EP2213419B1 - Hand-held power tool with tensioning device for a tool - Google Patents

Description

The invention relates to a power-driven hand tool with a housing, with a work spindle for driving a tool, wherein the tool between a tool-side end of the work spindle and a fastener is fixed, with a displacement device with a pivotable about a pivot axis clamping lever for displacement of the fastener of a release position, in which the fastener is detachable from the work spindle, and a clamping position in which the fastener is biased against the work spindle by a spring, the work spindle having a spindle tube, which in its upper part by means of a bearing and in its lower part by means of a bearing is mounted in the housing, and wherein at the outer end of the spindle tube, the fastening device is arranged, which engages in an opening on the tool.

Such a power tool with a clamping device for manual clamping of a tool is from the WO 00 2005 102 605 A1 known.

According to the EP 1 517 050 A1 is a self-locking screw for clamping a tool on a power tool known.

In the known power tool of the clamping lever is provided with an eccentric, which cooperates with a pressure body, so that the clamping lever can not change abruptly from its release position to the clamping position.

Due to the interaction between an eccentric and a pressure body, however, only an insufficient adaptation of the pivoting movement during a transition from the release position into the tensioning position can be ensured. In other words, even in this solution, an abrupt turning of the clamping lever from the release position in the direction of the clamping position is not excluded, as soon as the clamping lever is pivoted by a certain amount and the eccentric moves along the pressure body.

A similar embodiment of a power tool with a movable work spindle is from the EP 1 180 416 A2 known. In this case, the clamping lever cooperates in its release position with a pressure piece which is formed on the work spindle. When the engine is turned on while the cocking lever is in its release position, the cocking lever gradually moves from its release position to the cocked position due to the transition from static friction to sliding friction.

A disadvantage of this arrangement is the friction between the pressure piece and the clamping lever, which adjusts when the motor is switched on and can lead to signs of wear.

From the EP 0 650 805 A1 Another power-driven hand tool is known in which the clamping lever is mechanically coupled by means of a shift rod so that the clamping lever is movable only when the engine is in the release position.

Here, the mechanical coupling by means of the shift rod is relatively expensive. In addition, it is not excluded even in this embodiment, that the clamping lever can move abruptly from its release position into the clamping position, which can lead to a risk of injury to the user.

Finally, out of the US 5,158,331 a biased locking element for a pivotable lever known.

Against this background, the present invention seeks to provide a power tool of the type mentioned, with easy handling, reliable attachment of the tool, which further allows easy replacement of the tool.

This object is achieved by a power-driven hand tool according to claim 1.

The object of the invention is completely solved in this way.

In accordance with the invention, the transition of the tensioning lever from the release position to the tensioning position can be influenced, in order to avoid a quick turning over of the tensioning lever. In this way, the handling is simplified, while the reliability of the attachment of the tool is maintained. A simple change of the tool is still possible.

For the purposes of this application is to be understood by release position that position of the displacement device in which the fastening element is moved in such a way that the tool is detachable. Accordingly, the clamping position is the position in which the displacement device and the fastening element are arranged such that the tool is securely clamped against the work spindle.

Since the inhibiting device has at least one elastic restraining element in the form of a metal spring and a counter-contour which is movable relative thereto, the force required to inhibit the pivoting movement of the tensioning lever can be applied in a controlled manner by simple geometrical configuration of the opposing contour depending on the respective relative position to the restraining element. The abrupt transition of the clamping lever between release and clamping position is prevented. The change of the tool is simplified.

In an advantageous embodiment of the invention, the mating contour is formed in a pivoting range of the clamping lever between release position and clamping position for non-positive cooperation with the inhibiting element.

In this way, the quick turning of the clamping lever between release position and clamping position can be prevented by a force is applied via frictional contact between the mating contour and the locking element, which inhibits the movement of the clamping lever between release position and clamping position. This simplifies the handling of the hand tool.

In an advantageous embodiment of the invention, the mating contour in the clamping position of the clamping lever on a detent position for the inhibitor.

