EP2170562B1 - Tool holder for an electric tool, particularly for a chisel hammer and/or drill hammer - Google Patents

Description

State of the art

The invention relates to a tool holder, in particular for a chisel and / or rotary hammer, according to the preamble of the main claim. For holding and axial locking of drilling or chiselling tools in hitting power tools different tool holder are known.

Tool holders, such as those in DE 4405697 A1 or in DE 10 2005 015 100 A1 are described, have a tool holder for receiving a inserted through an insertion cylindrical shaft of an insertion tool. In the cylindrical peripheral surface of the shaft two diametrically opposed locking recesses are provided. Furthermore, the tool holder has a locking device, which comprises a locking element, a locking element and a return element.

The locking of the insert tool in the tool holder is done automatically when plugging. The locking element is in this case axially counteracted with a restoring force - usually realized by a prestressed return spring - acted upon return element in the direction of the housing of the power tool until it can escape radially behind the blocking element in a defined by the return element Ausweichraum. Upon further insertion of the insert tool, the locking element can then dip radially into one of the detent recesses provided in the shank of the insert tool and is pushed by the axially biased return element again in the axial direction below the blocking element.

By axially displacing the locking element of the rest position defined by the restoring force and a contact surface rest position, the locking element can dip radially out of the detent recess so that it can be removed from the tool holder by train on the insert tool.

The tool lock must ensure a secure holding of the insert tool in the tool holder in all operating conditions.

In particular, in the transition from the impact to the idle state of the power tool strong, on the tool axis defined by the tool axis in the direction of the power tool directed away, the application tool accelerating forces. This so-called jerky movement of the insert tool must be absorbed by the locking element and the movement stopped. The locking element is exposed to both axial and radial strong loads.

Due to the steadily increasing impact performance of power tools, the resulting increased loads on the locking element result in accelerated wear of components of the locking device - in particular of the locking element. Due to the shock-like load, the oscillatory locking device is also stimulated in addition to vibrations that adversely affect the load distribution. Out EP 1 958 734 A2 For this purpose, a tool holder according to the preamble of claim 1 is known. EP 1 958 734 A2 belongs to the state of the art under Article 54 (3) EPG.

Disclosure of the invention Advantages of the invention

A tool holder according to the main claim of the invention has a tool holder and a locking device with two locking elements, a locking element and a return element. The two locking elements increase in a structurally simple and cost-effective manner the safety of use and life of the locking device. The restoring element according to the invention exerts different forces on the locking elements when inserting the shank of the insert tool into the tool receptacle. It can thereby be achieved that despite the increased locking effect by the two locking elements when changing tools no increased force is applied by the operator.

The vibrations excited by the shock loads of the locking device propagate axially along the tool axis both in the shaft end direction and in the opposite direction. One around the Tool holder in the direction of the insertion opening arranged frontal damping element has an advantageous effect on the vibration and thus wear behavior of the locking device.

The measures listed in the dependent claims, advantageous refinements and improvements of the main claim features.

By a located on the inner circumferential surface of the locking element axial contact surface, the radial movement of the locking elements is effectively and simultaneously limited cost.

An axially displaceable return element allows an extended radial movement of the locking elements. As a result, a particularly robust unlocking of the locking device is realized for the insertion of the insert tool.

A preferred embodiment of the restoring element has an elastic element and a holding element. The elastic element generates a restoring force. While the retaining element forwards the restoring force to the locking element and the locking elements. By this construction, a particularly cost-effective production of the return element is achieved.

The elastic element can be executed in a particularly cost-effective manner as a spring.

A particularly advantageous embodiment of the elastic element results from the use of an elastic damping element. This alone or in combination with a spring, on the one hand, provide the restoring force necessary for locking and, on the other hand, act in a damping manner on the oscillations of the locking device induced by the impact-type operating loads.

