EP2576145A1

EP2576145A1 - Portable power tool with a mechanical percussion mechanism

Info

Publication number: EP2576145A1
Application number: EP11721277.9A
Authority: EP
Inventors: Peng Eng Lin; Sim Teik Yeoh; Chuan Cheong Yew; Daniel Brogli
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-06-01
Filing date: 2011-05-12
Publication date: 2013-04-10
Also published as: WO2011151145A1; CN102905852A; DE102010029559A1

Abstract

In a portable power tool (100) with a mechanical percussion mechanism (122) which is provided for percussive driving of an insertable tool (140) and has a percussion body (225), which is acted upon in the direction of the insertable tool (140) by a compression spring (228) and is connected to an associated drive shaft (120) for conjoint rotation and is mounted in an axially displaceable manner on the drive shaft (120), wherein the compression spring (228) bears at the end (227) thereof which faces away from the percussion body (225) against a washer (240), the washer (240) is mounted in an axially displaceable and rotatable manner on the drive shaft (120).

Description

description

title

Hand tool with a mechanical percussion prior art

The present invention relates to a hand tool with a provided for a beating drive an insert tool mechanical percussion having acted upon by a compression spring in the direction of the inserting impactor, which is rotatably connected to an associated drive shaft and axially slidably mounted on the drive shaft, said Compressive spring bears against a washer at its end facing away from the impactor body. From the prior art, such, designed as a rotary impact wrench hand tool is known, which has a mechanical percussion for a beating drive an insert tool. This mechanical percussion mechanism has an impact body which is connected in a rotationally fixed manner to an associated drive shaft of the handheld power tool and is mounted so as to be axially displaceable on the drive shaft. The impactor is acted upon with an associated compression spring in the direction of the insert tool.

A disadvantage of the prior art is that in no-load operation of the power tool, ie in an operating mode in which no impact generation is required, the striker is rotated with the drive shaft, while the compression spring in the direction of rotation of the drive shaft remains substantially immobile, ie not is turned. This causes due to friction occurring here unwanted vibrations in the power tool, which can lead to a significant noise and thus loss of comfort when using the power tool. Disclosure of the invention

An object of the invention is therefore to provide a new hand tool with a mechanical striking mechanism, in which at least a reduction of the noises generated by the impact mechanism in no-load operation is made possible.

This problem is solved by a hand tool with a provided for a beating drive an insert tool mechanical percussion, which has acted upon by a compression spring in the direction of the inserting impactor, which is rotatably connected to an associated drive shaft and axially slidably mounted on the drive shaft. The compression spring abuts against a washer at its end facing away from the impactor body. The washer is axially displaceable and rotatably mounted on the drive shaft.

The invention thus makes it possible to provide a hand tool with a mechanical impact mechanism, in which the washer and thus the compression spring in the no-load operation of the power tool can rotate with the drive shaft, so that no friction can occur between compression spring and washer and thus unwanted vibration and a resulting undesirable Noise development can be reduced at least.

According to one embodiment, the washer has a disk body, on which an annular groove is formed, in which the direction away from the impactor end of the compression spring is arranged.

Thus, a secure and stable fixation of the compression spring on the washer can be achieved.

The annular groove of the disk body preferably has a beveled in the direction of the insert tool ring collar in a radially away from the drive shaft direction.

Thus, a radial displacement of the compression spring relative to the drive shaft can be prevented in a simple manner. Reinforcement struts are preferably formed on the disk body.

Thus, a stable and reliable disk body can be provided.

According to one embodiment, an attenuator is disposed between the washer and the striker.

The invention thus enables a safe damping of axial movements of the impactor in a Schlagerzeugung.

The washer is preferably formed by plastic injection to the direction away from the impactor end of the compression spring.

Thus, in a simple manner a simultaneous rotation of compression spring and washer in the no-load operation of the power tool can be achieved.

According to one embodiment, the striker has an annular groove facing the compression spring, in which an end of the compression spring facing the striker is arranged.

Thus, a secure and stable fixation of the compression spring can be achieved on the impact body.

In the annular groove of the impactor a pressure ball bearing is preferably arranged. The impactor facing the end of the compression spring is preferably against the thrust ball bearing.

Thus, a twisting of the impactor relative to the compression spring can be made possible in a simple manner in a Schlaßzeugung by the percussion.

Between the thrust ball bearing and the impactor facing the end of the compression spring an annular disc is preferably arranged. Thus, a uniform load of the thrust ball bearing can be achieved by the compression spring in the axial direction.