In this way, the clamping position is additionally secured by the inhibiting element. On further elements for securing the clamping position of the clamping lever can be dispensed with, it results in a more cost-effective design of the hand tool.

Furthermore, can be effected by the interaction of the mating contour with the detent position with the restraining element in the clamping position of the clamping lever securing the clamping position without additional force input through the inhibitor. This can be made possible by the inhibiting element overcoming a dead center on the mating contour, in which the restraining element experiences maximum elastic deformation, and subsequently being extensively relaxed in a detent position. This locking position can only be left by again overcoming the dead center.

In this way, influences by the restraining element on the clamping position, in which the tool is clamped by means of the spring between the tool-side end of the work spindle and the fastening element, can be avoided. The reliable attachment of the tool will continue to be ensured.

According to a further embodiment of the invention, the counter contour is arranged on the clamping lever and the inhibiting element on the housing.

In this way, simplifies the structure of the hand tool, since it is possible to take into account the counter contour directly in the production of the clamping lever. This results in a cost-effective design of the hand tool.

In an expedient development of the invention, the mating contour is arranged on a circumferential region of the clamping lever radially offset from the pivot axis.

In this way, there is a small footprint of the inhibitor laterally of the clamping lever. The elements of the inhibiting device can be covered and protected in the release position or the clamping position of the clamping lever.

According to a further embodiment of the invention, the mating contour is arranged on a side surface of the clamping lever.

This can be advantageous in terms of production, e.g. can be demolded in molded tooling of the clamping lever, the counter contour and the contour for the pivot axis in a tool direction. Furthermore, there is a small footprint of the inhibiting device in the radial peripheral region of the clamping lever.

According to an alternative embodiment of the invention, the inhibiting element is arranged on the clamping lever and the mating contour on the housing.

By this measure, it can be effected that the mating contour is mounted directly on the housing in the manufacture of the housing. The structure of the hand tool can be simplified.

According to a further embodiment of the invention, the inhibiting element is arranged on the pivot axis.

In this way, the inhibiting element can be mounted on the pivot axis and secured axially. It may have additional elements for attaching the hemmelement be waived. As a result, a cost-effective, further simplified construction of the hand tool can be made possible.

It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

Fig. 1

eine erste Ausführung eines erfindungsgemäßen Handwerkzeuges mit einem Oszillationsantrieb im Bereich des Getriebekopfes in geschnittener Darstellung mit einer Position des Spannhebels zwischen Lösestellung und Spannstellung;

Fig. 2

das Handwerkzeug gemäß Fig. 1 in der Spannstellung;

Fig. 3

das Handwerkzeug gemäß Fig. 1 in der Lösestellung;

Fig. 4

einen Teilschnitt einer zweiten Ausführung eines erfindungsgemäßen Handwerkzeuges;

Fig. 5

einen Teilschnitt einer dritten Ausführung eines erfindungsgemäßen Handwerkzeuges;

Fig. 6

einen Teilschnitt durch das Handwerkzeug gemäß Fig. 5 längs der Linie VI-VI;

Fig. 7

eine vergrößerte Darstellung eines erfindungsgemäßen Hemmelements;

Fig. 8

einen Teilschnitt einer vierten Ausführung eines erfindungsgemäßen Handwerkzeuges;

Fig. 9

einen Teilschnitt durch das Handwerkzeug gemäß Fig. 8 längs der Linie IX-IX.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. Show it:

Fig. 1

a first embodiment of a hand tool according to the invention with an oscillating drive in the region of the gear head in a sectional view with a position of the clamping lever between release position and clamping position;

Fig. 2

the hand tool according to Fig. 1 in the clamping position;

Fig. 3

the hand tool according to Fig. 1 in the release position;

Fig. 4

a partial section of a second embodiment of a hand tool according to the invention;

Fig. 5

a partial section of a third embodiment of a hand tool according to the invention;

Fig. 6

a partial section through the hand tool according to Fig. 5 along the line VI-VI;

Fig. 7

an enlarged view of a Hemmelements invention;

Fig. 8

a partial section of a fourth embodiment of a hand tool according to the invention;

Fig. 9

a partial section through the hand tool according to Fig. 8 along the line IX-IX.

