GB2472890A

GB2472890A - Device for generating an additional effect in a hand-held power tool

Info

Publication number: GB2472890A
Application number: GB201011414A
Authority: GB
Inventors: Gerhard Meixner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2009-08-19
Filing date: 2010-07-06
Publication date: 2011-02-23
Also published as: DE102009028633A1; GB201011414D0

Abstract

The device for generating an additional effect 100 for a hand tool machine 10 includes a tool holder 18 disposed at least partially on a housing 12 for receiving a tool 20. A drive device 26 is disposed in the housing for driving the tool. The tool by means of a principal working direction 44 defines a principal axis 46 of the hand tool machine. The device includes a mass element (104A, Figure 2) which is mounted movably along an axis R1 relative to the housing, in particular is mounted rotatably about an axis of rotation R2 relative to the housing, and is eccentric relative to the axis R1 and/or R2. At least one driving means interacts with the drive device 26 to drive the mass element. The axis R1 and/or R2 is aligned at an angle WR differing from zero relative to the principal axis 46, in particular substantially at right angles to the principal axis.

Description

Description Title

Device for a hand tool machine and hand tool machine

Background art

The invention relates to a device for generating an additional effect for a hand tool machine according to the preamble of the independent claim.

From EP 1 223 010 a device for generating an additional effect is known. Here, by an additional effect is meant in particular a pulse, an impulse, a moment and/or a component of force, understood in addition to, in particular selectively in addition to a driving torque and/or a driving force of a drive of a tool of the hand tool machine. The device of EP 1 223 010 is configured in this case as a vibrating device. EP 1 223 010 describes a motor-driven hammer having a tool holder and an air cushion hammering mechanism that is formed in a cylinder to generate repeated striking pulses upon a tool insert accommodated in the tool holder. The vibrating device for generating an additional effect comprises an eccentric mass element, which may be fastened so as to rotate about the axis of the cylinder and may be driven in a rotational manner.

When using tools, in particular tools driven axially along a principal axis, as in the case of the hammer described in EP 1 223 010, increasing frictional forces between the tool and a workpiece may lead repeatedly to binding or even jamming of the tool in the workpiece. If the tool insert due to the occurrence of binding forces becomes stuck, then the additional effect generated by means of the device may contribute towards improved extrication of the tool.

In the case of the device of prior art, it has proved disadvantageous that only an additional effect lying substantially in a plane at right angles to the principal axis may be generated. It is further to be regarded as a drawback that the device is limited in its design for reasons relating to installation space.

Disclosure of the invention

Advantages of the invention The device according to the invention having the features of the main claim has the advantage that by virtue of the axis Rl and/or R2, along and/or about which the mass element of the device according to the invention is movable, being aligned at an angle WR differing from zero relative to the principal axis, an additional effect may be generated at a selectively adjustable angle by two components that are oriented in particular in, and at right angles to, the principal axis. It is further to be regarded as an advantage that the device according to the invention may be disposed optimally in terms of installation space in a housing of the hand tool machine.

According to the invention the device is used in this case at least to generate an additional effect, preferably a plurality of additional effects, in particular in a particularly advantageous manner a plurality of periodic additional effects. Here, by the principal axis is meant an axis that is defined by a principal working direction of the tool during machining of a workpiece. Here, by the principal working direction is meant in particular a direction, in which an advancing of the tool relative to the workpiece is generated and/or in which a removal of material occurs. The machining is preferably percussion machining such as for example chiselling, rotary machining such as for example drilling, and/or linear-sawing machining of the workpiece.

Advantageous developments and improvements of the features indicated in the main claim arise as a result of the measures outlined in the sub-claims.

A particularly economical version of a device according to the invention is achieved if the mass element is disposed on the driving means. It is particularly advantageous if the mass element is formed integrally with the driving means or is connected thereto.

Particularly effective versions of the device according to the invention are achieved if the mass element is of a multi-part construction, in particular comprises at least one fluid.

In a particularly flexible version of the device according to the invention, it is provided that the driving means is designed to be switchable relative to the drive device. On the housing an actuating means is further provided, by means of which the driving means may be switched back and forth between a state ZO uncoupled from the drive device and a state Z1 workingly connected to the drive device.

The effect achievable by such a development of the device according to the invention is in particular that a user of the hand tool machine may selectively activate or deactivate the device according to the invention.