The problem mentioned at the outset is also solved by a mechanical hammer mechanism for the impact drive of an insertion tool of a hand tool, which has an impactor acted upon by a compression spring in the direction of the insertion tool, which is rotatably connected to a drive shaft associated with the power tool and axially slidably mounted on the drive shaft , The compression spring abuts against a washer at its end facing away from the impactor body. The washer is axially displaceable and rotatably mounted on the drive shaft.

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 shows a sectional view of a proximal section of the mechanical percussion mechanism of the hand tool of FIG. 1 according to one embodiment, FIG. 3 shows a perspective view of the washer of FIG. 2, FIG.

Fig. 4 is a plan view of a top and a side view of the washer of Fig. 3, Fig. 5 is a perspective view of a washer for the mechanical

Striking mechanism of Fig. 2 according to a further embodiment,

6 is a plan view of an upper side and a side view of the washer of FIG. 5, FIG. FIG. 7 is a sectional view of a distal portion of the mechanical percussion mechanism of the portable power tool of FIG. 1 according to an embodiment; and FIG

Fig. 8 is a perspective view of the thrust ball bearing of Fig. 7. Description of the embodiments

1 shows a hand tool 100 provided with a tool holder 150, which has a housing 110 having 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.

In the housing 1 10 a supplied by the battery pack 130 with electric, e- lektrischer drive motor 1 14, a transmission 1 18 and a mechanical hammer mechanism 122 are arranged. The drive motor 1 14 is z. B. via a manual switch 128 actuated, d. H. can be switched on and off, and can be any type of engine, eg. As an electronically commutated motor or a DC motor. Preferably, the drive motor 1 14 so electronically controlled or controlled that both a reversing operation, as well as specifications with respect to a desired rotational speed can be realized. The mode of operation and the design of a suitable drive motor are sufficiently known from the prior art, so that a detailed description of the description is omitted here for the purpose of conciseness of the description.

The drive motor 1 14 is connected via an associated motor shaft 1 16 to the transmission 1 18, which converts a rotation of the motor shaft 1 16 in a rotation of a provided between the transmission 1 18 and striking mechanism 122 drive shaft 120. This conversion is preferably such that the drive shaft 120 rotates relative to the motor shaft 116 with increased torque but reduced rotational speed. The drive motor 1 14 is illustratively arranged in a motor housing 1 15 and the transmission 1 18 in a transmission housing 1 19, wherein the transmission housing 1 19 and the motor housing 1 15 are arranged for example in the housing 1 10. The mechanical percussion mechanism 122 connected to the drive shaft 120 is an example of a rotary striking mechanism which generates sudden high-intensity angular momentum and acts on an output shaft 124, e.g. B. an output spindle transmits. The tool holder 150 is provided on the output shaft 124, which is preferably designed for receiving insert tools and, according to one embodiment, can be connected both to an insert tool 140 with external polygon coupling 142 and to an insert tool having an internally polygonal coupling , The insert tool 140 is exemplified as a screwdriver bit with the external polygon coupling 142, illustratively an octagonal coupling formed. Such a screwdriver bit is sufficient from the

State of the art known, so that here for the sake of scarcity of the description is dispensed with a detailed description.

It should be noted that the power tool 100 is exemplified as a cordless impact wrench. However, the present invention is not limited to cordless impact wrench, but rather can be found in different power tools application in which the mechanical percussion 122 is used to beat production, z. For example, in a percussion drill, etc., regardless of whether the power tool is net inde pendent with a battery pack or network-dependent operable.

FIG. 2 shows a distal portion of the transmission 1 18 of FIG. 1 arranged in the transmission housing 1 19 and a proximal portion of the mechanical impact mechanism 122 of FIG. 1 according to an embodiment. This is il- lustrativ arranged in a housing part 222 which on the transmission housing

1 19 is attached.

The transmission 1 18 is an example of a planetary gear and illustratively has a sun gear 209, at least one planetary gear 215, 217, a planet carrier or driver 218, as well as an axially and radially immovable in the transmission housing 1 19 arranged ring gear 206. The sun gear 209 is an example Bearing device 219 rotatably mounted on the drive shaft 120. The driver 218 is illustratively formed integrally with the drive shaft 120, z. B. molded on this. Alternatively, the driver 218 may be connected to the drive shaft 120 via a suitable connection device. The planetary gear 1 18 may be switchable between a plurality of stages according to an embodiment and is illustratively switchable between a first and a second stage, wherein the first stage of the sun gear 209, the at least one planetary gear 215, 217, the planet carrier 218 and the Ring gear 206 is formed. A second stage 21 1 is merely indicated for the purpose of scarcity and clarity of the drawing. It should be noted, however, that a person skilled in a suitable structure of a suitable planetary gear is well known, so that can be dispensed with a detailed description here.

