EP2632641A1

EP2632641A1 - Mechanical striking mechanism for a hand machine tool

Info

Publication number: EP2632641A1
Application number: EP11763936.9A
Authority: EP
Inventors: Chi Hoe Leong; Daniel Brogli; Chuan Cheong Yew; Cheeuee Neoh
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-10-28
Filing date: 2011-09-30
Publication date: 2013-09-04
Also published as: WO2012055669A1; JP5678196B2; CN103201074A; JP2013540601A; US20140020921A1; DE102010063200A1

Abstract

The invention relates to a handheld power tool having a mechanical striking mechanism (200), which comprises a striking body (500) that has at least one drive cam, and having an output shaft (400) that has at least one output cam (412, 414) and that is connected to a tool holder (450) for holding a tool, wherein the drive cam is designed to drive the output cam (412, 414) in a striking manner during the striking operation of the mechanical striking mechanism (200). The striking body (500) containing the drive cams is arranged upstream of the output cams (412, 414) in an axial direction of the output shaft (400) facing away from the tool holder (450).

Description

description

title

MECHANICAL IMPACT FOR A CRAFT EUGMACHINE state of the art

The present invention relates to a portable power tool with a mechanical impact mechanism, which has a provided with at least one drive cam impact body and provided with at least one output cam output shaft which is provided with a tool holder for receiving a

Tool is connected, wherein the drive cam is formed for the striking drive of the output cam in the impact mode of the mechanical percussion. From DE 20 2006 014 850 U1 such, designed as a rotary impact wrench power tool is known, which has a mechanical percussion with a striker and an output shaft. In non-impact operation of the rotary impact wrench, drive cams formed on the impactor engage in output cams provided on the output shaft such that rotational movement of the impactor is transmitted to the output shaft. In the impact mode of the rotary impact wrench or percussion drive the drive cams drive the output cam in an associated direction of rotation, wherein in a corresponding impact generation in each case a drive cam hammer-like beats against an associated output cam.

A disadvantage of the prior art is that the impact generation in the percussion mode of the percussion on the one hand leads to vibrations of the power tool and on the other hand to an undesirable noise and thus to loss of comfort in the use of such a power tool. Disclosure of the invention

An object of the invention is therefore to provide a new hand tool that has a mechanical percussion that allows at least a reduction of noise in the impact mode.

This problem is solved by a hand tool with a mechanical striking mechanism, which has a provided with at least one drive cam impact body and provided with at least one output cam output shaft which is connected to a tool holder for receiving a tool. The drive cam is designed for the impact drive of the output cam in the impact mode of the mechanical impact mechanism. The impactor body with the drive cams is disposed in front of the output cams in an axial direction of the output shaft facing away from the tool receptacle.

The invention thus makes it possible to provide a hand-held power tool with a mechanical percussion mechanism, in which by an impact generation in the direction away from the tool holder axial direction, d. H. in the direction of a transmission or drive motor provided for driving the output shaft, at least a reduction of vibrations of the hand tool machine resulting from the impact generation is made possible.

The output shaft is preferably drivable by a pot-like drive body which surrounds the output shaft at least in sections and forms a cavity in which the impactor is arranged axially displaceably on the output shaft.

Thus, a Schlock production can take place within a pot-like drive body, which thus serves as a damping member for noise reduction in the impact generation.

According to one embodiment, the impactor is acted upon by a spring element arranged in the cavity in the direction of the output cam. The direction of the output cam corresponds to an axial direction of the output shaft facing away from the tool holder. Thus, in a simple manner, a blow generation can be made possible at a stroke position spaced by a predetermined distance from the tool holder.

The spring element is preferably a compression spring.

Thus, a stable and inexpensive spring element can be provided. Preferably, a transmission for driving a drive member is provided, which is rotatably connected to the drive body.

Thus, the drive body can be driven safely and reliably via the drive member.

According to one embodiment, the transmission is designed as a planetary gear, wherein a planet carrier of the planetary gear train forms the drive member.

Thus, an uncomplicated and robust transmission can be provided.

The impactor is preferably supported on at least one steel ball on the drive body.

Thus, an axial displacement of the impactor in the drive body can be made possible in a simple manner by means of the steel ball.

The drive body preferably has an inner wall, on which at least one groove-like recess for guiding the at least one steel ball is formed.