By the aforementioned, the robustness of the locking of the insert tool enhancing features of the tool holder according to the invention greater locking forces are initially achieved. An inventive restoring element with a contact shoulder and an extended shoulder area ensures a high level of operating comfort when changing the insert tool. The contact shoulder is supported on the blocking element. Due to the restoring force of the restoring element, the blocking element is held in its axial position via the abutment shoulder. The extended shoulder region according to the invention creates two unequal alternative spaces for the Locking elements. In this alternative spaces the locking elements dive radially during insertion of the insert tool, wherein the unequal shape of the alternate spaces has a different force effect on the individual locking elements result. Thus, the force required during the insertion of the insert tool is limited in a simple and robust manner in the tool holder.

A cost-effective production and easy mountability of a restoring element can be achieved by an asymmetrically annular, in particular asymmetrically conical, shaping of the extended shoulder region. The asymmetrical shape defines the unequal alternative spaces for the locking elements.

An alternative embodiment of the extended shoulder region with two tongues allows a particularly cost-effective production. The tongues are inclined at different angles W1 and W2 to the tool axis defined by the insertion tool for this. As a result, two unequal alternative spaces for the locking elements are defined.

In both embodiments of the extended shoulder area performs the entire restoring element when inserting the insert tool, a movement axially and / or tilting relative to the surrounding, the locking device receiving elements of the tool holder. As a result, the locking device and the receiving elements are mechanically stressed and exposed to wear. An inventive restoring element in which the extended shoulder region has two tongues, which exert different elastic forces on the respective locking elements, limits the number of elements subjected to a relative movement in an effective and at the same time cost-effective manner.

Particularly advantageous in terms of vibration damping acts a combination of a frontal damping element and a damping element as an elastic element of the locking device.

Description of the drawings

• Fig. 1 einen Längsschnitt eines Werkzeughalters eines elektrischen Handmeißel- oder Handbohrhammers mit teilweise eingesetztem Werkzeug nach dem
• Oberbegriff des Anspruchs 1 Fig. 2 eine Längsschnittansicht einer erfindungsgemäßen Ausführung eines Werkzeughalters
• Fig. 3 eine Ausgestaltung des Halteelementes
• Fig. 4 eine alternative Ausgestaltung des Halteelementes.

The invention will be explained in more detail in two embodiments with reference to the accompanying drawings. Show it:

• Fig. 1 a longitudinal section of a tool holder of an electric hand chisel or hand drill with partially inserted tool after the
• Preamble of claim 1 Fig. 2 a longitudinal sectional view of an embodiment of a tool holder according to the invention
• Fig. 3 an embodiment of the retaining element
• Fig. 4 an alternative embodiment of the retaining element.

Description of the embodiments

Of the Fig. 1 illustrated tool holder (10) of a chisel and / or hammer drill according to the prior art is provided for receiving a cylindrical shank (12) of an insert tool (14). In this insert tool (14), the cylindrical shank (14) has in its peripheral surface two diametrically opposed latching recesses (16, 18).

The known tool holder (10) comprises an internally tubular tool holder (20), a protective cap (22) and an actuating element (24). The actuating element (24) is preferably designed as an actuating sleeve (26). The tool holder (20) serves to receive the cylindrical shaft (12) inserted through an end-side insertion opening (28) of the tool holder (10). In addition, the tool holder (10) has a locking device (30) for the cylindrical shaft (12) of the insert tool (14).

According to the invention, the locking device (30) comprises two locking elements (32, 34), a locking element (36) and a return element (38). In a preferred embodiment, the locking elements (32, 34) are designed as locking balls (32a, 34a), but other shapes such as e.g. in particular locking rollers or pins possible.

In the in Fig. 1 shown preferred embodiment of the tool holder (10) according to the invention, the return element (38) is executed, wherein one-, three- or multi-part designs of the reset element are conceivable. It comprises a holding element (40) and an elastic force generating the restoring force Element (42). In this case, the elastic element (42) is realized as a spring element (42a).

