Transmission system assembly for personal care device

Abstract

According to an aspect, there is provided a transmission system assembly (1) for a personal care device (10). The transmission system assembly (1) comprises a shaft (2), a frame (4) comprising an opening in a surface (4a) of the frame (4), the shaft (2) extending through the opening, and a bearing (3) arranged in cooperation with the shaft (2). An engagement surface (3a) of the bearing (3) is configured to engage with the surface (4a) of the frame (4) such that relative movement between the frame (4) and the shaft (2) along a given direction (d) is prohibited beyond a threshold distance.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to electric motors for personal care devices such as electric toothbrushes, electric shavers, and skin care devices. Background Technology

[0002] The drive system in personal care devices is an electromagnetic module that generates the necessary movement of the device. In an electric toothbrush, the drive system generates the oscillating movement of the toothbrush head. The drive system includes a motor and shafts (output shaft, drive shaft), the motor comprising a rotor and a stator.

[0003] Personal care devices, such as electric toothbrushes, are typically sensitive to drop incidents—that is, they are easily dropped by users or struck from countertops or similar raised surfaces. A scenario that can be particularly damaging to personal care devices is when they are dropped onto a ceramic floor (or a similar hard surface) and the drive shaft impacts the floor directly. In this case, the force applied to the shaft can be as high as several kN, which can severely damage the personal care device.

[0004] As mentioned above, the shaft is part of the transmission system, and the transmission system of the personal care device is sensitive to drop forces, which could cause the transmission system to fail due to axial drop on the shaft.

[0005] The expectation is to provide personal care devices with drop protection, such as electric toothbrushes. Summary of the Invention

[0006] According to an embodiment of the first aspect, a drive system assembly for a personal care device is provided, the drive system assembly comprising: a shaft; a frame including an opening in a surface of the frame through which the shaft extends; and a support cooperating with the shaft, wherein an engagement surface of the support is configured to engage with a surface of the frame such that relative movement between the frame and the shaft in a given direction is prohibited from exceeding a threshold distance.

[0007] Therefore, according to an embodiment of the invention, the support is configured to engage with the frame of the transmission system such that movement of the shaft relative to the frame is prohibited (hindered, hindered, or blocked). That is, the support is positioned on the shaft to allow the shaft to move in a given direction to a point (threshold distance) where the support engages with the frame to prevent / prohibit further movement of the shaft. More specifically, the engagement surface of the support engages with the surface of the frame through which the shaft extends.

[0008] Therefore, the support provides a drop protection element that protects vulnerable components of the drivetrain by redirecting the path of the force applied to the shaft, causing the shaft to move away from vulnerable / sensitive components of the drivetrain in a given direction. Once the shaft has moved a threshold distance, the path of the force is redirected through the frame by engaging the support surface with the frame. Because the path of the force applied to the shaft is redirected away from sensitive components of the drivetrain, the likelihood of component failure is reduced in the event of a drop of the personal care device. Therefore, this threshold distance can be considered as the distance the shaft is allowed to move before the force path is redirected through the frame via the support. The threshold distance can be, for example, 0.2 mm (+ / - 0.05 mm). The path through the frame can be considered a robust path that bypasses vulnerable components of the drivetrain.

[0009] As described above, the support abuts the frame to prevent the shaft from moving beyond a threshold distance. More specifically, the mating surface of the support abuts the surface of the frame through which the shaft extends. The support can also be considered a blocking element, stop, obstacle, obstruction, or impediment. The shaft can be considered an output shaft or a drive shaft. The shaft is arranged in the transmission system assembly such that it extends through an opening (aperture, hole, channel, slot) provided in the surface of the frame, and the support is configured to engage with that surface. The support is configured to cooperate with the shaft such that the support moves together with the shaft, i.e., the support and the shaft move jointly, cooperatively, uniformly, or integrally.

[0010] A given direction can be along the longitudinal axis of the shaft, thus the shaft can move a threshold distance relative to the frame along the longitudinal axis. The longitudinal axis of the shaft can also be considered as the axial direction of the shaft. Movement of the shaft in a given direction may be caused by a force applied to the shaft. For example, this force could be a drop force caused by dropping a personal care device, resulting in the shaft contacting a hard surface and moving the shaft along its longitudinal axis in the given direction. Movement of the shaft may not only be in the given direction but may extend beyond the threshold distance, causing the mating surface of the support to engage with the surface of the frame.

[0011] According to a preferred embodiment, the support may be a collar comprising: a body having an inner diameter corresponding to the diameter of the shaft; and an engagement portion configured to project from the body and provide an engagement surface. If the support is a collar, the collar can be positioned over the shaft to provide a fit between the shaft and the collar, such that the shaft extends through the collar. That is, the collar includes an opening or core configured to receive the shaft. Therefore, the inner diameter of the collar body can correspond to the diameter of the shaft, such that the shaft receives the collar and the collar is tightly fitted onto the shaft. Therefore, the diameter of the shaft can be slightly smaller than the inner diameter of the collar body. Therefore, the inner diameter of the body and the diameter of the shaft can be interdependent or complementary, such that the inner diameter of the body can determine the diameter of the shaft, and vice versa.

[0012] Different parts of the shaft may have different diameters. If this is the case, then the inner diameter of the collar body can correspond to the diameter of the shaft at the location where the collar is installed. The internal shape of the collar can correspond to the external shape of the shaft at the location where the collar is installed. That is, the shape of the shaft's cross-section can match the shape of the opening of the collar's cross-section. The collar can also be considered a flanged collar, sleeve, or bearing. If the collar is considered a flanged collar, then the flange can be the mating part.

[0013] The engaging portion of the collar extends from the body, such that it is configured to engage with the surface of the frame. Therefore, it is evident that the engaging portion protrudes beyond the opening on the surface, and thus the total diameter or width of the collar including the engaging portion is greater than the width of the opening. The engaging portion can also be considered as a protrusion or lip, or multiple protrusions or multiple lips.

