Power tool having an Anti-vibration assembly

Abstract

A power tool, comprising: an outer housing; a motor disposed within the outer housing; an output shaft for performing an operation on a work piece, the output shaft adapted to be driven by the motor; a bearing configured to bear the output shaft; an inner housing at least partially disposed within the outer housing and configured to receive a portion of the bearing; and an anti-vibration assembly configured to reduce vibration to the outer housing, wherein the anti-vibration assembly comprises a first anti-vibration member mounted between the bearing and the outer housing, the first anti-vibration member adapted to be in direct or indirect contact with the bearing and the outer housing and being free of direct contact with the inner housing.

Description

TECHNICAL FIELD

[0001] The present invention relates to a power tool having an anti-vibration assembly to reduce vibration transmission to its outer housing.

[0002] EP 3 385 034 A1 shows the preamble of claim 1.

[0003] Other power tools are known from US 2020 / 384597 A1, WO 2016 / 127930 A1, EP 3 208 049 A1, US 2017 / 008160 A1 or EP 2 749 381 A1.BACKGROUND

[0004] Power tools utilize the rotation of a motor to provide useful torque for operations such as cutting, sanding, grinding, removing material, drilling, driving fasteners, and the like. However, vibration in power tools, particularly in portable power tools, always reduces their manipuility.

[0005] One way of reducing the vibration is providing an elastomeric film on the handle portion so that it absorbs a portion of the vibration before it is transmitted to a user's hand. But such effect is limited if the film is not thick enough. However, if wrapping the handle portion of the power tool with a thicker elastomeric film, it not only increases manufacturing cost, but also makes it less ergonomic for the user to grip the handle portion.

[0006] Therefore, it is wishful to provide a power tool with anti-vibration elements to effectively reduce the transmission of vibration.SUMMARY OF INVENTION

[0007] In accordance with an aspect of the present invention, there is provided a power tool, comprising: an outer housing; a motor disposed within the outer housing; an output shaft for performing an operation on a work piece, the output shaft adapted to be driven by the motor; a supporting unit configured to bear the output shaft so that the output shaft is rotatable in relative to the outer housing; an inner housing at least partially disposed within the outer housing and configured to receive a portion of the supporting unit; and an anti-vibration assembly configured to reduce vibration to the outer housing, wherein the anti-vibration assembly comprises a first anti-vibration member mounted between the supporting unit and the outer housing, the first anti-vibration member adapted to be in direct or indirect contact with the supporting unit and the outer housing and being free of direct contact with the inner housing.

[0008] In an embodiment, the first anti-vibration member extends between the supporting unit and the outer housing in a direction substantially perpendicular to an axial direction of the output shaft.

[0009] In an embodiment, the inner housing has an opening through which the first anti-vibration member passes so that the first anti-vibration member extends between the supporting unit and the outer housing

[0010] In an embodiment, the opening is an indentation formed on the inner housing.

[0011] In an embodiment, the first anti-vibration member is movable between the outer housing and the supporting unit.

[0012] In an embodiment, the first anti-vibration member is unmovably mounted between the outer housing and the supporting unit.

[0013] In an embodiment, the supporting unit is a bearing.

[0014] In an embodiment, the supporting unit is a bushing.

[0015] In an embodiment, the supporting unit comprises a bearing and a bushing sleeved on and coupled to the bushing

[0016] In an embodiment, the first anti-vibration member is independent from both the supporting unit and the outer housing.

[0017] In an embodiment, the first anti-vibration member is formed by overmolding integrally with at least a portion of the outer housing.

[0018] In further an embodiment, the first anti-vibration member is formed integrally with the bushing.

[0019] In an embodiment, the first anti-vibration member is formed with a groove to engage with at least a portion of the outer housing and / or the supporting unit.

[0020] In an embodiment, the first anti-vibration member is an elastomeric element.

[0021] In an embodiment, the anti-vibration assembly comprises a pair of said first anti-vibration members symmetrically disposed on opposite sides of the supporting unit.