In a preferred development of the device according to the invention, the drive device comprises a gear device, wherein the gear device comprises at least one gear shaft, which is not aligned parallel to the principal axis, and the driving means is disposed substantially parallel to said gear shaft.

In a particularly simple version of the device according to the invention, the driving means is disposed rotatably on the gear shaft.

A more flexible version of the device according to the invention is notable for the fact that the driving means is disposed on an additional shaft that is substantially parallel to the gear shaft. A particularly compact version is achieved in that said gear device comprises an input-side shaft, which is aligned at an angle WZ differing from zero, in particular substantially at right angles to the principal axis.

In a particularly advantageous further development of the device according to the invention, the driving means comprises an intermediate gear. In particular, by means of the intermediate gear a stepping-down or stepping-up of an input speed to a working speed of the mass element may be achieved.

In a further aspect of the invention, the invention relates to a hand tool machine having a housing and a tool holder disposed on the housing for receiving a tool. In the housing a drive device for driving the tool is disposed.

The tool in this case by means of a principal working direction defines a principal axis of the hand tool machine. The hand tool machine moreover comprises a device accordingto the invention for'generating an additional effect, whereby in an advantageous manner the tool, which occasionally during operation of the hand tool machine becomes stuck in a workpiece, may be extricated more easily.

In a further aspect of the invention, a device according to the invention for generating an additional effect is advantageously used to release a tool that has become stuck during operation.

Description of the drawings

Further advantages and improvements of the invention emerge from the illustrated embodiments described below.

The drawings show: Fig. 1 a diagrammatic side view of a hammer drill, as an example of a hand tool machine, Fig. 2 a partial section of a hammer drill having two variants of a first embodiment of the device according to the invention, Fig. 3 a partial section of a hammer drill having two variants of a second embodiment of the device according to the invention.

Description of the embodiments

Figure 1 shows a diagrammatic side view of a hammer drill lOasan example of a hand tool machine. The hammer drill comprises a housing 12 and a handle 14 disposed on the housing 12. The handle 14 may in this case be connected, in particularly resiliently, to the housing 12 or be formed integrally with the housing 12. On an opposite end face 16 of the housing 12 to the handle 14 a tool holder 18 is further provided. The tool holder 18 is disposed in particular rotatably on the housing 12. In alternative versions of a hand tool machine the tool holder 18 may in particular also be accommodated at least partially in the housing. The tool holder 18 is further used to receive a tool 20. The tool 20 has a longitudinal extent 22.

On an end region of the housing 12 remote from the handle 14 an additional handle 24 familiar to the person skilled in the art is further provided. The additional handle 24 is used for improved manipulability of the hammer drill 10.

In the housing 12 of the hammer drill 10 a drive device 26 is further accommodated. The drive device 26 comprises an input unit 28, a translation unit 30 and an output unit 32.

In the present example according to Figure 1 the input unit 28 is formed by a motor 34, in particular by an electric motor 35. The translation unit 30 is provided for translating a movement, in particular a rotational movement of the output unit 32, 34, 35 into a movement required for driving the tool 20. In the case of the hammer drill 10 described here, the translation unit 30 comprises a rotary drive gear 36 and an axial drive gear 38. The output unit 32 of the hammer drill 10 comprises a rotary output. 40 for rotary driving of the tool holder 18, which rotary output is workingly connected to the rotary drive gear 36, as well as a striking mechanism 42 for transmitting impact pulses to the tool 20, which striking mechanim 42 in turn is workingly connected to the axial drive gear 38.

During operation of the drive device 26 the tool 20 accommodated in the tool holder 18 is advanced in a principal working direction 44, which extends substantially parallel to the longitudinal extent 22, relative to a workpiece that is not represented here, in particular into the workpiece. The principal working direction 44 in this case defines a principal axis 46 of the hammer drill 10.

In the housing 12 of the hammer drill 10 a device 100 according to the invention for generating an additional effect is further disposed. For actuating the device 100 an actuating element 102 is further provided on the housing 12. In the event of the tool 20 becoming wedged or jammed in the course of machining of the workpiece, a user of the hammer drill 10 may set the device 100 in operation by actuating the actuating element 102. The additional effect generated by the device 100 is transmitted in particular by the drive device 26 in such a way to the tool 20 that the tool 20 may be released more easily from its wedged state.

Fig. 2 shows in a partial section of the hammer drill 10 two versions of a first embodiment of a device 100 according to the invention for generating an additional effect. In particular, Figure 2 shows the input unit 28 in the form of an electric motor 35 with a motor shaft 48.