In Fig. 1 is an inventive power-driven hand tool shown cut in the region of its gear head and designated overall by the numeral 10. The hand tool 10 is an oscillating drive for oscillating driving a tool with a small pivot angle and high frequency about the longitudinal axis 35 of a work spindle 12. Such oscillatory drives are used to perform numerous special work, including the removal of motor vehicle windows by means of an oscillatingly driven knife Sawing with oscillating driven saw blades, grinding and much more. Alternatively, it could be an angle grinder with rotatably driven work spindle.

The work spindle 12 has a spindle tube 14, which is mounted in its upper region by means of a bearing 20 and in its lower region by means of a bearing 22 in the housing 16.

For fastening the tool 18 at the outer end of the spindle tube 14, a fastening device designated overall by 38 is provided, which engages in an opening in the tool 18. The fastening device 38 is further connected to the spindle tube 14 and clamped in the clamping position by a clamping shaft 44 against the work spindle 12 such that the tool 18 is clamped by a clamping sleeve 58 against the outer end of the spindle tube 14. To transmit the clamping forces, the inner flange 42 and the outer flange 40 are provided on the clamping sleeve 58 and on the clamping shank 44. The clamping sleeve 58 is arranged on the clamping shaft 44 and secured by a securing ring 45.

The clamping force required for clamping the tool 18 is applied via a spring 48, which is designed as a cup spring package. The spring 48 is arranged in the spindle tube 14, guided on a spring sleeve 49, which is secured axially in the spindle tube 14 by means of a securing element 52. The spring 48 generates a force along the extension of the clamping shaft 44, which is directed against a clamping sleeve 50. The clamping sleeve 50 has at its periphery cutouts in which clamping pieces 54 are guided along an inclined surface 51. Advantageously, over the circumference of the clamping sleeve 50 three or four cutouts with inclined surfaces 51 and clamping pieces 54 are provided at equal angular intervals to each other. In the region of the clamping sleeve 50, the clamping shaft 44 has a toothing 46. The clamping pieces 54 have a corresponding counter toothing 60. Due to the force exerted by the spring 48, the clamping sleeve 50 undergoes a displacement in the longitudinal direction of the clamping shank 44. The inclined surface 51 results in force components which are directed axially to the longitudinal axis 35 and radially to the longitudinal axis 35. The radial components cause a frictional connection in addition to the positive connection of the corresponding toothing 46 and the counter toothing 60. The axial component causes an axial displacement of the clamping pieces 54 and thereby also a displacement of the fastening device 38 in the direction of the lower end of the spindle tube 14. As a result, the clamping force on the clamping sleeve Transfer 58 and the tool 18 and the attachment secured non-positively.

The clamping pieces 54 have at their upper end holes 64, in which springs 62 are arranged. The springs 62 act together with a pressure piece 31, which is arranged longitudinally displaceably in the upper portion of the spindle tube 14.

The pressure piece 31 has a contact surface 30 at its upper end. The contact surface 30 cooperates with an eccentric 28, which is part of a generally designated 24 displacement device. The displacement device 24 is pivotally mounted on a pivot axis 32. The displacement device 24 has a clamping lever 26, via which the pivoting movement of the eccentric 28 is applied about the pivot axis 32.

In addition to the displacement device 24, an inhibiting device, generally designated 66, is arranged. The inhibiting device 66 has an inhibiting element 68 which cooperates with a mating contour 70 which is associated with the tensioning lever 26. The retarder 68, in the form of a bent leaf spring, is secured to the housing 16 by means of a fastener 72, in the form of a screw threaded into a thread 74.