[0022] In an embodiment, the first anti-vibration member is a rubber pin.

[0023] In an embodiment, the outer housing comprises a groove or a socket to receive an end portion of the first anti-vibration member.

[0024] In an embodiment, the first anti-vibration member contacts the outer housing and / or the supporting unit via an intermediate damper.

[0025] In an embodiment, the anti-vibration assembly further comprises a second anti-vibration member disposed between with the inner housing and the outer housing at a location around the output shaft.

[0026] In an embodiment, the anti-vibration assembly further comprises a third anti-vibration member disposed between the inner housing and the outer housing around the motor.BRIEF DESCRIPTION OF DRAWINGS

[0027] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying figures in which: Figure 1 is a perspective view of a first embodiment showing a power tool containing an anti-vibration assembly and an inner housing of the power tool, with an outer housing hidden, in accordance with the present invention. Figure 2 is a cross sectional view along the plane A-A' of the power tool of Figure 1 with an outer housing. Figure 3 is an aggregated right view of the power tool of Figure 1 with a half piece of outer housing. Figure 4 is a cross sectional view of a second embodiment showing a power tool containing an anti-vibration assembly and an inner housing of the power tool in accordance with the present invention. DETAILED EMBODIMENTS

[0028] The present invention pertains to a power tool which is provided with an anti-vibration assembly to effectively reduce transmission of vibration in the power tool.

[0029] With reference to Figure 1, there is an embodiment showing an anti-vibration assembly as a constitutional part of the power tool in accordance with the present invention. In this embodiment, the power tool is a portable power tool that has an inner housing 100, an output shaft 200 driven by a motor (not shown) to perform an operation on a work piece (not shown), a bearing 310 that is partially supported by the inner housing 100 and bears the output shaft 200. The bearing 310 is for example a needle bearing. The portable power tool also has an outer housing 700 (shown in Figures 2 and 3) to receive at least a portion of the inner housing 100. A portion of the outer housing 700 is configured as a handle portion (not shown) that can be gripped by a user.

[0030] The motor and the output shaft 200 generate vibration when the power tool is in operation. Particularly, the vibration is caused by the output shaft and moving components (not shown) near the output shaft. The vibration is transmitted to the inner housing 100 which is in indirect contact with the output shaft. The vibration then could be transmitted to the outer housing 700 which receives the inner housing 100.

[0031] In order to eliminate or at least reduce the vibration transmitted to the outer housing (i.e. to the handle portion of the power tool), in the present invention an anti-vibration assembly is provided to the power tool.

[0032] In this first embodiment, the anti-vibration assembly comprise a pair of first anti-vibration members 410. Each first anti-vibration member 410 is mounted between the bearing 310 and the outer housing 700 in direct contact, and free of direct contact with the inner housing 100. The inner housing 100 is provided with an opening 110 through which the first anti-vibration member 410 passes through so that the first anti-vibration member 410 extends between the outer housing 700 and the bearing 310, so that the first anti-vibration member 410 bypasses the inner housing 100. This is to ensure that the first anti-vibration member 410 directly absorb at least a portion of vibration energy mainly generated by the output shaft and the moving components near the output shaft before it is transmitted to the inner housing 100 and / or the outer housing 700. In another embodiment, the first anti-vibration member indirectly contacts the outer housing and / or the bearing via an intermediate damper.

[0033] The opening 110 in the inner housing 110 is configured as an indentation so as to minimize the possibility of contact between the first anti-vibration member 410 and the inner housing 100. The indentation has a substantial "U" shape. In other embodiments, the opening 110 may be a closed opening with any regular or irregular shape.

[0034] In this first embodiment, the two first anti-vibration members 410 are configured as a pair of elastomeric elements, such as a pair of rubber pins. The pair of rubber pins are symmetrically disposed on opposite sides of the bearing 310 and extend from the bearing 310 to the outer housing 700 in opposite directions perpendicular to an axial direction of the output shaft 200 and an axial direction of the inner housing 100. Skilled person should understand that in variations of the invention, the inner housing 100 may or may not be symmetric, and the "axial direction of the inner housing 100" refers to the direction perpendicular to radial directions of the inner house 100.

