Head for an electric toothbrush

Abstract

This utility model discloses a toothbrush head for an electric toothbrush, including a handle housing having an inner cavity, a brush plate assembly rotatably disposed at the front end of the handle housing; an inner liner inserted into the inner cavity from the rear end of the handle housing; and a rocker arm disposed in the inner cavity, the rocker arm being held between the constraint surfaces of the inner liner and the handle housing along the longitudinal direction of the toothbrush head; wherein, the front end of the rocker arm has a driving part, the brush plate assembly has a driven part, the driving part engaging with the driven part, and the toothbrush head including an elastic device integrally formed on the rocker arm or the inner liner to provide a forward biasing elastic force to the rocker arm in the longitudinal direction, causing the driving part to engage with the driven part. Due to the forward elastic force of the elastic device, the driving part is forced back to a set ideal engagement position, ensuring good transmission of driving force from the rocker arm to the brush plate assembly.

Description

Technical Field

[0001] This utility model relates to the field of oral care appliances, specifically to a toothbrush head for an electric toothbrush. Background Technology

[0002] In the brush head structure of an electric toothbrush, the handle assembly and the brush plate assembly together constitute the core transmission mechanism. The brush plate assembly is rotatably mounted on the front end of the handle assembly. The rotation of the handle drive shaft or the reciprocating oscillation around axis L1 is transmitted to the brush plate assembly through the internal transmission components of the handle assembly, driving it to reciprocate around the rotation axis L2. The rotation axis L2 of the brush plate assembly is approximately perpendicular to the drive axis L1.

[0003] The brush handle assembly mainly includes a brush handle housing, a rocker arm located within the housing cavity, and an inner bushing for fixing the rocker arm. Due to manufacturing tolerances, the driving part at the end of the rocker arm is difficult to stably engage with the driven part of the brush disc, resulting in the rocker arm being in an uncontrolled state. Simultaneously, the motion-fit design of the handle drive shaft and the rocker arm (allowing for detachment) further exacerbates displacement fluctuations along the L1 direction, severely interfering with the mechanical coupling between the driving and driven parts.

[0004] The aforementioned problems will cause the drive unit to uncontrolledly detach from the driven unit, resulting in excessively large clearances causing additional noise and wear, or insufficient clearances limiting transmission power and reducing energy transfer efficiency. Therefore, the existing structure, under the combined effect of tolerance accumulation and motion degrees of freedom, struggles to maintain stable power transmission, especially during prolonged use. Thus, there is an urgent need to optimize the transmission reliability of existing toothbrush heads. Utility Model Content

[0005] To overcome the shortcomings of the prior art, this utility model provides a toothbrush head for an electric toothbrush, including a handle housing having an inner cavity, a brush plate assembly rotatably disposed at the front end of the handle housing; an inner liner inserted into the inner cavity from the rear end of the handle housing; and a rocker arm disposed in the inner cavity, the rocker arm being held between the constraint surface of the inner liner and the constraint surface of the handle housing along the longitudinal direction of the toothbrush head; wherein, the front end of the rocker arm has a driving part, the brush plate assembly has a driven part, the driving part engages with the driven part, and the toothbrush head includes an elastic device integrally formed on the rocker arm or the inner liner to provide a forward biasing elastic force to the rocker arm in the longitudinal direction, causing the driving part to engage with the driven part.

[0006] If the driving and driven parts at the front end of the lever fail to be in the ideal engagement position due to factors such as manufacturing tolerances or excessive wear during use, once the driving part shifts backward relative to the driven part away from the ideal engagement position, the elastic force of the elastic device on the forward side forces the driving part back to the set ideal engagement position, ensuring good transmission of driving force from the lever to the brush assembly.

[0007] According to another aspect of the present invention, the swing arm has two swing arm constraint surfaces that respectively contact the constraint surface of the inner bushing and the constraint surface of the brush handle housing, and an elastic device is integrally formed at the end or middle of the swing arm so that the longitudinal length C1 between the swing arm constraint surfaces can be varied.