The holding element (30) according to the invention is characterized by an abutment shoulder (44) and an extended shoulder area (46). The extended shoulder region (46) forms, together with a radial contact surface (48) on the blocking element (36), two unequal escape spaces (50, 52). The two receiving legs (54, 56) of the extended shoulder region (46) are inclined at different angles of inclination W1 and W2 against the tool axis (58) defined by the insert tool (14).

The elastic element (42, 42a) is arranged in such a way that a restoring force (FR) separating the holding element (40) and the reference surface (59) is arranged between a reference surface (59) oriented toward the end-side insertion opening (28) and the holding element (40). generated. By this restoring force (FR), the abutment shoulder (44) of the holding element (40) against the radial contact surface (48) of the locking element (36) is pressed, whereby this is biased in its axial position with this restoring force (FR).

The tool holder (20) has at some distance from the front-side insertion opening (28) has two diametrically opposite locking recesses (60, 62). By means of these locking recesses (60, 62), one locking element (32, 34) can each be brought into engagement with a respective latching recess (16, 18) of the inserted cylindrical shank (12) of the inserting tool (14). The locking recesses (60, 62) are designed so that the locking elements (32, 34) can not pass completely through the tool holder (20).

In Fig. 1 are further from the front-side insertion opening (28) in the direction of the locking device (30) has two Entriegelungsausnehmungen (64, 66). These are bounded radially to the tool axis (58) through the tool holder (20) and away from the tool axis (58) by two guide surfaces (68). The guide surfaces (68) have a conical and a cylindrical portion in the form shown here. Of course, other shapes such as a hyperbolic shape of the guide surfaces (68) are possible. The axial limitation is achieved by two frontal boundary surfaces (70) in the direction of the end-side insertion opening (28) and by the locking elements (32, 34).

The locking elements (32, 34) are radially bounded by a blocking element (36) by means of two axial abutment surfaces (72). The blocking element (36) is arranged in the circumferential direction around the tool holder (20). With the help of the actuating element (24, 26), the blocking element (36) against the restoring force (FR) in relation to the tool holder (20) along the tool axis (58) axially displaceable away from the front-side insertion opening (28). Thereby, the two Entriegelungsausnehmungen (64, 66) in its axial position around the locking elements (32, 34) positioned so that they can dip radially out of the locking recesses (60, 62). By dipping the locking elements (32, 34), the insert tool (14) is unlocked.

When inserting the cylindrical shaft (12) of the insert tool (14) through the frontal insertion opening (28) in the tool holder (20), the locking elements (32, 34) initially blocked by the axial abutment surfaces (72) in their radial movement. As a result, the locking elements (32, 34) are pressed axially against the receiving legs (54, 56) of the widened shoulder region (46). Due to the steeper angle of inclination W1 of the receiving leg (54), first the first locking element (32) comes into contact with it. By further insertion of the insert tool (14), the holding element (40) is now displaced axially and tilted by the one-sided contact with the tool axis (58). As a result, the first escape space (50) for the radial replacement of the first locking element (32) is released. The first locking element (32) no longer acts blocking the insertion of the insertion tool (14). Since the opposite receiving leg (56) is not yet in contact with the associated second locking element (34), the contact shoulder (44) is pressed against the radial contact surface (48) by the restoring force (FR) on this side, and the blocking element (36 ) held in position.

If now by continued insertion of the insert tool (14) and the second locking element (34) pushed against the second receiving leg (56) with shallow angle of inclination W2 of the holding element (49) and this axially displaced, then this locking element (34) in the Immerse the second escape space (52). The blocking element (36) is now held in position via the dressing shoulder (44) on the side of the first locking element (32) and this locking element (32) with the axial restoring force (FR) of the elastic element (14).