Thus, a secure and stable guidance of the steel ball on the inner wall of the drive body can be made possible.

The impactor body preferably has an outer wall, on which at least one recess for supporting the at least one steel ball is formed. Thus, a reliable storage of the steel ball on the impactor can be made possible.

According to one embodiment, the at least one steel ball in Schlag- operation of the mechanical impact mechanism in the groove-like recess of the drive body and the recess of the impactor is movable to allow rotation of the impactor relative to the output shaft and relative to the drive body. Thus, a rotation of the impactor relative to the output shaft and relative to the drive body can be made possible in a simple manner.

The problem mentioned at the outset is also solved by a mechanical impact mechanism for a hand tool, with a shock body provided with at least one drive cam and with an output shaft provided with at least one output cam, which is connected to a tool holder for receiving a tool. The drive cam is designed for the impact drive of the output cam in the impact mode of the mechanical impact mechanism. The impactor body with the drive cams is disposed in front of the output cams in an axial direction of the output shaft facing away from the tool receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail in the following description with reference to exemplary embodiments illustrated in the drawings. Show it:

1 is a schematic view of a hand tool with an insertion tool according to an embodiment,

2 is an enlarged sectional view of a section of the power tool of FIG. 1,

3 is a perspective view of the drive body of Fig. 1 and 2,

4 is a perspective view of the output shaft of Fig. 1 and 2, Fig. 5 is a perspective view of the impactor of Fig. 1 and 2, and

Fig. 6 is a perspective view of the mounted on the transmission housing of Fig. 2 output shaft of Fig. 1 and 2, on which the striking body, the spring element and the steel ball of Fig. 2 are arranged.

Description of the embodiments

1 shows a hand tool machine 100, which is provided with a tool holder 450 and a mechanical striking mechanism 200 and has a housing 110 with a handle 126. According to one embodiment, the handheld power tool 100 for mains-independent power supply can be mechanically and electrically connected to a battery pack 130.

The hand tool 100 is exemplified as a cordless rotary impact wrench. It should be noted, however, that the present invention is not limited to cordless impact drivers, but rather may be applied to various power tools in which a tool is rotated, e.g. B. in a percussion drill, etc., regardless of whether the power tool is independent of the mains with a battery pack or network dependent operable. In addition, it should be understood that the present invention is not limited to power hand tools, but is generally applicable to tools in which the hammer mechanism 200 described in FIGS. 2-6 may find application.

In the housing 110, one of the battery pack 130 powered with electric drive motor 1 14, a gear 1 18 and the hammer mechanism 200 are arranged. The drive motor 114 is z. B. via a manual switch 128 actuated, that is switched on and off, and may be any type of engine, for. As an electronically commutated motor or a DC motor. Preferably, the drive motor 1 14 is so electronically controlled or controlled that both a re versierbetrieb, as well as specifications with respect to a desired rotational speed can be realized. The operation and structure of a suitable drive motor are well known from the prior art and are therefore not further described here for the sake of brevity of the description. The drive motor 114 is connected via an associated motor shaft 116 to the transmission 1 18, which converts a rotation of the motor shaft 116 in a rotation of a drive member 125. This conversion preferably takes place in such a way that the drive member 125 increases in size relative to the motor shaft 116

Torque, but reduced rotational speed turns. The drive motor 1 14 is illustratively arranged in a motor housing 115 and the gear 118 in a gear housing 119, wherein the gear housing 119 and the motor housing 115 are arranged for example in the housing 1 10.

The mechanical percussion mechanism 200 connected to the drive member 125 is exemplified by a rotary percussion mechanism arranged in an illustrative striking mechanism housing 220, which has a striking body 500 which carries sudden high-intensity angular momentum via associated drive cams 512, 514 and an output shaft 400, z. B. an output spindle transmits. It should be understood, however, that the use of impactor housing 220 is merely exemplary in nature and is not intended to limit the invention. This can also be found in striking mechanisms without separate impact mechanism housing application, the z. B. are arranged directly in the housing 110 of the power tool 100. An exemplary construction of percussion mechanism 200 will be described in connection with a detail 150 of handheld power tool 100 shown in FIG. 2.