[0008] According to another aspect of the present invention, an elastic device is integrally formed at the front end of the inner liner so that the distance C2 between the constraint surface of the inner liner and the constraint surface of the brush handle housing can be varied, wherein the constraint surface of the inner liner is provided by the elastic device.

[0009] According to another aspect of the present invention, an elastic device is disposed at the end of a swing arm or an inner bushing. The elastic device includes an elastic arm and a support portion connecting the elastic arm to the end. A gap is formed between the elastic arm and the end to allow deformation of the elastic arm, wherein one or both ends of the elastic arm are held to the end by the support portion.

[0010] According to another aspect of the present invention, the elastic device is integrally formed in the middle of the swing arm and adjacent to the front end of the hollow portion of the swing arm.

[0011] According to another aspect of the present invention, the elastic device is in the form of one or more thin-walled portions, the thickness of which is set such that the thin-walled portions can deform inward into the hollow portion of the swing arm.

[0012] According to another aspect of the present invention, the swing arm further includes a front elastic device disposed on the front side of the positioning hole of the swing arm and separated from the positioning hole by a gap, the front elastic device including a suspension ring or a forked cantilever with a central hole.

[0013] According to another aspect of the present invention, a drive unit is integrally disposed at the front end of the swing arm, the drive unit being engaged with the driven unit, thereby converting the reciprocating rotation of the swing arm about the longitudinal axis L1 into the reciprocating rotation of the brush assembly about the axis L2, wherein the axis L1 is substantially perpendicular to the axis L2.

[0014] According to another aspect of the present invention, the drive unit is disposed at the front end of the swing arm via an independent brush handle drive shaft.

[0015] According to another aspect of the present invention, the swing arm has two swing arm constraint surfaces that respectively match the constraint surface of the inner bushing and the constraint surface of the brush handle housing. The longitudinal length between the two constraint surfaces of the swing arm is C1, and the longitudinal length between the constraint surface of the inner bushing and the constraint surface of the brush handle housing is C2, wherein C2-0.5mm≤C1≤C2+0.5mm. Preferably, C2≤C1≤C2+0.3mm. Attached Figure Description

[0016] Figure 1 A perspective view of the outer contour of a toothbrush head for an electric toothbrush according to the present invention is shown.

[0017] Figure 2 A perspective view of the internal structure of a toothbrush head according to a first embodiment of the present invention is shown.

[0018] Figure 3 A perspective view of the rocker arm and inner bushing assembly according to a first embodiment of the present invention is shown.

[0019] Figure 4 A partial perspective view of the rear end of the lever of a toothbrush head according to a first embodiment of the present invention is shown.

[0020] Figure 5 A cross-sectional perspective view of a brush handle housing with an inner liner according to a first embodiment of the present invention is shown.

[0021] Figure 6 A perspective view of the rocker arm and inner bushing assembly according to a first embodiment of the present invention is shown.

[0022] Figure 7 A cross-sectional view of the lever according to a first embodiment of the present invention is shown.

[0023] Figure 8 A perspective view of the lever according to a second embodiment of the present invention is shown.

[0024] Figure 9 A perspective view of the lever according to a third embodiment of the present invention is shown.

[0025] Figure 10 A perspective view of the lever according to the fourth embodiment of the present invention is shown.

[0026] Figure 11 A cross-sectional view of the rocker arm according to the fourth embodiment of the present invention is shown.

[0027] Figure 12 A perspective view of the lever according to the fifth embodiment of the present invention is shown.

[0028] Figure 13A perspective view of the lever according to the sixth embodiment of the present invention is shown.

[0029] Figure 14 A perspective view of the internal structure of a toothbrush head according to a seventh embodiment of the present invention is shown.

[0030] Figure 15 A cross-sectional view of the handle housing of a toothbrush head according to the seventh embodiment of the present invention is shown.