The motor shaft 48 on an end remote from the electric motor has a pinion 50. Via the pinion 50 of the motor shaft 48 both the axial drive gear 38 and the rotary drive gear 36 may be driven.

The first variant 100A of the device 100 according to the invention is disposed according to Figure 2 on the rotary drive gear 36. The rotary drive gear 36 in this case comprises a first spur gear 52, which meshes with the pinion 50 and is disposed rotatably on a first gear shaft 53 in the housing. The gear shaft 53 is aligned substantially at right angles to the principal axis 46.

The spur gear 52 in the present example is connected in a rotationally fixed manner to a bevel gear 54. However, hammer drills, in which an overload safety clutch is disposed between the spur gear 52 and the bevel gear 54, are also known and, in such hammer drills too, the device 100A may be used advantageously and in accordance with the invention. The bevel gear 54 in turn meshes with a bevel gear 56, which is connected in a rotationally fixed manner to the rotary output 40. In the present example the rotary output 40 is configured in particular as a hammer tube 56.

On a shaft 76 of the rotary drive gear 36 a rotatably mounted mass element 104A is disposed. An axis of rotation of the shaft 76 at the same time forms the axis R2 of the device bOA. The mass element lO4A in the present case takes the form of an eccentric mass 2OGA. Here, by an eccentric mass 106A is meant in particular a mass body having a mass distribution that is not symmetrical to an axis of rotation 108A. In a preferred manner the mass distribution of the eccentric mass 106A is concentrated substantially at one side of the mass body. At an end face 11OA of the eccentric mass 106A a tooth system 112A is provided. Atooth system 114A thatis complementary to this tooth system 112A is provided on an end face 116A of the spur gear 52 facing the eccentric mass 106A. The eccentric mass 106A is disposed in such an axially displaceable manner on the shaft 76 that the tooth systems 112A and 114A may be brought into congruence to form a drive of the eccentric mass 106A. The tooth systems 112A and 114A therefore form the driving means 118A of the device bOA according to the invention. In a radial peripheral surface l2OA of the eccentric mass 106A a control groove l22A is further provided. A control pin 124A workingly connected to the actuating element 102A engages into this control groove 122A. In the present example according to Figure 2 the actuating element 102A takes the form of a rotary switch, wherein the control pin 124 takes the form of an eccentric pin. If the actuating element 102A is turned, the eccentric mass lO6A is displaced axially along the shaft 76.

On the housing 12 a detent element l26A is further provided. In an opposite end face of the eccentric mass 106A to the end face 11OA the eccentric mass 106A has detent recesses 128A. If the eccentric mass 106A is displaced by means of the control pin 124A axially along the shaft 76 in the direction of the housing 12, the detent element 126A engages into one of the detent recesses 128A.

The eccentric mass 106A is therefore connected in a rotationally fixed manner to the housing 12. The result is therefore an uncoupled state ZO, in which the tooth systems 112A, ll4A of the driving means 118A are moved apart from one another and the eccentric mass lO6A is not drivable by the driving means 118A. If, on the other hand, the eccentric mass lO6A is displaced by means of the control pin 124A axially in the direction of the spur gear 52, the tooth systems 112A, 114A of the driving means 118A come into engagement and the device 100A according to the invention, in particular the drive device, is switched to a Figure 2 further shows an alternative variant 100B of a device 100 according to the invention that is disposed on the axial drive gear 38.

The axial drive gear 38 likewise comprises a spur gear 60, which meshes with the pinion 50. The spur gear 60 in the present example according to Figure 2 has a sleeve-like receiving region 62, in which a pivot bearing 64 is disposed around a bearing extension 66 provided on the housing 12. The bearing extension 66 in this case forms a second gear shaft 61 and corresponds to the axis R2 of the variant 100B of the device according to the invention. On the spur gear 60 an eccentric pin 68 is further provided for driving a connecting rod 70 of the axial drive gear 38.

The connecting rod 70 in this case drives a piston unit 72 of a striking mechanism 42 in the form of air cushion striking mechanism 74. Such striking mechanisms 42 are sufficiently known and are not described in detail here.

In the present example, the axial drive gear 38 therefore forms a striking mechanism drive gear.