[0035] Referring to Figure 2, the outer housing 700 is provided with a groove or a socket 710 to receive an end of each first anti-vibration member 410 at each side of the bearing 310. Another end of the first anti-vibration member 410 is extruded from outer circumference of the bearing 310, so that the first anti-vibration member 410 is movable between the outer housing 700 and the bearing 310. This enables the first anti-vibration member 410 to adjust itself so as to further release excess amount of absorbed vibration energy when the first anti-vibration member 410 is over-compressed and / or over-deformed. In a variation of the embodiment, the first anti-vibration member is unmovably mounted between the outer housing and the bearing.

[0036] With reference to Figures 1 and 3, the anti-vibration assembly also contains a second anti-vibration member 500 disposed between and in contact with the inner housing 100 and the outer housing 700 so as to reduce vibration transmission from the inner housing 100 to the outer housing 700. In this embodiment, the second anti-vibration member 500 is in direct contact with a first end of the inner housing 100 near an end tool (not shown) that is coupled to the output shaft and to work on the work piece. The second anti-vibration member 500 is disposed around the output shaft just like the first anti-vibration members 400. In a variation of the embodiment, the second anti-vibration member may contact with the first end of the inner housing via a first intermediate member. With the presence of the second anti-vibration member 500, the inner housing 100 and the outer housing 700 are physically isolated and the vibration transmission therebetween is further reduced. The shape of the second anti-vibration member 500 may be tailored to at least partially fit in the space between the outer housing 700 and the inner housing 100 at the first end.

[0037] With reference to Figures 1 and 3, the anti-vibration assembly further contains a third anti-vibration member 600 disposed between and in contact with the inner housing 100 and the outer housing 700 so as to reduce vibration transmission from the inner housing 100 to the outer housing 700. The third anti-vibration member 600 contacts with the second end of the inner housing 100 via a first intermediate member 610. The third- anti-vibration member 600 is located around the motor. In a variation of the embodiment, the third anti-vibration member 600 may be in direct contact with the second end of the inner housing 100. Like the second anti-vibration member 500, the third anti-vibration member 600 physically isolates the inner housing 100 and the outer housing 700 and reduces vibration transmission therebetween. The shape of the third anti-vibration member 500 may be tailored to at least partially fit in the space between the outer housing 700 and the inner housing 100 and at the second end.

[0038] In this application, the "first end of the inner housing" and the "second end of the inner housing" are termed only for the purpose to distinguish one another, and may be or may not be a distal end of the inner housing.

[0039] Figure 4 showe a second embodiment of the present invention that shows an alternative arrangement of the first anti-vibration member. In this second embodiment, the inner housing, the output shaft, the outer housing, the opening of the inner housing, the second and third anti-vibration member can be the same as in the first embodiment. They are represented by using same numbers as in the first embodiment and are not repeatedly descripted herein.

[0040] In this second embodiment, the supporting unit is a flanged bushing 320 that is partially supported by the inner housing 100 and bears the output shaft 200. The anti-vibration assembly comprises a first anti-vibration member 420, for example a rubber ring, adapted to be engaged with at least a portion of the flanged bushing 320. The first anti-vibration member 420 is provided with a groove in one side to receive a flange of the flanged bushing 320, and an opposite side of the first anti-vibration member 420 contacts with the inner wall of the outer housing 700. In alternative embodiments, the first anti-vibration member can be formed integrally with the bushing.

[0041] The first anti-vibration member 420 and at least a portion of the flanged bushing 320 extend through the opening 110 formed in the inner housing 100, and are free of direct contact with the inner housing 100 to ensure that the first anti-vibration member 420 directly absorb at least a portion of vibration energy of the motor and the output shaft before it is transmitted to outer housing 700.