[0014] The support can also be a ring or washer, or any other component capable of mates with the shaft and engages with the frame. The support can also be formed as part of the shaft. For example, the shaft may include one or more protrusions extending beyond the openings in the frame and configured to engage with surfaces of the frame, such that they provide engagement surfaces. Similarly, a widening of the shaft can be provided to engage with the frame and provide both a support and engagement surfaces. If the support is incorporated as part of the shaft, the drivetrain can be assembled such that the shaft is positioned relative to the frame before the rotor assembly, providing a small air gap between the surface of the frame through which the shaft extends and the engagement surface of the support.

[0015] Furthermore, the body of the collar can have an outer diameter corresponding to the width of the opening. That is, the outer diameter of the body can correspond to the width of the opening, allowing the body to be fitted into the opening with minimal or no friction, i.e., the opening is configured to receive the body of the support. Therefore, the outer diameter of the body can be slightly smaller than the width of the opening to allow for a clearance for the body to fit into the opening without engaging with the edge of the opening. Thus, the outer diameter of the body and the width of the opening can be interdependent or complementary, such that the outer diameter of the body determines the width of the opening, and vice versa.

[0016] Of course, it's important to understand that the width of the opening is related to the size of the opening on the section of the receiving collar. If the opening is circular, then the width refers to the diameter of the opening. The receiving collar body within the opening prevents the shaft from moving laterally within the opening in one or more directions. That is, movement in directions(s) substantially perpendicular to a given direction. The shape of the opening can at least partially match the external shape of the collar, such that the opening is configured to receive the collar body.

[0017] The drive system assembly may further include: an electric motor, which includes a rotor and a stator. The rotor may include a rotor surface; the stator may include a stator surface disposed opposite to the rotor surface; and the threshold distance may be less than the distance between the stator surface and the rotor surface. The rotor and stator of the electric motor are separated by an air gap, and the distance between the stator surface and the rotor surface may define the air gap of the electric motor. A shaft may be attached or connected to the rotor such that movement of the shaft will also cause the rotor to move toward the stator and reduce the air gap. Therefore, if the threshold distance is less than the distance between the rotor surface and the stator surface, movement of the shaft and the rotor will be prevented by the support before the rotor surface contacts the stator surface. Thus, the engagement of the support and the frame can prevent the air gap of the electric motor from closing.

[0018] The threshold distance can preferably correspond to a predetermined force applied to the shaft in a given direction. That is, the threshold distance can correspond to or be equal to the distance the shaft moves in a given direction when a predetermined force is applied to the shaft. Therefore, the support can be positioned on the shaft at a point that prevents the shaft from moving (corresponding to the force applied to the shaft) beyond a certain point. If a force less than the predetermined force is applied to the shaft, the distance the shaft moves can be less than the threshold distance, so that the support does not engage with the frame. If a force greater than the predetermined force is applied to the shaft, then by engaging the support with the surface of the frame, the shaft is prevented from moving beyond the threshold distance.

[0019] The predetermined force can correspond to a force considered to be the safety limit of sensitive components in the transmission system. That is, the predetermined force can be a tolerable force for sensitive components of the transmission system, such that applying the predetermined force to the shaft will not cause component failure. For forces applied to the shaft reaching the predetermined force, the support does not engage with the surface of the frame, and the force path passes through the shaft and components of the transmission system (such as an electric motor). Therefore, the predetermined force and forces less than the predetermined force can be forces that the components of the transmission system can withstand without failure. For forces greater than the predetermined force, the support engages with the frame, so the force path is redirected through the frame and away from the components of the transmission system.

[0020] According to embodiments of the invention, the shaft and the support can be configured to move together relative to the frame between a primary position and a secondary position. The mating surface of the support and the surface of the frame may not engage in the primary position; and the mating surface of the support and the surface of the frame may engage in the secondary position. A threshold distance may correspond to or be equal to the distance between the mating surface of the support and the surface of the frame in the primary position.

[0021] The primary position can be considered the position of the shaft and support during normal operation. In this position, a gap is provided between the mating surface of the support and the surface of the frame. The secondary position can be considered the position of the shaft when a predetermined force, such as a falling force, is applied to it. In the secondary position, the shaft and support have moved in a given direction such that there is no gap between the mating surface of the support and the surface of the frame, and the two surfaces are in contact. The engagement of the surfaces prevents further movement of the shaft and support.

[0022] Therefore, when a force is applied to the shaft, causing the shaft and support to move in a given direction, the shaft and support move from the primary position, and the distance between the mating surface of the support and the surface of the frame decreases. If the force increases to a predetermined force or greater, then the support and shaft reach the secondary position. The distance between the mating surface of the support and the surface of the frame at the primary position is the threshold distance. That is, the threshold distance is the distance the mating surface of the support moves between the primary and secondary positions.

[0023] The support can preferably be fixed to the shaft. That is, the fit between the shaft and the support can be achieved by fixing the support to the shaft. The support can be fixed to the shaft by any suitable means, such as, for example, by laser welding. The position of the support on the shaft can be determined by the position of the shaft relative to the frame and the threshold distance. The threshold distance can be 0.2 mm or less.

[0024] According to an embodiment of the second aspect, a personal care device is provided, which includes a transmission system component according to the above aspects of the invention. For example, the personal care device may be an oral care device such as an electric toothbrush, an electric shaver, or a skin care device such as a skin massager. Embodiments of the invention can be applied to any personal device having a shaft on which relatively large forces may be applied, for example, drop forces due to the device being dropped.

[0025] Therefore, embodiments of the present invention are extended to drivetrain components and personal devices including such drivetrain components. Features of the first aspect are applied to the second aspect with necessary modifications to details, and vice versa.

