OPERATING MODE SWITCH FOR SETTING AT LEAST ONE OPERATING MODE IN A HAND-HELD POWER TOOL

Abstract

An operating mode switch for setting at least one operating mode in a hand-held power tool, comprising an adjustment ring rotatable manually around its axis and movable into at least one rotational position which activates an operating mode, and a locking device controlled by the adjustment ring and engaging in the adjustment ring, the locking device being configured such that in the at least one rotational position of the adjustment ring it automatically falls into a locking position which locks the adjustment ring in position, while the engagement ring is engageable from the at least one rotational position by manually rotating the adjustment ring.

Description

CROSS-REFERENCE TO A RELATED APPLICATION

The invention described and claimed hereinbelow is also described in German Patent Application DE 102005059182.5 filed on Dec. 12, 2005. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention is based on an operating mode switch for setting at least one operating mode in a hand-held power tool, in particular for selectively turning the “impact drilling” mode on or off in an impact drill.

With a known impact drill with an operating mode switch for selecting several operating modes (DE 100 06 641 A1), the operating mode switch includes two adjustment or switching rings which are located next to each other on the machine housing and are designed such that one switching ring, in two consecutive setting positions, selects the “impact drilling on/off” mode, and the other switching ring selects the “drill” mode” and the “screw” mode, and, in the “screw” mode, the disengagement torque or rotational torque of a safety clutch is specified via several setting positions. A blocking or disengagement device is coupled with both switching rings, which blocks the safety clutch in the “impact drilling” and “drill” modes. The disengagement device is deactivated in the third setting position of the first setting ring for selecting the “screw” mode, and the disengagement torque or rotational torque of the safety clutch is determined by the coupling spring, the preload of which is adjustable using the second switching ring.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an operating mode switch for setting at least one operating mode in a hand-held power tool, which eliminates the disadvantages of the prior art.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in an operating mode switch for setting at least one operating mode in a hand-held power tool, comprising an adjustment ring rotatable manually around its axis and movable into at least one rotational position which activates an operating mode; and a locking device controlled by said adjustment ring and engaging in said adjustment ring, said locking device being configured such that in the at least one rotational position of said adjustment ring it automatically falls into a locking position which locks said adjustment ring in position, while said adjustment ring is engageable from said at least one rotational position by manually rotating said adjustment ring.

When the operating mode switch is designed in accordance with the present invention it has the advantage that the locking device ensures the functionality of the hand-held power tool in the selected operating mode—which is activated using the setting ring—despite vibrations, handling errors, and other external influences, e.g., accidental rotation of the setting ring caused by circumstances in the operating environment. This is particularly significant for the “impact drilling” mode, since considerable impact-related vibrations are produced in this case, which cause the unsecured setting ring to rotate, thereby resulting in malfunction.

According to an advantageous embodiment of the present invention, the locking device includes at least one recess located in a sliding track formed in the adjustment ring, and an axially displaceable, non-rotatably held locking element designed to at least partially engage in the recess in a form-fit manner and which bears against the sliding track with an axially directed spring force. This design of the locking device is simple and robust, and it ensures reliable locking quality.

According to an advantageous embodiment of the present invention, the locking element is designed as a sliding wedge which is acted upon by a compression spring and includes a wedge angle pointing toward the sliding track. This recess is triangular, with a triangular angle corresponding to the wedge angle. By adjusting the wedge angle of the sliding wedge and adapting the triangular angle of the triangular recess accordingly, it is possible to adapt the manual force required to disengage the locking device to the customer's preference and to attain an optimum between locking quality and ease of use.

The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view, in sections, of a hand-held power tool with an operating mode switch in accordance with the present embodiment, and

FIG. 2 shows a section of a schematized top view of the operating mode switch with locking device in accordance with the present embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With the hand-held power tool shown in an exploded view, in sections, in FIG. 1, it is possible to switch to three different operating modes, i.e., the “impact drilling on/off” mode, the “drill” mode, and the “screw” mode, using an operating mode switch composed of two adjustment rings. In the “screw” mode, it is possible to preselect various starting torques. If this torque is exceeded, a safety clutch is activated, and the screwing tool cannot be driven.

The section of the hand-held power tool shown in FIG. 1 shows a guide sleeve 11 which is fixedly connected with the front region of a machine housing (not shown here) which accommodates an electric motor and a gearbox. A tool spindle (not shown here) is rotatably supported in guide sleeve 11, and operating mode switch 10 is located on guide sleeve 11. Operating mode switch 10 includes a setting ring for the “drill” and “screw” modes—and only one threaded ring 13 is shown—and a setting ring 12 with which the “impact drilling” mode can be engaged and disengaged.

Setting ring 12 has a two-component design and is composed of a manually holdable outer ring 121 and an inner ring 122. Inner ring 122 is rotatably supported on guide sleeve 11 and is rotatably connected with outer ring 121. Rotatable threaded ring 13 bears against the inner surface of inner ring 122 and can be rotated using the setting ring (not shown here) for the “drill” and “screw” modes. Inner ring 122 has two control curves 14 on its front side. Only control curve 14 is shown in FIG. 1. Two control cams, which are not shown in FIG. 1, are positioned on both control curves 14 such that, when setting ring 12 is rotated into its “impact drilling” position, the control cams each run up onto a blocking element 15.

Both blocking elements 15 are guided on guide sleeve 11 in an axially displaceable manner and are pressed via compression springs 16 against control curve 14 of inner ring 122 and threaded ring 13. When the control cams run onto blocking elements 15, the latter are pushed back against the force of compression spring 16 and block the safety clutch in this position. In this rotational position of setting ring 12, an actuating unit—which is not shown here—switches on the impact mechanism.

