WO2021087788A1

WO2021087788A1 - Power tool and gear mechanism for power tool

Info

Publication number: WO2021087788A1
Application number: PCT/CN2019/115840
Authority: WO
Inventors: Liguo Ma; Qingfeng ZHANG; Junda YANG
Original assignee: Techtronic Cordless Gp
Priority date: 2019-11-06
Filing date: 2019-11-06
Publication date: 2021-05-14
Also published as: EP4054802A4; CN219255408U; EP4054802A1

Abstract

A power tool comprises a housing, a motor encased in the housing and having an output shaft (140) producing a torque, a spindle receiving the torque and arranged to rotate, and a gear mechanism (100). The gear mechanism comprises a gear unit (130) provided between the output shaft of the motor and the spindle, and a locking sleeve (110) movably coupled to the housing and arranged to engage with the gear unit such that axial movement of the locking sleeve controls the power tool to provide different speeds at the spindle. A gear mechanism for a power tool is also disclosed.

Description

POWER TOOL AND GEAR MECHANISM FOR POWER TOOL

FIELD OF INVENTION

This invention relates to power tools, and more particularly to a gear mechanism for power tools.

BACKGROUND OF INVENTION

Power tools are typically used both in commercial and personal settings for a wide variety of tasks.

Power tools are commonly used for a wide range of tasks daily. Given the versatility of power tools and their many applications, it is advantageous that these power tools have reliable and efficient speed control means. Typically, to ensure reliable speed control of the power tool, complex gear mechanisms are required that include a large number of components. The large number of components that make up complex gear mechanisms for power tools result in a large number of assembly steps that drive up manufacturing costs without necessarily providing reliable speed control of the power tool, thereby driving up costs of the power tool without ensuring a positive end user experience. Power tools with improved gear mechanisms for reliable speed control are desired.

SUMMARY OF INVENTION

In the light of the foregoing background, it is an object of the present invention to provide a power tool which eliminates or at least alleviates the above technical problems.

The above object is met by the combination of features of the main claim; the sub-claims disclose further advantageous embodiments of the invention.

One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.

Accordingly, the present invention, in a first aspect, is a power tool which includes a housing, a motor encased in the housing and having an output shaft producing a torque, a spindle receiving the torque and arranged to rotate, and a gear mechanism. The gear mechanism includes a gear unit provided between the output shaft of the motor and the spindle, and a locking sleeve movably coupled to the housing and arranged to engage with the gear unit such that axial movement of the locking sleeve controls the power tool to provide different speeds at the spindle.

In one embodiment of the first aspect, the locking sleeve comprises a locking mechanism arranged to engage with a first internal gear of the gear unit such that the first internal gear cannot rotate when engaged with the locking sleeve.

In one embodiment of the first aspect, the locking sleeve is arranged to engage with a second internal gear of the gear unit upon axial movement of the locking sleeve.

In one embodiment of the first aspect, the locking mechanism comprises teeth around a circumferential direction.

In one embodiment of the first aspect, the locking mechanism comprises two sets of teeth arranged in parallel.

In one embodiment of the first aspect, axial movement of the locking sleeve is adapted to enable the spindle to rotate at a first speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing, at a second speed by prohibiting rotation of the other one of the first internal gear and the second internal gear relative to the housing, and at a third speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing, pushing the third internal gear axially away so that the third internal gear separates from a third sun gear, and prohibiting the rotation of the third internal gear relative to the housing.

In one embodiment of the first aspect, only one of the first internal gear and the second internal gear is engaged with the locking sleeve at any time.

In one embodiment of the first aspect, the first internal gear and the second internal gear are coupled with a first plurality of planetary gears and a second plurality of planetary gears respectively; the first plurality of planetary gears and the second plurality of planetary gears engaging with different portions of a same sun gear, or each one of the first plurality of planetary gears is connected to a same rotation shaft with a corresponding one of the second plurality of planetary gears.

In one embodiment of the first aspect, the gear unit comprises a first internal gear, a second internal gear proximate to each other with or without intermediate part therebetween.

In one embodiment of the first aspect, the carrier is arranged to support three-tier planetary gears and three internal gears.

In one embodiment of the first aspect, the first internal gear and the second internal gear are axially arranged and independently rotatable with respect to each other.

