CN109262549B

CN109262549B - Electric tool

Info

Publication number: CN109262549B
Application number: CN201710580772.0A
Authority: CN
Inventors: 谢炬烽
Original assignee: Bosch Power Tools China Co Ltd
Current assignee: Bosch Power Tools China Co Ltd
Priority date: 2017-07-17
Filing date: 2017-07-17
Publication date: 2021-04-06
Anticipated expiration: 2037-07-17
Also published as: CN109262549A; DE102018211506A1

Abstract

The invention provides an electric tool, which comprises a driving component; a rotational motion assembly; a hammer action assembly; and a transmission assembly that converts rotational motion of the drive assembly into at least one of rotational motion of the rotary-action assembly and reciprocating motion of the hammer-action assembly, the transmission assembly comprising: an intermediate shaft (210); an impact transmission assembly (220) disconnectably engaged with the intermediate shaft (210) and, when engaged, transmitting rotational motion of the intermediate shaft (210) to the hammer action assembly for reciprocating movement thereof; and a first rotational speed transmission assembly (230) and a second rotational speed transmission assembly (240) which are disconnectably engaged with the intermediate shaft (210), respectively; the power tool has the following operating modes: a first operating mode in which the intermediate shaft (210) drives the first speed drive assembly (230) by engagement, but does not engage and thus does not drive either of the second speed drive assembly (240) and the impact drive assembly (220); a second operating mode in which the intermediate shaft (210) is not engaged and therefore does not drive the first speed drive assembly (230), but drives both the second speed drive assembly (240) and the impact drive assembly (220) by engagement.

Description

Electric tool

Technical Field

The present invention relates to an electric tool, and more particularly to an electric tool, particularly a hammer drill, capable of outputting two different rotational speeds.

Background

In general, a hammer drill may have a drill mode that outputs only a rotational motion and a hammer mode that outputs only a reciprocating hammering motion, or some hammer drills also have a hammer drill mode that outputs both a rotational motion and a hammering motion.

Currently, most hammer drills include only a single gear mechanism providing a single gear ratio, and in both the drill mode and the hammer drill mode the output hammer tube of the hammer drill is engaged with the gear mechanism so that the rotational speed of the tool is the same in both modes.

However, in practical applications, the user may wish to be able to select different rotational speeds depending on the target workpiece material or other requirements. For example, in drill mode, the user typically desires a larger range of available speeds, a higher speed for higher drilling efficiency, such as 3000 RPM. In hammer drill mode, the user typically desires a lower rotational speed and a higher torque to be transmitted, thereby reducing the impact of the rotation of the tool on the impact efficiency. It is clear that the "three modes" described above do not meet this speed requirement.

The hammer drill capable of outputting two rotating speeds is available, but a rotating shaft is additionally introduced, so that the hammer drill is heavy and complex in structure, and is high in cost.

It is desirable to solve the above problems.

Disclosure of Invention

The invention aims to provide a hammer drill which can output two rotating speeds and has a simpler structure.

To this end, the present invention provides a power tool comprising a drive assembly providing rotational motion; a rotary action assembly including a hammer tube driven to rotate and drive a cutter of the electric tool to rotate together; a hammering action assembly which is positioned in the hammer pipe and performs reciprocating motion to hammer the cutter; and a transmission assembly that converts rotational motion of the drive assembly into at least one of rotational motion of the rotary-action assembly and reciprocating motion of the hammer-action assembly, the transmission assembly comprising:

an intermediate shaft driven for rotation by the drive assembly, the intermediate shaft defining an axial direction and a circumferential direction perpendicular to the axial direction;

an impact transmission assembly disconnectably engaged with the intermediate shaft and, when engaged, transmitting rotational motion of the intermediate shaft to the hammer action assembly for reciprocation; and

a first and second rotational speed drive assembly that are disconnectably engaged with the intermediate shaft, respectively, and that, when engaged, transfer rotational motion of the intermediate shaft to the hammer tube, causing the hammer tube to rotate at a high speed and a low speed, respectively;

wherein the power tool has the following modes of operation: a first operating mode in which the intermediate shaft drives the first speed drive assembly by engagement, but does not engage and thus does not drive either of the second speed drive assembly and the impact drive assembly; a second operating mode in which the intermediate shaft is not engaged and thus does not drive the first speed drive assembly, but both the second speed drive assembly and the impact drive assembly are driven by engagement.

According to a second aspect of the present invention, there is provided a power tool comprising a drive assembly providing rotational motion; a rotary action assembly including a hammer tube driven to rotate and drive a cutter of the electric tool to rotate together; a hammering action assembly which is positioned in the hammer pipe and performs reciprocating motion to hammer the cutter; and a transmission assembly that converts rotational motion of the drive assembly into at least one of rotational motion of the rotary-action assembly and reciprocating motion of the hammer-action assembly, the transmission assembly comprising:

a first rotational speed drive assembly and a second rotational speed drive assembly each disconnectably engaged with the intermediate shaft and transmitting rotational motion of the intermediate shaft to the hammer tube when engaged to rotate the hammer tube at a high speed and a low speed, respectively,

wherein the second rotational speed drive assembly drives the hammer tube to rotate through the first rotational speed drive assembly when driven by the intermediate shaft.

According to the electric tool provided by the invention, the two-rotation-speed rotary motion of the electric tool is realized by a simple structure only comprising the intermediate shaft and the clutch member, so that the electric tool at least has three operation modes, namely a high-speed drilling mode and a low-speed hammer drilling mode, and the requirements of most applications of the hammer drill are met. In addition, the electric tool of the invention is also provided with a protection mechanism which can automatically disconnect the joint between the driving motor of the hammer drill and the hammer pipe when the cutter meets the resistance force which exceeds a preset value or the hammer pipe meets the resistance moment which exceeds a preset value in a low-speed hammer drill operation mode, thereby avoiding the danger that the hammer drill damages the motor or other parts of the hammer drill when the hammer drill is used for hammering a workpiece which is too hard, and even causes the loss of personnel and property.