[0026] The present invention extends to the method aspect, which corresponds to the apparatus aspect.

[0027] Specifically, according to an embodiment of the third aspect, a method of manufacturing a drivetrain assembly for a personal care device is provided, the method comprising: elastically mounting a shaft in a frame of the drivetrain assembly such that the shaft extends through an opening in a surface of the frame; placing a support to be movably engaged with the shaft at a first position on the shaft such that an engagement surface of the support engages with a surface of the frame; applying a predetermined force to the shaft in a given direction along a longitudinal axis of the shaft such that the shaft moves relative to the frame in the given direction, and the support moves to a second position on the shaft due to the engagement of the engagement surface of the support and the surface of the frame; releasing the predetermined force applied to the shaft such that the shaft moves relative to the frame in a direction opposite to the given direction, and the support moves together with the shaft such that the support is held at the second position on the shaft and the engagement surface of the support is no longer engaged with the surface of the frame; and securing the support to the shaft at the second position.

[0028] Therefore, the above-described method can be used to manufacture transmission system components according to embodiments of the present invention. This manufacturing method allows for the precise provision of a small, predefined distance between the mating surface of the support and the surface of the frame. This distance corresponds to (or is equal to) the distance the shaft moves when a predetermined force applied to the shaft is released, and this distance can be considered equal to the aforementioned threshold distance. This distance depends on the force applied to the shaft and the elasticity of the shaft mounted in the frame.

[0029] In this manufacturing method, a predetermined force is applied to the shaft due to surface engagement with the frame. This predetermined force causes the support to move from a first position on the shaft to a second position on the shaft. The shaft is elastically mounted in the frame such that when the predetermined force is no longer applied to the shaft, the shaft returns to a position corresponding to (equal to or similar to) the position it was in before the force was applied. The shaft moves relative to the frame.

[0030] The support is movably engaged with the shaft, allowing both elements to move together unless engagement with the frame prevents the support from moving in unison with the shaft. If the support engages with the surface of the frame, this movable engagement allows the support to move along the shaft when a force is applied to it. That is, since the support contacts the surface of the frame and does not at least completely pass through an opening in the surface of the frame, the support moves along the shaft to a second position when the shaft moves relative to the frame in a given direction. Therefore, it can also be considered that the shaft moves relative to the support when it engages with the frame. Because the shaft moves in a given direction, the movement of the support from the first position to the second position is in a direction opposite to the given direction. The movable engagement of the support and the shaft means that when the force is released from the shaft and the shaft moves in a direction opposite to the given direction, the support moves with the shaft because the movement of the support is not hindered by the frame; that is, the support moves away from the frame with the shaft, and therefore the support is no longer engaged with the frame.

[0031] In other words, when a force is applied to the shaft and the shaft moves relative to the frame in a given direction, the engagement of the frame and the support impedes the support and prevents it from moving with the shaft. Conversely, when the shaft returns to its initial position after the force is released from the shaft, the direction of movement of the shaft is opposite to the given direction, and the support moves with the shaft. Since the shaft moves away from the frame, the movement of the support and the shaft is not impeded. Therefore, due to the engagement of the shaft and the support, the support remains in the second position and moves with the shaft.

[0032] The distance between the first and second positions of the support defines a threshold range of movement of the shaft relative to the frame. Once the support is fixed to the shaft, when a force is applied to the end of the shaft, the support will prevent the shaft from moving more than the threshold distance in a given direction.

[0033] The support can be a collar comprising: a body having an inner diameter corresponding to the diameter of the shaft; and an engagement portion configured to project from the body and provide an engagement surface. The collar can be positioned to movably engage with the shaft by sliding it over the shaft. Thus, the shaft can receive the collar such that the shaft extends through an opening in the collar. To provide movable engagement between the shaft and the support, the inner diameter of the collar's body can be configured to have the diameter of the shaft to provide a tight fit of the collar over the shaft. Therefore, the inner diameter of the body can be slightly larger than the diameter of the shaft. Thus, the inner diameter of the body and the diameter of the shaft can be interdependent or complementary, such that the inner diameter of the body determines the diameter of the shaft, and vice versa.

[0034] Furthermore, if the support is configured as a collar, the outer diameter of the body can correspond to the width of the opening in the surface of the frame. For example, if the opening is configured as a hole, the width of the opening can also be considered as the diameter of the opening. Therefore, the outer diameter of the collar body can correspond to the width of the opening in the surface of the frame, allowing the collar body to be received within the opening and providing a tight fit between the body and the opening. Thus, the outer diameter of the collar body can be slightly smaller than the width of the opening in the surface of the frame. Therefore, the outer diameter of the body and the width of the opening can be interdependent or complementary, such that the outer diameter of the body determines the width of the opening, and vice versa.

[0035] Therefore, the body of the collar can extend through the opening in the surface of the frame and fit tightly into the opening, such that lateral movement of the shaft within the opening is prohibited by the body of the collar. Of course, since the engaging portion of the collar provides a mating surface for the support that engages with the surface of the frame, it is obvious that the engaging portion of the collar does not at least completely extend through or through the opening of the frame. Therefore, it can be considered that the total diameter of the collar, including the engaging portion, is greater than the width of the opening.

[0036] The support can be secured to the shaft in the second position by any suitable method. For example, the support can be secured to the shaft in the second position by laser welding.

[0037] The predetermined force can correspond to the force considered to be the safety limit of sensitive components in the transmission system. That is, the predetermined force can be a force that the sensitive component can withstand without failure or malfunction. The predetermined force can be 50 N or less.

