AU2021462050A1

AU2021462050A1 - Power tool with anti-vibration structures

Info

Publication number: AU2021462050A1
Application number: AU2021462050A
Authority: AU
Inventors: De Li CHEN; Shi Chun Liu; Matthew Samstag
Original assignee: Techtronic Cordless GP
Current assignee: Techtronic Cordless GP
Priority date: 2021-08-26
Filing date: 2021-08-26
Publication date: 2024-02-22
Also published as: CN220863918U; WO2023024021A1

Abstract

The invention provides a power tool that includes a housing, a vibration body at least partially received in the housing, and a handle. The vibration body contains an electric motor. The handle contains a first end and a second end, the first end being moveably mounted to the housing via a first mounting assembly, the second end being moveably mounted to the housing via a second mounting assembly. The handle further contains a gripping portion between the first and second ends. Both the first and second mounting assemblies substantially limit a movement of the handle relative to the housing in only a linear direction that forms an angle with a longitudinal direction of the gripping portion. The first mounting assembly includes a first guiding mechanism and a first spring located between the first end of the handle and the housing, where the first guiding mechanism is in direct contact with the first spring. The second mounting assembly includes a second guiding mechanism and a second spring located between the second end of the handle and the housing, where the second guiding mechanism being separated from the second spring. The power tool is therefore provided with different vibration damping structures respectively at two connection points between the handle and the tool housing, which achieves an improved vibration decoupling between the handle and the tool housing.

Description

Power Tool with Anti-vibration Structures

FIELD OF INVENTION

This invention relates to portable power tools, and in particular portable electric power tools with anti-vibration structures.

BACKGROUND OF INVENTION

Electric power tools are widely used in various applications such as building, construction and interior decoration. These power tools provide necessary tool functions to the user using the driving power generated by an on-board drive motor. At the same time, the power tools are usually manufactured to be compact and light-weight, so that their users have no difficulty in carrying and manipulating the power tools.

However, some types of power tools during their operation generate substantial amounts of vibrations, for example the vibrations come from the gearbox of an impact tool, and/or from the drill bit as an end tool of the impact tool when it is striking the workpiece. To enhance the user experience of operating the power tools, it is desired to isolate or at least alleviate vibrations from being transmitted from a vibrating body of the power tool to a gripping portion of the power tool.

SUMMARY OF INVENTION

In the light of the foregoing background, it is an object of the present invention to provide an alternate power tool design 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 one aspect, is a power tool including a housing, a vibration body at least partially received in the housing, and a handle having a first end and a second end. The vibration body contains an electric motor. The first end of the handle is moveably mounted to the housing via a first mounting assembly, and the second end of the handle is moveably mounted to the housing via a second mounting assembly. The handle further includes a gripping portion between the first and second ends. Both the first and second mounting assemblies substantially limit a movement of the handle relative to the housing in only a linear direction that forms an angle with a longitudinal direction of the gripping portion. The first mounting assembly contains a first guiding mechanism and a first spring located between the first end of the handle and the housing; the first guiding mechanism being in direct contact with the first spring. The second mounting assembly includes a second guiding mechanism and a second spring located between the second end of the handle and the housing; the second guiding mechanism being separated from the second spring.

In some embodiments, the first guiding mechanism further includes a first guiding pin and the second guiding mechanism further includes a second guiding pin. The first guiding pin extends along a direction different from that of the second guiding pin.

In some embodiments, the first guiding pin extends along the linear direction, and the second guiding pin extends along a normal direction to the linear direction.

In some embodiments, the first spring sleeves onto the first guiding pin. One end of the first guiding pin fixed to one of the first end of the handle and the housing, and another end of the first guiding pin slidably received in a receiving member formed with or attached to the other one of the first end of the handle and the housing.

In some embodiments, the first mounting assembly further includes a vibration damper abutting the first spring.

In some embodiments, the vibration damper is coupled to the first guiding pin at a fixed end thereof.