[0031] List of reference numerals

[0032] 1 toothbrush head

[0033] 11 Cleaning Components

[0034] 12,612 disk brushing components

[0035] 21,621 Brush Handle Housing

[0036] 22 positioning posts

[0037] 23 constraint surfaces

[0038] 31 Inner Liner

[0039] 32 constraint surfaces

[0040] 33 Lining protrusion

[0041] 41 Handle Drive Shaft

[0042] 51, 151, 251, 351, 451, 551, 651 oscillating rods

[0043] 52 swing arm buckle

[0044] 53 positioning holes

[0045] 54, 154, 254 gaps

[0046] 50, 150, 250, 350a, 350b, 450, 550a, 550b, 650 elastic devices

[0047] 55, 155, 255 flexible arms

[0048] 56, 156, 256 support sections

[0049] 57, 457 hollow section

[0050] 58, 558 rocker arm drive unit

[0051] 459 Thin-walled section

[0052] 559b Flexible Arm

[0053] 560b gap

[0054] 561b Support Section

[0055] 670 brush handle drive shaft Detailed Implementation Plan

[0056] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0057] In the following description, the term "front end / front side" refers to the end or side of the cleaning element located near the toothbrush head, while the term "rear end / rear side" refers to the end or side of the cleaning element located away from the toothbrush head. The term "longitudinal direction" refers to the direction parallel to the front end to the rear end of the toothbrush head, which is substantially parallel to the axis around which the reciprocating rotation of the lever is centered.

[0058] Figure 1 A toothbrush head 1 for an electric toothbrush according to the present invention is shown. In the structure of this toothbrush head 1, the handle assembly and the brush plate assembly 12 constitute the main components. A handle drive shaft 41, a component of the handle assembly of this electric toothbrush, extends from the rear end of the toothbrush head 1. The brush plate assembly 12 is rotatably mounted to the front end of the handle assembly. The brush plate assembly 12 mainly includes a brush plate body and a cleaning element 11 fixed to the brush plate body. The cleaning element 11 is, for example, bristles. Figure 2 As shown, the handle drive shaft 41 reciprocates around the longitudinal axis L1 (approximately along the longitudinal direction of the toothbrush head 1), transmitting the signal to the brush plate assembly 12 through components inside the handle assembly, thus driving the brush plate assembly 12 to rotate or reciprocate around its rotation axis L2. The rotation axis L2 of the brush plate assembly 12 is approximately perpendicular to the longitudinal axis L1.

[0059] Figures 2 to 7A toothbrush head according to a first embodiment of the present invention is shown. The toothbrush head handle assembly mainly includes a handle housing 21, a rocker arm 51 located in the inner cavity of the handle housing 21, and an inner sleeve 31 disposed at the rear end of the toothbrush head 10. The inner sleeve 31 is engaged with the rear end of the handle housing 21 by an inner sleeve protrusion 33 on its outer surface. A handle drive shaft 41 is inserted into the toothbrush head through the rear opening of the inner sleeve 31 and further inserted into the hollow portion 57 inside the rocker arm 51. The rocker arm 51 is engaged with a corresponding recess formed on the handle drive shaft 41 by a rocker arm latch 52. The handle drive shaft 41 is connected to the rocker arm 51, thereby driving the rocker arm 51 to rotate together. On the other hand, the front end of the rocker arm 51 is provided with a positioning hole 53, and a corresponding positioning post 22 is provided in the handle housing 21 near the front end. The rotational positioning of the rocker arm 51 and the handle housing 21 is achieved by the cooperation of the positioning post 22 and the positioning hole 53.