Upon further insertion of the insert tool (14) finally, the locking elements (32, 34) radially to the tool axis (58) in the locking recesses (16, 18) of the cylindrical shaft (12) dive. The abutment shoulder (44) of the retaining element (40) is pushed back axially into the rest position by the restoring force (FR) of the elastic element (42, 42a) of the restoring element (38) in the direction of the frontal insertion opening (28). The now around the locking elements (32, 34) seated locking element (36) prevents by means of its axial abutment surfaces (72) a radial deflection of the locking elements (32, 34) and thus unlocking of the insert tool (14). The loads occurring during operation are thus distributed to two locking elements which act symmetrically about the tool axis (58).

In subsequent FIGS. 2 to 4 were the same elements / features of a tool holder (110) according to the invention with the same designations as in Example 1 occupied. Over the description of the embodiment 1 beyond elements / features obtained consecutive reference numbers. The reference numbers have been added with 100 for clarity each Fig.

Fig. 2 shows a preferred embodiment of a tool holder (110) according to the invention according to the type of the main claim. The elastic element (142) is arranged here as a prestressed damping element (142b) between the reference surface (159) and the retaining element (140). The damping element (142b) acts during the tool change as the restoring force (RF) generating elastic element (142) analogous to Embodiment 1. The during operation - especially when transitioning from working to idle state - occurring impulsive accelerations of the insert tool (114) in the locking device (130) induces along the tool axis (158), towards the in Fig. 2 not shown main part of the power tool to be propagated vibrations of the locking device (130). These vibrations are damped by the damping element (142b). As a result, induced relative movements of individual components of the tool holder (110) in particular of the locking device (130) are greatly reduced.

Possible extensions of in Fig. 2 realized elastic element (142) result, inter alia, combinations of one, two or more spring elements (142a) similar embodiment 1 and / or one, two or more damping element (142b).

The tool holder (110) according to the invention in FIG Fig. 2 is further characterized by a frontal damping element (174). This is arranged towards the front-side insertion opening (128), between the locking elements (132, 134) and the frontal boundary surfaces (170). During operation, the frontal damping element (174) acts similarly to the damping element (142b) described in the preceding paragraph to those portions of vibration that propagate along the tool axis (158) toward the insertion opening (128).

As is immediately obvious, both damping elements (142b, 174) can be used independently in tool holders according to the type of the main claim. The described embodiments represent only particularly clear forms of the claims claimed in the claims. Thus, inter alia, by a two-, three- or multi-part of / the damping elements (142b, 174) result in advantageous embodiments. Preferably, the damping elements are made of elastomers or elastic foams. Also advantageous developments are conceivable by combinations with spring elements (142a).

FIG. 3 shows a first embodiment of a holding element (240) with a contact shoulder (244) and an extended shoulder region (246). The extended shoulder region (246) is in this case designed as an asymmetrically conically shaped abutment formation (276). By appropriate assembly this Anlageanformung (276) forms the two receiving legs (254, 256), which identify the inclination angle W1 and W2 to the tool axis (258) by the asymmetric conical shape. When inserting the cylindrical shank (212) of the insert tool (214), the receiving limbs (254, 256) and the abutment shoulder (244) act as geometric holding and guiding elements on the locking elements (232, 234) as described in exemplary embodiments 1 and 2. or the blocking element (236).

The holding element (240) characterized in this way is obvious to the person skilled in the art by further features such as e.g. an element for confusion-free, oriented assembly or a broken and / or structured surface expandable.

FIG. 4 shows an alternative, second embodiment of a holding element (340), wherein the extended shoulder portion (346) by two to the tool axis inclined guide tongues (378, 380) is formed. With this fundamental Design arise two, in principle, different in their mode of action, individually or in combination usable variants of a holding element (340).

In a first embodiment, the guide tongues (378a, 380a) are formed by two different angles of inclination W1 and W2 to the tool axis (358).

The guide tongues (378a, 380a) act in this way as receiving legs (354, 356) of the extended shoulder region (346) of the holding element (340). The receiving legs (354, 356) thus realize an identical function of the holding element (340) as embodiment 1.