[0038] Therefore, it can be seen that embodiments of the present invention can provide a means for preventing the shaft from moving relative to the frame beyond an acceptable distance. The engagement of the support and the frame can redirect the path of the force applied to the shaft away from sensitive components of the transmission system, thereby protecting sensitive components in the event of, for example, an axial drop on the shaft. As discussed above, the manufacturing method according to embodiments of the present invention allows the distance between the support and the frame to be set to a suitable distance. Attached Figure Description

[0039] The embodiments disclosed herein may take the form of various components and component arrangements, as well as various steps and step arrangements. Therefore, the accompanying drawings are for illustrative purposes only and should not be construed as limiting the embodiments. In the drawings, the same reference numerals refer to the same elements. Additionally, it should be noted that the drawings may not be drawn to scale.

[0040] Figure 1 It is a graph showing the relationship between drop force and axial stiffness;

[0041] Figures 2(a) to 2(c) are diagrams of the impact force model;

[0042] Figures 3(a) and 3(b) are diagrams of prior art electric toothbrushes known in the art;

[0043] Figures 4(a) and 4(b) are diagrams of prior art electric toothbrushes known in the art;

[0044] Figure 5 This is a block diagram representation of a personal care device according to a general embodiment of one aspect of the present invention;

[0045] Figure 6 The diagram shows an electric toothbrush from which various aspects of the present invention can be applied;

[0046] Figures 7(a) and 7(b) are diagrams of a transmission system assembly according to an embodiment of one aspect of the present invention;

[0047] Figure 8 This is a diagram of a portion of a transmission system assembly according to an embodiment of one aspect of the present invention;

[0048] Figure 9A diagram showing a portion of a shaft according to an embodiment of one aspect of the present invention;

[0049] Figure 10 This is a diagram that is part of the framework of an embodiment of one aspect of the present invention;

[0050] Figure 11 A diagram of a support according to an embodiment of one aspect of the present invention;

[0051] Figure 12 This is a flowchart of a manufacturing method according to an embodiment of the present invention;

[0052] Figures 13(a) to 13(d) are a series of diagrams for explaining a manufacturing method according to another aspect of the present invention;

[0053] Figure 14 This is a diagram of a portion of a transmission system assembly according to an embodiment of one aspect of the present invention;

[0054] Figure 15 A diagram showing a portion of a transmission system assembly according to an embodiment of one aspect of the present invention; and

[0055] Figure 16 This is a diagram of a portion of a transmission system assembly according to an embodiment of one aspect of the present invention. Detailed Implementation

[0056] Embodiments of this disclosure, along with their various features and advantageous details, have been explained more fully with reference to the non-limiting examples described and / or illustrated in the accompanying drawings and described in detail and / or illustrated in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and those skilled in the art will use features of one embodiment with those of other embodiments, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted to avoid unnecessarily obscuring the embodiments of this disclosure. The examples used herein are intended only to facilitate an understanding of how embodiments of the invention can be practiced and to further enable those skilled in the art to practice such embodiments. Therefore, the examples herein should not be construed as limiting the scope of embodiments of this disclosure, which is defined only by the appended claims and applicable law.

[0057] It should be understood that the embodiments of this disclosure are not limited to the specific methods, protocols, devices, apparatuses, materials, applications, etc., described herein, as these can vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claimed embodiments. It must be noted that, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this disclosure pertain. Preferred methods, apparatus, and materials are described, although any methods and materials similar to or equivalent to those described herein may be used to implement or test the embodiments.

[0059] As discussed above, it is desirable to provide a personal care device with drop protection. Methods for reducing drop force have been considered in the art, and such methods rely on reducing the axial stiffness of the transmission system to delay the impact and average the impact force over time, thereby limiting the effects of axial drops.

[0060] Figure 1 A graphical representation of the relationship between drop force and reduced axial stiffness is shown. From Figure 1 The drop model shows that the drop force can be reduced by decreasing the stiffness of the transmission system. Therefore, by reducing the axial stiffness of the transmission system in devices such as electric toothbrushes, the peak drop force is also reduced, but the duration is longer. A lower drop force is less likely to cause internal damage to the electric toothbrush. Figure 1 In the simplified model, stiffness can be viewed as the (mutual) sum of the contact stiffness (e.g., that of the floor) and the internal stiffness of the transmission system.

[0061] Figures 2a to 2c An exemplary model of the impact force of dropping a device onto a surface such as a floor is shown. Figure 2a The diagram illustrates a device of mass m falling from a height h. The stiffness of the transmission system is k_DT, and the contact stiffness of the floor is k_floor. The device has no velocity at this point. Figure 2b In the middle, the device contacts the floor. At this moment, the two springs can be combined into one spring, k_total. The velocity is at its maximum immediately before contact. Figure 2c In this scenario, all energy is absorbed by the spring, thus the spring deflection is at its maximum and the velocity is zero. The force within the spring is proportional to the square root of the mass and the total stiffness. Therefore, reducing the stiffness of the equipment reduces the magnitude of the falling force.

[0062] Figure 3a and Figure 3b An electric toothbrush 90 with reduced axial stiffness is shown. Figure 3a and Figure 3b In the electric toothbrush 90, at least one spring 92 is provided to reduce the impact force. Figure 3b(As indicated by the arrow in the diagram) and protects the fragile components 91 of the transmission system. However, reducing the axial stiffness of the transmission system has several disadvantages. First, it increases design complexity by requiring additional and / or more complex components to achieve low stiffness in the axial direction while retaining the main functions of the transmission system. Second, when stiffness is reduced, the size requirements of the device increase because more space is needed for the transmission system components to slide backward.

[0063] An alternative strategy to reduce the impact of axial falls is to redirect the impact force to less sensitive parts of the drivetrain construction. This can be achieved by closing the air gap between the hub and the drivetrain frame. Closing this gap effectively redirects the force path away from the most vulnerable parts of the drivetrain. Figure 4a and Figure 4a An electric toothbrush 90 with this configuration is shown. Figure 4a An air gap is provided between the hub 94 and the frame 93, and... Figure 4b The closed air gap is shown in the figure.