Drawings

The above and other features and advantages of the present application will be better understood from the following description of preferred embodiments of the present application taken in conjunction with the accompanying drawings, in which:

fig. 1 is a simplified schematic view, partly in section, of a hammer drill according to the invention, with details of parts not relevant to the invention omitted;

FIGS. 2a-2b are, respectively, a cross-sectional view and a perspective view of a sleeve member of a hammer drill according to a first embodiment of the present invention;

FIG. 3 is a perspective view of an intermediate member of the sleeve member of the hammer drill according to the first embodiment of the present invention;

FIGS. 4a-4b are a sectional view and a perspective view, respectively, of a pendulum bearing of a hammer drill according to a first embodiment of the present invention;

FIGS. 5a-5b are a sectional view and a perspective view, respectively, of a modification of the pendulum bearing of the hammer drill according to the first embodiment of the present invention;

FIG. 6 is a perspective view of the first drive gear of the first speed drive assembly of the first embodiment of the hammer drill according to the present invention;

FIG. 7 is a perspective view of the spacer for the second drive gear of the second speed drive assembly in accordance with the first embodiment of the hammer drill according to the present invention;

8a-8f show partial cross-sectional views of five modes of operation of a hammer drill according to a first embodiment of the present invention, respectively, wherein FIGS. 8c and 8d show two different neutral modes;

FIGS. 9a-9b are, respectively, a cross-sectional view and a perspective view of a sleeve member of a hammer drill according to a second embodiment of the present invention;

FIG. 10 is a perspective view of a rocking bearing of the hammer drill according to the second embodiment of the present invention;

11a-11d are partial cross-sectional views of three modes of operation of a hammer drill according to a second embodiment of the present invention, wherein FIGS. 11b and 11c show two different neutral modes, respectively;

FIGS. 12a-12d are partial cross-sectional views of four modes of operation, respectively, of a hammer drill according to a third embodiment of the present invention;

13a-13d are partial cross-sectional views of four modes of operation, respectively, of a hammer drill according to a fourth embodiment of the present invention; and

fig. 14 and 15 are perspective views of the first and second driven gears of the hammer drill in cooperation with each other according to the present invention.

Detailed Description

The present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings. Throughout the drawings, the same reference numbers include components that are structurally or functionally the same or similar. Those skilled in the art will appreciate that the illustrations presented in the figures are merely illustrative embodiments and do not limit the scope of the invention in any way. Components shown in the drawings are not necessarily present in all embodiments, and components not shown in the drawings may be present in embodiments.

A first embodiment according to the invention is first described with reference to fig. 1-8 f.

As shown in fig. 1, a hammer drill according to the present invention generally includes a driving assembly (not shown) that provides power and outputs rotational motion, a hammer tube assembly 10 that provides rotational motion to a cutter of the hammer drill to cause the hammer drill to perform a drilling function, an impact assembly 40 (only schematically identified in fig. 1) that reciprocates a hammering cutter within a hammer tube 110 of the hammer tube assembly 10 to perform a hammer function, a transmission assembly 20 that transmits the power of the driving assembly to the hammer tube assembly 10 and the impact assembly 40, and a cutter holder 30 (only schematically identified in fig. 1) that is held by the hammer tube 110 to be rotatable therewith and that itself holds the cutter of the hammer drill. The hammer tube 110 of the hammer tube assembly 10 drives the tool carrier 30 of the hammer drill and the tools thereon into a rotational motion, and the impact assembly 40 outputs a hammering motion to the tools on the hammering tool carrier 30. The drive assembly, hammer tube assembly 10, impact assembly 40 and tool holder 30 are not material to the present invention and only the transmission assembly 20 will be described in detail herein.

According to the present invention, the transmission assembly 20 basically includes an intermediate shaft 210, an impact driving assembly 220 for converting the rotational motion of the intermediate shaft 210 into the reciprocating motion of the impact assembly 40, a first rotational speed transmission assembly 230 for converting the rotational motion of the intermediate shaft 210 into the first rotational speed rotational motion of the hammer tube 110 of the hammer tube assembly 10, a second rotational speed transmission assembly 240 for converting the rotational motion of the intermediate shaft 210 into the second rotational speed rotational motion of the hammer tube 110, and a clutch assembly 250 disposed on the intermediate shaft 210. First and second speed drive assemblies 230 and 240 have first and second gear ratios, respectively, such as the first gear ratio being less than the second gear ratio as shown in the illustrated embodiment. Thus, the hammer tube 110, and thus the tool rack 30 and the tools thereon, are driven at a higher speed by the first speed drive assembly 230 than by the second speed drive assembly 240.

The intermediate shaft 210 is supported by

bearings

212 and 214 at both ends, and a main gear 216 driven by a motor shaft of a driving motor of the driving assembly to rotate the intermediate shaft 210, a swing bearing 222 as a part of the impact driving assembly 220, a clutch member, specifically, a sleeve member 252 constituting a part of the clutch assembly 250, a first driving gear 232 as a part of the first rotation speed transmission assembly 230, and a second driving gear 242 as a part of the second rotation speed transmission assembly 240 are sequentially provided on the intermediate shaft 210. The intermediate shaft 210, and all of these components thereon, have a common axis of rotation, defining a common axial direction and a common circumferential direction perpendicular to the axial direction, referred to herein as the "axial direction" and the "circumferential direction", respectively.

The wobble bearing 222 of the impact drive assembly 220 is supported by the intermediate shaft 210 and is free to rotate independently of the intermediate shaft 210. In addition to the swing bearing 222, the impact drive assembly 210 includes a swing link 224 that engages the swing bearing 222. The pendulum 224 is connected at one end to the pendulum bearing 222 and at the other end pivotally connected to the impact assembly 40 within the hammer tube 110. When the swing bearing 222 rotates, the swing rod 224 swings back and forth in the plane of the page, so that the impact assembly 40 reciprocates in the hammer tube 110, and the tool of the hammer drill outputs the hammer motion.

