiving section 90C, a second receiving section 91C, and a third receiving section 91C, which are similarly intended to receive the eccentric shaft section, as can be seen in Figures 6A to 6C.

[0037] Figure 5 is an enlarged cutaway detail view of the motion transducer 8C from Figure 4A. In this figure, the motion transducer 8C comprises three receiving parts 90C, 91C, and 92C. The first receiving part 90C has an essentially U-shaped receiving body 901C, an elongated receiving hole 902C, and an O-shaped reinforcing element 903C. The second receiving part 91C has an essentially U-shaped receiving body 911C, an elongated receiving hole 912C, and an O-shaped reinforcing element 913C. The third receiving part 92C has an essentially U-shaped receiving body 921C, an elongated receiving hole 922C, and an O-shaped reinforcing element 923C. The reinforcing elements 903C and 923C face in one direction, while the second reinforcing element 913C faces in the opposite direction; this design was chosen for manufacturing reasons. A more extensive discussion of the structure of the support and each eccentric shaft extension element is provided in relation to Figure 6C, and a more general discussion of the structure of the support is given with reference to Figure 7.

[0038] Figure 6A is a side view of the drive unit 25D, which includes a motion transducer 5D that may be the same as the one shown in Figures 4A, 4B, and 5. Figure 6B is a cross-sectional view through the drive unit 25C shown in Figure 6A, where the drive unit is rotated 90 degrees around its longitudinal axis. Figure 6C is a close-up view of the connector 8D and motor shaft extension 40D shown in Figure 6B.

[0039] The drive unit 25D shown in Figure 6A comprises a drive 30D, which can be implemented as a commercially available DC motor, a motion transducer 5D, and a drive shaft 70D. The motion transducer 5D comprises a deformable portion 50D, a mounting portion 60D, a connector portion 8D, and a coupling portion 59D. The drive or motor 30D comprises a motor shaft 31D and a motor shaft extension 40D. These elements, as well as their functions and structures, have already been described in the previous paragraphs and do not need to be repeated. The cross-section shown in Figure 6B is specifically taken in a plane extending through the motor shaft 31D, the motor shaft extension 40D, and the three eccentric shaft elements 41D, 42D, and 43D. Figure 6B shows portion A, which is shown in enlarged view in Figure 6C. In Figure 6C, it can be seen that the first eccentric shaft element 41D extends through a U-shaped notch 902D in the form of an elongated U-shaped hole in the first receiving portion 90D. The second eccentric shaft element 42D extends through a U-shaped notch 912D in the form of a U-shaped elongated hole in the second receiving portion 91D. The third eccentric shaft element 43D extends through a U-shaped notch 922D in the form of a U-shaped elongated hole in the third receiving portion 92D. As has already been considered with respect to the motion transducer 5C partially shown in Figure 5, each of the receiving portions 90D, 91D and 92D is provided with respective O-shaped reinforcing elements 903D, 913D and 923D that provide stability to the open ends of the U-shaped elongated holes 902D, 912D and 922D against bending and opening. Furthermore, it can be seen that the receiving portions 90D, 91D and 92D, and therefore the respective elongated holes 902D, 912D and 922D, each taper toward the closed end of their respective receiving portions. This can lead to better deformation of the molding protrusions that define the elongated hole.

[0040] Figure 7 is a schematic diagram of the receiving portion 90E of the connector section, which is part of the motion transducer for the drivetrain proposed herein. The eccentric shaft element 41E is shown as an arm 801E of the connector section by a dashed line. Figure 7 focuses on the structure of the receiving portion 90E and its interactions, as well as the resulting motion caused by the motion of the eccentric shaft element 41E.