[0064] However, this method has many drawbacks. Due to the tolerances of the transmission system, it is difficult to achieve the required air gap size in production, which is ideally as small as possible to limit the force passing through the transmission system. A larger air gap means that a higher force is applied to the transmission system before the air gap closes. Therefore, a higher force is applied to the transmission system, and the elastic components of the transmission system may be damaged.

[0065] Therefore, it is desirable to overcome the shortcomings of the above methods and provide a transmission system component with drop protection.

[0066] Figure 5 This is a block diagram of a personal care device according to a general embodiment of one aspect of the present invention. According to an embodiment of the present invention, the personal care device 10 includes a transmission system assembly 1. For example, the personal care device 10 may be an oral care device such as an electric toothbrush, or a skin care device such as an electric shaver or a skin massager.

[0067] Figure 6 An exemplary personal care device 10 is shown that can implement the teachings of this disclosure. Figure 6The personal care device described herein is in the form of an electric toothbrush, but it is to be understood that this is not limiting, and the teachings of this disclosure can be implemented in other devices that include an electric motor. For example, the teachings can be applied to personal care devices such as tongue cleaners, razors, hair trimmers or trimmers, hair removal devices, or skin care devices. Personal care device 10 has an attachment structure 116 and a handle portion 112. The handle portion has an electric motor 11. In one embodiment, the attachment structure 116 includes or is a replaceable accessory, i.e., the attachment structure 116 can be removed from the personal care device 10 and replaced by another attachment structure 116. Personal care device 10 preferably includes or is an electric toothbrush, and the attachment structure 116 may include a brush head 118. The handle 112 includes a drive system 1 and a drive shaft 2. When the attachment structure 116 is attached to the handle 112, the drive shaft 2 extends from the distal end of the handle 112 and enters the attachment structure 116.

[0068] The electric motor 11 may include a motor controller (i.e., control electronics), which may be any suitable controller, microcontroller, processor, power supply, and / or other electronic equipment to provide power and control signals or any combination thereof for performing various functions, as further discussed herein. In embodiments, the electric motor 11 may be configured to provide and control one or more operations of the drive system 1 to generate mechanical stimulation. Mechanical stimulation may include vibrations or other movements at high frequencies, such as frequencies greater than 50 Hz and frequencies in the range of, for example, 250 to 300 Hz. The drive system 1 and drive shaft 2 may be provided as part of a drive system assembly according to embodiments of the invention.

[0069] Still refer to Figure 6 The remote end of Annex 116 may include an operating component 120, configured according to the specific application requirements of Annex 116. Figure 6 In the example, the personal care device is an electric toothbrush, and the operating component 120 is the toothbrush head. However, it is understood that the operating component will vary for different types of personal care devices. In operation, in response to the operation of the motor 11 to control the operation of the transmission system 1 and the drive shaft 2 to generate mechanical stimulation, the attachment structure 116 performs the cleaning motion of the operating component 120.

[0070] Figure 7a and Figure 7a An arrangement according to an embodiment of one aspect of the present invention is shown. Figure 7a and Figure 7bThe personal care device 10 includes a drivetrain assembly 1. The drivetrain assembly 1 includes a shaft 2, a support 3, and a frame 4. The support 3 cooperates with the shaft 2 to provide an air gap 9 between an engagement surface 3a of the support 3 and a surface 4a (frame surface) of the frame 4. In this embodiment, the air gap 9 corresponds to a threshold distance, allowing the shaft 2 to move a threshold distance in a given direction to close the air gap 9. That is, the shaft 2 and the support 3 can move toward the frame 4. When the air gap 9 is closed, the support 3 and the frame 4 engage, preventing further movement of the shaft 2 in the given direction. Therefore, the force flow applied to the shaft 2 (causing the shaft 2 to move in the given direction) is directed through the frame 4 and away from the sensitive component 91 of the drivetrain.

[0071] Figure 7a The initial positions of shaft 2 and support 3 are shown, which can be considered as their positions during normal operation, i.e., the primary positions. Figure 7b In this process, a force F is applied to shaft 2, causing shaft 2 and support 3 to move together in a given direction, such that air gap 9 closes and the engagement surface 3a of support 3 engages with the surface 4a of frame 4 through which shaft 2 extends. This position can be considered as the drop position reflecting a drop event of personal care device 10 including transmission system assembly 1, i.e., the secondary position.

[0072] Support 3 is a component that acts as a drop protector. The support works in conjunction with the drivetrain shaft (rotor) and is configured to contact the drivetrain frame in the event of a drop of the personal care device, effectively redirecting force flow away from sensitive parts inside the drivetrain. Due to the arrangement of the support, shaft, and frame, a very small air gap can be provided between the support (drop protector) and the drivetrain frame (drivetrain frame).

[0073] Figure 8 A portion of a transmission system assembly according to an embodiment of one aspect of the invention is shown. A support 3 is configured to mate with a shaft 2. A gap 9 is provided between the mating surface 3a of the support 3 and the surface 4a of the frame 4. The gap 9 corresponds to a threshold distance, and the shaft is capable of moving the threshold distance in a given direction D before further movement is prohibited by the engagement of the support 3 and the frame 4.

[0074] exist Figure 8 In the illustrated embodiment, the support 3 is configured as a collar positioned above the shaft 2, although other configurations are possible. The body of the collar corresponds to the opening 4b in the frame 4, such that the body of the collar is at least partially received in the opening 4b. The collar further includes a lip, protrusion, or engagement portion extending from the body of the collar and beyond the opening 4b in the frame 4. The engagement portion provides an engagement surface 3a configured to engage with a surface 4a of the frame 4.