The clutch assembly 250 essentially comprises said sleeve member 252, the sleeve member 252 being directly or indirectly engaged to the intermediate shaft 210 for rotation with the intermediate shaft 210 and being axially slidable along the intermediate shaft 210 by means of a mode switching assembly, not shown. Specifically, in the illustrated embodiment, sleeve member 252 is engaged to intermediate shaft 210 via intermediate member 254. The intermediate member 254 may be a unitary member with the intermediate shaft 210 or may be formed separately from the intermediate shaft 210 and then attached thereto as in the illustrated embodiment. Intermediate member 254 and sleeve member 252 are engaged by engagement features that prevent relative rotation therebetween but allow relative sliding movement in the axial direction.

In an embodiment of the present invention, the sleeve member 252 and the intermediate member 254 have the exemplary configurations shown in FIGS. 2a-2b and FIG. 3, respectively. The sleeve member 252 has at least one protrusion 2524, e.g., a set of protrusions 2524, four protrusions 2524 in the figure, extending radially inward from its inner circumferential surface. The protrusions 2524 are distributed in the circumferential direction of the sleeve member 252, with a space defined between adjacent protrusions 2524. Accordingly, as shown in fig. 3, the intermediate member 254 is formed with protrusions 2546 elongated in the axial direction on the outer peripheral surface thereof, with recesses 2544 between adjacent protrusions 2546. The boss 2524 of the sleeve member 252 is received within the recess 2544 of the intermediate member 254 and is slidable within the recess 2544 in the axial direction. In this way, the sleeve member 252 can rotate synchronously with the intermediate member 254, and therefore with the intermediate shaft 210, while being able to slide axially relative to the sleeve member 252, and therefore relative to the intermediate shaft 210.

The first rotation speed transmission assembly 230 basically includes a first driving gear 232 and a first driven gear 234 engaged with each other, the first driving gear 232 is directly or indirectly disposed on the intermediate shaft 210 and can rotate independently of the intermediate shaft 210, and the first driven gear 234 is fixed to the hammer tube 110 by any means known in the art, such as a key connection, an overload protection coupling, etc., so that rotation of the first driven gear 234 drives the hammer tube 110 to rotate synchronously.

The second rotation speed transmission assembly 240 mainly includes a second driving gear 242 and a second driven gear 244 engaged with each other. The second drive gear 242 is supported on the countershaft 210 by a spacer 246, and the second drive gear 242 is fixed for rotation with the spacer 246 in synchronism with, but independent of, the countershaft 210. As shown in FIG. 7, the spacer 246 is nested on the intermediate shaft 210 and includes a small diameter section 2467 that passes through the internal bores of the first and second drive gears 232, 242 and a large diameter section 2469 that is adapted to be disconnectably engaged with the sleeve member 252 of the clutch assembly 250. The second driven gear 244 is sleeved on the hammer tube 110 and is disconnectably engaged with the first driven gear 234.

The sleeve member 252 is selectively disengageably engageable with one of the spacer 246 (i.e., the second drive gear 242) and the first drive gear 232. Thus, when the sleeve member 252 is engaged with the spacer 246 such that rotation of the intermediate shaft 210 is transmitted to the second rotational speed drive assembly 240, rotation of the second driven gear 244 of the second rotational speed drive assembly 240 is transmitted to the hammer tube 110 via the keyed connection of the first driven gear 234 with the hammer tube 110, causing the hammer tube 110 to rotate at the second rotational speed, at a lower speed. When the sleeve member 252 is engaged with the first driving gear 232 to transmit the rotation of the intermediate shaft 210 to the first rotational speed transmission assembly 230, the rotation of the first driven gear 234 of the first rotational speed transmission assembly 230 is directly transmitted to the hammer tube 110 through the key connection thereof with the hammer tube 110, so that the hammer tube 110 rotates at a high speed at the first rotational speed.

Of course, the sleeve member 252 may not engage the first speed drive assembly 230, specifically the first drive gear 232, and the second speed drive assembly 240, specifically the spacer 246. At this point, the sleeve member 252 may be selectively engaged to the swing bearing 222 of the impact drive assembly 220 to convert the rotational motion of the intermediate shaft 210 into a hammering action of the impact assembly 40 against the hammer drill bit, or to the swing bearing 222, when the hammer drill is in an idle mode with the bit performing neither a drilling action nor a hammer action. These two cases are referred to herein collectively as "neutral mode", which includes an idle mode as described in the former and a hammer mode as described in the latter.

As described above, rotation of the intermediate shaft 210 is transmitted to the impact drive assembly 220 and/or to either of the first and second

speed drive assemblies

230 and 240 via the sleeve member 252 of the clutch assembly 250, the sleeve member 252 being disconnectably connected to the wobble bearing 222, to the first drive gear 232, and to the second drive gear 242, respectively, and such "connecting" herein includes directly engaging and connecting the two, and also includes connecting the two via at least one intermediate member for synchronous movement. In particular, the sleeve member 252 is arranged to be slidable along the intermediate shaft 210 and is preset with at least three preset positions, for example four or five preset positions, each of which corresponds to one mode of operation of the hammer drill. Correspondingly, the hammer drill of the invention has at least three, for example three or four or five, operating modes.

The first preferred embodiment according to the present invention has five modes of operation, and the structure of this first embodiment will be described below with reference to fig. 4a-8 f.

In this first preferred embodiment, as shown in fig. 2a-2b, the sleeve member 252 further includes a set of tabs 2522 projecting radially inwardly from the inner circumferential surface of the sleeve member 252 for driving the impact drive assembly 220. The illustrated tabs 2522 are distributed along the circumferential direction of the sleeve member 252, with adjacent tabs 2522 defining gaps 2523 therebetween. Sleeve member 252 also includes another set of tabs 2526 projecting radially inwardly from the inner peripheral surface of sleeve member 252 for driving either of first and second

speed drive assemblies

230 and 240. As with tabs 2522, tabs 2524 and tabs 2526 are spaced apart in the circumferential direction, with adjacent tabs each defining a gap therebetween for engaging a mating tab. In the present embodiment, the boss 2522 configured to engage with the swing bearing 222 is disposed on the side (upstream side) closer to the drive motor with respect to the transmission path, the boss 2526 configured to engage with the first or

second drive gear

232 or 242 is disposed on the side (downstream side) closer to the cutter with respect to the transmission path, the boss 2524 configured to engage the intermediate 254 is located between the boss 2522 and the boss 2526 (intermediate side), and the boss 2524, the boss 2522, and the boss 2526 all include four bosses spaced apart uniformly in the circumferential direction, however, it will be understood by those skilled in the art that the number of bosses per set is not limited to four.