[0060] In this toothbrush head, the swing arm 51, located in the inner cavity of the handle housing 21, is constrained along the longitudinal direction of the toothbrush head by the constraint surface 32 of the inner sleeve 31 and the constraint surface 23 of the handle housing 21, respectively. That is, the swing arm 51 is located between the constraint surface 32 of the inner sleeve 31 and the constraint surface 23 of the handle housing 21. In this embodiment, the constraint surface 32 of the inner sleeve 31 is the end face of its front end. A fixed surface on the side of the handle housing 21 opposite to the inner sleeve 31 provides the constraint surface 23 of the handle housing 21. In this embodiment, the bottom surface of the recess on the outer periphery of the positioning post 22 of the handle housing 21 provides the constraint surface 23 of the handle housing 21.

[0061] Furthermore, such as Figure 2 As shown, the front end of the swing arm 51 has a swing arm drive part 58, and the brush body in the brush assembly 12 has a corresponding driven part. The swing arm drive part 58 and the driven part cooperate with each other to achieve a gear-like meshing motion, thereby converting the rotation of the swing arm 51 around the axis L1 into the rotation of the brush assembly 12 around the axis L2.

[0062] In particular, such as Figure 4 As shown, an elastic device 50 is provided at the rear end of the swing arm 51. This elastic device 50 is configured to elastically deform at least in the direction along the axis L1 (i.e., the longitudinal direction of the toothbrush head) to provide a spring force tending to engage the swing arm drive portion 58 at the front end of the swing arm 51 with the driven portion of the brush plate assembly 12. This spring force causes the swing arm to bias towards the front of the toothbrush head in the longitudinal direction. In the first embodiment, the elastic device 50 provided on the swing arm 51 allows the length of the swing arm 51 to vary between the constraint surface 32 of the inner bushing 31 and the constraint surface 23 of the brush handle housing 21. In other words, it allows the length between the two opposing constraint surfaces of the swing arm 51 to vary. In this embodiment, the two constraint surfaces of the swing arm 51 are the rear surface of the elastic device 50 and the front surface of the positioning hole 53.

[0063] The elastic device 50 is integrally formed on the swing arm 51. The elastic device 50 includes an elastic arm 55 and a support portion 56 connecting the elastic arm 55 to the rear end of the swing arm 51. Specifically, the elastic device 50 of the first embodiment has two support portions 56, radially opposite each other on the rear end face of the swing arm 51. The elastic arm 55 is in the form of a simply supported beam, each arm being curved, and its two ends are held by the two support portions 56 respectively. The rear surface of the elastic arm forms an undulating surface, thereby forming two rearwardly projecting protrusions in the direction of the axis L. A gap 54 is formed between the cantilever and the rear end of the swing arm 51, which allows the cantilever to elastically deform. When the swing arm 51 is installed into the brush handle housing 21, the cantilever abuts against the inner bushing 31 when the positioning hole 53 of the swing arm 51 and the mutually engaging constraint surfaces of the positioning post 22 of the brush handle housing 21 abut. Alternatively, in some cases, a small gap may be left, typically less than 0.5 mm. Thus, the elastic device 50 on the rocker arm 51 provides a force to move the rocker arm 51 forward, enabling the drive unit to enter its ideal engagement position, allowing for a relatively wide range of manufacturing tolerances, and avoiding noise, wear, or power loss.

[0064] Figure 8 A perspective view of a rocker arm 151 according to a second embodiment of the present invention is shown. The rocker arm 151 has an elastic device 150 at its rear end, which includes an elastic arm 155 in the form of a simply supported beam and a support portion 156 connecting the elastic arm 155 to the rear end of the rocker arm 151. In the second embodiment, the elastic arm 155 is annular, and the support portion 156 supports the rocker arm 155 arranged radially opposite to it. Four protrusions are provided on the rear end face of the elastic arm 155, forming a gap 154 ​​between the elastic arm 155 and the rear end of the rocker arm 151, providing space for the elastic arm 155 to deform.