In the Fig. 1 is an offset between the longitudinal axis 35 and the pivot axis 32 arranged perpendicular thereto recognizable. This offset and the configuration of the eccentric 28 in the illustrated position of the clamping lever 26, together with the force of the spring 48, which is transmitted by means of the clamping sleeve 50 on the pressure piece 31, a pivoting moment in the clockwise direction about the pivot axis 32. This pivoting torque supports pivoting of the clamping lever 26 from a release position into a clamping position. As a result, a reliable reliable clamping of the tool 18 is ensured. The panning happens very abruptly. In the in Fig. 1 shown position of the clamping lever 26, the restraining element 68 comes into contact with a mating contour 70 on the clamping lever 26. This causes an inhibiting force which inhibits the abrupt pivotal movement.

It is understood that the rapid turnover of the clamping lever 26 can also be effected by other circumstances, which do not correspond to the example shown here.

In Fig. 2 is the hand tool of the invention Fig. 1 in a clamping position, characterized by the new position of the clamping lever 26 ', shown and generally designated 10'. In the illustrated clamping position there is no contact between the eccentric 28 and the contact surface 30 of the pressure piece 31. Consequently, the tensioning lever 26 'must be guided on its pivoting track in order not to automatically move To perform pivoting movement. The mating contour 70 has a dead center, a point with a maximum distance from the pivot axis 32, which must overcome the inhibitor 68 when the clamping lever 26 is pivoted to the clamping position. It lies now, as in Fig. 2 shown, a detent position in which the inhibitor 68 is largely relaxed. When pivoting out of this detent position, the restraining element 68 must again overcome the dead center on the mating contour 70. Consequently, the tensioning lever 26 'is secured. In the clamping position of the clamping lever 26 ', the inhibiting device 66 is covered by the clamping lever 26' and thus not visible from the outside.

The hand tool off Fig. 1 is in Fig. 3 in a release position for releasing the tool, characterized by the position of the clamping lever 26 ", shown and designated 10 in total. The required to release the tool displacement of the pressure piece 31 is effected by contact of the contact surface 30 of the pressure piece 31 with the eccentric 28 in the region of its largest radial extent. The pressing piece 31 displaces the clamping sleeve 50 against the spring 48 in such a way that contact no longer exists between the clamping sleeve 50 and the clamping piece 54 along the inclined surface 51 (not shown here). Consequently, by pulling on the fastening device 38, the toothing 46 of the clamping shaft 44 axially disengage from the positive engagement with the counter teeth, the clamping pieces 54 are thereby displaced radially outward. The fastening device 38 can be removed from the opening of the spindle tube 14 and the tool 18 can be changed.

In Fig. 4 a second embodiment of a hand tool according to the invention is shown. The tensioning lever 26 is in turn in a pivoting position between the release position and the clamping position. The inhibiting device 66, provided with a designed as a bent leaf spring retainer 68 and a fastener 72 is disposed near the end face of the housing 16 of the hand tool at a radial distance from the pivot axis 32. In the release position of the tensioning lever 26, the inhibiting device 66 is covered by the tensioning lever 26. The counter contour 70 is in turn formed on a radially offset from the pivot axis 32 peripheral portion of the clamping lever 26, provided with by way of example a geometry for cooperation with the restraining element 68. In the position shown, the clamping lever 26, a frictional interaction between the locking element 68 and the mating contour 70, such that a rapid turning of the clamping lever 26 is inhibited by the release position in the clamping position.

A third embodiment of a hand tool according to the invention is in Fig. 5 and, as a section corresponding to the line VI-VI in Fig. 5 , in Fig. 6 shown. Again, the clamping lever 26 is in a pivotal position between release position and clamping position. The inhibiting device 66 again has an inhibiting element 68 designed as a curved leaf spring. The mating contour 70 is arranged along two side surfaces 33 and 34 of the tensioning lever 26, while the eccentric 28 is furthermore formed in a circumferential region of the tensioning lever 26 offset radially from the pivoting axis 32. The mating contour 70 is also designed here for position-dependent interaction with the inhibiting element. Locking positions for securing the position of the clamping lever 26 in different positions are in Fig. 5 and Fig. 6 characterized by depressions 71 on the side surfaces 33 and 34.