Accordingly, the present invention, in a second aspect, is a gear mechanism for use in a power tool that includes a gear unit encased in a housing and provided between an output of a motor and a spindle, and a locking sleeve movably coupled to the housing and arranged to engage with the gear unit; wherein axial displacement of the locking sleeve controls the power tool to vary the speed at the spindle.

In one embodiment of the second aspect, the locking sleeve comprises a locking mechanism arranged to engage with a first internal gear of the gear unit such that the first internal gear cannot rotate when engaged with the locking sleeve.

In one embodiment of the second aspect, the locking sleeve is arranged to engage with a second internal gear of the gear unit upon axial movement of the locking sleeve.

In one embodiment of the second aspect, the locking mechanism comprises teeth around a circumferential direction.

In one embodiment of the second aspect, the locking mechanism comprises two sets of teeth arranged in parallel.

In one embodiment of the second aspect, axial movement of the locking sleeve is adapted to enable the spindle to rotate at a first speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing, at a second speed by prohibiting rotation of the other one of the first internal gear and the second internal gear relative to the housing, and at a third speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing, pushing the third internal gear axially away so that the third internal gear separates from a third sun gear, and prohibiting the rotation of the third internal gear relative to the housing.

In one embodiment of the second aspect, only one of the first internal gear and the second internal gear is engaged with the locking sleeve at any time.

In one embodiment of the second aspect, the first internal gear and the second internal gear are coupled with a first plurality of planetary gears and a second plurality of planetary gears respectively; the first plurality of planetary gears and the second plurality of planetary gears engaging with different portions of a same sun gear, or each one of the first plurality of planetary gears is connected to a same rotation shaft with a corresponding one of the second plurality of planetary gears.

In one embodiment of the second aspect, the gear unit comprises a first internal gear, a second internal gear, and a third internal gear positioned proximate to each other with or without intermediate part therebetween.

In one embodiment of the second aspect, the gear unit comprises an internal gear, a sun gear, a planetary gear, and a carrier that do not move axially.

In one embodiment of the second aspect, the carrier is arranged to support three-tier planetary gears and three internal gears.

In one embodiment of the second aspect, the first internal gear and the second internal gear are axially arranged and independently rotatable with respect to each other.

The embodiments of the present invention thus provide a power tool that includes and employs an improved and simpler gear mechanism that allows an operator of the power tool to select from different rotational speeds for the spindle. The locking sleeve that is movably coupled to the housing of the power tool is employed as a selector and axially movable between different positions to engage with the gear unit and operable from the outside of the housing for quick and easy speed control of the power tool by the operator.

A simple gear mechanism that provides easy and reliable speed control of the power tool is achieved by axial movement of the locking sleeve wherein the locking sleeve engages with, and prohibits rotation of, one or more internal gears instead of achieving such transmission by sliding the internal gears, which do not move axially. The gear mechanism advantageously reduces the number of components required as well as manufacturing costs, whilst providing a user-friendly power tool capable of efficient and reliable speed selection and control effected by simple axial movement of a locking sleeve.

BRIEF DESCRIPTION OF FIGURES

The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figures, of which:

Figure 1 shows a perspective view of a gear mechanism of a power tool in accordance with an example embodiment.

Figure 2A is a perspective view of a locking sleeve of the gear mechanism in Figure 1 in accordance with an example embodiment.

Figure 2B is a perspective view of a gear unit of the gear mechanism in Figure 1 in accordance with an example embodiment.

Figure 3 is a side view of the gear mechanism in Figure 1 in accordance with an example embodiment.

Figure 4 shows an exploded side view the gear mechanism in Figure 1 in accordance with an example embodiment.

Figure 5 is a front view of the gear mechanism in Figure 1 in accordance with an example embodiment.

Figure 6 is a cross-sectional side view of the gear mechanism in Figure 1 in a first speed in accordance with an example embodiment.

Figure 7 is a cross-sectional side view of the gear mechanism in Figure 1 in a second speed in accordance with an example embodiment.

Figure 8 is a cross-sectional side view of the gear mechanism in Figure 1 in a third speed in accordance with an example embodiment.