The device 1008 according to the invention is disposed in a gear train of the axial drive gear 38. In this case, the eccentric mass lO6B of the device 100B is disposed in a rotatable and axially displaceable manner on a cylindrical lateral surface 78 of the sleeve-like receiving region 62 of the spur gear 60. Like the design variant 100A already described above, this design variant 100B also comprises corresponding tooth systems 112B, 114B on the eccentric mass 106B and the spur gear 60 respectively. As the design variant 100B is structurally no different from the design variant 100A, reference is made to the description of the design variant 100A.

If the eccentric mass 106A, 106B is transferred by the respective actuating element lO2A, 102B into the workingly connected state Zi, then the rotary drive of the eccentric mass 106A, 106B gives rise to a component of force rotating about the shaft 76 and/or 66. This component of force is transmitted via the housing 12 and in particular the output unit 32 to the tool 20. A tool 20 that has become jammed in a workpiece therefore experiences force influences having alternating directional components, which may promote an extrication of the jammed tool 20 from the workpiece.

Figure 3 shows a second embodiment of a device according to the invention in two variants 100C, 100D. In its basic construction the hammer drill 10 of Figure 3 does not differ substantially from the version already described in Figure 2, to the description of which reference is made at this point. Only the essential differences of the device 100C, 100B according to the invention are represented below.

Compared to the design variants bOA, 100B already described, the variant 100C of the device 100 according to the invention has its own additional shaft 130C. The additional shaft 1300 is accommodated in the housing 12 of the hammer drill 10 so as to be rotatable and at least to a limited extent axially displaceable along an axis of rotation 131C, which in this case may also be referred to as axis R2. A mass element 1040 in the form of eccentric mass 1060 of the device 100C according to the invention is disposed on one end of the additional shaft 1300, in particular is connected in a rotationally fixed manner to the additional shaft 1300. A tooth system 1120 is disposed on a peripheral surface 1200 of the eccentric mass 1060 so that the tooth system ll2C may mesh directly with spur teeth of the spur gear 52. By means of the actuating mechanism already described above, the eccentric mass 1060 together with the additional shaft 1300 may be switched back and forth between the uncoupled state ZO and the state Zi workingly connected to the drive device 26, in particular to the spur gear 52. As the variant 1000 of the device 100 according to the invention in its function does not differ substantially from the embodiments 100A, 1008 already described above, reference is made to the

description of these embodiments bOA, bOB.

Like the variant 1008 of the first embodiment of the device according to the invention, it is also possible in a variant 100D to dispose the device 1003 of the second embodiment of the invention in the train of the axial drive gear 38. This variant is denoted in Figure 3 by the reference character 100D. In its construction and function this variant 100D corresponds to the variant 1000 just described, so that reference may be made to the description of the variant 1000.

Besides the embodiments and design variants described here, further modifications are known to the person skilled in the art. In particular, many different versions of an actuating mechanism are known to the person skilled in the art as variants or extensions of the rotary slide mechanism comprising the actuating element 102, the control pin 124 and the control groove 122 that is shown here, without thereby altering the character essential for the invention of the device 100.

Further advantageous possible developments of the device according to the invention are to be found by the person skilled in the art for example in the region of the driving means 118 where, instead of the tooth systems 112, 114 shown here, for example friction drive, wheel drives or similar known drive mechanisms may be used.

It may moreover be advantageous for the mass element 104, in particular the eccentric mass 106, to be of a multi-part construction. A particular advantage may arise if the mass element 104 is provided with a component comprising a fluid.

Contrary to the version shown here, it may also be advantageous for the driving means 118 and the mass element 104 not to be of an integral construction, in particular not to be connected directly to one another.

With regard to an adaptation of the efficiency of the device 100 shown here, it may in particular be advantageous for the driving means 118 to comprise an intermediate gear, by means of which the component of force may be adapted in accordance with the speed ratios.

Alternatively or additionally the driving means 118 may comprise an angular gear that allows an arrangement of the axis o rotation of the mass body 104 at an angle greater than 0° up to the 90° shown in the embodiments of Figs. 2 and 3 relative to the principal axis 46.

To the person skilled in the art, besides a hammer drill 10 described here, versions of hand tool machines that only a rotary drive gear 36 -as for example in a screwdriver or a drill -or only an axial drive gear 38 -as i.e. in a chisel hammer or a sabre-or compass saw -are moreover known, in which the device 100 according to the invention may be used advantageously, so that the presently discussed use of the device according to the invention in a hammer drill (10) is to be understood as merely by way of example.