Fig. 7 shows an enlarged view of a Hemmelements invention 68. It is a curved leaf spring. The inhibiting element 68 has a bore 76 for passing through a fastening element 72. Furthermore, a front-side spring section 78 and two lateral spring sections 80 and 82 are provided. The end-side spring section 78 cooperates with a mating contour 70, which is formed on a radially offset to the pivot axis 32 peripheral region of the clamping lever 26. The lateral spring sections 80 and 82 engage in a mating contour 70, which is arranged on the side surfaces 33, 34 of the clamping lever 26. By means of the two lateral spring sections 80 and 82 and the end-side spring section 78, many effective surface pairings can be realized, whereby the inhibition of the pivoting movement can be made more pronounced and can be controlled in a more targeted manner. Alternatively, it is conceivable that, for example, the end-side spring portion 78 only serves the non-positive cooperation with the clamping lever 26 in a pivoting range between the release position and the clamping position, and the lateral spring portions 80 and 82 only to cooperate with locking positions on the Counter contour 70 to secure the position of the clamping position of the clamping lever 26 serve. In addition, the illustrated inhibiting element 68 has a positive locking element 84 for the positional orientation and the positional and anti-rotation lock on the housing 16.

A fourth embodiment of a hand tool according to the invention is in Fig. 8 and, as a section along the line IX-IX in Fig. 8 , in Fig. 9 shown. The tensioning lever 26 is also shown in a pivotal position between release position and tensioning position. The inhibiting element 68, designed as a bent wire spring, is arranged on the pivot axis 32. The inhibiting element 68 has an end region 86 for support on the housing 16. The restraining element 68 in turn comes into contact with a mating contour 70, which is formed on a radially offset from the pivot axis 32 peripheral region of the clamping lever 26. Again, a position-dependent interaction of the locking element 68 and the mating contour 70 is possible.

Claims (8)

1. A power-driven hand tool (10) comprising a housing (16), a work spindle (12) for driving a tool (18), which tool (18) can be located between a tool end of the work spindle (12) and a fixing mechanism (38), further comprising a displacing mechanism (24) with a clamping lever (26), adapted to pivot about a pivot axis (32) for displacing the fixing mechanism (38) between a releasing position, in which the fixing mechanism (38) can be released from the work spindle (12), and a clamping position in which the fixing mechanism (38) is clamped on the work spindle (12) by a spring (48), wherein the work spindle (12) comprises a spindle tube (14) which in its upper part is received by means of a bearing (20) and in its lower part by means of a bearing (22) within the housing (16) and wherein the fixing mechanism (38) is provided at the outer end of the spindle tube (14) and protrudes into an opening of the tool (18), characterized in that an impeding mechanism (66), interacting with the clamping lever (26), is provided for impeding the pivoting movement of the clamping lever (26) between the releasing position and the clamping position, and in that the impeding mechanism (66) comprises at least one elastic impeding element (68) configured as a metal spring and a counter-contour (70) cooperating therewith frictionally that can be moved relative to that element.
2. The hand tool (10) of claim 1, characterized in that the configuration of the counter-contour (70) in a pivoting zone of the clamping lever (26) between the releasing position and the clamping position is configured to ensure frictional engagement with the impeding element (68).
3. The hand tool (10) of any of the preceding claims, characterized in that the counter-contour (70) has a position of rest for the impeding element (68) in the clamping position of the clamping lever (26).
4. The hand tool (10) of any of the preceding claims, characterized in that the counter-contour (70) is provided on the clamping lever (26), the impeding element (68) on the housing (16).
5. The hand tool (10) of any of the preceding claims, characterized in that the counter-contour (70) is disposed on a circumferential area of the clamping lever (26) radially offset from the pivoting axis (32).
6. The hand tool (10) of any of the preceding claims, characterized in that the counter-contour (70) is provided on a lateral surface (33, 34) of the clamping lever (26).
7. The hand tool (10) of any of claims 2 to 5, characterized in that the impeding element (68) is disposed on the clamping lever (26), the counter-contour (70) on the housing (16).
8. The hand tool (10) of any of claims 2 to 5, characterized in that the impeding element (68) is disposed on the pivot axis (62).

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