In the drawings, like numerals indicate like parts throughout the several embodiments described herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is given by way of example only to illustrate preferred embodiments of the invention. In particular, the language and terminology used herein is for descriptive purposes only and is not intended to limit the scope or functionality of the invention. The invention may be employed in various combinations or embodiments utilizing various elements and means not explicitly described herein, but within the knowledge and skill of one skilled in the art.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Terms such as “horizontal” , “vertical” , “upwards” , “downwards” , “above” , “below” and similar terms as used herein are for the purpose of describing the invention in its normal in-use orientation and are not intended to limit the invention to any particular orientation.

Example embodiments of the present invention are directed to a power tool (not shown) that includes a housing (not shown) , a motor encased in the housing and having an output shaft producing a torque, and a spindle receiving the torque and arranged to rotate, and a gear mechanism. Figure 1 is a perspective view of a gear mechanism 100 of a power tool in accordance with an example embodiment. The gear mechanism 100 includes a gear unit 130 provided between the output shaft 140 of the motor and the spindle, and a locking sleeve 110 movably coupled to the housing and arranged to engage with the gear unit 130 such that axial movement of the locking sleeve 110 controls the power tool to provide different speeds at the spindle.

Figures 2A, 2B and 3 are perspective views of the locking sleeve 110 (Figure 2A) and the gear unit (Figure 2B) constructed according to the teachings of the present invention. The locking sleeve 110 is movably coupled to the housing of the power tool, preferably fitted around the housing in a manner that permits the sleeve 110 to move axially with respect to the housing. The locking sleeve 110 includes a locking mechanism that engages with the gear unit 130. In this embodiment, the locking mechanism includes teeth 120 around a circumferential direction of the locking sleeve 110, preferably two sets of teeth 120 arranged in parallel.

The gear unit 130 shown in Figure 2B and Figure 3 is an epicycle gear unit that includes three axially arranged gears, i.e. a first internal gear 200, a second internal gear 210, and a third internal gear 220, a sun gear 150, a third sun gear 160, a plurality of first planetary gears 400, a plurality of second planetary gears 401 and a plurality of third planetary gears 402, and a carrier 300. The

internal gears

200, 210, sun gears 150, 160,

planetary gears

400, 401, 402, and carrier 300 do not move axially.

With reference to Figure 4, the first internal gear 200 and the second internal gear 210 are positioned proximate to each other, i.e. axially adjacent to one another with no intermediate part therebetween. The

internal gears

200, 210, 220 are axially arranged and capable of rotation independently of each other. The

internal gears

200, 210, 220 each has on its outer peripheral surface profiled axial ridges or teeth 420 that engage with the locking mechanism 120 of the locking sleeve 110. Axial movement of the locking sleeve 110 results in engagement of the first internal gear 200. Further axial movement of the locking sleeve 110 results in engagement of the second internal gear 210. Only one of the first internal gear 200 and the second internal gear 210 is engaged with the locking sleeve 110 at any time, i.e. the first internal gear 200 and the second internal gear 210 cannot be engaged with the locking sleeve 110 simultaneously.

Figure 4 shows an exploded view of the gear mechanism 100 in which the first internal gear 200 supports, and is coupled to a plurality of a first planetary gears, and in particular four first planetary gears 400. The plurality of the first planetary gears 400 revolve on the first internal gear 200. The second internal gear 210 supports, and is coupled to, a plurality of a second planetary gears 401, and in particular four second planetary gears 401. The plurality of the second planetary gears 401 revolve on the second internal gear 210. As the

planetary gears

400 and 401 engage the output shaft 140 of the motor and the carrier 300 is secured to the spindle (not shown) , the gear unit 130 is capable of transmitting the torque from the output shaft 140 to the spindle while varying the rotational speed.

The carrier 300 is arranged to support three-tier

planetary gears

400, 401, 402 and three

internal gears

200, 210, 220.

With reference to Figure 4, in this embodiment the plurality of the first planetary gears 400 are connected to a same rotation shaft 410 with a corresponding one of the plurality of the second planetary gears 401.