Correspondingly, as shown in fig. 4a-4b, the wobble bearing 222, in particular the bearing segment for engagement with the sleeve member 252, comprises a set of protrusions 2222 distributed in the circumferential direction on its outer circumference, the adjacent protrusions 2222 defining gaps 2223 (fig. 4b) adapted to receive the protrusions 2522 of the sleeve member 252. When the protrusions 2522 of the sleeve member 252 are received in the gaps 2223 of the swing bearing 222 while the protrusions 2222 of the swing bearing 222 are received in the gaps 2523 of the sleeve member 252, the swing bearing 222 engages the sleeve member 252 and is driven by the sleeve member 252 to rotate with the intermediate shaft 210, and the hammer drill outputs a hammering motion. When the protrusion 2522 of the sleeve member 252 is placed in the space left of the protrusion 2222 of the swing bearing 222 (the space between the ball bearing segment where the swing bearing 222 engages the rocker 224 and the protrusion 2222) while the protrusion 2222 of the swing bearing 222 is received in the space between the

protrusions

2522 and 2524 of the sleeve member 252, the swing bearing 222 is disengaged from the sleeve member 252, the swing bearing 222 is not driven by the sleeve member 252, and the hammer drill does not output a hammering motion.

Figures 5a-5b illustrate an alternative embodiment of the rocking bearing 222 which differs from the one in figures 4a-4b only in that the rocking bearing 222 in figures 5a-5b includes two sets of

protrusions

2222 and 2224 spaced apart in the axial direction, the axial length of the circumferential annular gap 2225 between the two sets of

protrusions

2222 and 2224 being equal to or slightly greater than the axial length of the protrusions 2522 of the sleeve member 252. When either of the two sets of

protrusions

2222 and 2224 of the swing bearing 222 is engaged with the protrusions 2522 of the sleeve member 252, the swing bearing 222 is engaged with the sleeve member 252 to be driven by the sleeve member 252 to rotate with the intermediate shaft 210, so that the cutters of the hammer drill are hammered by the impact assembly 40. Conversely, when the tabs 2522 of the sleeve member 252 are disposed in the circumferential annular slot 2225 of the swing bearing 222, the swing bearing 222 is disengaged from the sleeve member 252 and the swing bearing 222 is not driven by the sleeve member 252 and does not hammer the hammer drill bit.

In fig. 6, a structure of the first driving gear 232 according to the first embodiment of the present invention is shown. The first drive gear 232 includes a large diameter intermeshing gear segment and a small diameter segment for engagement with the sleeve member 252, the small diameter segment of the first drive gear 232 including a circumferentially aligned set of lobes 2322 projecting radially outwardly from an outer peripheral surface thereof, adjacent lobes 2322 defining gaps 2323 adapted to receive the lobes 2526 of the sleeve member 252. When the boss 2526 of the sleeve member 252 is received in the gap 2323 of the first drive gear 232, the first drive gear 232 is driven by the sleeve member 252 to rotate with the intermediate shaft 210, whereby the tool of the hammer drill outputs a first high-speed rotational motion. When the sleeve member 252 moves axially to move the protrusion 2526 out of the gap 2323 of the first driving gear 232, the first driving gear 232 is disengaged from the sleeve member 252, and the first driving gear 232 is not driven by the sleeve member 252.

A spacer 246 according to a first embodiment of the present invention is shown in fig. 7 secured with the second drive gear 242. The small diameter section 2467 of the spacer 246 is secured only to the second drive gear 242, and the large diameter section 2469 is adapted to engage the sleeve member 252. The second axial segment 2469 is formed with a set of lobes 2462 projecting radially outward from its outer peripheral surface, with adjacent lobes 2462 defining a gap 2463 therebetween adapted to receive the lobes 2526 of the sleeve member 252. When the boss 2526 of the sleeve member 252 is received in the gap 2463 of the spacer 246, and thus the second drive gear 242, is driven by the sleeve member 252 to rotate with the intermediate shaft 210, whereby the hammer drill bit outputs a second, lower rotational speed rotational motion. When the sleeve member 252 is moved axially to move the protrusion 2526 out of the gap 2463 of the spacer 246, the spacer 246 and the second driving gear 242 are disengaged from the sleeve member 252 and are not driven by the sleeve member 252.

The various preset positions of the sleeve member 252 along the intermediate member 210 and the corresponding modes of operation of the hammer drill are described below with reference to figures 8a-8f, respectively, wherein the wobble bearing 222 arrangement shown in figures 4a-4b and 5a-5b is employed in figures 8c and 8d, respectively. It is noted that the terms "left" and "right" are used hereinafter for clarity, both relative to an observer viewing the referenced figures.

As shown in fig. 8a, the sleeve member 252 is placed in a first predetermined position along the intermediate shaft 210. In this position, the protrusions 2522 of the sleeve member 252 are not engaged with the protrusions 2222 of the swing bearing 222, but are located axially to the right of the protrusions 2222, but the protrusions 2526 of the sleeve member 252 are received in the gaps 2323 between the protrusions 2322 of the first drive gear 232 of the first rotation transmission assembly 230, while the gaps of the protrusions 2526 receive a respective one of the protrusions 2322. The boss 2526 does not engage the boss 2462 on the spacer 246. Therefore, at this time, the sleeve member 252 is engaged with the first driving gear 232 and disengaged from the swing bearing 222 and the second driving gear 242, and the rotation of the intermediate shaft 210 is not transmitted to the swing bearing 222 and the second driving gear 242 through the sleeve member 252, but is transmitted only to the first driving gear 232, and the tool on the tool rack 30 is driven to perform the rotational operation at the first rotational speed, i.e., at the high speed, through the first rotational speed transmission assembly 230. Thereby, a high speed drilling mode of the hammer drill is obtained.