In a distal portion of the transmission housing 1 19, a trained as a ball bearing bearing 234 for supporting the drive shaft 120 is arranged by way of example. It should be understood, however, that other types of bearings may be used within the scope of the present invention. For example, bearing 234 may alternatively be realized as a plain bearing, needle sleeve, roller bearing, or other type of rolling bearing.

According to one embodiment, a washer 240 associated with the mechanical percussion mechanism 122 is arranged on a distal end face 299 of the transmission housing 12, which has an opening 242 and is rotatably and axially displaceably mounted on the drive shaft 120 via this. In addition, a shock body 225 rotatably connected to the drive shaft 120 and axially slidably mounted on this. Between the impactor 225 and the washer 240 is an illustratively mounted on the drive shaft 120 damper 244 is arranged, and a drive shaft 120 embracing compression spring 228 for impact generation during operation of the power tool 100 of FIG. 1, as described below.

The compression spring 228 is located at its end facing away from the impactor 225 end

227 against the washer 240, wherein the washer 240 z. B. may be formed by plastic injection to the compression spring 228. Alternatively, the compression spring 228 and the washer 240 may be integrally formed. A the impactor 225 facing the end 226 of the compression spring

228 is disposed in the striker 225 as described below in FIG. 7. According to one embodiment, the compression spring 228 is supported on the washer 240 and acts on the striking body 225 in the distal direction, ie in the direction of the insertion tool 140 of FIG. 1, as indicated by an arrow 229. In the no-load operation of the hand tool 100 of FIG. 1, ie, if no impact generation is required, the striker 225 rotates in a distal end position shown in FIG. 2 with the drive shaft 120. The compression spring 228 rotates and, with this, the washer 240 at least substantially frictionless also with the drive shaft 120th

In a Schlagerzeugung the mechanical percussion mechanism 122 in operation of the power tool 100 of FIG. 1, the impactor body 225 against the force of the compression spring 228 axially in the proximal direction, d. H. in the direction of the washer 240 or opposite to the arrow 229, moved. Here, by the force exerted on the washer 240 of the compression spring 228 further rotation of the washer 240 and thus the compression spring 228 is suppressed, while the impactor 225 as described in Fig. 7 continues its rotation. In order to avoid an excessive axial displacement of the impactor 225, this is blocked in a predetermined proximal end position of the damping member 244 in the axial direction, wherein a striking of the impactor 225 is damped by the damping member 244. The impactor 225 is then sprung back to the generation of impact by the compression spring 228 back into the distal end position shown in FIG. Since the operation of a mechanical impact mechanism and the impact produced by such a striking mechanism are well known to those skilled in the art, is omitted here for the sake of brevity of the description to a detailed description.

Fig. 3 shows the washer 240 of Fig. 2 with the opening 242, which is exemplified approximately centrally. According to one embodiment, the washer 240 has a reinforcement struts 341, 342, 343, 344, 345 provided

Disk body 340, to which a substantially perpendicular thereto formed annular wall 346 is integrally formed so that disk body 340 and ring wall 346 are formed about the reverse pot-shaped. The annular wall 346 is provided with a radial extension 349, which in

2 in a direction radially pointing away from the drive shaft 120 approximately pa- extends parallel to the disk body 340 and on which an annular collar 348 is formed, which is tapered with respect to the radial extension 349 such that an annular groove 347 is formed between the annular wall 346 and the annular collar 348. After mounting the washer 240 in the power tool 100 of FIG. 1, this annular collar 348 is in the direction of the one shown in FIG

Insert tool 140 of Fig. 1 beveled. In the annular groove 347, the end facing away from the impactor 225 end 227 of the compression spring 228 is arranged in Fig. 2. FIG. 4 illustrates the reinforcing struts 341, 342, 343, 344, 345 provided on the disk body 340 and an angle 410 with which the annular collar 348 is bevelled by the radial extension 349.

FIGS. 5 and 6 show an exemplary alternative embodiment of a washer 500 for the mechanical percussion mechanism 122 of FIGS. 1 and 2. In contrast to the washer 240 of FIGS. 2 to 4, this does not have an annular collar 348.

FIG. 7 shows a distal section of the mechanical percussion mechanism 122 of FIGS. 1 and 2 according to one embodiment, with the impactor 225 mounted on the drive shaft 120, which is acted upon by the compression spring 228 in the direction of the output shaft 124. This is rotationally fixed to the drive shaft 120 via an output cam 724.

According to one embodiment, the impactor body 225 is cup-shaped, with an annular bottom portion 798, the output shaft 124 facing end face 730 rests against the output cam 724 in load-free operation of the power tool 100 of FIG. An inner, annular wall section 732 and an outer, annular wall section 734 are integrally formed on the bottom section 798 formed with a central opening 799, which form with the bottom section 798 a ring groove 736 facing the compression spring 228 in FIG.