Figure 5 is a front view of the gear mechanism 100 which illustrates the locking mechanism 120 according to an example embodiment. In this embodiment, the locking mechanism 120 includes teeth 120 arranged axially on the inner periphery of the locking sleeve 110. The locking sleeve 110 is arranged such that axial movement of the sleeve 110 causes the teeth 120 of the sleeve 110 to engage with axially arranged complementary ridges or geometric features 420 on the outer periphery of the first 200, second 210, or third 220 internal gears. Engagement of the locking sleeve 110 with the

internal gear

200, 210, 220 prohibits rotation of the particular gear. The locking mechanism 120 includes two sets of teeth 120 arranged in parallel that ensures optimal engagement with the gear unit 130 for maximal prevention of rotation of the

internal gears

200, 210, 220.

Figures 6-8 are cross-sectional side views of the gear mechanism 100 illustrating the spindle rotating at three different speeds.

In Figure 6, the locking mechanism and in particular the teeth 120 of the locking sleeve 110 is engaged with the first internal gear 200 of the gear unit 130, thus enabling the spindle to rotate at a first speed by prohibiting rotation of the first internal gear 200 relative to the housing. The second internal gear 210 is not engaged with the locking sleeve 110 and is able to rotate independently while the first internal gear 200 is engaged with the locking sleeve 110.

In Figure 7, the locking mechanism and in particular the teeth 120 of the locking sleeve 110 is engaged with the second internal gear 210 of the gear unit 130, thus enabling the spindle to rotate at a second speed by prohibiting rotation of the second internal gear 210 relative to the housing. The first internal gear 200 is not engaged with the locking sleeve 110 and is able to rotate independently while the second internal gear 210 is engaged with the locking sleeve 110.

In Figure 8, the locking mechanism and in particular the teeth 120 of the locking sleeve 110 is engaged with the first internal gear 200 and the third internal gear 220 of the gear unit 130, thus enabling the spindle to rotate at a third speed by prohibiting rotation of the first internal gear 200 and the third internal gear 220 simultaneously relative to the housing. The third internal gear 220 is axially pushed away so that the third internal gear 220 separates from the third sun gear 160. The second internal gear 210 is not engaged with the locking sleeve 110 and is able to rotate independently while the first internal gear 200 and the third internal gear 220 are simultaneously engaged with the locking sleeve 110.

The gear mechanism 100 as described above advantageously provides a power tool with enhanced and improved user control wherein a user can choose a speed for the power tool easily and expeditiously by axially sliding the locking sleeve 110 to choose a speed best suited for the task at hand.

The engagement of the locking sleeve 110 with the

internal gears

200, 210, 220 of the gear unit 130 via the locking mechanism 120 provides three speeds simply by axially moving the locking sleeve 110 without the need for sliding the internal components which are not axially movable. This reduces and simplifies the number of internal components of the power tool 100 and reduces the number of assembly steps and manufacturing costs of the power tool 100 whilst beneficially ensuring reliable and convenient speed change operation.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In a variation of the embodiment mentioned above, the locking mechanism of the locking sleeve may be simultaneously engaged with the second internal gear and the third internal gear among three consecutive internal gears of the gear unit. This enabling the spindle to rotate at a third speed by prohibiting rotation of the second internal gear and the third internal gear simultaneously relative to the housing. Similarly, the first internal gear is not engaged with the locking sleeve and rotates independently while the second internal gear and the third internal gear are simultaneously engaged with the locking sleeve.

In an alternative embodiment, the first plurality of planetary gears and the second plurality of planetary gears engage with different portions of a same sun gear.

Example embodiments are also directed to a gear mechanism for a power tool, particularly the gear mechanism as described previously. The gear mechanism includes a gear unit encased in a housing and provided between an output of a motor and a spindle, a locking sleeve movably coupled to the housing and arranged to engage with said gear unit, wherein axial displacement of the locking sleeve controls the power tool to vary the speed at the spindle.

The skilled person will appreciate that although the example embodiments of the gear mechanism have been described as being employed with the epicycle gear unit having three stages, the present invention is not limited by the number of internal gears, planetary gears or carriers and can be used in combination with, for example, two-stage gear set or a single-stage gear set.