As shown in fig. 8b, sleeve member 252 is moved leftward along intermediate shaft 210 a distance substantially equal to or slightly exceeding the axial length of boss 2526 to a second predetermined position. At this point, the boss 2522 of the sleeve member 252 is moved into engagement with the boss 2222 of the swing bearing 222 so that the sleeve member 252 is engaged with the swing bearing 222, and the rotation of the intermediate shaft 210 is transmitted via the sleeve member 252 to the impact transmission assembly 220, thereby driving the cutters on the cutter holder 30 into a hammering motion. On the other hand, since the length of the protrusions 2322 of the first drive gear 232 in the axial direction is set to be greater than the above-described distance of movement of the sleeve member 252 to the left along the intermediate shaft 210, the first drive gear 232 remains engaged with the sleeve member 252, and the protrusions 2526 of the sleeve member 252 remain engaged with the protrusions 2322 of the first drive gear 232 without engaging the protrusions 2462 on the spacer 246. Therefore, rotation of the intermediate shaft 210 can still be transmitted through sleeve member 252 to the first rotatable drive assembly 230 and thus to the tools on tool rack 30 for high speed rotational movement of the tools. Thereby, a high-speed hammer drill mode of the hammer drill is obtained.

In fig. 8c, as the sleeve member 252 is moved further to the left along the intermediate shaft 210, the lobes 2526 of the sleeve member 252 move away from the first drive gear 232, but the lobes 2526 of the sleeve member 252 have not yet engaged the lobes 2462 of the spacer 246 of the second drive gear 242. Therefore, neither the first drive gear 232 nor the second drive gear 242 are engaged with the sleeve member 252, the sleeve member 252 cannot transmit the rotational motion of the intermediate shaft 210 to either of the first rotational speed drive assembly 230 and the second rotational speed drive assembly 240, and the hammer tube 110, and therefore the tool, cannot perform rotational motion. On the other hand, the protrusions 2522 of the sleeve member 252 remain engaged with the protrusions 2222 of the swing bearing 222 (swing bearing 222 in FIGS. 4a-4 b), i.e., the sleeve member 252 remains engaged with the swing bearing 222, so that the sleeve member 252 transfers the rotational motion of the intermediate shaft 210 to the swing bearing 222 and the impact assembly 40 hammers the tool bit of the hammer drill. Thus, in fig. 8c, the hammer drill is in the hammer mode, which is one of the neutral modes.

Also in this position, if the swing bearing 222 employs the configuration of FIGS. 5a-5b, with the projections 2522 of the sleeve member 252 engaged in the circumferential annular gap 2225 between the two sets of

projections

2222 and 2224 of the swing bearing 222, as shown in FIG. 8d, the sleeve member 252 is disengaged from the swing bearing 222, the sleeve member 252 cannot transmit the rotational motion of the intermediate shaft 210 to the swing bearing 222, and no hammering motion is output, and the hammer drill is in the lost motion mode, which is the second neutral mode.

In FIG. 8e, continuing to move the sleeve member 252 to the left along the intermediate shaft 210, the boss 2522 of the sleeve member 252 is in engagement with the boss 2222 of the swing bearing 222, i.e., the sleeve member 252 is engaged with the swing bearing 222, and the hammer drill is able to output a hammering motion. The protrusions 2526 of the sleeve member 252 are moved into engagement with the protrusions 2462 of the spacer 246 of the second driving gear 242, i.e., the sleeve member 252 is engaged with the second driving gear 242, so that the sleeve member 252 transmits the rotational motion of the intermediate shaft 210 to the second rotational speed transmission assembly 240 having a larger transmission ratio through the spacer 246, and the hammer tube 110 and thus the tool perform a low-speed rotational motion. Therefore, the hammer drill is in the low speed hammer drill mode.

Continuing to move the sleeve member 252 to the left along the intermediate shaft 210 to the position shown in fig. 8f, the boss 2522 of the sleeve member 252 is disengaged from the boss 2222 of the swing bearing 222, i.e., the sleeve member 252 is disengaged from the swing bearing 222 and the hammer drill no longer outputs a hammering motion. While the protrusions 2526 of the sleeve member 252 and the protrusions 2462 of the spacer 246 are still engaged with each other, i.e., the sleeve member 252 and the second driving gear 242 are engaged, the cutter still performs a low speed rotation motion. At this time, the hammer drill is in the low speed drill mode.

In all five modes of the present first embodiment, the middle set of lobes 2524 of sleeve member 252 are always engaged with the axial lobes 2524 of intermediate member 252 to enable the transmission of the rotation of intermediate shaft 210.

In this first embodiment, the length of the convex portion 2222 of the rocking bearing 222 in the axial direction is substantially equal to three times the length of the convex portion 2522 of the sleeve member 252 in that direction, so the impact drive assembly 40 of the hammer drill can drive the cutter of the hammer drill to perform a hammer action in all three of the five preset positions of the sleeve member 252, the hammer drill including three operation modes including a hammer action among the high speed hammer drill mode, the low speed hammer drill mode, and the neutral mode.

In the first embodiment, the length of the protrusion 2322 of the first driving gear 232 in the axial direction is substantially equal to twice the length of the protrusion 2526 of the sleeve member 252 in the axial direction, so that the first rotary drive assembly 230 of the hammer drill can drive the tool of the hammer drill to rotate at high speed in two of the five preset positions of the sleeve member 252, and the hammer drill includes two operation modes including a high-speed drilling mode and a high-speed hammer drill mode. Likewise, the length of the projections 2462 on the spacer 246 in the axial direction is substantially equal to twice the length of the projections 2526 on the sleeve member 252 in this axial direction, so that the second rotary drive assembly 240 of the hammer drill is capable of driving the cutters of the hammer drill to rotate at low speeds, both low speed drill modes and low speed hammer modes of operation involving low speed rotary motion.