[0075] Figures 9 to 11Various components of a transmission system assembly according to an embodiment of one aspect of the present invention are shown. Specifically, Figure 9 A schematic diagram of a portion of shaft 2 according to an embodiment of one aspect of the present invention is shown; Figure 10 A schematic diagram of a portion of frame 4 according to an embodiment of one aspect of the present invention is shown; and Figure 11 A schematic diagram of a support 3 according to an embodiment of one aspect of the present invention is shown. Figure 10 As shown, frame 4 includes a frame opening 4b, which is an opening through which shaft 2 extends when the transmission system assembly is constructed. Frame 4 further includes a frame surface 4a. Figure 11 As shown, the support 3 includes a main body 3b and a mating portion 3c. The support 3 further includes a mating surface 3a, which is configured to engage or contact the frame surface 4a of the frame. The mating surface 3a is the surface of the mating portion 3c. Therefore, when assembling the transmission system components, the mating surface 3a is set to face (i.e., opposite to) the frame surface 4a. Figures 9 to 11 The components can be Figure 8 The components of the transmission system shown.

[0076] Therefore, embodiments of the present invention can utilize existing (typically low) axial flexibility in the transmission system. The support is placed on the shaft as an adapter at a location providing a very small clearance from the transmission system frame. As illustrated in FIG7(b), the small clearance can close in the event of a drop event. The distance between the support and the frame can be 0.2 mm or less. The air gap provided by embodiments of the present invention can be smaller than the air gap provided in alternative devices known in the art, such as FIG4. Air gaps in such devices known in the art are typically formed by two sub-assemblies comprising multiple elements that must be placed opposite each other. Due to component tolerances, it is difficult to achieve an air gap of less than 0.5 mm; that is, if the nominal transmission system design will include an air gap of 0.2 mm, there is a risk that a certain percentage of manufactured equipment will have zero air gap (air gap closure). Air gap closure results in significant friction between the transmission system and the rotor, leading to defective equipment.

[0077] Figure 12This is a flowchart of a manufacturing method according to an embodiment of the present invention. First, in step S121, a shaft is elastically mounted in a frame of a transmission system assembly such that the shaft extends through an opening in the surface of the frame. In step S122, a support is placed at a first position on the shaft, movably engaged with the shaft, such that the engagement surface of the support engages with the surface of the frame in this step. Then, a predetermined force is applied to the shaft in a given direction along its longitudinal axis, such that in step S123, the shaft moves relative to the frame along the given direction and with the support. In step S124, the predetermined force applied to the shaft is released, such that the shaft moves relative to the frame in a direction opposite to the given direction, and the support moves with the shaft, such that the support is held at a second position on the shaft, and the engagement surface of the support no longer engages with the surface of the frame. Finally, in step S125, the support is secured to the shaft at the second position.

[0078] Figures 13a to 13d These are a series of figures illustrating a method for manufacturing a portion of a transmission system assembly according to an embodiment of one aspect of the present invention. The method is described by way of example only with reference to a portion of the transmission system assembly shown in FIG7. Figures 13a to 13d The transmission system assembly shown also includes an electric motor comprising a rotor 5 and a stator 6. A shaft 2 is connected to the rotor 5 such that movement of the shaft 2 (e.g., due to the application of a force to the shaft 2) also causes movement of the rotor 5. Similarly, movement of the rotor 5 (e.g., due to the operation of the electric motor) also causes movement of the shaft 2. The manufacture of these parts of the transmission system assembly will not be described here.

[0079] like Figure 13a As depicted, the support (fall protector) 3 is positioned to movably engage with the shaft 2, allowing the support 3 to move along the shaft. Figures 13a to 13d In the illustrated embodiment, the support 3 is a collar that slides above the shaft 2. Due to the dimensions of the collar and the shaft 2, there is sufficient friction for the collar to slide above the shaft 2 to grip it, but not enough friction to prevent it from sliding along the shaft 2. Although the support is depicted as a collar, embodiments of the invention are not limited to this arrangement. For example, the support may be a ring or a washer, or it may be configured to engage movably with the shaft and with the frame, or any other component.

[0080] like Figure 13b As depicted, the support 3 is pushed against the frame 4 such that there is no space or gap between the support 3 and the surface 4a of the frame 4; that is, the support 3 is pressed against the frame 4 such that the mating surface 3a of the support 3 contacts / engages with the surface 4a (frame surface) of the frame 4. This position can be considered the first position.

[0081] like Figure 13cAs shown, a predetermined preload F is then applied to shaft 2 in the given (axial / longitudinal) direction. Due to the flexibility of the transmission system, the shaft moves slightly backward in the axial direction. That is, shaft 2 moves slightly along the given direction. Since support 3 engages with surface 4a of frame 4, support 3 slides forward relative to the axial direction, that is, support moves along the shaft in a direction opposite to the given direction.

[0082] Due to the structural flexibility and the connection between support 3 and frame 4, support 3 slides into a position corresponding to the applied force. This position can be considered a secondary position. As an example, the applied force F can be 50 N.

[0083] Then release the axial force on shaft 2, such as Figure 13d As depicted. Since shaft 2 is elastically mounted, when the force is released, shaft 2 moves forward relative to frame 4. That is, shaft 2 moves in a direction opposite to the given direction to return to its starting position or a position close to its starting position. Support 3 cooperates with shaft 2 such that when shaft 2 moves in a direction opposite to the given direction, support 3 moves with shaft 2. Therefore, a small air gap 9 is created between support (fall protection device) 3 and frame 4. When the force is released, support 3 remains in the same position on shaft 2 due to its cooperation with shaft 2. Therefore, support 3 can be considered to remain in the second position.