[0042] Same as the first embodiment, the outer housing 700 may be provided with a groove or a socket 710 to receive an end of each first anti-vibration member 420.(Disclaimers)

[0043] Throughout the specification and claims, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0044] It would be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

[0045] For example, in an alternative embodiment (not shown), the first anti-vibration member is an integral member with various shapes. In another embodiment, the anti-vibration assembly comprises more than two first anti-vibration members. The or each of the first anti-vibration member is arranged in direct or indirect contact with outer circumference of the bearing and inner surface of the outer housing. When the power tool is in operation, the first anti-vibration member bears vibration particularly in the direction in which the first anti-vibration member extends.

[0046] In the embodiments shown in Figures 1-4, the first anti-vibration member is shown as a rubber pin or a rubber ring independent from the bearing and the outer housing. One should realize that other types of anti-vibration member can also be used for the invention. For example, instead of being made from an elastomer material, the first anti-vibration member could also be a coil spring. In further variations, the first anti-vibration member could be made using overmolding and as part of an outer housing.

[0047] In the embodiments shown in Figures 1-4, the supporting unit is an un-flanged bearing 310 or a flanged bushing 320. In other variations, the supporting unit may be a flanged bearing or un-flanged bushing, or may consist of a bearing and a bushing that is sleeved onto a bearing.

[0048] In the embodiments shown in Figures 1-4, the power tool is a multi-tool. However, skilled persons in the art should realize that other types of power tools can also be applied with the anti-vibration structure of the invention.

[0049] Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated.

Claims

1. A power tool, comprising: an outer housing (700); a motor disposed within the outer housing; an output shaft (200) for performing an operation on a work piece, the output shaft adapted to be driven by the motor; a supporting unit (310,320) configured to bear the output shaft so that the output shaft is rotatable in relative to the outer housing; an inner housing (100) at least partially disposed within the outer housing (700) and configured to receive a portion of the supporting unit; and an anti-vibration assembly (410,420,500,600) configured to reduce vibration to the outer housing, characterized in that the anti-vibration assembly comprises a first anti-vibration member (410) mounted between the supporting unit and the outer housing, the first anti-vibration member adapted to be in direct or indirect contact with the supporting unit and the outer housing and being free of direct contact with the inner housing.

2. The power tool according to claim 1, wherein the first anti-vibration member extends between the supporting unit and the outer housing in a direction substantially perpendicular to an axial direction of the output shaft.

3. The power tool according to claim 1 or 2, wherein the inner housing has an opening through which the first anti-vibration member passes so that the first anti-vibration member extends between the supporting unit and the outer housing.

4. The power tool according to claim 3 wherein the opening is an indentation (110) formed on the inner housing.

5. The power tool according to any one of the preceding claims, wherein the first anti-vibration member is movable between the outer housing and the supporting unit.

6. The power tool according to any one of the preceding claims, wherein the first anti-vibration member is unmovably mounted between the outer housing and the supporting unit.

7. The power tool according to any one of claims 1-6, wherein the supporting unit is a bearing (310).

8. The power tool according to any one of claims 1-6, wherein the supporting unit is a bushing (320).

9. The power tool according to any one of claims 1-6, wherein the supporting unit comprises a bearing and a bushing sleeved on and coupled to the bushing.

10. The power tool according to any one of claims 1-9, wherein the first anti-vibration member is independent from both the supporting unit and the outer housing.

11. The power tool according to any one of claims 1-9, wherein the first anti-vibration member is formed by overmolding integrally with at least a portion of the outer housing.

12. The power tool according to claim 9, wherein the first anti-vibration member is formed integrally with the bushing.

13. The power tool according to any one of the preceding claims, wherein the first anti-vibration member is formed with a groove to engage with at least a portion of the outer housing and / or the supporting unit.

14. The power tool according to any one of the preceding claims, wherein the first anti-vibration member is an elastomeric element.

15. The power tool according to any one of the preceding claims, wherein the anti-vibration assembly comprises a pair of said first anti-vibration members symmetrically disposed on opposite sides of the supporting unit.

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