The hammer drill having five modes of operation has been described above with respect to the first embodiment of the present invention. It should be understood that a hammer drill in accordance with the principles of the present invention may not have all of the five modes of operation described above. For example, if the high speed hammer mode and the low speed drill mode are less applicable, the hammer drill may not have either of these two modes. This may be accomplished by varying the length of either or any of the

protrusions

2522 and 2526 on the sleeve member 252, the protrusions 2322 on the first drive gear 232, the protrusions 2462 on the spacer 246 in the axial direction.

A second embodiment of the invention is described below with reference to fig. 9a-11 d.

In this second embodiment, as shown in FIGS. 9a-9b, the projection 2522 'on the sleeve member 252' for driving the swing bearing 222 'is elongated in axial length to continue with the projection (projection 2524 in FIG. 1) for engagement with the projection 2546 of the intermediate member 254, as indicated by 2522'. Fig. 10 shows the structure of the rocking bearing 222 'in the present second embodiment, the length of the convex portion 2222' in the axial direction thereof is also lengthened. The other component structures in this embodiment are the same as those in the first embodiment.

Fig. 11a-11d show only three operating modes of the hammer drill according to the second embodiment, namely a high speed drill mode, a low speed hammer drill mode and a neutral mode.

Fig. 11a shows the high speed drilling mode of the hammer drill of this second embodiment, wherein the boss 2522 'of the sleeve member 252' is in a disengaged state from the boss 2222 'of the swing bearing 222', i.e. the sleeve member 252 'is disengaged from the swing bearing 222', so the hammer drill cannot output a hammering motion at this time. The protrusion 2526 of the sleeve member 252 'is in engagement with the protrusion 2322 of the first drive gear 232 of the first speed drive assembly 230, i.e., the sleeve member 252' is in engagement with the first drive gear, so that the tool of the hammer drill can now output a high-speed rotary motion.

In fig. 11b, the sleeve member 252 'has been moved to the left so that the protrusions 2526 thereof do not engage the protrusions 2322 of the first drive gear 232 and the protrusions 2462 of the spacer 246, i.e., the sleeve member 252' is disengaged from both the first and second drive gears so that the tool of the hammer drill does not output any rotational movement. The sleeve member 252 'protrusions 2522' are also not engaged with the protrusions 2222 'of the swing bearing 222', i.e., the sleeve member 252 'is also disengaged from the swing bearing 222', so the hammer drill cannot output a hammering motion at this time. The hammer drill is in the idle mode in the neutral mode at this time.

Alternatively, the hammer drill of fig. 11c differs from the hammer drill of fig. 11a, 11b only in that a slightly modified sleeve member 252 "is used, the projections 2522" of the sleeve member 252 "being somewhat longer than the axial length of the projections 2522 'of the sleeve member 252', so that in the same position as in fig. 11b the projections 2522" of the sleeve member 252 "are engaged to the projections 2222 'of the swing bearing 222', i.e. the sleeve member 252 'is engaged with the swing bearing 222', so that the hammer drill is now able to output a hammering movement. The hammer drill is in the hammer mode in the neutral mode at this time.

Returning to the configuration shown in fig. 11a, 11b, next, in fig. 11d, the sleeve member 252 'is moved further to the left with its boss 2526 engaged to the boss 2462 of the spacer 246, i.e., the sleeve member 252' is engaged with the spacer 246 and the second drive gear, so that the tool of the hammer drill outputs a low speed rotational motion. While the sleeve member 252 'protrusions 2522' are still engaged with the protrusions 2222 'of the swing bearing 222', i.e., the sleeve member 252 'is engaged with the swing bearing 222', the hammer drill is still able to output a hammering motion. The hammer drill is in a low-speed rotary hammer mode at the moment.

Fig. 12a-12d show a hammer drill according to a third preferred embodiment of the present invention. In the present embodiment, the hammer drill is designed with four operation modes, which are a high-speed drill mode shown in fig. 12a, a neutral mode shown in fig. 12b (only the idle mode is shown in the present embodiment), a low-speed drill mode shown in fig. 12c, and a low-speed hammer drill mode shown in fig. 12d, respectively. In this embodiment, the axial length of the convex portion of the rocking bearing is greatly shortened, so that the hammer drill in this embodiment has only one mode of operation involving hammer operation. With regard to other aspects of the present embodiment, reference is made to the embodiments described above.

13a-13d show a hammer drill according to a fourth preferred embodiment of the present invention. Unlike the hammer drill shown in the previous three embodiments, the sleeve member 252 of the hammer drill of the present embodiment includes two component parts, a first part 252a configured to be driven by the intermediate member 254 to drive the wobble bearing 222, a second part 252b configured to be driven by the intermediate member 254 to drive the spacer 246 of the first drive gear 232 or the second drive gear 242, the first and

second parts

252a, 252b being rotatable independently of each other and axially coupled together by the third part 252c for simultaneous axial movement.

Specifically, the first member 252a has a first convex portion configured to engage with the convex portion 2546 of the intermediate member 254 and a second convex portion configured to engage with the convex portion 2522 of the rocking bearing 222 formed on the inner peripheral surface. In fig. 13a-13d, the first and second projections are configured as a continuous projection 2522a that extends the entire axial length of the first part 252 a. The second member 252b has formed on its inner periphery a third projection 2522b arranged to be engaged with the projection 2546 of the intermediate 254, and a fourth projection 2524b arranged to be engaged with the projection 2322 of the first drive gear 232 or the projection 2462 of the spacer 246 of the second drive gear 242.

In the high speed drilling mode shown in FIG. 13a, the sleeve member of the first 252a, second 252b and third 252c members is in a first predetermined axial position, with the tabs 2522a of the first member 252a engaging only the tabs 2546 of the intermediate member 254 and not the tabs 2222 of the swing bearing 222, with the third tabs 2522b of the second member 252b engaging the tabs 2546 of the intermediate member 254 and with the fourth tabs 2524b engaging the tabs 2322 of the first drive gear 232.

In the hammer mode shown in fig. 13b, the sleeve member is in the second predetermined axial position, the protrusion 2522a of the first member 252a is engaged with the protrusion 2546 of the intermediate member 254 and with the protrusion 2222 of the swing bearing 222, the third protrusion 2522b of the second member 252b is engaged with the protrusion 2546 of the intermediate member 254 and the fourth protrusion 2524b is not engaged with either the protrusion 2322 of the first drive gear 232 or the protrusion 2462 of the spacer 246.