A second embodiment of a retaining element (340) in the manner of the second embodiment is characterized by different elastic properties of the two guide tongues (378b, 380b) inclined to the tool axis (358). Due to the different elastic properties, the guide tongues (378b, 380b) act on the locking elements (332, 334) in their function as receiving legs (354, 358) with different elastic forces. With such an expression, an abutment shoulder (344) which bears permanently on the blocking element (336) can be converted. Thereby, a relative movement and thus wear between the abutment shoulder (344) of the holding element (340), the blocking element (336) and other elements of the tool holder (310) is avoided.

Further developments of a retaining element (340) with at least two guide tongues (378, 380) are possible, in particular, by combining the features of the two variants described in the preceding sections.

The in the FIGS. 3 and 4 Embodiments shown for a holding element (40, 140, 240, 340) represent exemplary possibilities for an embodiment. Thus, in particular embodiments with non-closed eg by slits and / or recesses for the favorable developments of a holding element according to the invention (40, 140, 240, 340). Advantageous embodiments are also conceivable by shapes of the outer and / or inner contours deviating from the radial symmetry about the tool axis (58, 158, 258, 358), such as, for example, shapes having mainly four-, six- or octagonal or other regular or irregular polygonal contour lines.

Claims (8)

1. Tool holder (110) for an electric tool, in particular for a demolition and/or rotary hammer, having a tool receptacle (20) for receiving a cylindrical shank (112), introduced through a plug-in opening (28), of an application tool (114) which has in its circumferential surface at least two diametrically opposite latching depressions (16, 18), and having a locking device (30) having at least two locking elements (132), at least one blocking element (36) and at least one restoring element (38), wherein the locking elements (132, 134) can be brought into engagement with in each case one latching depression (16, 18) in the introduced cylindrical shank (112) of the application tool (114), and wherein the blocking element (36) limits a movement of the locking elements (132, 134), said movement being directed radially outwards from the tool axis (158) defined by the application tool (114), by way of an axial abutment surface (72) located on the inner lateral surface of the blocking element (36), characterized in that the restoring element (38) exerts in each case different forces on the different locking elements (32, 34) of the locking device (30) when the cylindrical shank (312) of the application tool (114) is inserted into the tool receptacle (20), and furthermore the axial movement of the locking elements (32, 34) is damped by at least one frontal damping element (74) arranged around the tool receptacle (20) in the direction of the plug-in opening (28).
2. Tool holder according to Claim 1, characterized in that the restoring element (38) is axially displaceable and when displaced axially allows an extended radial movement of the locking elements (32, 34).
3. Tool holder according to either of Claims 1 and 2, characterized in that the restoring element (38) is constructed from an elastic element (142) that produces the restoring force and from a holding element (40).
4. Tool holder according to Claim 3, characterized in that the elastic element (142) is at least one elastic damping element (142b) and acts between the holding element (40) and a reference surface (59) of the tool receptacle (20).
5. Tool holder according to one of the preceding claims, characterized in that the restoring element (38) has an abutment shoulder (44) for abutment against the blocking element (36) and an extended shoulder region (46) for creating two unequal yielding spaces (50, 52) for the locking elements (32, 34).
6. Tool holder according to Claim 4, characterized in that the extended shoulder region (46) is formed in an asymmetrically annular, in particular asymmetrically conical manner.
7. Tool holder according to Claim 4, characterized in that the extended shoulder region (46) is formed by at least two guide tongues (78, 80) which extend from the abutment shoulder (44) in the direction of a tool axis (58) defined by the application tool (14), at different angles W1 and W2 to the tool axis (58).
8. Tool holder according to Claim 4, characterized in that the extended shoulder region (46) is formed by at least two guide tongues (78, 80) which act with different elastic forces on the locking element (32, 34) assigned to them.

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