In some embodiments, the first guiding pin is secured with a baffle plate by a screw, the baffle plate fixedly received in a first recess formed in the one of the first end of the handle and the housing so as to fix the one end of the first guiding pin.

In some embodiments, the second end of the handle is movably received in a second recess formed on the housing, and the second guiding mechanism substantially limits the second end of the handle to move only in the linear direction in the recess.

In some embodiments, the second spring is configured between an internal wall of the second recess and a first face of the second end of the handle. The internal wall is further configured with an elongated groove extending along the linear direction so that the second guiding pin is adapted to move in the elongated groove, thus substantially guiding the movement of the handle relative to the housing in the linear direction.

In some embodiments, the power tool further contains a trigger switch located on the gripping portion. An electrical wire connecting the trigger to a circuit board runs through the second guiding mechanism.

In some embodiments, the electric motor is orientated in a way that its motor shaft extends along a direction normal to the linear direction.

In some embodiments, the vibration body further contains a gearbox housing receiving a gearbox of the power tool and at least partially receiving the electric motor. The first mounting assembly is connected between the first end of the handle and the gearbox housing.

In some embodiments, the housing contains an extension portion that extends along the linear direction. The second recess of the housing is formed on the extension portion. The second end of the handle is inserted into the second recess along the longitudinal direction of the gripping portion.

In some embodiments, at least one of the first guiding pin and the second guiding pin is coupled to the vibration body in a fixed way or a movable way.

Some embodiments of the invention provide therefore an effective vibration decoupling between the handle and the vibration body, so that vibrations created by the vibration body in the tool housing are greatly attenuated at multiple vibration damping mechanisms between the handle and the tool body, which limit the relative movement between the handle and the tool body substantially in a single linear direction. In addition, the different vibration damping mechanisms configured at the two ends of the handle allow most of the vibrations irrespective of their types, directions, and magnitude be sufficiently attenuated.

In some embodiments, the vibration damping mechanisms at ends of the handle easily allow any electric wire (e.g. those connected to a trigger switch in the handle) to pass through and extend to the circuit board in the tool body. For example, the wire can be made to extend next to the spring in the vibration damping mechanism of the power tool so that the trigger switch at the handle portion can be electrically connected with a circuit board in the front.

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:

Fig. 1 is a perspective view of a handheld power tool according to a first embodiment of the present invention.

Fig. 2 is a top view of the power tool in Fig. 1.

Fig. 3 shows a side view of the power tool in Fig. 1, with half of the tool housing and the handle housing be hidden to show the internal components.

Fig. 4 is a partial cross-sectional view of the power tool along the line A-Ain Fig. 2, showing the lower anti-vibration structure between the handle and the tool housing.

Fig. 5 is a perspective view of the upper anti-vibration structure between the handle and the tool housing with half of the tool housing be hidden to show the internal components.

Fig. 6 is the view of the portion of the power tool in Fig. 5 from another angle.

Fig. 7 illustrates in a side view of the power tool in Fig. 1 the approximate region in which the center of gravity falls.

Fig. 8 is a partial view of the tool housing of the power tool in Fig. 1 with illustrations of the air vents and air flow direction.

Fig. 9 shows in a side view of the power tool in Fig. 1 with part of the tool housing hidden to illustrate the air flow path inside the power tool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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.

As used herein and in the claims, “couple” or “connect” refers to electrical coupling or connection either directly or indirectly via one or more electrical means unless otherwise stated.

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.

Referring now to Figs. 1-2, the first embodiment of the present invention is a power tool 20 which is designed to be handheld. As shown in the drawing the power tool 20 is an electric hammer drill. The power tool 20 has a tool housing 28 connected to handle 24 in a vibration-decoupled fashion which will be described in more details later. At a front end of the tool housing 28 there is configured a tool bit holder 22 which is used to removably install an end tool (e.g. a drill bit, not shown) in order for the power tool 20 to fulfill one or more of its dedicated functions. There is an electric drive motor (not shown in Fig. 1) mounted inside the tool housing 28, and the drive motor is configured to driving one or more movable parts in the power tool, including at least an intermediate gear mechanism and an percussion mechanism (both not shown) and ultimately the tool bit holder 22. The drive motor is a brushless DC motor. An auxiliary handle 19 is removably attached to the front end of the tool housing 28, and a depth gauge 17 is movably connected to the auxiliary handle 19.