In the low speed hammer mode shown in fig. 13c, the sleeve element is in a third preset axial position, the protrusions 2522a of the first part 252a are engaged with both the protrusions 2546 of the intermediate piece 254 and the protrusions 2222 of the swing bearing 222, the third protrusions 2522b of the second part 252b are engaged with the protrusions 2546 of the intermediate piece 254 and the fourth protrusions 2524b are engaged with the protrusions 2462 of the spacer 246.

In the low speed drill mode shown in fig. 13d, the sleeve member is in the fourth preset axial position, the protrusion 2522a of the first part 252a is only engaged with the protrusion 2222 of the swing bearing 222 but not engaged with the protrusion 2542 of the intermediate member 254, i.e. no rotation is transmitted from the intermediate shaft 210, so no hammering operation is output, the third protrusion 2522b of the second part 252b is engaged with the protrusion 2546 of the intermediate member 254 and the fourth protrusion 2524b is engaged with the protrusion 2462 of the spacer 246, so the hammer drill transmission assembly 20 outputs only low speed rotational movement.

In view of the above four embodiments, it can be seen that at least two operation modes of the hammer drill can be obtained by appropriately selecting the dimensions in the axial direction of any one or more of the convex portion on the outer peripheral surface of the swing bearing, the convex portion of the sleeve member or its constituent member, the convex portion of the intermediate member of the second drive gear, and the convex portion of the first drive gear, and that three, four, or five operation modes can be obtained as necessary. Further, the neutral mode of the hammer drill can be set to either the idle mode or the hammer mode, again by appropriately setting the configuration or size of the protrusions on the rocking bearing.

The above has described a hammer drill comprising at least a high speed drill mode of operation, a low speed hammer drill mode of operation and a neutral mode of operation with reference to the accompanying drawings, the technical object being achieved by a transmission comprising only one intermediate shaft and one clutch member, the structural design and the manufacturing assembly being relatively simple.

The structure of the invention has another technical advantage: that is, the second driven gear 244 of the second rotational speed transmission assembly 240 is not directly coupled to the hammer tube 110, but is coupled to the first driven gear 234 of the first rotational speed transmission assembly 230, so that the hammer tube 110 is driven to rotate at the second low speed via the connection between the first driven gear 234 and the hammer tube 110. The first and second driven

gears

234 and 244 and the hammer tube 110 rotate about another common rotational axis that is parallel to the central axis of the intermediate shaft 210.

As shown particularly in fig. 14 and 15, the first driven gear 234 is formed with a projection 2342 extending toward the first driven gear 234 on the side perpendicular to the common rotational axis toward the second driven gear 244, and accordingly, the second driven gear 244 is formed with a recess 2442 for receiving the projection 2342 on the side perpendicular to the common rotational axis toward the first driven gear 234, and the second driven gear 244 is elastically urged toward the first driven gear 234 so that the first and second driven

gears

234 and 244 are disconnectably engaged by the projection 2342 and the recess 2442.

Advantageously, the protrusion 2342 tapers in the protruding direction away from the first driven gear 234, forming an obliquely extending guiding surface 2344 adapted to guide the protrusion 2342 into the recess 2442, and correspondingly, the recess 2442 is also formed with a mating chip extending surface 2444. These inclined surfaces also have the function of automatically disengaging the engagement between the first and second driven

gears

234 and 244 when the cutters of the hammer drill encounter resistance exceeding a certain predetermined value, i.e., when the hammer tube 110 encounters resistance exceeding a predetermined resistance torque, in the low speed hammer drill mode of operation of the hammer drill, which causes the rotational motion from the second rotational speed transmission assembly 240, or the rotational motion from the drive motor, to no longer be transmitted to the hammer tube 110, thereby protecting the hammer drill from damage.

The present invention is applicable not only to the hammer drill shown in the drawings but also to all electric power tools that output a rotating motion and a hammering motion.

The invention has been shown and described based on several preferred embodiments, but the invention is not limited to the details shown in the drawings and described above. Rather, various modifications or variations may be made without departing from the spirit or scope defined in the appended claims.

Claims

1. A power tool comprising a drive assembly providing rotational motion; a rotary action assembly including a hammer tube (110) driven to rotate and drive a cutter of the electric tool to rotate together; a hammer action assembly located within the hammer tube (110) for reciprocating the hammer bit; and a transmission assembly that converts rotational motion of the drive assembly into at least one of rotational motion of the rotary-action assembly and reciprocating motion of the hammer-action assembly, the transmission assembly comprising:

an intermediate shaft (210) driven in rotation by the drive assembly, the intermediate shaft (210) defining an axial direction and a circumferential direction perpendicular to the axial direction;

an impact transmission assembly (220) disconnectably engaged with the intermediate shaft (210) and, when engaged, transmitting rotational motion of the intermediate shaft (210) to the hammer action assembly for reciprocating movement thereof;

a first rotational speed transmission assembly (230) and a second rotational speed transmission assembly (240) which are disconnectably engaged with the intermediate shaft (210), respectively, and which, when engaged, transmit the rotational motion of the intermediate shaft (210) to the hammer tube (110), rotating the hammer tube (110) at first and second rotational speeds, respectively; and

a clutch member (252) rotatable synchronously with the intermediate shaft (210) but slidable along the intermediate shaft (210), wherein the impact transmission assembly (220) and the first and second speed transmission assemblies (230, 240) are both disconnectably engaged with the clutch member (252),

wherein the power tool has the following modes of operation: a first operating mode in which the intermediate shaft (210) drives the first speed drive assembly (230) by engagement, but does not engage and thus does not drive the second speed drive assembly (240) and the impact drive assembly (220); a second operating mode in which the intermediate shaft (210) is not engaged and therefore does not drive the first speed drive assembly (230), but drives both the second speed drive assembly (240) and the impact drive assembly (220) by engagement.