[0041] The receiving portion 90E has an essentially U-shaped notch in the form of an elongated hole 902E in the receiving portion 90E and a generally U-shaped body 901E. The U-shaped body 901E has a U-shaped base 9011E and two U-shaped legs 9012E and 9013E, which together define the elongated hole 902E. The U-shaped legs 9012E and 9013E have free leg ends 9014E and 9015E, respectively, which are fixed to each other by a bar-shaped reinforcing element 903E in the shown embodiment. Figure 7 shows a coordinate system defining the x, y, and z directions. The bar-shaped reinforcing element 903E extends in the y direction. The reinforcing element 903E is clearly a three-dimensional object extending in all three spatial directions, but as used herein, “extension direction” is understood to generally refer to the principal extension direction. The elongated U-shaped hole 902E has a length l extending in the x-direction, a width w extending in the y-direction, and a height h extending in the z-direction with respect to the given coordinate system. The reinforcing element 903E is configured and positioned such that access to the elongated hole 902E is provided across its entire width w and height h in the x-direction. This makes it possible to define the receiving portion 90E with two halves of a mold, which are closed by moving the two halves of the mold together in the x-direction. This is not possible if the elongated hole is an O-shaped notch, i.e., an O-shaped hole is closed along its periphery, whereas a U-shaped hole has an opening; therefore, as already stated above, the elongated hole can only be defined by an additional core extending in the z-direction. In the operation of a drivetrain as considered in this disclosure, the eccentric shaft element 41E extends through the z-shaped elongated hole 902E. The eccentric shaft element 41E has a cylindrical shape, a diameter d that essentially matches the width w of the elongated hole, and a central axis A that extends in the z direction. E The cylindrical eccentric shaft element 41E also has a certain height, i.e., extends above and below the receiving portion 90E, so that the vertical movement of the receiving portion 90E due to the deformation of the deformable portion is adapted by the cylindrical portion. The motor shaft (not shown) has a longitudinal central axis A MAssume that the eccentric shaft extension 41E rotates around the axial cable and is connected to the eccentric shaft extension 41E so that it moves along a circle C having a diameter D as shown in Figure 7. As the eccentric shaft extension 41E moves along the circle C, motion along the x-direction occurs freely within the elongated hole 902E, and motion in the y-direction is transmitted to the receiving portion 90E, so that the receiving portion moves periodically in the y-direction along the bidirectional arrow P with an interpeak amplitude that matches the diameter D of the circle C. The arm 801E transmits this motion to the deformable portion of the motion transducer, which will deform periodically as discussed in the previous paragraph. At least the outer surface region of the eccentric shaft extension 41E is in contact with the elongated hole 902E, and / or at least the inner surface of the elongated hole 902E may be coated to reduce friction between the two components.

[0042] The dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​listed. Instead, unless otherwise specified, each such dimension is intended to mean both the listed value and the functionally equivalent range encompassing that value. For example, a dimension disclosed as "40 mm" is intended to mean "approximately 40 mm."

Claims

1. A motion transducer configured to convert rotational motion provided by a motor shaft into linear reciprocating motion of a drive shaft, Deformable part, A mounting portion connected to the deformable portion, A coupling portion connected to the deformable portion, configured to receive the drive shaft or comprising the drive shaft, A motion transducer comprising: a connector portion connected to the deformable portion, comprising: a first essentially U-shaped receiving portion having a U-shaped base and two U-shaped legs that together define a first elongated hole having length, width and height, and configured to receive a first eccentric shaft element of the motor shaft; and a first reinforcing element connecting the two U-shaped legs of the first essentially U-shaped receiving portion at their free ends so as to provide access to the first elongated hole across the width and height of the first elongated hole; preferably, the first reinforcing element being bar-shaped, U-shaped, or O-shaped, and the length being measured from the inner surface of the U-shaped base to the free ends of the U-shaped legs.

2. The motion transducer according to claim 1, wherein the motion transducer is an integrated element, preferably a plastic injection molded element.

3. The motion transducer according to claim 1 or 2, wherein the connector portion comprises at least a first arm element that connects the first essentially U-shaped receiving portion to the deformable portion.

4. The deformable portion is configured to deform periodically along the z-direction to provide the linear reciprocating motion along the z-direction and to deform periodically along the y-direction, the z-direction and the y-direction extend in a plane, and the first elongated hole extends vertically along the x-direction perpendicular to the plane extending in the z-direction and the y-direction, as described in any one of claims 1 to 3.