The tool housing 28 has a main portion 28a that extends substantially along a vertical direction shown in Fig. 1 which is also a shaft direction defined by the motor shaft of the drive motor. The handle 24 is connected to and extends from the tool housing 28 at two connection points 38, 40. An upper connection point 38 is located substantially along an axial direction defined by the central axis of the end tool, and is located behind the tool housing 28 and in front of a top portion 24b of the handle 24 that extends substantially along the front-rear direction. On the other hand, the lower connection point 40 is located at the joint of a lower end of the gripping portion 24a of the handle 24 and an extension portion 28b of the tool housing 28. The gripping portion 24a is therefore located between two ends of the handle 24 wherein the two ends are located at the two connection points 38, 40 respectively. The extension portion 28b extends substantially in the front-rear direction from the main portion 28a of the tool housing 28 and near the lower end of the main portion 28a. A bottom side of the extension portion 28b together with the rear wall of the main portion 28a define a battery receiving area 26 in which an external battery pack (not shown) can be at least received and removably installed to the power tool 20. The battery pack is adapted to electrically connect to the power tool 20 to supply power to the electrical circuit inside the power tool 20. The tool housing 28 therefore exhibits an L shape, and the handle 24 exhibits a flipped L shape, then the tool housing 28 together with the handle 24 form a close shape with a hollow 23 as the two are connected at the upper and lower connection points 38, 40. It should be noted that the gripping portion 24a is not perfectly aligned with a vertical direction, but instead it is inclined slightly forward with respect to a vertical axis (not shown) when the axial direction mentioned above is a horizontal direction.

On a side of the main portion 28a a mode selector 21 is provided to offer the choices of a drill mode, a hammer mode, and a hammer drill mode of the power tool 20. On the gripping portion 24a, a trigger switch 30 is configured where the trigger switch 30 is exposed to the outside for the user’s manipulation to turn on/off the power tool 20. Also, at the upper connection point 38 there is a deformable sleeve 39 (e.g. bellows) connected between the handle 24 and the tool housing 28.

Turning to Fig. 3, which shows the power tool 20 with half of the tool housing 28 removed (including an entire head housing, the tool housing 28, and the housing of the handle 24) to expose the internal components of the power tool 20. A gearbox housing 34 is received within the main portion 28a of the tool housing 28 and the main portion 28a in turn receives a gearbox (not shown) of the power tool 20 including the intermediate gear mechanism and the percussion mechanism as mentioned above, wherein one or both of a rotary force transmission and a percussion force transmission can be put into the power transmission path from the drive motor 32 to the tool bit holder 22. The gearbox contains two parallel intermediate shafts and a wobbling gear (not shown) . The drive motor 32 connects to the gearbox at a bottom end of the gearbox housing 34, and the gearbox housing 34 receives also a part of the drive motor 32. The gearbox together with the drive motor 32 define a vibration body of the power tool 20, where the gearbox housing 34 is the vibration body housing. Further down in the main portion 28a underneath the drive motor 32 is a circuit board (not shown in Fig. 3) that is accommodated in a heatsink clamshell 36 with an open end facing upward. The heatsink clamshell 36 is used both as a protecting cover for the circuit board and also a heatsink for electric components on the circuit board such as a controller and multiple switching elements (all not shown) for driving the drive motor 32. The working principles of the drive motor 32, the gearbox (including the rotary force transmission and the percussion for transmission) , and the motor control /drive circuit in general are well-known to those skilled in the art so they will not be described in any further details herein.