2. The power tool of claim 1, wherein the power tool further has at least one of the following modes of operation:

a third operating mode in which the intermediate shaft (210) is not engaged and therefore does not drive the first and second speed drive assemblies (230, 240), the intermediate shaft (210) being engageable and drivable or not engageable and therefore does not drive the impact drive assembly (220);

a fourth operating mode in which the intermediate shaft (210) is not engaged and therefore does not drive the second speed drive assembly (240), but drives both the first speed drive assembly (230) and the impact drive assembly (220) by engagement;

a fifth mode of operation wherein the clutch (252) drives the second speed drive assembly (240) by engagement but does not engage and thus does not drive the first speed drive assembly (230) and the impact drive assembly (220).

3. A power tool comprising a drive assembly providing rotational motion; a rotary action assembly including a hammer tube (110) driven to rotate and drive a cutter of the electric tool to rotate together; a hammer action assembly located within the hammer tube (110) for reciprocating the hammer bit; and a transmission assembly that converts rotational motion of the drive assembly into at least one of rotational motion of the rotary-action assembly and reciprocating motion of the hammer-action assembly, the transmission assembly comprising:

an impact transmission assembly (220) disconnectably engaged with the intermediate shaft (210) and, when engaged, transmitting rotational motion of the intermediate shaft (210) to the hammer action assembly for reciprocating movement thereof; and

a first rotational speed transmission assembly (230) and a second rotational speed transmission assembly (240) which are disconnectably engaged with the intermediate shaft (210), respectively, and which, when engaged, transmit the rotational motion of the intermediate shaft (210) to the hammer tube (110), respectively rotating the hammer tube (110) at a high speed and at a low speed, wherein the first and second rotational speed transmission assemblies (230, 240) respectively comprise a first and second driving gear (232, 242) mounted on the intermediate shaft (210) and a first and second driven gear (234, 244) capable of driving the hammer tube (110) in rotation, the first driven gear (234) being designed to be circumferentially engaged to the hammer tube (110) in rotation therewith, the second driven gear (244) being disconnectably engaged to the first driven gear (234) and driving the hammer tube (110) in rotation via the first driven gear (234); and

a clutch member (252) rotatable synchronously with the intermediate shaft (210) but slidable along the intermediate shaft (210), wherein the impact transmission assembly (220) and the first and second speed transmission assemblies (230, 240) are both disconnectably engaged with the clutch member (252).

4. The power tool according to claim 3, wherein the power tool has:

a first operating mode in which the intermediate shaft (210) drives the first speed drive assembly (230) by engagement, but does not engage and thus does not drive the second speed drive assembly (240) and the impact drive assembly (220); and a second mode of operation in which the intermediate shaft (210) is not engaged and thus does not drive the first speed drive assembly (230), but drives both the second speed drive assembly (240) and the impact drive assembly (220) by engagement.

5. The power tool of claim 4, wherein the power tool further has at least one of the following modes of operation:

6. The power tool according to any one of claims 1-5, wherein the clutch (252) is a unitary piece and includes a first engagement feature disconnectably engageable with the impact transmission assembly (220) and a second engagement feature disconnectably engageable with the first and second speed transmission assemblies (230, 240).

7. The power tool according to any one of claims 1-5, wherein the clutch (252) comprises at least a first part (252a) and a second part (252b), the first part (252a) and the second part (252b) being rotatable relative to each other and axially connected together by a third part (252c) such that the first part and the second part are synchronously axially movable, the first part (252a) comprising a first engagement feature disconnectably engageable with the impact transmission assembly (220) and the second part (252b) comprising a second engagement feature disconnectably engageable with the first rotational transmission assembly (230) and the second rotational transmission assembly (240).

8. The power tool according to claim 6,

the first engagement feature is configured as at least one first protrusion (2522) projecting radially inward from an inner circumferential surface of the clutch (252);

the impact transmission assembly (220) comprises a swing bearing (222) mounted on the intermediate shaft (210) but free to rotate relative to the intermediate shaft (210), the swing bearing (222) comprising a first corresponding protrusion (2222) disconnectably engaged with the first protrusion (2522).

9. The power tool according to claim 6,

the second engagement feature is configured as at least one second lobe (2526) projecting radially inward from an inner circumferential surface of the clutch (252),

the first and second rotational speed transmission assemblies (230, 240) respectively comprise first and second driving gears (232, 242) mounted on the intermediate shaft (210) but freely rotatable relative to the intermediate shaft (210) and first and second driven gears (234, 244) capable of driving the hammer tube (110) in rotation, the first and second driving gears (232, 242) or the spacers fixed together with the first and second driving gears (232, 242) respectively comprise second corresponding protrusions disengageably engaged with the second protrusions (2526).

10. The power tool of claim 9, wherein a portion of the second drive gear (242) of the second speed drive assembly (240) or a spacer (246) secured to the second drive gear (242) is disengageably engageable with the clutch member (252) through the first drive gear (232) of the first speed drive assembly (230).

11. The power tool according to claim 10, wherein the first driven gear (234) is circumferentially engaged to the hammer tube (110), and the second driven gear (244) rotates independently of the hammer tube (110) and is disconnectably engaged to the first driven gear (234).

12. The power tool according to claim 3 or 11, wherein the first driven gear (234) comprises a protrusion (2342) protruding towards the second driven gear (244), respectively the second driven gear (244) comprises a recess (2442) adapted to receive the protrusion.

13. The power tool of claim 12, wherein the protrusion (2342) tapers away from the first driven gear (234) to define an obliquely extending surface, and the recess (2442) includes an obliquely extending surface corresponding to the obliquely extending surface.

14. The power tool according to any one of claims 1-5, wherein the power tool further comprises a protection mechanism that disengages the second speed drive assembly (240) from the hammer tube (110) when the hammer tube (110) encounters a resistive torque that exceeds a predetermined value.

15. The power tool according to any one of claims 1-5, further comprising a shift assembly for sliding the clutch (252) in an axial direction of the intermediate shaft (210) to shift an operation mode of the power tool, the clutch (252) including an engagement feature with the shift assembly.

16. The power tool according to any one of claims 1 to 5, wherein the power tool is a hammer drill.