[0084] Then, the support 3 is fixed to the appropriate position on the shaft 2 by, for example, laser welding 8 at a location on the shaft 2 (i.e., at the second position). A small air gap 9 is maintained, which is independent of component tolerances. The only factors affecting the gap are the flexibility of the transmission system and the preload applied during step (3). As an example, a gap of 0.2 mm may appear between the support 3 and the frame 4 when the force is released.

[0085] The rotor 5 includes a rotor surface 5a, and the stator 6 includes a stator surface 6a, which is disposed opposite to the rotor surface 5a. A distance is defined between the rotor surface 5a and the stator surface 6a. This distance can be greater than a threshold distance, such that the shaft 2 is prohibited from moving relative to the frame 4 until the distance between the rotor surface 5a and the stator surface 6a becomes zero. That is, since the shaft 2 is attached to the rotor 5, movement of the shaft 2 in a given direction will cause the rotor 5 to move toward the stator 6, and the distance between the rotor surface 5a and the stator surface 6a will decrease. Since the support 3 prohibits the shaft 2 from moving beyond the threshold distance, the support 3 will prevent the rotor 5 from contacting the stator 6 as long as the threshold distance (corresponding to the air gap 9) is less than the distance between the rotor surface 5a and the stator surface 6a.

[0086] Therefore, this method allows the support to be positioned and secured at a location corresponding to a predetermined force and the final movement of the shaft. The force traveling through the sensitive part of the transmission system will not exceed the magnitude of a predetermined preload F. That is, when a force greater than the predetermined force (such as, for example, a drop force) is applied to the shaft, the support engages with the frame to prevent further shaft movement and redirect the force through the frame. The predetermined force may be relatively small compared to the maximum load limit of the sensitive part, thus creating a robust protection mechanism.

[0087] Figure 14 A schematic diagram of a portion of a transmission system assembly according to an embodiment of one aspect of the present invention is shown. Figure 14 The transmission system assembly illustrates an arrangement in which a support 3' is configured as a widening of a shaft 2. More specifically, a portion of the shaft 2 is wider than the opening of the frame 4 (through which the shaft 2 extends), such that the wider portion of the shaft 2 provides the support 3'. Therefore, the wider portion of the shaft 2 includes a mating surface 3'a configured to engage with a surface 4a of the frame 4. A gap is provided between the mating surface 3'a of the support 3' and the surface 4a of the frame 4. This gap corresponds to a threshold distance, and the shaft 2 is capable of moving a threshold distance in a given direction d before further movement is prohibited by the engagement of the support 3' and the frame 4. Since the support 3' is provided as part of the shaft 2, the threshold distance is determined by the positioning of the shaft 2 relative to the frame 4. Therefore, the shaft 2 can be positioned during the manufacturing process to provide the desired clearance.

[0088] Figure 15 A schematic diagram of a portion of a transmission system assembly according to an embodiment of one aspect of the present invention is shown. Figure 15 The transmission system assembly illustrates an arrangement in which a support 3” is configured as a protrusion extending from a shaft 2. This protrusion projects from a surface of the shaft 2 such that it extends beyond an opening in a frame 4 through which the shaft 2 extends, and the wider portion of the shaft 2 provides the support 3”. Therefore, each protrusion extending from the shaft 2 includes an engagement surface 3”a, which is configured to engage with a surface 4a of the frame 4. Although in Figure 15 Two protrusions are shown, but shaft 2 may include only one or more protrusions. A gap is provided between the mating surface 3”a of each protrusion of support 3” and the surface 4a of frame 4. This gap corresponds to a threshold distance, and shaft 22 is able to move the threshold distance along a given direction d before further movement is prohibited by the mating of support 3” and frame 4. Since support 3” is set as part of shaft 2, the threshold distance is determined by the positioning of shaft 2 relative to frame 4. Therefore, shaft 2 can be positioned during the manufacturing process to provide the desired gap.

[0089] Figure 16 A schematic diagram of a portion of a transmission system assembly according to an embodiment of one aspect of the present invention is shown. Figure 16 The transmission system assembly illustrates an arrangement in which a support 3”' is configured as a threaded collar, washer, or nut to engage with a corresponding threaded portion 2a of the shaft 2. More specifically, the portion 2a of the shaft is threaded such that the threaded inner surface of the support 3”' engages with the thread 2a of the shaft 2, and the support 3”' can be tightened (rotated) onto the shaft 2 to a desired position. The support 3”' is wider than the opening of the frame 4 through which the shaft 2 extends, and the support 3”' includes an engagement surface 3”'a configured to engage with a surface 4a of the frame 4.

[0090] A clearance is provided between the mating surface 3"'a of the support 3"' and the surface 4a of the frame 4. This clearance corresponds to a threshold distance, and the shaft 2 is able to move the threshold distance in a given direction d before the engagement of the support 3"' and the frame 4 prohibits further movement. The clearance can be set and adjusted by tightening (rotating) the support 3"' onto the shaft 2. Therefore, the shaft 2 can be positioned during the manufacturing process to ensure that the threaded portion 2a coincides with the opening of the frame 4, and the support 3"' can be tightened onto the shaft 2 so that the distance between the mating surface 3"'a and the surface 4a of the frame 4 corresponds to the desired clearance. The clearance can be adjusted by tightening or unscrewing the support 3"' to adjust the position of the support 3"' on the shaft 2.

[0091] As can be seen from the above, embodiments of the present invention can provide a transmission system component and a method of manufacturing it, including drop protection. The transmission system component and method of manufacturing can be used in personal care devices, such as electric toothbrushes. Embodiments of the present invention can overcome the disadvantages of the prior art discussed above.

[0092] Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily recognize that many modifications can be made to the exemplary embodiments without substantially departing from the novel teachings and advantages of the embodiments of this disclosure. The above-described embodiments of the invention can be advantageously used independently of any other embodiment, or in any feasible combination with one or more other embodiments.