In the annular groove 736, the impactor 225 facing the end 226 of the compression spring 228 is arranged, which illustratively rests against an annular disc 760, which may be attached to the compression spring 228 or formed on this. The compression spring 228 acts on the annular disc 760 in the direction of the bottom Section 798 and thus in the direction of the output cam 724 against an arranged in the annular groove 736 thrust ball bearing 750. This has an approximately U-shaped support ring 752 in which a plurality of balls 754, 756 are arranged. The annular disc 760 abuts against the carrier ring 752 and the balls 754, 756 thus against the bottom portion 798. It should be noted, however, that the annular disc 760 is used only to achieve an improved pressure distribution on the thrust ball bearing 750 and thus also an embodiment of the mechanical percussion 122 without the annular disc 760 is possible, in which the impactor 225 facing the end 226 of the compression spring 228 rests directly against the thrust ball bearing 750.

According to one embodiment, the thrust ball bearing 750 is designed to permit a rotation of the striking body 225 relative to the compression spring 228 when the impact mechanism 122 generates impact during operation of the power tool 100 of FIG. 1. As already described with reference to FIG. 2, in such impact generation, rotation of the pressure spring 228 is prevented, while the impactor body 225 continues its rotation or rotation about the drive shaft 120. In this case, the impactor body 225 also rotates relative to the thrust ball bearing 750, which is prevented by the force of the compression spring 228 from further rotation and whose balls 754, 756 thus perform a rolling movement in the annular groove 736. After the impact generation or in load-free operation of the power tool 100 of FIG. 1, the thrust ball bearing 750 rotates again with the compression spring 228, the annular disc 760 and the impactor body 225 until the next generation of whip.

FIG. 8 illustrates an exemplary embodiment of the thrust ball bearing 750 of FIG. 7. FIG. 8 illustrates a plurality of balls disposed in the approximately U-shaped carrier ring 752, of which only the balls 754, 756 are used for simplicity and clarity of the drawing Marked are. It should be noted, however, that the configuration of a suitable thrust ball bearing 750 is sufficiently well known to those skilled in the art, so that a detailed description is omitted here for the sake of brevity of the description.

Claims

claims

1 . Powered hand tool (100) having a mechanical percussion mechanism (122) provided for a striking drive of an insert tool (140), which has a striker (225) acted upon by a compression spring (228) in the direction of the insert tool (140), which is non-rotatable with an associated drive shaft (120) is connected and axially displaceably mounted on the drive shaft (120), wherein the compression spring (228) abuts against its end facing away from the impactor (225) end (227) against a washer (240), characterized in that the washer ( 240) is axially displaceable and rotatably mounted on the drive shaft (120).

2. Hand tool according to Claim 1, characterized in that the washer (240) has a disk body (340) on which an annular groove (347) is formed, in which the impactor (225) pioneering end (227) of the compression spring (228 ) is arranged.

3. Hand tool according to Claim 2, characterized in that the annular groove (347) of the disk body (340) in one of the drive shaft (120) radially pioneering direction in the direction of the insert tool (140) beveled annular collar (348).

4. Hand tool according to Claim 2 or 3, characterized in that on the disk body (340) reinforcing struts (341, 342, 343, 344, 345) are formed.

5. Hand tool according to one of the preceding claims, characterized in that between the washer (240) and the striker (225), an attenuator (244) is arranged.

6. Hand tool according to one of the preceding claims, characterized in that the washer (240) by Kunststoffsprit- zen to that of the impactor body (225) pioneering end (227) of the compression spring (228) is integrally formed.

Powered hand tool according to one of the preceding claims, characterized in that the impactor (225) has a compression spring (228) facing annular groove (736) in which the impactor (225) facing the end (226) of the compression spring (228) is arranged.

Hand tool according to claim 7, characterized in that in the annular groove (736) of the impactor (225) a thrust ball bearing (750) is arranged, wherein the impactor (225) facing the end (226) of the compression spring (228) against the thrust ball bearing (750 ) is present.

Powered hand tool according to claim 8, characterized in that between the thrust ball bearing (750) and the impact body (225) facing the end (226) of the compression spring (228) an annular disc (760) is arranged.

Mechanical percussion mechanism (122) for the impact drive of an insert tool (140) of a hand tool machine (100) which has a striker (225) acted upon by a compression spring (228) in the direction of the insert tool (140), which is rotationally fixed to one of the hand tool machine (100). associated drive shaft (120) is connected and axially displaceable on the drive shaft (120) is mounted, wherein the compression spring (228) abuts at its from the impact body (225) pioneering end (227) against a washer (240), characterized in that the Washer (240) is axially displaceable and rotatably mounted on the drive shaft (120).