GB2433224A

GB2433224A - Function selector switch

Info

Publication number: GB2433224A
Application number: GB0624678A
Authority: GB
Inventors: Bruno Aeberhard; Felix Buehlmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-12-12
Filing date: 2006-12-11
Publication date: 2007-06-20
Anticipated expiration: 2026-12-11
Also published as: CN1983486B; GB0624678D0; US20070163793A1; DE102005059182A1; CN1983486A; GB2433224B

Abstract

A function selector switch for setting at least one function in a hand-held machine tool, comprises a setting ring 12 that can be rotated manually about its axis and transferred into at least one torsional position in order to activate a function. A locking device (17, fig 2), which is controlled by the setting ring, acts upon the setting ring for the purpose of holding it in its selected position. The locking device is constructed in such a way that it can automatically drop into a locking position which arrests the setting ring, and can be cancelled again by manually twisting the setting ring out of the torsional position. The machine tool may be one that is capable of drilling, impact drilling, and screwdriving.

Description

ROBERT BOSCH GMBH, 70442 Stuttgart Function selector switch for setting

at least one function in a hand-held machine tool

Prior art

The starting point of the invention is a function selector switch in accordance with the pre-characterising clause of claim 1, for setting at least one function in a hand-held machine tool, in particular for selectively switching the "impact drilling" function on and off in an impact drilling machine.

In a known impact drilling machine having a function selector switch for calling up a number of operating modes (DE 100 06 641 Al), said function selector switch has two adjusting or change-over rings which are disposed side by side on the housing of the machine and are constructed in such a way that one change-over ring calls up the "impact drilling on/off" operating mode in two successive adjusting positions, and the other change-over ring calls up the "drilling" operating mode and the "screwing" operating mode and, in the "screwing" operating mode, predetermines the over-latching or torsional moment of an over-latching clutch via a number of adjusting positions. Also coupled to the two change-over rings is an inhibiting or disengaging device which inhibits the over-latching clutch in the "impact drilling" arid "drilling" operating modes.

In the third adjusting position of the first adjusting ring for calling up the "screwing" operating mode, the disengaging device is deactivated and the over-latching or torsional moment of the over- latching clutch is determined by the clutch spring, the initial tension of which can be set up by means of the second change-over ring.

Advantages of the invention The function selector switch according to the invention having the features in claim 1 has the advantage that the locking device secures the functioning of the hand- held machine tool in the function which has been selected and activated by means of the setting ring, against vibrations, mistakes in handling or other external influences, for example against unintentional twisting of the setting ring as a result of effects emanating from the operating environment. This is of particular importance, particularly for the "impact drilling" function, since in the latter case considerable impact vibrations occur which lead to twisting of the unsecured setting ring and, thereby, to malfunctioning.

Advantageous further developments of, and improvements to, the function selector switch indicated in claim 1 are possible by means of the measures set out in the other claims.

According to one advantageous form of embodiment of the invention, the locking device has a clearance which is disposed in a slide-way constructed on the setting ring, and an axially displaceable locking element which is held in a non-rotatable manner, is constructed for at least partial, form-locking penetration into said clearance, and rests, with axially directed spring force, against said slide-way. This constructional realisation of the locking device is simple in design and robust and has a reliable locking quality.

According to one advantageous form of embodiment of the invention, the locking member is constructed as a sliding wedge which is acted upon by a compression spring and has a wedging angle which points towards the slide-way. The clearance is of triangular design with an angle of the triangle which corresponds to the wedging angle. By setting the wedging angle of the sliding wedge and suitably adapting the triangular angle of the triangular clearance, the manual force which has to be applied in order to unlock the locking device can be adapted to the customer's wishes and an optimum can be achieved between the locking quality and ease of operation.

Drawings The invention is described in greater detail below with the aid of an exemplified embodiment which is represented in the drawings, in which: fig. 1 shows part of an exploded representation of a hand-held machine tool having a function selector switch; and fig. 2 shows part of a schematised plan view of the function selector switch having the locking device.