[0065] Figure 9 A perspective view of a swing arm 251 according to a third embodiment of the present invention is shown. The swing arm 251 has an elastic device 250 at its rear end, comprising an elastic arm 255 in the form of a cantilever beam and a support portion 256 connecting the elastic arm 255 to the rear end of the swing arm 251. Specifically, the elastic device 250 includes two radially opposite support portions 256, each supporting a pair of elastic cantilevers that extend away from each other. The free end of the elastic cantilevers is closer to the rear side relative to its fixed end in the direction of axis L1, such that when the swing arm 251 is mounted on the brush handle housing 21, the free end of the elastic cantilevers first abuts against the front surface of the inner liner 31.

[0066] Figure 10 and Figure 11A perspective view of a rocker arm 351 according to a fourth embodiment of the present invention is shown. The rocker arm 351 includes a rear elastic device 350a and a middle elastic device 350b. The rear elastic device 350a is similar to the elastic device 250 in the third embodiment. The middle elastic device 350b is disposed at the middle position of the rocker arm 351, that is, between the two longitudinal ends of the rocker arm 351, such as... Figure 11 As shown, the central elastic device 350b is positioned approximately adjacent to the front end of the hollow portion 57 of the rocker arm 351. The central elastic device 350b is in the form of a longitudinally extending thin-walled portion, that is, the thickness of a portion of the rocker arm 351 from its outer surface to the inner circumferential surface of the hollow portion 57 is reduced such that the wall portion can deform inward into the hollow portion 57, thereby constituting the elastic device 350b.

[0067] The rear elastic device 350a and the middle elastic device 350b can work together to compensate for the change in the longitudinal engagement length between the swing arm 351 and the inner cavity of the brush handle housing 21, ensuring good engagement between the swing arm drive part 358 and the driven part.

[0068] Figure 12 A perspective view of a rocker arm 451 according to a fifth embodiment of the present invention is shown. In this embodiment, the rocker arm 451 includes only a central elastic device 450. The central elastic device 450 includes two separate thin-walled portions 459 extending longitudinally, each end of which is integrally connected to the body of the rocker arm 451. Preferably, the thin-walled portions 459 are arranged opposite each other across a longitudinal axis L1. The thin-walled portions 459 are elastically deformable inward toward the hollow portion 457 of the rocker arm 451, allowing for variation in the longitudinal length of the rocker arm 451. The number of separate thin-walled portions 459 can also vary, such as three or four. The thin-walled portions 459 are adjacent to the front end of the hollow portion of the rocker arm 451, where the handle drive shaft 41 may not be inserted into the hollow portion, thereby allowing the thin-walled portions 459 to deform inward.

[0069] Figure 13 A perspective view of a rocker arm 551 according to a sixth embodiment of the present invention is shown. In this embodiment, the rocker arm 551 includes a rear elastic device 550a and a front elastic device 550b, wherein the rear elastic device 550a has the same structure as the elastic device 50 in the first embodiment, and will not be described again here.

[0070] A front elastic device 550b is disposed on the front side of the positioning hole of the rocker arm 551 and separated by a gap. The positioning hole of the rocker arm 551 and the rocker arm drive portion 558 are offset from each other in the radial direction (perpendicular to the axis L1), and the portion of the rocker arm 551 below the positioning hole extends further forward, with the front end of this portion forming the rocker arm drive portion 558. In other words, the front end of the positioning hole is located on the longitudinal rear side of the rocker arm drive portion 558. In this case, the front elastic device 550b has an elastic arm 559b and a support portion 561b. The elastic device 550b is integrally disposed on the front side of the front end of the positioning hole of the rocker arm 551 and is integrally formed with a portion of the front end of the rocker arm 551 extending out of the positioning hole 53 via the support portion 561b. The elastic arm 559b can be as follows: Figure 13 The suspension ring shown has a protrusion on its front surface, or it could be a forked cantilever. When the lever 551 is installed into the inner cavity of the brush handle housing, the positioning pin is inserted into the center hole of the ring, and the suspension ring abuts against the brush handle housing 21 in the longitudinal direction, thus providing a certain amount of longitudinal length variation. The front elastic device 550b is provided to avoid power transmission difficulties caused by the drive unit being over-inserted into the driven unit.