Claims

A power tool, comprising:

a housing;

a motor encased in the housing and having an output shaft producing a torque;

a spindle receiving the torque and arranged to rotate; and

a gear mechanism, comprising:

a gear unit provided between the output shaft of the motor and the spindle, and

a locking sleeve movably coupled to the housing and arranged to engage with the gear unit such that axial movement of the locking sleeve controls the power tool to provide different speeds at the spindle.
The power tool of claim 1, wherein said locking sleeve comprises a locking mechanism arranged to engage with a first internal gear of the gear unit such that the first internal gear cannot rotate when engaged with the locking sleeve.
The power tool of claim 2, wherein said locking sleeve is arranged to engage with a second internal gear of the gear unit upon axial movement of the locking sleeve.
The power tool of claim 2, wherein the locking mechanism comprises teeth around a circumferential direction.
The power tool of claim 4, wherein the locking mechanism comprises two sets of teeth arranged in parallel.
The power tool of any one of claims 2 to 5, wherein axial movement of the locking sleeve is adapted to enable the spindle to rotate

at a first speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing,

at a second speed by prohibiting rotation of the other one of the first internal gear and the second internal gear relative to the housing, and

at a third speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing, pushing the third internal gear axially away so that the third internal gear separates from a third sun gear, and prohibiting the rotation of the third internal gear relative to the housing.
The power tool of claim 3, wherein only one of the first internal gear and the second internal gear is engaged with the locking sleeve at any time.
The power tool of claim 3, wherein the first internal gear and the second internal gear are coupled with a first plurality of planetary gears and a second plurality of planetary gears respectively; the first plurality of planetary gears and the second plurality of planetary gears engaging with different portions of a same sun gear, or each one of the first plurality of planetary gears is connected to a same rotation shaft with a corresponding one of the second plurality of planetary gears.
The power tool of claim 1, wherein the gear unit comprises a first internal gear, a second internal gear proximate to each other with or without intermediate part therebetween.
The power tool of claim 1, wherein the gear unit comprises an internal gear, a sun gear, a planetary gear, and a carrier that do not move axially.
The power tool of claim 10, wherein the carrier is arranged to support three-tier planetary gears and three internal gears.
The power tool of claim 3, wherein the first internal gear and the second internal gear are axially arranged and independently rotatable with respect to each other.
A gear mechanism for use in a power tool, comprising:

a gear unit encased in a housing and provided between an output of a motor and a spindle; and

a locking sleeve movably coupled to the housing and arranged to engage with said gear unit, wherein axial displacement of the locking sleeve controls the power tool to vary the speed at the spindle.
The gear mechanism of claim 13, wherein said locking sleeve comprises a locking mechanism arranged to engage with a first internal gear of the gear unit such that the first internal gear cannot rotate when engaged with the locking sleeve.
The gear mechanism of claim 14, wherein said locking sleeve is arranged to engage with a second internal gear of the gear unit upon axial movement of the locking sleeve.
The gear mechanism of claim 14, wherein the locking mechanism comprises teeth around a circumferential direction.
The gear mechanism of claim 16, wherein the locking mechanism comprises two sets of teeth arranged in parallel.
The gear mechanism of any one of claims 14 to 17, wherein axial movement of the locking sleeve is adapted to enable the spindle to rotate

at a first speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing,

at a second speed by prohibiting rotation of the other one of the first internal gear and the second internal gear relative to the housing, and

at a third speed by prohibiting rotation of one of the first internal gear and the second internal gear relative to the housing, pushing the third internal gear axially away so that the third internal gear separates from a third sun gear, and prohibiting the rotation of the third internal gear relative to the housing.
The gear mechanism of claim 15, wherein only one of the first internal gear and the second internal gear is engaged with the locking sleeve at any time.
The gear mechanism of claim 15, wherein the first internal gear and the second internal gear are coupled with a first plurality of planetary gears and a second plurality of planetary gears respectively; the first plurality of planetary gears and the second plurality of planetary gears engaging with different portions of a same sun gear, or each one of the first plurality of planetary gears is connected to a same rotation shaft with a corresponding one of the second plurality of planetary gears.
The gear mechanism of claim 13, wherein the gear unit comprises a first internal gear, a second internal gear, and a third internal gear positioned proximate to each other with or without intermediate part therebetween.
The gear mechanism of claim 13, wherein the gear unit comprises an internal gear, a sun gear, a planetary gear, and a carrier that do not move axially.
The gear mechanism of claim 22, wherein the carrier is arranged to support three-tier planetary gears and three internal gears.
The gear mechanism of claim 15, wherein the first internal gear and the second internal gear are axially arranged and independently rotatable with respect to each other.