Description of the exemplified embodiment

With the hand-held machine tool, part of which is shown in an exploded representation in fig. 1, it is possible to switch over, by means of a function selector switch consisting of two setting rings, into three different functions, namely the "impact drilling on/off" function, the "drilling" function and the "screwing" function, it being possible to preselect different quantities of starting torque in the "screwing" function. If this torque is exceeded, an over-latching clutch comes into operation and the screwing tool ceases to be driven.

The hand-held machine tool, part of which is represented in fig. 1, exhibits a guide bush 11 which is fixedly connected to the front region of a machine housing (not represented here) which receives an electric motor and a gear unit. A tool spindle (not represented here) is rotatably mounted in the guide bush 11, and the function selector switch 10 is disposed on said guide bush 11. Said function selector switch 10 has a setting ring for the "drilling" and "screwing" functions, of which ring only a threaded ring 13 is represented, and a setting ring 12 by means of which the "impact drilling" function can be engaged and disengaged again. Said setting ring 12 is constructed in two parts and consists of a manually grippable outer ring 121 and an inner ring 122. Said inner ring 122 is rotatably mounted on the guide bush 11 and connected in a torsion-proof manner to the outer ring 121. The rotationally revolving threaded ring 13, which can be twisted, via the setting ring which is not represented here, for the "drilling" and "screwing" functions, is supported on the inner face of the inner ring 122. on its end face, said inner ring 122 carries two radial cams 14, of which only one radial cam 14 can be seen in fig. 1. Two peripheral cams, which cannot be seen in fig. 1, are positioned on the two radial cams 14 in such a way that, when the setting ring 12 is rotated into its "impact drilling" adjusting position, said peripheral cams each run up onto an inhibiting element 15.

The two inhibiting elements 15 are guided in an axially displaceable manner on the guide bush 11 and pressed, by compression springs 16, against the radial cam 14 on the inner ring 122 and also on the threaded ring 13. As the peripheral cams run up onto the inhibiting elements 15, the latter are pushed back against the force of the compression spring 16 and, in this position, inhibit the over-latching clutch. Furthermore, in this torsional position of the setting ring 12, an actuating unit, which is not represented here, looks after the switching-on of the striking mechanism.

In order to guarantee reliable positioning and holding of the setting ring 12, at least n its torsional position in which the "impact drilling" function is set, a locking device 17 controlled by the setting ring 12 is provided, which acts upon said setting ring 12, that is to say on the inner ring 122 of the latter, and is constructed in such a way that it automatically drops into a locking position which arrests the setting ring 12 when the latter is in the torsional position for the "impact drilling" function, and that said locking position can be cancelled again by manually twisting the setting ring 12 out of said torsional position for the "impact drilling" function. For this purpose, the locking device 17 has at least one clearance 18 which is disposed in the radial cam 14 on the inner ring 122, and an axially displaceable locking element 19 which is held in a non-rotatable manner, is constructed for at least partial, form-locking penetration into the at least one clearance 18, and rests, with axially directed spring force, against said radial cam 14. In the exemplified embodiment in figs. 1 and 2, the locking element 19 is a sliding wedge 21 which is acted upon by a compression spring 20 and has a wedging angle which points towards the setting ring 12. Said sliding wedge 21 is held in an axially displaceable manner on the guide bush 11 in a guide groove 22 which extends in the axial direction. A blind hole 23 is constructed on that closed end 221 of the guide groove 22 which points away from the setting ring 12.

One end of the compression spring 20 is received, preferably in a form-locking manner, in said blind hole 23.

Said compression spring 20 is supported, at one end, on the base 231 of the blind hole 23 and, at the other end, on that end of the sliding wedge 21 which faces away from the wedging angle. Said compression spring 20 is pushed onto a receiving peg 24 which projects from that end of the sliding wedge 21 which faces away from the wedging angle.

The clearance 18 is of triangular construction, with a tip which points in the axial direction and has an angle of the triangle which is adapted to the wedging angle of the sliding wedge 21, so that said sliding wedge 21 is able to at least partially penetrate into the clearance 18 with its wedging angle in a form-locking manner.