On the output shaft 400 illustratively the tool holder 450 is provided, which is preferably designed for receiving insert tools and with an insert tool 140 with outer polygonal coupling 142 is connectable. In addition, the tool holder 450 according to an embodiment also or alternatively thereto with an insert tool with polygon socket coupling, z. B. a socket, connectable. The insert tool 140 is exemplified as a screwdriver bit with the external polygon coupling 142, illustratively an octagonal coupling formed in a suitable inner receptacle (455 in Fig. 2) of the tool holder 450 is arranged. Such a screwdriver bit and a suitable socket wrench are sufficiently known from the prior art, so that is omitted here for the purpose of scarcity of the description to a detailed description. Fig. 2 shows the detail 150 of Fig. 1 with the arranged in the transmission housing 1 19 gear 118 and standing in operative connection with the output shaft 400, mechanical percussion 200 of FIG. 1 with the striking mechanism housing 220. The mechanical percussion 200 has as in Fig. 1 described with the drive member 125 of the transmission 1 18 connected drive body 300 which is arranged together with the impactor 500 in the striking mechanism housing 220.

The output shaft 400 has, by way of example, a shaft body 250 provided with an annular shoulder 255, on which at least one and illustratively two output cams 412, 414 are formed, as well as the tool holder 450 of FIG. B. is provided with an octagonal interior shot 455. An axial end of the shaft body 250, on which the output cams 412, 414 are provided, is illustratively connected to a bearing member 270. According to one embodiment, the output shaft 400 is rotatably mounted in the striking mechanism housing 220 via a sliding bearing 280 and in the gear housing 119 via the bearing part 270. The gear housing 1 19 and the striking mechanism housing 220 are illustratively attached to each other.

According to one embodiment, the transmission 118 is a reduction gear, the z. B. is designed in the manner of a planetary gear and has one or more planetary stages. Illustratively, the planetary gear 1 18 has a single planetary stage 201 with a sun gear 203, planetary gears 204, 205, a ring gear 208 and a planet carrier 207, which exemplifies the drive member 125 of FIG. 1 and rotatably connected to the rotary drive of the drive body 300 with this , The sun gear 203 is driven by a drive element 202 which is rotatably connected to the motor shaft 1 16 or z. B. can be formed on this or formed integrally with this. The sun gear 203 and the drive element 202 are preferably also integrally formed. Since the structure and operation of a planetary gear are well known to those skilled in the art, a further description of the planetary gear 118 is omitted here for brevity of the description.

The planet carrier 207 illustratively has a fastening device 240 for the rotationally fixed attachment of the planetary carrier 207 to the drive body 300. This has an example cooperating with the fastening device 240 Counter fastening device 340. The fastening device 240 and the counter-fastening device 340 together form, for. B. a press connection. It should be noted, however, that other types of connection are possible, for. As clamping, locking or tooth-tooth gaps connections that allow a rotationally fixed connection between the planet carrier 207 and drive body 300.

The drive body 300 is exemplified pot-shaped and has at a first axial end 351 a pot bottom-like wall 350 which is provided with an opening 360. This illustratively forms an annular collar 254. At its opposite axial end 352, the cup-shaped drive body 300 has an opening 305, on which the counter-fastening device 340 is formed. According to one embodiment, the drive body 300 surrounds the output shaft 400 at least in sections. Illustratively, the cup-shaped drive body 300 has an inner wall 320 and forms a cavity 310, in which the shaft body 250 with the two output cams 412, 414 of the output shaft 400 is arranged up to the annular shoulder 255 provided thereon, so that the output shaft 400 is rotatable, but is arranged axially immovable in the drive body 300. In this case, the annular shoulder 255 bears against the ring collar 254 formed on the drive body 300 by way of example. In addition, within the cavity 310 on the output shaft 400 by way of example the impactor 500 is rotatably arranged and axially displaceable.

The impactor 500 is exemplified pot-shaped and has an outer wall 510 and a bottom wall 550, which form an interior 560. In the bottom wall 550, an opening 599 is formed, through which the shaft body 250 of the output shaft 400 passes. The impactor body 500 is moved by a likewise arranged in the cavity 310 spring element 242 in the direction of

Output cam 412, 414 acted upon. This direction of the output cams 412, 414 corresponds to an axial direction of the output shaft 400 facing away from the tool holder 450, which is indicated by 244 by way of example. For this purpose, the z. B. formed as a compression spring spring element 242 preferably between see the annular collar 254 and the cup bottom-like wall 350 of the drive body 300 and the bottom wall 550 of the impactor 500 arranged wherein the spring element 242 passes through the interior 560 of the impactor body 500, as illustrated in FIG. 6.