To ensure reliable positioning and holding of setting ring 12 at least in its rotational position in which the “impact drilling” mode is selected, a locking device 17 controlled by setting ring 12 is provided, which engages in setting ring 12 and, in fact, in inner ring 122 of setting ring 12, and it designed such that, in the rotational position of setting ring 12 for the “impact drilling” mode, it automatically falls into a locking position which locks setting ring 12 in position, and the locking position can be disengaged by manually rotating setting ring 12 out of the rotational position for the “impact drilling” mode.

To this end, locking device 17 includes at least one recess 18 located in control curve 14 of inner ring 122, and an axially displaceable, non-rotatably held locking element 19 designed to at least partially engage in the at least one recess 18 in a form-fit manner and which bears against the control curve 14 with axially directed spring force. In the exemplary embodiment shown in FIGS. 1 and 2, locking element 19 is a sliding wedge 21 which is acted upon by a compression spring 20 and has a wedge angle which points toward setting ring 12. Sliding wedge 20 is held in an axially displaceble manner in a guide groove 22—which extends in the axial direction—on guide sleeve 11.

A blind hole 23 is formed in groove end 221 of guide groove 22 pointing away from setting ring 12. One end of compression spring 20 is preferably accommodated in a form-fit manner in blind hole 23. Compression spring 20 bears against hole base 231 of blind hole 23 and against the end of sliding wedge 21 facing away from the wedge angle. Compression spring 20 is slid onto a mounting peg 24 which projects out of the end of sliding wedge 21 facing away from the wedge angle. Recess 18 is designed triangular in shape with a triangle tip pointing in the axial direction, the triangle tip having a triangular angle which corresponds to the wedge angle of sliding wedge 21, so that sliding wedge 21 can engage in recess 18 via its wedge angle, at least partially, and in a form-fit manner.

If setting ring 12 is located in any rotational position in which it has switched off the impact mechanism for the “impact drilling” mode, sliding wedge 21 is pressed via its wedge angle by compression spring 20 against control curve 14 on inner ring 122. Setting ring 12 can be easily rotated in the circumferential direction, and it is only necessary to overcome the frictional force between the tip of sliding wedge 21 and control curve 14. If, when setting ring 12 is rotated manually, it reaches its rotational position in which it activates the impact mechanism, recess 18 reaches the region of sliding wedge 21, and the latter falls—via action of compression spring 20—into recess 18, thereby locking setting ring 12 relative to its rotation in the circumferential direction.

To switch off the “impact drilling” mode, setting ring 12 is rotated back manually. Due to the resultant rotational motion of inner ring 122, via one triangular surface of triangular recess 18, sliding wedge 21 is pushed back via its wedge flank against the force of compression spring 20 until the wedge tip of sliding wedge 21 rests against control curve 14 again. A greater amount of manual force is therefore required to disengage the “impact drilling” mode.

It is also possible, of course, to lock setting ring 12 in both rotational positions, i.e., also in the “impact drilling off” rotational position, using locking device 17. To this end, it is only necessary to provide an additional recess 25 (FIG. 1)—which is offset by an angle of rotation—in control curve 14 in inner ring 122.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in an operating mode switch for setting at least one operating mode in a hand-held power tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of reveal present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention.

Claims

1. An operating mode switch for setting at least one operating mode in a hand-held power tool, comprising an adjustment ring rotatable manually around its axis and movable into at least one rotational position which activates an operating mode; and a locking device controlled by said adjustment ring and engaging in said adjustment ring, said locking device being configured such that in the at least one rotational position of said adjustment ring it automatically falls into a locking position which locks said adjustment ring in position, while said adjustment ring is engageable from said at least one rotational position by manually rotating said adjustment ring.

2. An operating mode switch as defined in claim 1, wherein said locking device includes at least one recess located in a sliding track formed in said adjustment ring, and an axially displaceable non-rotatably held locking element configured to at least partially engage in said recess in a form-fit manner and which bears against said sliding track with an axially directed spring force.

3. An operating mode switch as defined in claim 2, wherein said locking element is configured as a sliding wedge; and further comprising a compression spring acting upon said sliding wedge, said sliding wedge having a wedge angle pointing toward said adjusting ring, said recess being configured triangular in shape with a triangular angle corresponding an angle of said wedge.

4. An operating mode switch as defined in claim 3; and further comprising a mounting peg which projects axially from an end of said sliding wedge facing away from said wedge angle, and a compression spring being slid onto said mounting pad and bearing, with preload, against said end of said sliding wedge via one spring end and also bearing via another spring end against a spring support located in an axial distance away from said mounting peg.

5. An operating mode switch as defined in claim 4; and further comprising a guide sleeve, said adjustment ring being rotatably seated on said guide sleeve, said sliding wedge being accommodated in a guide groove which extends in an axial direction in said guide sleeve.

6. An operating mode switch as defined in claim 5, wherein said groove has a closed groove end pointing away from said adjusting ring and provided with a blind hole which accommodates one end of said compression spring, while a spring stop is formed by a hole base of said blind hole.

7. An operating mode switch as defined in claim 1, wherein said adjustment ring has a first rotational position for an “impact drilling mode on” operating mode, and a second rotational position for an “impact drilling mode off” operating mode, said locking device being effective in at least said first rotational position.

8. An operating mode switch as defined in claim 1, wherein said adjustment ring has several rotational positions for activating particular operating modes, and said locking device is effective in every one of said rotational positions.

9. An operating mode switch as defined in claim 1, wherein said adjustment ring includes a manually holdable outer ring and an inner ring which is rigidly coupled with said outer ring and is provided with a sliding track.

10. An operating mode switch as defined in claim 9, wherein said sliding track is formed by a control curve for actuating blocking elements for a safety switch.