[0071] With the toothbrush head installed, preferably, the rear elastic device 550a of the swing arm 551 is in direct elastic contact with the front end face of the inner bushing 31 or has a small gap 254, usually less than 0.5mm, while the front elastic device 550b of the swing arm 551 and the relative surface of the brush handle housing 21 are in elastic contact with each other or have a small gap 560b, usually less than 0.5mm.

[0072] Alternatively, the rear elastic device 550a of the sixth embodiment can also be replaced by the elastic device 150 or 250 of the second or third embodiment.

[0073] Figure 14 A toothbrush head for an electric toothbrush according to a seventh embodiment of the present invention is shown, while Figure 15 A cross-sectional view of the brush handle housing 621 of the toothbrush head is shown. In this toothbrush head, a lever 651 drives the brush disc assembly 612 via a brush handle drive shaft 670. Specifically, the brush handle drive shaft 670 passes through a hollow area in a boss below the brush disc assembly 612, preventing the brush disc assembly 612 from detaching from the brush handle housing 621. The brush handle drive shaft 670 is typically metal and has a drive wheel fitted onto it, which has a drive wheel drive portion that engages with the brush disc driven portion of the brush disc. In this embodiment, the drive wheel is housed in a brush disc receiving portion formed at the front end of the brush handle 621.

[0074] An elastic device 650 is integrally provided at the rear end of the swing arm 651 to provide for the variation in the longitudinal length of the swing arm 651. The structure of the elastic device 650 can be in the form of a simply supported beam or a cantilever beam.

[0075] For toothbrush heads with an independent handle drive shaft 670, although the drive wheel on the handle drive shaft 670 is constrained by the receiving part on the front side of the handle housing, and the lever 651 cannot completely detach from the handle housing in the longitudinal direction, there is still a possibility of mismatch between the length of the lever 651 and the length of the lever 651 corresponding to the length accommodated in the inner cavity of the handle 621 due to tolerances or wear. This can also cause the drive part to detach from the proper matching position of the driven part, resulting in additional wear of the drive part and brush head noise. By introducing an elastic device 650 at the rear end of the lever 651, it is ensured that the lever 651 and the inner cavity of the handle housing 621 are in an ideal longitudinal matching position, thus avoiding accelerated wear of the drive part of the drive wheel.

[0076] In other alternative embodiments, the elastic device may also be integrally disposed on the inner sleeve, so that the longitudinal length of the inner sleeve can change as the elastic device deforms, thereby correspondingly changing the longitudinal length C2 between the opposing constraint surfaces of the inner sleeve and the brush handle housing, wherein the constraint surface of the inner sleeve is provided by the elastic device. The elastic deformation devices 50, 150, and 250 located at the rear end of the swing arm as described in the first, second, and third embodiments above can be integrally disposed on the front end face of the inner sleeve 631. When the inner sleeve with the elastic deformation device is installed in the inner cavity of the brush handle housing, the elastic deformation device abuts against the end of the swing arm.

[0077] In the above embodiments, when the elastic device is in a state of elastic deformation due to contact, the relative constraint surfaces of the positioning hole of the swing arm and the positioning post of the brush handle housing are in contact. In order to reduce the frictional resistance between the relative constraint surfaces, the constraint surfaces can be mirror polished to make the coefficient of friction as small as possible. In addition, the contact area can also be reduced.