Between the top portion 24b of the handle portion 24 and the main portion 28a of the tool housing 28, there is an upper mounting assembly 50. Similarly, between the lower end of the gripping portion 24a of the handle portion 24 and the extension portion 28b of the tool housing 28, there is a lower mounting assembly 52. Both the upper and lower mounting assemblies 50, 52 allow a relative movement between the tool housing 28 and the handle 24 to be substantially in the front-rear direction only. The front-rear direction forms an angle with a longitudinal direction of the gripping portion 24a. It can be seen from Fig. 3 that an electric wire 44 connecting from the trigger switch 30 to the circuit board passes through the lower mounting assembly 52. Also connected to the circuit board are electric wires 48 from a battery connector 46 configured in the extension portion 28b and partially exposed in the battery receiving area 26. The upper and lower mounting assemblies 50, 52 will now be described separately in details.

Turning now to Fig. 4, the lower mounting assembly 52 is illustrated with its internal components. As mentioned above the extension portion 28b is movably connected to the lower end of the gripping portion 24a with vibration decoupling. The extension portion 28b is formed with an opening 28d facing upward, and the opening 28d is delimited together by two halves (Fig. 4 shows one of the halves) of the extension portion 28b. A leg portion of the gripping portion 24a at the lower end thereof is inserted into the opening 28d, and received in a recess (not shown) formed inside the extension portion 28b. The leg portion has a hollow pin mounting portion 24c with a substantially elliptical shape, and within the pin mounting portion 24c two pins 58 that has a corresponding elliptical shape is secured. Both of the pins 58 extend in a lateral direction that is normal to the front-rear direction. Two ends of each pin 58 extend from the pin mounting portion 24c in opposite directions respectively, and are respectively received in an elongated groove 56a of two sliding seats 56. The two sliding seats 56 are fixedly connected respectively to the two halves of the extension portion 28b. As the pins 58 and the sliding seats 56 are respectively fixed to the handle 24 and the extension portion 28b of the tool housing 28, the tool housing 28 is therefore allowed to move with respect to the handle 24 substantially in the front-rear direction that is also defined by the elongated grooves 56a. The pins 58 and the sliding seats 56 therefore form a lower guiding mechanism of the lower mounting assembly 52.

The leg portion also has a spring seat 60 fixedly connected to the pin mounting portion 24c and located in front of the pin mounting portion 24c. A lower spring 54 is coupled to the spring seat 60 and in particular a stopping face 60c of the spring seat 60 at one end, and to a stopping face 28c of the extension portion 28b, where the stopping face 28c is located behind the battery connector 46 and facing rearward. The stopping face 28c is a part of the internal wall of the recess of the extension portion 28b. To secure its connection with the lower spring 54 the spring seat 60 further includes a guiding rod 60a extending forward from the stopping face 60c to insert into the lower spring 54 so as to guide any extension /compression of the lower spring 54 to a linear direction. Such guiding is also provided by a top face 60b of the spring seat 60 extending forward from a top end of the stopping face 60c which limits any lateral movement of the lower spring 54 away from the length direction of the lower spring 54. One can also see that the lower guiding mechanism is separated from the lower spring 54 when the lower spring 54 and the lower guiding mechanism are located on two opposite sides of the spring seat 60.