5. The motion transducer according to claim 4, wherein the first bar-shaped, U-shaped, or O-shaped reinforcing element connecting the two U-shaped legs of the first essentially U-shaped receiving portion to their free ends extends in a plane parallel to the plane that extends in the z-direction and the y-direction.

6. The motion transducer according to any one of claims 1 to 5, wherein the connector portion comprises a second essentially U-shaped receiving portion having a U-shaped base and two U-shaped legs that together define a second elongated hole having length, width and height, and the connector portion comprises a second bar-shaped, U-shaped, or O-shaped reinforcing element that connects the two U-shaped legs of the second essentially U-shaped receiving portion to their free ends so as to provide access to the second elongated hole across the width and height of the second elongated hole.

7. The motion transducer according to claim 6, wherein the connector portion comprises at least a second arm element that connects the second essentially U-shaped receiving portion to the deformable portion.

8. The motion transducer according to claim 6 or 7, wherein the connector portion comprises a third essentially U-shaped receiving portion having a U-shaped base and two U-shaped legs that together define a third elongated hole having length, width and height, and configured to receive a third eccentric shaft element, and a third bar-shaped, U-shaped, or O-shaped reinforcing element that connects the two U-shaped legs to their free ends so as to provide access to the third elongated hole across the width and height of the elongated hole.

9. The motion transducer according to claim 8, wherein the connector portion comprises at least a third arm element that connects the third essentially U-shaped receiving portion to the deformable portion, and preferably the second arm and the third arm are joined to each other.

10. The motion transducer according to any one of claims 1 to 9, wherein the deformable portion has a generally convex quadrilateral structure having four edges and four vertices, preferably a rhombic structure, the mounting portion and the connecting portion are provided at two essentially opposing vertices of the convex quadrilateral structure, and the connector portion is connected to at least one of the other two vertices, preferably both of the other essentially opposing vertices.

11. The motion transducer according to claim 10 and any one of claims 6 to 9, wherein the first arm is connected to one of the vertices, and the second arm is connected to the respective opposing vertices.

12. A drive unit comprising a motion transducer according to any one of claims 1 to 11, A drive shaft connected to the aforementioned coupling portion, which provides the linear reciprocating motion during operation, A motor having a motor shaft and providing rotational motion around the longitudinal central axis of the motor shaft during operation, A motor shaft extension coupled to or connected to the motor shaft, further comprising a first eccentric shaft element positioned eccentrically with respect to the longitudinal central axis so as to move along a circular path around the longitudinal central axis during operation, A drive unit comprising: a first eccentric shaft element extending through the first elongated hole along the height direction of the first elongated hole; a first eccentric shaft element having a diameter that fits tightly into the first elongated hole in the width direction of the first elongated hole; and a first eccentric shaft element being able to move freely within the first elongated hole in the length direction of the first elongated hole during operation.

13. The drive unit according to claim 12, wherein the motor shaft extension has a second eccentric shaft element positioned eccentrically with respect to the vertical central axis, the second eccentric shaft element extends in the height direction through the second elongated hole, the second eccentric shaft element has a diameter that fits tightly into the second elongated hole in the width direction, and the second eccentric shaft element can move freely within the second elongated hole in the length direction during operation.

14. The drive unit according to claim 13, wherein the first eccentric shaft element and the second eccentric shaft element are provided facing each other with respect to the vertical central axis so as to rotate around the vertical central axis by an angular distance of 180 degrees during operation.

15. A personal care device comprising a drive unit according to any one of claims 12 to 14, wherein the personal care device comprises a head section coupled to the drive shaft, the head section or the driven element of the head section is driven to a forward-backward motion such as a rocking motion or a reciprocating motion during operation, optionally the mounting portion of the motion transducer is fixedly mounted to the motor, and optionally, during operation, the circular motion of at least the first eccentric shaft element transmits a periodic force to the deformable portion to at least the first essentially U-shaped receiving portion, thereby causing the deformable portion to deform periodically, preferably the periodic deformation means a periodic deformation in the z direction and a periodic deformation in the y direction perpendicular to the z direction with a 180° phase shift.

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