[0093] Therefore, all such modifications are intended to be included within the scope of embodiments of this disclosure as defined in the following claims. In the claims, the device-plus-function clauses are intended to cover structures described herein as performing the described functions, and not only structural equivalents but also equivalent structures.

[0094] Furthermore, any reference numerals placed in parentheses within one or more claims should not be construed as limiting the claims. The terms "comprising" and "comprises," etc., do not exclude the presence of elements or steps other than those listed in any claim or the entire specification. A singular reference to an element does not exclude a plural reference to such an element, and vice versa. One or more embodiments may be implemented by means of hardware comprising several different elements. In a claim enumerating several manners of apparatus or device, several of these manners may be embodied by a single, identical hardware item. The fact that certain measures are listed in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

Claims

1. A drive system assembly (1) for a personal care device (10), the drive system assembly (1) comprising: Axis (2); An electric motor including a rotor (5) and a stator (6); A frame (4) including an opening (4b) in a surface (4a) of the frame (4), wherein the shaft (2) is elastically mounted in the frame (4) such that the shaft (2) extends through the opening (4b). as well as A support (3) located outside the frame (4) is fixedly connected to and cooperates with the shaft (2), and the support (3) is positioned to movably engage with the shaft (2) at a first position on the shaft (2), wherein... The engagement surface (3a) of the support (3) is configured to engage with the surface (4a) of the frame (4) such that relative movement between the frame (4) and the shaft (2) along a given direction (d) is prohibited from exceeding a threshold distance, wherein the given direction (d) is a rearward direction along the longitudinal axis of the shaft (2). The shaft (2) is subjected to a predetermined force along its longitudinal axis in the given direction (d), and the support (3) moves to a second position on the shaft (2) due to the engagement of the mating surface (3a) and the surface (4a). Subsequently, the predetermined force is released, causing the shaft (2) to move relative to the frame (4) in a direction opposite to the given direction (d), and the support (3) moves together with the shaft (2), such that the support (3) remains at the second position on the shaft (2), and the mating surface (3a) no longer engages with the surface (4a).

2. The transmission system assembly (1) according to claim 1, wherein the support (3) is a collar, the collar comprising: The main body (3b) has an inner diameter corresponding to the diameter of the shaft (2); as well as The joining portion (3c) is configured to protrude from the body (3b) and is configured to provide the joining surface (3a).

3. The transmission system assembly (1) according to claim 2, wherein the body (3b) has an outer diameter corresponding to the width of the opening (4b).

4. The transmission system assembly (1) according to claim 1, wherein The rotor (5) includes a rotor surface (5a); The stator (6) includes a stator surface (6a) disposed opposite to the rotor surface (5a); and The threshold distance is less than the distance between the stator surface (6a) and the rotor surface (5a).

5. The transmission system assembly (1) according to claim 1, wherein the threshold distance corresponds to a predetermined force applied to the shaft (2) in the given direction (d).

6. The transmission system assembly (1) according to claim 1, wherein The shaft (2) and the support (3) are configured to move together relative to the frame (4) between a primary position and a secondary position; The mating surface (3a) of the support (3) and the surface (4a) of the frame (4) are not mated at the primary position. The mating surface (3a) of the support (3) and the surface (4a) of the frame (4) are mated at the secondary position; and The threshold distance corresponds to the distance between the engagement surface (3a) of the support (3) and the surface (4a) of the frame (4) at the primary position.

7. The transmission system assembly (1) according to claim 1, wherein the support (3) is fixed to the shaft (2).

8. The transmission system assembly (1) according to claim 1, wherein the threshold distance is 0.2 mm or less.

9. A personal care device (10) comprising the drive system component (1) as described in any of the preceding claims.

10. A method of manufacturing a drive system assembly (1) for a personal care device (10), wherein the drive system assembly (1) has an electric motor including a rotor (5) and a stator (6), the method comprising: The shaft (2) is elastically mounted in the frame (4) of the transmission system assembly (1) such that the shaft (2) extends through an opening (4b) in the surface (4a) of the frame (4). The support (3) located outside the frame (4) is positioned at a first position on the shaft (2) and movably engaged with the shaft (2) such that the engagement surface (3a) of the support (3) engages with the surface (4a) of the frame (4), wherein the support (3) is fixedly connected to the shaft (2). A predetermined force is applied to the shaft (2) in a given direction (d) along the longitudinal axis of the shaft (2), causing the shaft (2) to move relative to the frame (4) in the given direction (d), and the support (3) moves to a second position on the shaft (2) due to the engagement of the engagement surface (3a) of the support (3) and the surface (4a) of the frame (4), wherein the given direction (d) is a rearward direction along the longitudinal axis of the shaft (2); Release the predetermined force applied to the shaft (2) so that the shaft (2) moves relative to the frame (4) in a direction opposite to the given direction (d), and the support (3) moves together with the shaft (2) so that the support (3) remains at the second position on the shaft (2), and the engagement surface (3a) of the support (3) no longer engages with the surface (4a) of the frame (4); as well as The support (3) is fixed to the shaft (2) at the second position.

11. The method according to claim 10, wherein the support (3) is a collar, the collar comprising: The main body (3b) has an inner diameter corresponding to the diameter of the shaft (2); as well as The joining portion (3c) is configured to protrude from the body (3b) and is configured to provide the joining surface (3a), wherein By sliding the collar on the shaft (2), the collar is positioned to movably engage with the shaft (2).

12. The method according to claim 11, wherein the body (3b) has an outer diameter corresponding to the width of the opening in the surface (4a) of the frame (4).

13. The method according to any one of claims 10 to 12, wherein the support (3) is fixed to the shaft (2) at the second position by laser welding.

14. The method according to any one of claims 10 to 12, wherein the predetermined force is 50 N or less.

Images