The upper mounting assembly 50 are illustrated in Figs. 5-6. Similar to the lower mounting assembly 52, the upper mounting assembly 50 contains an upper spring 68 for vibration damping purpose, but in addition the upper mounting assembly 50 contains two damping blocks 66 as vibration dampers that work together with the upper spring 68. The upper spring 68 sleeves onto a guiding pin 70, and a fixed end (not shown) of the guiding pin 70 is secured with a baffle plate 62 by a screw 65 that screws into the guiding pin 70 axially from the fixed end. The guiding pin 70 extends in the front-rear direction. The baffle plate 62 which has a squircle shape is fixedly received in a corresponding recess 64 formed in the top portion 24b of the handle 24. Because of the connection of the baffle plate 62 and the guiding pin 70 the latter is therefore fixed relative to the handle 24. The other end of the guiding pin 70 is a moving end (not shown) that is received movably in a receiving member on the gearbox housing 34, and the receiving member is a protruded sleeve 34a that protrudes from the rest part of the gearbox housing 34. Because the movable end of the guiding pin 70 is movably received in the protruded sleeve 34a, this structure limits the relative movement between the handle 24 and the tool housing 28 to be substantially only in the front-rear direction. The guiding pin 70 and the protruded sleeve 34a therefore form an upper guiding mechanism of the upper mounting assembly 50. One can see that the upper guiding mechanism is in direct contact with the upper spring 68.

The upper spring 68 has its one end abutting the gearbox housing 34 at a surface surrounding the protruded sleeve 34a, and another end abutting the two damping blocks 66. As best shown in Fig. 6, each of the damping blocks 66 has a longitudinal direction along the axial direction of the guiding pin 70, and also a cross-sectional shape of a substantially “C” shape. The “C” shape defines semicircular recess 66a in each damping block 66 and together the two semicircular recesses 66a of the damping blocks 66 form a round hole for the guiding pin 70 to pass through but the damping blocks 66 grip the guiding pin 70 firmly at a fixed end thereof, as there is no relative movements between the them.

Having described the anti-vibration structures at the upper and lower connection points between the handle 24 and the tool housing 28, the working principles of these anti-vibration structures are now briefly discussed. As one will note from the structures mentioned above, in either the upper mounting assembly 50 or the lower mounting assembly 52, the relative movement between the handle 24 and the tool housing 28 is limited to substantially only the front-rear direction because of various limiting components such as the guiding pin 70 and the protruded sleeve 34a, the guiding rod 60a and the sliding seats 56. Any vibration generated on the side of the tool housing 28 such as those from the gearbox, the motor 32, or the end tool as it impacts the workpiece, will be effectively decoupled and results in a relative linear movement between the handle 24 and the tool housing 28. However, the upper spring 68 and the lower spring 54 that normally bias the handle 24 away from the tool housing 28, will be compressed in case of the movement of the handle 24 away from the tool housing 28 approximate each other, and such compression process damps most of the vibration. The two damping blocks 66 of the upper mounting assembly 50 also facilitates in the vibration damping. In this way, the user of the power tool 20 will not experience very significant vibration during operation, but is still able to ensure an accurate manipulation of the power tool 20 at the end tool by holding the handle 24, as there is no other relative movement between the handle 24 and the tool housing 28 than the front-rear direction movement.

Turning to Fig. 7, another view of the power tool 20 shows a barycenter (i.e. center of gravity) region 72 in which the center of gravity of the entire power tool 20 (when no battery pack is installed) will into. The barycenter region 72 as one can see is located generated in the main portion 28a of the tool housing 28 between the gearbox and the drive motor 32.

Turning to Fig. 8, another view of the power tool 20 shows the air inlets and outlets located in the power tool 20. There are multiple air inlets 74 near the bottom end of the main portion 28a of the tool housing 28, and some are located at side walls of the main portion 28a while some others are located in a rear wall of the main portion 28a that is adjust to the battery receiving area 26. Consequently, multiple air outlets 76 are located approximately at the middle position along the vertical dimension of the main portion 28a and these air outlets 76 are located at the peripheral of a motor fan (not shown) of the drive motor 32. Fig. 9 illustrates the air flow path between the air inlets 74 and the air outlets 76, where the air flow directions are indicated by arrows 78.

The exemplary embodiments of the present invention are thus fully described. Although the description referred to particular embodiments, it will be clear to one skilled in the art that the present invention may be practiced with variation of these specific details. Hence this invention should not be construed as limited to the embodiments set forth herein.

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.