[0078] In the above embodiments, the longitudinal length between the two constraint surfaces providing longitudinal constraints on the lever is defined as C1, while the longitudinal length between the constraint surface of the inner bushing and the binding surface of the brush handle housing is defined as C2. Preferably, C1 is within the range of C2 ± 0.5 mm (C2 - 0.5 mm ≤ C1 ≤ C2 + 0.5 mm). This ensures good engagement between the driving and driven parts inside the toothbrush head by utilizing the elastic force of the elastic device. It should be understood that when C1 is less than C2, the lever has longitudinal freedom within the inner cavity of the brush handle housing. During use, when the lever moves longitudinally rearward, the elastic device deforms under pressure, generating an elastic force that biases it forward. Preferably, C2 ≤ C1 ≤ C2 + 0.3 mm. This allows for a wider allowable tolerance range between the design and actual manufacturing values ​​of the various parts of the toothbrush head, and also ensures elastic contact between the elastic device and the opposite constraint surface, compensating for length mismatches caused by wear during subsequent use.

[0079] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible variations and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A toothbrush head for an electric toothbrush, comprising: A brush handle housing having an inner cavity, and a brush disc assembly rotatably disposed at the front end of the brush handle housing; Inner liner, the inner liner being inserted into the inner cavity from the rear end of the brush handle housing; as well as A swing arm is disposed in the inner cavity and is held between the constraint surface of the inner liner and the constraint surface of the brush handle housing along the longitudinal direction of the toothbrush head. The swing arm has a driving part at its front end, and the brush assembly has a driven part, with the driving part engaging with the driven part. The toothbrush head is characterized by including an elastic device integrally formed on the swing arm or the inner sleeve to provide a forward biasing force to the swing arm in the longitudinal direction, thereby causing the driving part to engage with the driven part.

2. The toothbrush head of claim 1, wherein, The rocker arm has two rocker arm constraint surfaces, one constraining the inner liner and the other constraining the brush handle housing. The elastic device is integrally formed at the end or middle of the swing arm so that the longitudinal length C1 between the constraint surfaces of the swing arm can vary.

3. The toothbrush head of claim 1, wherein, The elastic device is integrally formed at the front end of the inner liner, so that the distance C2 between the constraint surface of the inner liner and the constraint surface of the brush handle housing can vary. The constraint surface of the inner liner is provided by the elastic device.

4. The toothbrush head of claim 1, wherein, The elastic device is disposed at the end of the swing arm or the inner bushing. The elastic device includes an elastic arm and a support portion connecting the elastic arm to the end portion, with a gap forming between the elastic arm and the end portion to allow deformation of the elastic arm. One or both ends of the elastic arm are held to the end by the support portion.

5. The toothbrush head of claim 1, wherein, The elastic device is integrally formed in the middle of the swing arm and adjacent to the front end of the hollow portion of the swing arm.

6. The toothbrush head as described in claim 5, characterized in that, The elastic device is in the form of one or more thin-walled portions, the thickness of which is set such that the thin-walled portion can deform inward into the hollow portion of the rocker arm.

7. The toothbrush head as described in claim 1, characterized in that, The swing arm also includes a front elastic device, which is disposed on the front side of the positioning hole of the swing arm and separated from the positioning hole by a gap. The front elastic device includes a suspension ring or a forked cantilever with a central hole.

8. The toothbrush head as described in claim 1, characterized in that, The driving unit is integrally disposed at the front end of the swing arm, and the driving unit engages with the driven unit, thereby converting the reciprocating rotation of the swing arm about the longitudinal axis L1 into the reciprocating rotation of the brush assembly about the axis L2, wherein the axis L1 is substantially perpendicular to the axis L2. Alternatively, a separate brush handle drive shaft can be connected to the front end of the swing arm, the brush handle drive shaft having a drive wheel, and the drive wheel having the drive unit.

9. The toothbrush head of claim 1, wherein, The rocker arm has two rocker arm constraint surfaces that respectively match the constraint surface of the inner liner and the constraint surface of the brush handle housing. The longitudinal length between the rocker arm constraint surfaces is C1, and the longitudinal length between the constraint surface of the inner liner and the constraint surface of the brush handle housing is C2. Wherein, C2-0.5mm≤C1≤C2+0.5mm.

10. The toothbrush head of claim 9, wherein, C2≤C1≤C2+0.3mm.

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