It should be noted that according to the present invention, the impactor 500 is urged by the spring member 242 in the direction 244, d. H. in a direction axially opposite to a corresponding advancing direction of the hand tool 100 of FIG. 1 in operation. This propulsion direction is identified in FIG. 2 by way of example by 299.

According to one embodiment, the impactor body 500 is supported on the drive body 300 via at least one driver ball. Illustratively, the impactor 500 is supported on the drive body 300 via two steel balls 290, 295. For this purpose, at least one groove-like recess for guiding the at least one driver ball is formed on the inner wall 320 of the drive body 300. Illustratively, there is provided a preferably V-shaped groove-like recess 330 for guiding the steel ball 290 and a preferably V-shaped groove-like recess 335 for guiding the steel ball 295, which are also referred to below as "V-grooves." On the outer wall 510 of the impact body 500 Illustratively, a depression or recess 530 is provided for supporting the steel ball 290 and a recess or recess 535 for supporting the steel ball 295. The steel balls 290, 295 are in impact mode the mechanical percussion mechanism 200 in the V-grooves 330, 335 and the recesses or recesses 530, 535 movable to allow rotation of the impactor 500 relative to the output shaft 400 and relative to the drive body 300, as described below.

During normal operation of the handheld power tool 100 of FIG. 1, the planet carrier 207 forming the drive member 125 of FIG. 1 drives the pot-type drive body 300 in rotation. This takes over the steel balls 290, 295 the

Impact body 500 with, the drive cam (512, 514 in Fig. 1, 5 and 6) abut against the output cam 412, 414 of the output shaft 400, so that the impactor 300 also causes the output shaft 400 in rotation. Thus, in the impact-free operation or normal operation of the handheld power tool 100 of FIG. 1, a rotational movement of the planetary carrier 207 via the drive body 300, the Steel balls 290, 295 and the impactor 500 transmitted to the output shaft 400.

If now increases the torque demand on the output shaft 400 abruptly and their rotation is thus blocked, the mechanical

Schlagwerk 200 in a corresponding impact operation, in which the drive body 300 is further rotated by the planet carrier 207. Here, the steel balls 290, 295 are moved in the V-grooves 330, 335, so that the striking body 300 is pressed against a corresponding restoring force of the spring element 242 in the advancing direction 299, so that the drive cam (512, 514 in

FIGS. 1, 5 and 6) slip over the output cams 412, 414 and are then accelerated with a comparatively large torque against the output cams 414 and 412 and execute a rotary impact against them.

In the reversing operation of the power tool 100 of FIG. 1, the normal operation and the impact operation done in a similar manner, so here is omitted for the purpose of scarcity of the description on a detailed description of the reverse ierbetriebs. In addition, it should be noted that the operation of a V-slot rotary impact mechanism in principle from the state of

Technique is known, so here is a further description of the operation of the percussion 200 is also omitted.

FIG. 3 shows the cup-shaped drive body 300 of FIG. 2 with the opening 305 formed at the axial end 352 and the cup bottom-like wall 350 formed at the opposite axial end 351 provided with the opening 360. FIG. 3 illustrates the V-groove 330 formed on the inner wall 320 and the counter-fastening device 340 provided in the region of the opening 305.

FIG. 4 shows the output shaft 400 of FIG. 2 with the shaft body 250 and the tool receptacle 450 formed by way of example as an octagonal internal receptacle 455. FIG. 4 illustrates the exemplary lateral output cams 412, 414 formed on the output shaft 400 and the annular shoulder 255. The output cams 412, 414 are exemplified as substantially rectangular, radial Extensions to the output shaft 400 molded, and thus integrally connected thereto, and have illustratively rounded, outer corners.