If the setting ring 12 is located in any torsional position in which it has switched off the striking mechanism for the "impact drilling" function, the sliding wedge 21 is pressed with its wedging angle against the radial cam 14 on the inner ring 122 by the compression spring 20. The setting ring 12 can be easily twisted in the peripheral direction, it being merely necessary to overcome the frictional force between the tip of the sliding wedge 21 and the radial cam 14. If, when the setting ring 12 is twisted manually, said ring passes into its torsional position in which it switches the striking mechanism into operation, the clearance 18 arrives in the region of the sliding wedge 21 and the latter drops into said clearance 18 under the action of the compression spring 20 and thus locks the setting ring 12 with respect to its rotational movement in the peripheral direction. For turning off the "impact drilling" function, the setting ring 12 must be manually turned back again. As a result of the rotational movement of the inner ring 122 which is thereby initiated, the sliding wedge 21 is pushed back, via its flank, over one face of the triangular clearance 18 against the force of the compression spring 20, until the tip of said sliding wedge 21 rests on the radial cam 14 again. An increased expenditure of manual force is therefore required in order to disengage the "impact drilling" function.

Naturally, it is possible to arrest the setting ring 12 in both torsional positions, that is to say in the "impact drilling off" position as well, by means of the locking device 17. For this purpose, it is merely necessary to provide another clearance 25, which is offset by an angle of rotation, in the radial cam 14 on the inner ring 122 (fig. 1)

Claims

ROBERT BOSCH GMBH, 70442 Stuttgart Claims 1. Function selector switch

for setting at least one function in a hand-held machine tool, said switch having a setting ring (12) which can be rotated manually about its axis and can be transferred into at least one torsional position which activates a function, characterised in that a locking device (F?) controlled by the setting ring (12) acts upon said setting ring (12) and is constructed in such a way that it automatically drops into a locking position which arrests the setting ring (12) when the latter is in the at least one torsional position, and that said locking position can be cancelled again by manually twisting the setting ring (12) out of the said torsional position.

2. Function selector switch according to claim 1, characterised in that the locking device (17) has at least one clearance (18) which is disposed in a slide-way constructed on the setting ring (12), and an axially displaceable locking element (19) which is held in a non- rotatable manner, is constructed for at least partial, form-locking penetration into said clearance (18), and rests, with axially directed spring force, against said slide-way.

3. Function selector switch according to claim 2, characterised in that the locking element (19) is a sliding wedge (21) which is acted upon by a compression spring (20) and has a wedging angle which points towards the setting ring (12), and that the clearance (18) is of triangular construction with an angle of the triangle which corresponds to the wedging angle.

4. Function selector switch according to claim 3, characterised in that the compression spring (20) is pushed onto a receiving peg (24) which projects axially on that end of the sliding wedge (21) which faces away from the wedging angle, and that said compression spring (20) rests, under pretensioning, against the end of the sliding wedge with one end, and against a spring-supporting system disposed at an axial distance from the receiving peg (24) with the other.

5. Function selector switch according to claim 3 or 4, characterised in that the setting ring (12) is seated in a rotatable manner on a guide bush (11), and that the sliding wedge (21) is received in a guide groove (22), which extends in the axial direction, in said guide bush (11) 6. Function selector switch according to claim 5, characterised in that a blind hole (23) for receiving one end of the compression spring (20) is constructed in that closed end (221) of the guide groove (22) which points away from the setting ring (12), and that the stop for the spring is formed by the base (231) of the blind hole (23) 7. Function selector switch according to one of claims 1 to 6, characterised in that the setting ring (12) has a first torsional position for the "impact drilling on" function and a second torsional position for the "impact drilling off" function, and that the locking device (17) is operative at least in the first torsional position.

8. Function selector switch according to one of claims 1 to 6, characterised in that the setting ring (12) has a number of torsional positions for activating one function in each case, and that the locking device (17) is operative in each torsional position.

9. Function selector switch according to one of claims 1 to 8, characterised in that the setting ring (12) has a manually grippable outer ring (121) and an inner ring (122) which is rigidly coupled to said outer ring (121), and that the slide-way is constructed on said inner ring (122).

10. Function selector switch according to one of claims 2 to 9, characterised in that the slide-way is formed by a radial cam (14) for actuating inhibiting elements (15) for an over-latching clutch.

11. A function selector switch substantially as herein described with reference to the drawings.

12. A hand-held machine tool including a function selector switch according to any one of the preceding claims.