For example, the vibration body including the motor and the gearbox in the embodiment mentioned above are fully enclosed by the tool housing, but one skilled in the art could envisage that other configurations are also possible for example if the part of the gearbox housing and/or the motor housing is exposed to the outside of the power tool.

Although the above embodiment is described with very specific structures at the upper and lower mounting assemblies between the handle and the tool housing, those skill in the art should understand that other structures of the mounting assemblies are also possible and can be freely used as long as they limit the relative movement of the handle to the tool housing in substantially only one direction.

In the lower vibration damping structure of the power tool as illustrated in the embodiments above there are two pins received in a sliding groove which prevent the relative rotation between the handle portion and the tool housing at the lower point. However, instead of the two pin, one may also use a single, non-circular pin in the groove which equally could prevent rotation because of the non-circular shape.

Claims

A power tool, comprising:

a) a housing,

b) a vibration body at least partially received in the housing; the vibration body comprising an electric motor;

c) a handle having a first end and a second end, the first end being moveably mounted to the housing via a first mounting assembly, the second end being moveably mounted to the housing via a second mounting assembly;

wherein the handle comprising a gripping portion between the first and second ends; both the first and second mounting assemblies substantially limiting a movement of the handle relative to the housing in only a linear direction that forms an angle with a longitudinal direction of the gripping portion;

the first mounting assembly comprising a first guiding mechanism and a first spring located between the first end of the handle and the housing; the first guiding mechanism being in direct contact with the first spring; and

the second mounting assembly comprising a second guiding mechanism and a second spring located between the second end of the handle and the housing; the second guiding mechanism being separated from the second spring.
The power tool according to claim 1, wherein the first guiding mechanism further comprises a first guiding pin and the second guiding mechanism further comprises a second guiding pin; the first guiding pin extending along a direction different from that of the second guiding pin.
The power tool according to claim 2, wherein the first guiding pin extends along the linear direction; and the second guiding pin extends along a normal direction to the linear direction.
The power tool according to claim 3, wherein the first spring sleeves onto the first guiding pin; one end of the first guiding pin fixed to one of the first end of the handle and the housing, and another end of the first guiding pin slidably received in a receiving member formed with or attached to the other one of the first end of the handle and the housing.
The power tool according to claim 4, wherein the first mounting assembly further comprises a vibration damper abutting the first spring.
The power tool according to claim 5, wherein the vibration damper is coupled to the first guiding pin at a fixed end thereof.
The power tool according to claim 4, wherein the first guiding pin is secured with a baffle plate by a screw, the baffle plate fixedly received in a first recess formed in the one of the first end of the handle and the housing so as to fix the one end of the first guiding pin.
The power tool according to claim 3, wherein the second end of the handle is movably received in a second recess formed on the housing, and the second guiding mechanism substantially limits the second end of the handle to move only in the linear direction in the recess.
The power tool according to claim 8, wherein the second spring is configured between an internal wall of the second recess and a first face of the second end of the handle; the internal wall further configured with an elongated groove extending along the linear direction so that the second guiding pin is adapted to move in the elongated groove, thus substantially guiding the movement of the handle relative to the housing in the linear direction.
The power tool according to claim 2, further comprises a trigger switch located on the gripping portion; an electrical wire connecting the trigger to a circuit board running through the second guiding mechanism.
The power tool according to any one of the preceding claims, wherein the electric motor is orientated in a way that its motor shaft extends along a direction normal to the linear direction.
The power tool according to any one of the preceding claims, wherein the vibration body further comprises a gearbox housing receiving a gearbox of the power tool and at least partially receiving the electric motor; the first mounting assembly connected between the first end of the handle and the gearbox housing.
The power tool according to claim 8, wherein the housing comprising an extension portion that extends along the linear direction; the second recess of the housing formed on the extension portion; the second end of the handle inserted into the second recess along the longitudinal direction of the gripping portion.
The power tool according to claim 2, wherein at least one of the first guiding pin and the second guiding pin is coupled to the vibration body in a fixed way or a movable way.