FIG. 5 shows the striking body 500 of FIG. 2 with the exemplary drive noses 512, 514 of FIG. 1. These are preferably formed on the impact body 500, for B. integrally formed, and thus integrally connected to the impactor 500. Illustratively, the drive cams 512, 514 are designed as prism-like projections oriented in the axial direction of the impact body 500, with approximately trapezoidal base surfaces whose radially inner and outer sides aligned parallel to one another and adapting to the outer circumference of the cylindrical one

Impact body 500 are slightly rounded. According to one embodiment, the drive cams 512, 514 are formed as described above for strikingly driving the output cams 412, 414 of the output shaft 400 of FIG. 4 in the percussion mode of the hand tool 100 of FIG. 1 and the mechanical percussion 200 of FIG. 2, respectively.

Furthermore, Fig. 5 illustrates an exemplary embodiment of the recesses 530, 535. These have illustratively provided with rounded corners, approximately cottage-shaped cross-section.

FIG. 6 shows the percussion mechanism 200 and the transmission 1 18 of FIG. 2 without the percussion mechanism housing 220 of FIG. 2. The cup-shaped drive body 300 is shown in a transparent representation only in sections with its cup bottom-like wall 350 and the V-groove 335 to exemplify an interaction of V-groove 335, steel ball 295 and recess 535.

Furthermore, Fig. 6 illustrates the interior 560 of the impactor 500, through which the spring element 242 abuts against the bottom wall 550, to act on the impactor 500 in the direction of the transmission 1 18. In addition, FIG. 6 illustrates the annular shoulder 255 formed on the shaft body 250 of the output shaft 400.

Claims

Powered hand tool (100) having a mechanical percussion mechanism (200) which has a striker (500) provided with at least one drive cam (512, 514) and an output shaft (400) provided with at least one output cam (412, 414) which is provided with a tool holder (450) for receiving a tool (140) is connected, wherein the drive cam (512, 514) for the striking drive of the output cam (412, 414) in the impact mode of the mechanical impact mechanism (200) is formed, characterized in that the impact body (500 ) is preceded by the drive cam (512, 514) in a direction away from the tool holder (450) axial direction (244) of the output shaft (400) the output cam (412, 414).

Powered hand tool according to claim 1, characterized in that the output shaft (400) of a pot-like drive body (300) can be driven, which surrounds the output shaft (400) at least partially and forms a cavity (310), in which the impactor (500) axially displaceable is arranged on the output shaft (400).

Hand tool according to claim 2, characterized in that the impactor (500) of a in the cavity (310) arranged spring element (242) in the direction of the output cam (412, 414) is acted upon, the direction of the output cam (414, 414) of a from the tool holder (450) facing away axial direction (244) of the output shaft (400).

Powered hand tool according to claim 2 or 3, characterized in that the spring element (242) is a compression spring.

Hand tool according to one of the preceding claims, characterized in that a transmission (1 18) for driving a drive limb (125) is provided, which is non-rotatably connected to the drive body (300).

Powered hand tool according to claim 5, characterized in that the transmission (118) is designed as a planetary gear, wherein a planet carrier (207) of the planetary gear, the drive member (125) is formed.

Powered hand tool according to one of the preceding claims, characterized in that the impactor (500) via at least one steel ball (290, 295) on the drive body (300) is supported.

Powered hand tool according to claim 7, characterized in that the drive body (300) has an inner wall (320) on which at least one groove-like recess (330, 335) for guiding the at least one steel ball (290, 295) is formed.

Powered hand tool according to claim 8, characterized in that the striking body (500) has an outer wall (510) on which at least one recess (530, 535) for supporting the at least one steel ball (290, 295) is formed.

Powered hand tool according to claim 9, characterized in that the at least one steel ball (290, 295) in the impact mode of the mechanical percussion (200) in the groove-like recess (330, 335) of the drive body (300) and the recess (530, 535) of the impactor (500) is movable to allow a rotation of the impactor (500) relative to the output shaft (400) and relative to the drive body (300).

Mechanical percussion mechanism (200) for a hand tool (100), comprising a striker (500) provided with at least one drive cam (512, 514) and an output shaft (400) provided with at least one output cam (412, 414), which is provided with a tool receptacle (400). 450) for receiving a tool (140) is connected, wherein the drive cam (512, 514) for the striking drive of the output cam (412, 414) in the impact mode of the mechanical impact mechanism (200) is formed, characterized in that the impact body (500) with the drive cams (512, 514) in an axial direction (244) facing away from the tool holder (450) of the output shaft (400) the output cam (412, 414) is upstream.